*
! "# $ % & #
"++
,-./..//0123,,11-4
)*+
1,(1,1567( (.,12(,/(,1.
8+9152:
8
Trends in Food Science & Technology
'()
" (! "# ( # $(* '()(
0.,123 1,(1,1567( (.,12(,/(,1.(
8 ")9 ; ; (
% (8
% %
; ; ("
%;
% 7 (
ACCEPTED MANUSCRIPT
Spent coffee grounds: A review on current research and future prospects
RI
PT
Rocio Campos-Vegaa*, Guadalupe Loarca-Piñaa, Haydé Vergara-Castañedac and B.
Dave Oomahb
a Programa en Alimentos del Centro de la República (PROPAC), Research and Graduate
Studies in Food Science, School of Chemistry, Universidad Autónoma de Querétaro,
Querétaro, Qro. 76010, Mexico
SC
b (Retired), Formerly with the National Bioproducts and Bioprocesses Program, Pacific
Agri-Food Research Centre, Agriculture and Agri-Food Canada, Summerland, BC, Canada
V0H 1Z0
M
AN
U
c Nucitec, S.A. de C.V. Comerciantes 15-3, Colonia Peñuelas, Querétaro, México.
* Corresponding author. Tel.: (55) 1921304. E-mail address: chio_cve@yahoo.com.mx (R.
Campos-Vega).
D
Abstract
Spent coffee ground (SCG) contains large amounts of organic compounds (i.e. fatty acids,
2
amino acids, polyphenols, minerals and polysaccharides) that justify its valorization. Earlier
3
innovation explored the extraction of specific components such as oil, flavor, terpenes, and
4
alcohols as value-added products. However, by-products of coffee fruit and bean
5
processing can also be considered as potential functional ingredients for the food industry.
6
There is an urgent need for practical and innovative ideas to use this low cost SCG and
7
exploit its full potential increasing the overall sustainability of the coffee agro-industry.
8
Keywords: Spent coffee; macronutrients; functional compounds; proteins; phenolics;
9
lipids; minerals; non-protein nitrogeneous compounds; applications.
AC
C
EP
TE
1
1
Abbreviations
11
SCG
Spent coffee grounds
12
MOS
Mannooligosaccharides
13
AAA
Aromatic amino acids
14
MAE
Microwave assisted extraction
15
FOSHU
Food for Specified Health Uses
16
DF
Dietary fiber
17
AACC
American Association of Cereal Chemists
18
BCAA
Branched chain amino acids
19
SFE
Supercritical fluid extraction
20
HMW
High molecular weight
21
HMWM
High molecular weight melanoidins
22
COM
Cost of manufacturing
23
scCO2
Supercritical carbon dioxide
24
CGA
Chlorogenic acid
25
CQA
26
GAE
27
PHB
AC
C
EP
TE
D
M
AN
U
SC
10
RI
PT
ACCEPTED MANUSCRIPT
Caffeoylquinic acids
Gallic acid equivalents
Poly 3-hydroxybutyrate
2
ACCEPTED MANUSCRIPT
1. Introduction
Coffee, grown in about 80 countries, is one of the world’s most popular beverage and
29
second largest traded commodity after petroleum (Murthy & Naidu, 2012a). Global green
30
coffee production increased by almost 17%, probably due to increased yield (24%),
31
between 2000 and 2012. Several residues are obtained during coffee processing. Coffee
32
producing countries generate residues from the coffee fruit amounting to >50% of the fruit
33
mass (Tsai, Liu, & Hsieh, 2012). Spent coffee ground (SCG) is the residue obtained during
34
the brewing process (Cruz et al., 2012). The huge amount of residue generated annually in
35
the production of soluble coffee requires waste management plan consistent with existing
36
national regulations. For example, Nestlé, the world’s biggest food company pledges to
37
reduce waste in Europe by 2020 using spent coffee grounds as a source of renewable
38
energy in more than 20 Nescafé factories. In most of the soluble coffee producing
39
industries, the waste is collected by specialized agencies, which sell the residues for
40
different purposes (i.e. composting, gardening, bioenergy production, mushroom growth).
41
Spent coffee grounds (SCG) contain large amounts of organic compounds (i.e. fatty acids,
42
lignin, cellulose, hemicellulose, and other polysaccharides) that can be exploited as a
43
source of value-added products. Thus, coffee residue has been investigated for biodiesel
44
production (Caetano, Silva, & Mata, 2012), as source of sugars (Mussatto, Carneiro, Silva,
45
Roberto, & Teixeira, 2011a), precursor for activated carbon production (Kante, Nieto-
46
Delgado, Rangel-Mendez, & Bandosz, 2012), compost (Preethu, BhanuPrakash,
47
Srinivasamurthy, & Vasanthi, 2007), and as sorbent for metal ions removal (Fiol, Escudero,
48
& Villaescusa, 2008).
EP
TE
D
M
AN
U
SC
RI
PT
28
By-products of coffee fruit (Figure 1) and bean processing can also be considered as
50
potential functional ingredients for the food industry. The coffee husks, peel and pulp,
51
comprising nearly 45% of the cherry, are the main by-products of coffee agro-industry and
52
can be a valuable material for several purposes, including caffeine and polyphenols
53
extraction. Coffee husks and skins are traded as crops and livestock products with export
54
and import range of 857 – 27,209 and 490 – 11,474 tonnes from 2000 to 2012 according to
55
FAO Statistics. These export and import were valued at 2.2 – 62.7 and 1.7 – 24.3 million
56
US$, respectively for the same period. Other by-products of coffee processing such as
AC
C
49
3
ACCEPTED MANUSCRIPT
mucilage and parchment have been less studied; however, they are potential sources of
58
important ingredients. The pulp is easily fermented by yeast or metabolized by lactic acid
59
bacteria producing alcoholic beverages and vinegars. Furthermore, roasted coffee silverskin
60
has been evaluated for use as a dietary fiber rich ingredient with antioxidant properties.
61
Finally, SCG have been studied mainly for their antioxidant activities (Esquivel & Jiménez,
62
2012). These antioxidants have been associated with health benefits (Campos-Vega et al.,
63
2009; Vergara-Castañeda, Oomah, & Campos-Vega, 2013; Campos-Vega, Oomah, Loarca-
64
Piña, & Vergara-Castañeda, 2013).
SC
RI
PT
57
Spent coffee ground was rarely investigated until the beginning of this decade with half
66
(36 out of 72) of the total number of papers published in the last 4 years since 1973. A
67
cursory search of ‘spent coffee ground’ on “Scopus” produces similar result with 11, 27,
68
14, 15 and 2 publications annualy from 2014 to 2010. This review aims to use existing
69
knowledge on spent coffee ground and/or its components in developing a biorefinery
70
platform to add value to this inexpensive waste product.
D
M
AN
U
65
2. Carbohydrates
The coffee bean is a rich source of polysaccharides (~ 50% of the green bean’s dry weight)
74
mainly consisting of mannans or galactomannans, type II arabinogalactans, and cellulose.
75
Mannan, the main polysaccharide of coffee extract, is responsible for its high viscosity,
76
which in turn negatively affects the technological processes involved in instant coffee
77
production. This polysaccharide consists of ș-(1Ѝ4)-linked mannan chains substituted at
78
approximately every 100 residues in the O-6 position with single galactose residues.
79
Arabinogalactans have an arabinose/galactose ratio of 0.4/1 and consist of ș-(1Ѝ3)-linked
80
galactose backbone substituted at the O-6 position with arabinose and/or galactose residues.
81
The side-chains contain arabinose and galactose residues with arabinose as terminal
82
residue. These linkages are characteristic of type-II arabinogalactans, a polymer usually
83
covalently linked to protein (Bradbury & Halliday, 1990). The roasting process increases
84
both bean arabinogalactan and mannan solubility by loosening the cell-wall structure as it
AC
C
EP
TE
71
72
73
4
ACCEPTED MANUSCRIPT
swells and by polysaccharide depolymerization (Wei, Furihata, Koda, Hu, Miyakawa, &
86
Tanokura, 2012). The water-soluble polysaccharides that appear after roasting play an
87
important role in retaining volatile substances, and contribute to the coffee brew viscosity
88
and, thus, to the creamy sensation known as “body” in the mouth (Illy, Viana, & Roasting,
89
1995).
90
These galactomannans and arabinogalactans are extracted upon coffee roasting, during the
91
beverage preparation, using hot pressurized water (Nunes & Coimbra, 2001). However,
92
most of these polysaccharides remain as insoluble material bound to the SCG matrix
93
(Mussatto, Carneiro, Silva, Roberto, & Teixeira, 2011a; Simões, Nunes, Domingues, &
94
Coimbra, 2013). Galactomannans exhibit different physicochemical properties and are
95
therefore used in many applications: they are excellent stiffeners and emulsion stabilizers,
96
and the absence of toxicity allows their use in the textile, pharmaceutical, biomedical,
97
cosmetics and food industries. The main applications of galactomannans in food are in
98
dairy products, fruit-based water gels, powdered products, bakery, dietary products, coffee
99
whiteners, baby milk formulations, seasonings, sauces and soups, tinned meats and frozen
M
AN
U
SC
RI
PT
85
and cured meat foods (Prajapati et al., 2013).
101
Spent coffee ground is rich in sugars polymerized into cellulose and hemicellulose
102
structures, which correspond to almost half (45.3%, w/w, dry weight) of the material. SCG
103
contains 46.8% mannose, 30.4% galactose, 19% glucose, and 3.8% arabinose, with
104
mannans as the major polysaccharides (Mussatto, Carneiro, Silva, Roberto, & Teixeira,
105
2011a). However, further investigation by the same group (Mussatto, Machado, Carneiro,
106
& Teixeira 2012) revealed a lower (2.2-fold) sugar composition for the same SCG
107
consisting of 21.2% mannose, 13.8% galactose, 8.6% glucose, and 1.7% arabinose. This
108
SCG can be hydrolyzed (100 mg H2SO4/g dry matter; liquid/solid ratio 10 g/g; 163 °C, 45
109
min), and efficiently (> 85%) fermented to ethanol by yeast (Mussatto, Machado, Carneiro,
110
& Teixeira, 2012). Simões et al., (2009) reported the presence of mannose (57%), followed
111
by galactose (26%), glucose (11%), and arabinose (6%); the differences in chemical
112
composition of SCG probably reflect the variety of beans and processes used in roasting
113
and extraction. Earlier study (Stahl, Bayha & Fulger, 1984) showed that mannan, more
114
prevalent than cellulose in SCG, is substantially separately hydrolyzable from the cellulose
AC
C
EP
TE
D
100
5
ACCEPTED MANUSCRIPT
115
enabling production of pure mannan hydrolysate. This hydrolysate produces high (40%)
116
mannitol yield with sorbitol as a co-product.
Mannooligosaccharides (MOS), non-digestible oligosaccharides composed principally
118
of mannose, has also been derived by hydrolyzing mannan in spent coffee grounds at high
119
temperature (220 °C) and pressure (Asano et al., 2001). The major components of manno-
120
oligosaccharides were mannobiose, mannotriose, and mannotetraose. Studies in Japan
121
(Takao et al., 2006 and references therein) showed that MOS could promote bifidobacteria
122
growth in the intestines and improve the fecal characteristic on human subjects.
123
Furthermore, a daily intake of a 300 ml drink containing MOS (1 or 2 g/100 ml) reduced
124
abdominal and subcutaneous fat level in humans when administered daily for twelve
125
weeks. Further studies showed that MOS inhibited intestinal fat absorption from a high fat
126
diet by decreasing fat accumulation in the parametrial adipose tissue and liver, while
127
simultaneously increasing fat excretion. MOS derived from coffee mannan has been
128
developed as active prebiotic ingredient in Japan (Aginomoto Co. Inc.) and approved as
129
Food for Specified Health Uses (FOSHU) oligosaccharide functional food ingredient
130
(Fukami, 2010).
M
AN
U
SC
RI
PT
117
Espresso (dark roasted Arabica) SCG consisted mainly of mannose (46%), galactose
132
(27%), glucose (20%), and arabinose (7%) with galactomannans as the major
133
polysaccharide accounting for approximately 50% the total carbohydrates (Simões, Nunes,
134
Domingues, & Coimbra, 2013). Roasting SCG (160 °C) improves the extractability of
135
galactomannans (total 56%) without degradation, preserving their β-(1-4)-Man backbone,
136
Gal and Ara side chains, and acetylation. Microwave assisted extraction (MAE) allows the
137
recovery of arabinogalactans, while a re-extraction of the residual material (MAE2) enables
138
higher galactomannan yield. Through this method 74% and 66% of total galactose and
139
mannose could be extracted from SCG (Passos & Coimbra, 2013).
TE
EP
AC
C
140
D
131
141
The carbohydrate composition of exhausted coffee waste is reduced to only two
142
monomers: glucose (59.2 and 62.9% of total sugars) and mannose (40.8 and 37.1%) by
143
alkali extraction (Pujol et al., 2013). However, the hemicelluloses reported by these authors
144
contrast with previous studies (Mussatto, Ballesteros, Martins, & Teixeira, 2011; Simões et
145
al., 2009) indicating the presence of galactose and arabinose in SCG. These two
6
ACCEPTED MANUSCRIPT
146
monosaccharides are probably easily hydrolyzed during alkali extraction.
SCG are primarily composed of neutral detergent fiber (45.2%) occurring as
148
hemicellulose, cellulose, and lignin-associated compound, and acid detergent fiber (29.8%),
149
consisting of cellulose and lignin (Vardon et al., 2013). The isolation of dietary fiber (DF)
150
from plant by-products can be accompanied by the recovery of other constituents like
151
antioxidants or proteins; SCG, for example contains 43% total fiber (35% and 8% soluble
152
and insoluble, respectively) (Murthy & Naidu, 2012b). Furthermore, the coffee fibers from
153
SCG exhibit antioxidant properties: 2.4 mmol of trolox/100 g of dry weight (Murthy &
154
Naidu, 2012b) similar to well-known food antioxidant such as red wine products (43%) and
155
peaches (36%). Therefore, DF from SCG can be categorized as antioxidant dietary fiber,
156
useful as potential dietary supplement.
M
AN
U
3. Proteins
SC
RI
PT
147
SCG contain significant amount of proteins (13.6%, w/w). Total coffee nitrogen
160
compounds are relatively stable between species or even during roasting, ranging from 8.5
161
to 13.6% (Belitz, Grosch, Schieberte, 2004). Crude protein reported by Cruz et al., (2012)
162
in espresso coffee residues vary between 12.8 and 16.9%. The mean protein content of
163
SCG is 13.6% after soluble coffee preparation (Mussatto, Ballesteros, Martins, & Teixeira,
164
2011a; Silva, Nebra, Machado Silva, & Sanchez, 1998),
EP
TE
D
157
158
159
According to Arya & Rao (2007), roasted coffee contains on average 3.1% (w/w)
166
protein. The protein content in SCG is higher than in the coffee bean due to concentration
167
of the non-extracted components during instant coffee preparation. The protein content in
168
SCG may be overestimated due to the presence of other nitrogen-containing substances
169
(caffeine, trigonelline, free amines and amino acids) (Delgado, Vignoli, Siika-aho, &
170
Franco, 2008). However, many authors report similar protein contents, varying between
171
6.7% and 9.9% (Lago, Antoniassi, & Freitas, 2001) and up to 14% (Ravindranath, Khan,
172
Obi Reddy, ThirumalaRao, & Reddy, 1972).
AC
C
165
7
ACCEPTED MANUSCRIPT
Data on amino acids content is limited to a single report (Lago, Antoniassi, & Freitas,
174
2001) of SCG collected from three instant coffee producers using four different extractors.
175
SCG protein has similar or higher levels of the essential amino acids leucine, valine,
176
phenylalanine, and isoleucine than conventional feed products such as soybean meal (Table
177
1). Isoleucine, leucine and valine contents of SCG are over twice the levels in soybean
178
meal. Lysine content is low in SCG, although it is as high in coffee pulp and 11S protein as
179
in soybean meal (on a per gram nitrogen basis) (Elias, 1979). The essential amino acids
180
comprise almost half (~ 49%) of the total SCG amino acid mainly leucine contributing 13
181
or 21% of the total content. Most SCG amino acid contents, except arginine, aspartic acid,
182
lysine, phenylalanine, serine and threonine are considerably higher than those in coffee
183
pulp and/or 11S protein. The 11S protein, similar to other plant storage proteins, accounts
184
for approximately 45% of total proteins in coffee endosperm tissue, representing 5-7% of
185
coffee dry bean weight (estimated on 11-15% protein). This storage protein consists of a
186
high (α-component, ~32 kDa) and a low (β-component, ~22 kDa) molecular subunit easily
187
recognized on two-dimensional profiles of green coffee proteins (Rogers, Bézard,
188
Deshayes, Meyer, Pétiard, & Marraccini, 1999). The low level of the hydroxyl-amino acids
189
serine and threonine in SCG relative to those in coffee pulp and/or 11S protein reflects their
190
reactivity during the brewing process producing volatile heterocyclic compounds,
191
alkylpyrazines (Oestreich-Janzen, 2010).
TE
D
M
AN
U
SC
RI
PT
173
SCG protein is high in the essential branched chain amino acids (BCAA) and Fischer
193
ratio, higher than those of soymeal or soybean protein (Table 1). Some SCG protein with
194
low (< 1%) aromatic amino acid content has high Fischer ratio similar to those generally
195
derived by hydrolysis and extensive purification process. Proteins with high BCAA,
196
Fischer ratio and low content of aromatic amino acids are sought for producing
197
physiologically functional foods for specific needs, such as in patients with malnutrition
198
associated with cancers, burns, trauma, and liver failure, and for nutritional support of
199
children with chronic or acute diarrhoe or milk protein allergies (Oomah, 2001 and
200
references therein). Protein with Fischer ratio higher than 20 and aromatic amino acids
201
(AAA) lower than 2% have been used to treat patients with hepatic encephalopathy
202
(Udenigwe & Aluko, 2010); thus the SCG protein could be used to formulate food products
203
with multiple human health benefits during liver diseases, oxidative stress and
AC
C
EP
192
8
ACCEPTED MANUSCRIPT
204
hypertension. The lysine/arginine ratio, a determinant of the cholesterolaemic and
205
atherogenic effects of a protein, is high for SCG protein, suggesting that it can contribute to
206
hypercholesterolemic and atherogenic physiological effects.
207
excellent source of arginine, glutamine and histidine, the three amino acids known to have
208
strong effects on the immune functions of the body. The high cysteine and methionine
209
content of some SCG protein can boost the body’s antioxidant levels, potentially stabilizing
210
DNA during cell division and reducing the risk of certain forms of colon cancer. The
211
essential amino index of SCG is high (79-129%) relative to soybean protein and higher than
212
those of soymeal (Table 1) due primarily to the contribution of leucine and isoleucine.
SC
RI
PT
SCG protein is also an
Early studies (Silva et al., 1998 and references therein) showed that coffee grounds have
214
low nitrogen content (~ 2%), high acidity (~ 4.2 pH) containing only half of the essential
215
amino acids required for animal feed. In vivo evaluation of SCG in sheep showed negative
216
metabolisable energy contents (-1.5 & -1.1 MJ/kg dry matter), based primarily on the
217
negative crude protein digestibility (-0.53 & -0.92) despite the high gross-energy content
218
(Givens & Barber, 1986). However, the high non-protein nitrogen (~46% of the total
219
nitrogen) present in SCG (Sikka, Bakshi, & Ichhponani, 1985) may partly explain its low
220
biological effect observed in several animal feeding studies. SCG (12.55% protein) at 10%
221
of an isonitrogenous concentrate mixture has been safely incorporated in fattening pig
222
ration without adverse health effects on carcass quality (Sikka & Chawla, 1986). However,
223
15% SCG significantly depressed daily live weight gains and feed conversion efficiency.
224
Feed conversion ratios were 6.88, 6.95, and 8.10 for control (conventional feed ingredient
225
formulation), 10% and 15% SCG rations, respectively. The poor feedlot performance of the
226
pigs was attributed to the higher fiber content (14.8, 16.7, and 19.1% for control, 10%, and
227
15% SCG, respectively), thereby reducing the digestion of energy-yielding nutrients. SCG
228
has low nitrogen solubility (28.6%) primarily due to protein denaturation and low pepsin
229
digestibility (35.3%) resulting from intramolecular linkage formation during coffee bean
230
roasting (200 °C, 20 min), limiting enzyme hydrolysis (Sikka, Bakshi, & Ichhponani,
231
1985).
232
233
AC
C
EP
TE
D
M
AN
U
213
4. Non-protein nitrogeneous compounds
9
ACCEPTED MANUSCRIPT
Nitrogenous compounds (free amino acids, peptides, alkaloids) contribute considerably to
235
the development of coffee flavor and quality during roasting. The protein profile of coffee
236
changes during roasting, the proteins are both fragmented and polymerized, and integrated
237
into melanoidins. Other protein components such as peptides and free amino acids
238
constitute up to 1.5% of green coffee, whereas alkaloids (3-4%), of which trigonelline
239
represents about 1%, are transformed during roasting (Oestreich-Janzen, 2010). According
240
to Oestreich-Janzen (2010), total amino acid content of Arabica roast and brew amount to
241
10.1 and 6.4% dry weight, respectively, suggesting that 3.7% dry weight of amino acids
242
can be found in SCG.
243
The content of non-protein nitrogenous compounds in SCG could be useful in agriculture.
244
Compost and reclamation substrates from SCG can be used for intensive remediation,
245
positively affecting microbial activity and reducing leaching of mineral nitrogen (Nmin)
246
from the arable soil (Elbl et al., 2014). Compost available carbon increases microbial
247
activity, resulting in increased capacity for mineral nitrogen retention (additionally supplied
248
from compost and another mineral fertilizer). Nmin is captured in soil organic matter (Diaz,
249
Bertoldi, & Bidlingmaier, 2007). In this regards, SCG, after oil extraction, has a
250
carbon/nitrogen ratio of 19.8:1 (wt) (Kondamudi et al., 2008), similar to soil needs (20:1)
251
(Elbl et al., 2014). Despite this, the use of SCG is limited to gardens as compost for the
252
plants. Recently, the positive soil amendment impact of SCG has been confirmed in
253
enhancing the physical and nutritional features of lettuce, endorsing its potential use in
254
agroindustry (Cruz et al., 2014).
EP
TE
D
M
AN
U
SC
RI
PT
234
255
256
257
Caffeine, 1,3,7-trimethyl-xanthine, a purine alkaloid, is the quintessential single most
258
popular compound recognized in coffee and coffee products/ingredients. This alkaloid is
259
removed from coffee beans by the decaffeinating process commonly used in the industrial
260
scale. Although the caffeine content in coffee waste is lower than that in coffee beans, a
261
large amount of caffeine still remains. Higher caffeine can be extracted from coffee husks
262
(Tello, Viguera, & Calvo, 2011) or coffee pulp (Murty& Naidu, 2012) than from SCG.
263
Caffeine concentrations range from 0.734 to 41.3 µg/mg of spent coffee ground extracts,
AC
C
4.1. Caffeine
10
ACCEPTED MANUSCRIPT
obtained by low-pressure extraction (ultrasound and Soxhlet) and supercritical fluid CO2
265
extraction (SFE) varying in yield from 9 to 15% (Table 2) (Andrade et al., 2012). The
266
polar solvent, dichloromethane extracts the most caffeine at low pressure, whereas SFE at
267
high pressure (300 bars) is more efficient, both in terms of generating higher caffeine yield
268
and environmental footprint. Caffeine obtained from SCG is equivalent to 18 – 48% of
269
those extracted from coffee beans by supercritical CO2 (Saldaña, Mohamed, Baer, &
270
Mazzafera, 1999) or 8-31% of roasted coffee (Ramalakshmi, Rao, Takano-Ishikawa, &
271
Goto, 2009). Supercritical CO2 has long been used to decaffeinate coffee beans and
272
therefore can be integrated in processing SCG. Various caffeine concentrations (0.007 –
273
0.5%) have been reported depending on extraction process and SCG source (Andrade et al.,
274
2012; Cruz et al., 2012; Murty & Naidu, 2012; Ramalakshmi, Rao, Takano-Ishikawa, &
275
Goto, 2009). Thus, caffeine content for Arabica range between 0.9 to 1.6%, Robusta (1.4-
276
2.9%), mix (60 Arabic/40 Robusta) (1.7%). In espresso-style percolation, the very short
277
time available to extract caffeine from the cellular structure leads to 75 – 85% extraction
278
yield with only15-25% caffeine left in the SCG (Oestreich-Janzen, 2010).
M
AN
U
SC
RI
PT
264
Spent coffee extracts of both Arabica (0.5%) and Robusta (0.2%) contain lower caffeine
280
than low-grade green coffee beans (1.7%) (Ramalakshmi, Rao, Takano-Ishikawa, & Goto,
281
2009). However, high caffeine (6 – 11.5 mg/g dry matter) were detected in the extracts of
282
SCG from coffee bars; the higher amount observed in SCG from Robusta was nearly twice
283
that from Arabica (Panusa, Zuorro, Lavecchia, Marrosu, & Petrucci, 2013). Caffeine was
284
low in SCG extracts from capsules (obtained from an automatic espresso machine),
285
(0.96−0.97 mg/g dry sample) (Panusa, Zuorro, Lavecchia, Marrosu, & Petrucci, 2013). In
286
this regard, caffeine content ranged from 1.94 to 7.88 mg/g (DW), with a mean of 4.53
287
mg/g (DW) in espresso coffee (Cruz et al., 2012). The caffeine extractability coefficient in
288
espresso coffee is 75−85%, so these figures correspond to predicted mean caffeine content
289
of 22.5 mg/g (DW) in the original roasted beans, in accordance with the literature (Bicho,
290
Leitão, Ramalho, & Lidon 2011; Casal, Oliveira, Alves, & Ferreira, 2000).
AC
C
EP
TE
D
279
291
Caffeine (1.8 mg/g SCG) present in SCG prepared from espresso coffee may serve as a
292
chemical defence mechanism in some plants, while adversely inducing toxicity in other
293
plants such as lettuce (Cruz et al., 2012). Caffeine in SCG is completely degraded by
294
Pleutotusostreatus LPB 09 fungal cultures enabling economical utilization of SCG as
11
ACCEPTED MANUSCRIPT
substrates for edible fungi/mushroom cultivation without any pretreatments (Fan, Pandey,
296
Mohan, & Soccol, 2000). This observation has been used in the development of a patent
297
application where mycelium is used in reducing coffee bitterness. Caffeine presence as a
298
nitrogen precursor plays an important catalytic role in hydrogen sulphide oxidation in the
299
preparation of activated carbon from SCG (Kante, Nieto-Delgado, Rangel-Mendez, &
300
Bandosz, 2012). It also contributes significantly in lowering/reducing interfacial tension
301
equilibrium in oils, important in defining the emollient characteristics of pharmaceutical
302
and/or cosmetic products.
SC
RI
PT
295
303
304
305
The nitrogenous brown-colored compounds of coffee result from the non-enzymatic
306
browning (Maillard) reaction between reducing sugars and compounds with a free amino
307
group forming various products including the melanoidins (Moreira, Nunes, Domingues, &
308
Coimbra, 2012). Maillard reaction products may be useful for functional food application
309
and/or as food preservative, since they exhibit antioxidant capacity and inhibit lipid
310
peroxidation (Jung, Park, Ahn, & Je, 2014). Melanoidins are the high molecular weight
311
(HMW) brown products containing nitrogen, end products of the Maillard reaction (Nunes,
312
Cruz, & Coimbra, 2012) with small amounts (< 6%) of amino acids, primarily glutamic
313
acid and glycine released by acid hydrolysis. During coffee brewing, only 33% of the
314
original green coffee bean protein is extracted with hot water, the residual protein remains
315
insoluble due partly to denaturation and association with cell wall arabinogalactans
316
representing nearly 92% of the total nitrogen present in the high molecular weight
317
melanoidins (HMWM) (Nunes, Cruz, & Coimbra, 2012). Ethanol (70-80%)-soluble
318
HMWM has the highest protein content, but amino acid composition similar to all
319
melanoidin fractions. The amino acid composition of these melanoidin fractions (abundant
320
in alanine, aspartic acid/asparagine, glutamic acid/glutamine, and glycine) is similar to
321
those reported for roasted coffee beans and roasted coffee brews.
AC
C
EP
TE
D
M
AN
U
4.2. Brown-colored compounds
322
Browning index of SC extracts from Arabica (0.165) and Robusta (0.145) coffee from
323
filter coffeemaker was 3-5-fold higher than those obtained from espresso and plunger
324
coffeemakers (Bravo et al., 2012). Aqueous extracts from soluble SCG has lower browning
12
ACCEPTED MANUSCRIPT
325
index (0.271) compared to that from roasted coffee brews (0.305) (Yen, Wang, Chang, &
326
Duh, 2005).
327
extraction of brown compounds measured by absorbance at 420 nm (from 0.090 to 0.160)
328
(Bravo, Monente, Juániz, De Peña, & Cid, 2013). Passos & Coimbra (2013) suggested that
329
SCG consists of 16% melanoidins, whose chemical composition has not yet been
330
established (Nunes & Coimbra, 2010).
RI
PT
Furthermore, a solid–liquid method has been proposed as an efficient
331
5. Lipids
Spent coffee grounds have often been reported to contain 10 – 15 % (Jenkins, Stageman,
335
Fortune, & Chuck, 2014), and sometimes higher average 20% (range 19.9-27.8%) lipids
336
(Lago, Antoniassi & Freitas, 2001) or 13.9 – 29.2% ether extract, on dry weight basis
337
(Silva, Nebra, Machado Silva, & Sanchez, 1998). During the brewing process, lipids stick
338
to the spent grounds and are filtered off, in filter home brew as well as in instant coffee
339
production (Oestreich-Janzen, 2010). Lipid yield (7 – 13% dry weight) is low when SCG
340
suspended in fresh heptane (1:10 weight ratio) is stirred (3 h) at room temperature (Jenkins,
341
Stageman, Fortune, & Chuck, 2014). SCG extracted with hexane yield high oil (15.3%),
342
with low acid (3.65%) and saponification (173) values, parameters important for fatty acid
343
methyl ester (FAME) manufacturing (Al-Hamamre, Foerster, Hartmann, Kröger, &
344
Kaltschmitt, 2012). Commercial ethanol (99%) has been used to recover lipids from
345
industrial spent coffee grounds containing 25.6% oil (dry weight petroleum ether
346
extraction). Maximum oil yield (82%) was obtained at 1:7 SCG: alcohol ratio, 75 °C and
347
not affected by extraction time (1 or 2 h) and pretreatment (milling or extrusion). The
348
extracted oil had characteristics similar to petroleum ether extract (Freitas, Monteiro, &
349
Lago, 2000).
AC
C
EP
TE
D
M
AN
U
SC
332
333
334
350
SCG total lipids range from 9.3 to 16.2% (Cruz et al., 2012), 10-15% and 14-15.4%
351
from espresso coffee residues, filter and industrial soluble coffee, respectively (Kondamudi,
352
Mohapatra, & Misra, 2008; Couto, Fernandes, da Silva, & Simões, 2009; Calixto et al.,
353
2011). Also, the yield of SCG oil extracted using Soxhlet, is a function of extraction
354
conditions, particularly, the choice of solvent and the duration of extraction. Supercritical
13
ACCEPTED MANUSCRIPT
carbon dioxide extracts up to 85% of the total amount of SCG oil after 3 h (corresponding
356
to a maximum yield of 15.4 goil/100 gdry SC) (Couto, Fernandes, da Silva, & Simões, 2009).
357
Although hexane is the most widely and commonly used solvent, modern environmentally
358
friendly technology such as SFE is increasingly being used for SCG oil extraction. A
359
manufacturing cost of US$ 48.60/kg has been estimated for spent coffee oil obtained by
360
supercritical technology (200 bar, 50 °C, 90 min) and may reach US$ 460/kg depending on
361
process conditions (Andrade & Ferreira, 2013).
RI
PT
355
Commercial SCG contains higher oil (16.7 & 17.2%) compared to raw (9-12.6%),
363
roasted (12-15%), or laboratory extracted SCG (7.9-14%); free fatty acids (120-148 vs 4-10
364
acid value), and lower unsaponifiable matter (5.9-9.4% vs 9-13.2%) relative to those
365
produced in the laboratory (Ravindranath, Khan, Obi Reddy, ThirumalaRao, & Reddy,
366
1972). Coffee brews prepared by different methods showed that lipids (90.2%) mainly
367
remained in SCG with the following lipid composition (% total lipids), 84.4%
368
triacylglycerols, 12.3% diterpene alcohol esters, 1.9% sterols, 1.3% polar material, and
369
0.1% sterol esters. The lipid composition is similar to those of boiled or filtered coffee with
370
87-93% triglycerides, 7-13% diterpene alcohol esters, 0.2-0.9% sterols, and up to 0.8%
371
polar material (Ratnayake, Hollywood, O'Grady, & Stavric, 1993). However, the lipid
372
composition of SCG may vary analogous to those of green coffee oil depending on the
373
source, although generally up to 80 – 90% of the oil will be glycerides, including free fatty
374
acids, with the rest of the lipids containing terpenes, sterols and tocopherols (Jenkins,
375
Stageman, Fortune, & Chuck, 2014). Raw green coffee oil consists of: triacylglycerols
376
(75%), terpene esters (14%), partial acylglycerols (5%), free fatty acids (1%), free sterols
377
(1.5%), sterol esters (1%), and polar lipids (<1%) (Nikolova-Damyanova et al., 1998, cited
378
in De Azevedo et al., 2008). Khan & Brown (1953) provide a good review on earlier
379
investigation on raw and roasted coffee bean oil characteristics and composition. Coffee oil
380
contains excessive amounts of unusual unsaponifiables, 19% (or 24% for defective coffee
381
beans) according to Oliveira et al., (2008), the presence of which makes the oil unfit for
382
most uses. However, the unsaponifiables containing the diterpenes kahweol and cafestol
383
known for their beneficial physiological effects (UVB skin protection, anticarcinogenic,
384
anti-inflammatory and antioxidant activities) (Silva, Vieira, & Hubinger, 2014) can be
385
completely removed by molecular distillation.
AC
C
EP
TE
D
M
AN
U
SC
362
14
ACCEPTED MANUSCRIPT
SCG oils consist predominantly of linoleic, palmitic, stearic and oleic acids (Table 3).
387
Arachidic (≤ 7%) and linolenic (< 5%) acids are also present in most SCG oils, whereas
388
lauric and myristic acids are rarely detected depending on extraction conditions, processing
389
and origin. The contrasting fatty acid profile exemplifies the effects between two processes
390
used in obtaining SCG oil (Todaka, Kowhakul, Masamoto, Shigematsu, & Onwona-
391
Agyeman, 2013). SCG oils can be conveniently categorized into two clusters based on their
392
fatty acid profile; those with low palmitic (< 40%) and high linoleic (> 40%) acids and
393
conversely those with high palmitic (> 40%) and low linoleic (< 40%) acids (Table 3).
394
These clusters result in polyunsaturated/saturated ratios < 1 or >1 of the extracted oils. SCG
395
oils with polyunsaturated/saturated ratio > 1 are less atherogenic and thrombogenic than
396
those with ratio <1 due to the potential favorable reduction of serum cholesterol and
397
atherosclerosis and prevention of heart diseases (Rudel, Parks, & Sawyer, 1995). The
398
cholesterol-raising factor from coffee beans has been attributed to the presence and/or
399
concentration of the diterpenes kahweol and cafestol that varies depending on several
400
factors (Urgert, Schulz, & Katan, 1995) including the oil extraction process (Acevedo et al.,
401
2013).
M
AN
U
SC
RI
PT
386
D
402
High palmitic acid SCG oils represent a rich and suitable source of palmitic acid for
404
soap manufacture and/or the acid itself according to Ravindranath, Khan, Obi Reddy,
405
ThirumalaRao, & Reddy (1972). Furthermore, the combination of high linoleic (~44%),
406
palmitic (~36%) and oleic (~9%) acids, predominant in SCG oils can result in high biomass
407
and polyhydroxylalkanoates (PHA)-an alternative completely biodegradable synthetic
408
polymer- yields (Obruca et al., 2014). Fatty acid compositions of SCG oils differ
409
significantly under different SFE (pressure, temperature, co-solvent: CO2 mass ratio)
410
conditions (Ahangari & Sargolzaei, 2013; Couto, Fernandes, da Silva, & Simões, 2009).
411
SCG oil has efficiently been extracted (>90% yield) by supercritical carbon dioxide
412
(scCO2) recently in a pilot plant (Cruz et al., 2014) and used for producing high yielding
413
PHA (0.77 kg PHA/kg SCG oil; 97 kg per ton of SCG processed).
AC
C
EP
TE
403
414
SCG oil also contains minor lipid components, such as sterols well known for their
415
serum cholesterol lowering effect by reducing intestinal absorption of cholesterol. Sterols
416
constitute about 5.4% of the total lipids in Arabica coffee and consist of sitosterol (53%),
15
ACCEPTED MANUSCRIPT
stigmasterol (21%), campestol (11%), cycloartenol (8%), and the remaining sterols are each
418
5% or less of the total sterol fraction (Spiller, 1998). Sterol content of SCG depends on the
419
origin and source of roasted coffee (Table 4) with sitosterol, stigmasterol, and campesterol
420
as the most abundant sterols, predominating in higher plants and in typical diets. These
421
three sterols account for 88 - 92% of the total sterols in SCG or roasted coffee oils. The
422
concentration of the minor sterol, ∆5- avenasterol also varies in accordance with the level in
423
roasted coffee (Table 4) reaching up to 9% of the total sterols. In fact, sitosterol and ∆5-
424
avenasterol are the two most differentiating sterols used to separate Arabica from Robusta
425
coffee varieties (Carrera, León-Camacho, Pablos, & González, 1998) because its
426
polymerization protects oils from oxidation
SC
RI
PT
417
Several methods have been devised to extract/prepare the diterpenes, cafestol and
428
kahweol from coffee oil because of their potential use and applications in pharmacological
429
and cosmetic preparations. Cafestol is minimally affected by various treatments of coffee
430
beans and is one of the components that remains in spent coffee grounds (1.2%)
431
(Spiller,1998). Khan & Brown (1953) identified kahweol as one of the unsaponifiables with
432
characteristic brown precipitate formation of SCG oil extracted from fresh roasted blend of
433
Brazilian, Colombian, and Venezuelan coffees. Direct saponification produces high level of
434
diterpenes (2.14 and 4.66 mg/g SCG of kahweol and cafestol, respectively) compared to
435
saponification of oil extracted by solid liquid extraction or supercritical extraction
436
(Acevedo et al., 2013). Diterpene yield from SCG depends on processing conditions during
437
supercritical CO2 extraction; thus concentration of cafestol (0.207 mg/g SCG) and kahweol
438
(0.114 mg/g SCG) are lower at 40 °C/98 bar than those at 80 °C/379 bar (0.828 and 0.425
439
mg/g SCG for cafestol and kahweol, respectively) (Acevedo et al., 2013).
AC
C
EP
TE
D
M
AN
U
427
6. Minerals
440
441
442
SCG also contains ash (1.6 %), which, according to the ICP-AES analysis, consists of
443
several minerals. Potassium is the most abundant element, followed by phosphorus and
444
magnesium (Mussatto, Ballesteros, Martins, & Teixeira, 2011a). Potassium is also the
445
predominant mineral in coffee beans, corresponding to 40% of the oxide ash (Grembecka,
446
Malinowska, & Szefer, 2007). Most minerals are easily extracted with hot water during
16
ACCEPTED MANUSCRIPT
instant coffee preparation. Total mineral (K, Mg, P, Ca, Na, Fe, Mn, and Cu) content of
448
espresso SC varies from 0.82 to 3.52%, confirming mineral leaching during espresso coffee
449
preparation, although not as exhaustive as with soluble coffee (Cruz et al., 2012).
450
Potassium, the major mineral of espresso SC, ranges from 3.12 to 21.88 mg/g (Cruz et al.,
451
2012). The industrial SCG contains lower absolute (3.55 mg/g) and relative amounts (22%)
452
of this element. Coffee is regarded as an important source of Mg, comprising 11% of the
453
SCG minerals, again higher than those of industrial SC (Mussatto, Ballesteros, Martins, &
454
Teixeira, 2011a).
SC
RI
PT
447
7. Phenolic compounds
Phenolic compounds are the major determinant of antioxidant potentials found in high
458
concentrations in plants (Balasundram, Sundram, & Samman, 2006). Recently, interest in
459
plant-derived natural products has grown, mainly because synthetic antioxidants suffer
460
from several drawbacks. SCG contain several human health related compounds, such as
461
phenolics with demonstrated antioxidant, anti-bacterial, antiviral, anti-inflammatory and
462
anti-carcinogenic activities (De Souza et al., 2004).
D
M
AN
U
455
456
457
The recovery of phenolic compounds from the coffee industry by-products and their
464
antioxidant activity has been investigated recently. Phenolic compounds from coffee by-
465
products (coffee pulp, husk, silver skin, and SC) have been extracted using solvent mixture
466
of isopropanol and water (Murthy & Naidu, 2012b). The coffee by-products contained
467
about 1–1.5% total polyphenols with the highest yield for silver skin (25%), followed by
468
spent waste (19%) and cherry husk (17%) when pretreated with viscozyme. Chlorogenic
469
acid (CGA) was the major phenolic component when analyzed with high-performance
470
liquid chromatography. In fact, phenolic compounds are mainly found in green coffee
471
beans as CGA (up to 12% solids) (Esquivel & Jimenez, 2012). These CGA are water-
472
soluble esters formed between quinic acid and one or two moieties of caffeic acid, a trans-
473
cinnamic acid. Caffeoylquinic acids (CQA) are the most abundant phenolic compounds in
474
coffee. Monocaffeoylquinic acids (3-CQA, 4-CQA, 5-CQA) and dicaffeoylquinic acids
475
(3,4-diCQA, 3,5-diCQA, 4,5-diCQA) were identified and quantified in SC obtained from
AC
C
EP
TE
463
17
ACCEPTED MANUSCRIPT
different coffeemakers (filter, espresso, plunger, and mocha) and in their respective coffee
477
brews by Bravo et al (2012). All SCG, with the exception of those from the mocha
478
coffeemaker, have relevant amounts of total caffeoylquinic acids ranging from 11.05 mg
479
(espresso) to 13.24 mg (filter) per gram of Arabica SC and from 6.22 mg (filter) to 7.49 mg
480
(espresso) per gram of Robusta SC. Espresso SCG shows high variability, with 5-CQA
481
ranging from 0.397 to 2.642 mg/g (DW) and total CGA varying from 2.12 to 7.66 mg/g
482
(DW) (Cruz et al., 2012).
RI
PT
476
The antioxidant phenolic compounds from SCG have been extracted by the conventional
484
solid–liquid method. For example, extraction with 60% methanol (40 ml/g SCG
485
solvent/solid ratio, 90 min) produces a high phenolic extract (16 mg gallic acid equivalents
486
(GAE)/g SCG) with high antioxidant activity (FRAP of 0.10 mM Fe(II)/g) simultaneously
487
(Mussatto, Ballesteros, Martins, & Teixeira, 2011). Phenolic compounds from SCG [coffee
488
bars (SCG-1) or coffee capsules (SCG-2)] have been extracted by an environmentally
489
friendly and cost-effective process, using aqueous ethanol under mild temperature
490
conditions to preserve the activity of the phenolic compounds (Zuorro & Lavecchia, 2012).
491
Total phenolic content of SCG-1 and SCG-2 were 17.75 and 21.56 mg GAE/g,
492
respectively. Thus phenolic-rich extracts can be obtained from SCG using an
493
environmentally friendly and simple solvent-extraction procedure. Ethanol also influenced
494
microwave-assisted extraction of natural antioxidants from spent filter coffee (Pavlović,
495
Buntić, Šiler-Marinković, & Dimitrijević-Branković, 2013). The highest total phenolic
496
compounds (399 mg GAE/g extract, dry matter) was obtained with 20% aqueous ethanol
497
under just 40 s of microwave radiation (80 W), implying that the method is very effective,
498
saving time and chemicals. The extracts (20 µg/mL) exhibited high in vitro antioxidant
499
activities inhibiting 90% of DPPH radicals, supporting their biological stability. This
500
research group later found that total phenolic compounds of SCG were strongly correlated
501
with their DPPH scavenging activity, and therefore mainly responsible for the antioxidant
502
activity. An UHPLC-PDA-TOF-MS system was used to separate, identify, and quantify
503
phenolic and non-phenolic compounds in the SCG extracts. High amounts of CGA and
504
related compounds as well as caffeine demonstrate the high potential of SCG, a waste
505
material that is widely available in the world, as a source of natural phenolic antioxidants
506
(Panusa, Zuorro, Lavecchia, Marrosu, & Petrucci, 2013).
AC
C
EP
TE
D
M
AN
U
SC
483
18
ACCEPTED MANUSCRIPT
8. Ingenuity/knowledge gap
Table 5 provides a short survey of product and/or process innovation using SCG or
510
coffee products including SCG. Earlier innovation (pre 2005) explored the extraction of
511
specific components such as oil, flavor, terpenes, and alcohols as value-added products.
512
Later studies focus extensively on innovation in bioenergy and biorefinery using SCG as a
513
source product. In reality, there has been minimal attempt in complete integrated
514
fractionation and utilization of SCG components for industrial and/or other use, although
515
these components have been individually well researched (Figure 2).
RI
PT
507
508
509
Spent coffee grounds represent a resource for an integrated product focused biorefinery.
517
It has been proven that the conversion of biomass waste to bulk chemicals for example was
518
nearly 7.5 and 3.5 times more profitable than its conversion to animal feed or transportation
519
fuel, respectively, highlighting the marginal value of 1st generation food supply chain waste
520
recycling (anaerobic digestion, composting, animal feed) (Pfaltzgraff, Cooper, Budarin, &
521
Clark, 2013). The key to go beyond 1st generation waste valorization is to make use of all
522
the valuable components in waste, taking into consideration the presence of high-value
523
products. A good example of 2nd generation products is succinic acid obtained through
524
sugar fermentation of enzyme-hydrolyzed carbohydrates from SCG (Koutinas et al., 2013).
525
SCG oil is the single most economically valuable component easily extractable and a
526
potential low-cost and good quality feedstock source for fatty acid methyl esters production
527
by direct single step transesterification of SCG oil in supercritical methanol (Calixto et al.,
528
2011). The oil quality can be improved for use in cosmetic and pharmaceutical applications
529
or as a source of other valuable products such as caffeine, sterols, terpenes and tocopherols
530
by fractionation similar to those used for green coffee oil (De Azevedo et al., 2008). The
531
fractionated oil or its components can be stabilized by the spray drying process used for
532
encapsulating green coffee oil (Silva, Vieira, & Hubinger, 2014), particularly applicable to
533
the unsaponifiable fraction containing the diterpenes for medical and other associated uses.
534
Oil extracted from SCG can be used as a substrate for the production of poly (3-
535
hydroxybutyrate) (PHB). PHB is similar in mechanical properties to polypropylene or
536
polyethylene and is therefore considered a completely biodegradable alternative to
537
synthetic polymers (Obruca et al., 2014). When compared to other waste/inexpensive oils,
538
the utilization of SCG results in the highest biomass as well as PHB yields (up to 0.88 g of
AC
C
EP
TE
D
M
AN
U
SC
516
19
ACCEPTED MANUSCRIPT
PHB per g of oil vs 0.85 for soybean oil, or 0.83 for waste rapessed oil) (Obruca et al.,
540
2014; De Cruz, Ienczak, Delgado, & Taciro, 2012; Obruca, Marova, Snajdar, Mravcova, &
541
Svoboda, 2010). The utilization of oil extracted from SCG as a feedstock for PHB
542
production presents several advantages. The coffee industry is steadily growing; the annual
543
worldwide production of green coffee beans exceeded eight million tons (Murthy & Naidu
544
2012a). Therefore, SCG are available in millions of tons especially in coffee-producing
545
countries. Moreover, since oil extraction decreased the calorific value of SCG by only
546
about 9% (from 19.61 to 17.86 MJ/kg), residual SCG after oil extraction can be used as fuel
547
to at least partially cover heat and energy demands of fermentation, which should even
548
improve the economic feasibility of the process (Obruca et al., 2014). In addition to oil
549
extraction, several processes such as pyrolysis and gasification have been used to convert
550
industrial SCG into fuel, hydrogen-enriched fuel, bio-oils, liquid product mixture
551
comparable to fossil fuel oil and valuable biocide. Bio-oils produced from pyrolysis of
552
coffee grounds contain large amounts of various carboxylic acids enabling their further
553
upgrade into biodiesel or other petrochemical products and/or promote their conversion into
554
noncondensable volatiles that may be beneficial for combustible gas or syngas production
555
from SCG (Kan, Strezov, & Evans, 2014). The glyceride portion of SCG oil can be
556
transesterified with methanol to produce fatty acid methyl esters, known as biodiesel.
557
Potentially 1.3 billion litres of biodiesel (based on ~ 8 million tonnes of globally produced
558
coffee containing 10-15 % wt lipids [80-95% glycerides] could be added to the world fuel
559
supply from SCG, a value comparable to waste cooking oil (Jenkins, Stageman, Fortune, &
560
Chuck, 2014). Furthermore, spent coffee defatting and extract lyophilization produces spent
561
coffee extracts powder with high antioxidant capacity that can be used as an ingredient or
562
additive in food industry with potential preservation and functional properties (Bravo,
563
Monente, Juániz, De Peña, & Cid, 2013).
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
539
564
Enzyme technology (hydrolysis) can be used to hydrolyze SCG polysaccharides into
565
valuable food additives such as mannitol and higher mannosaccharide alcohols or source
566
raw material for bioethanol production (Jooste, García-Aparicio, Brienzo, van Zyl, &
567
Görgens, 2013; Stahl, Bayha, & Fulger, 1984). Alcohol production similar to process
568
generally used in distilled beverages generates a beverage with 40% ethanol alcohol,
569
comparable to liquors such as vodka and tequila with a pleasant smell and taste of coffee
20
ACCEPTED MANUSCRIPT
(Sampaio et al., 2013). Additionally, the residual solid material obtained after the
571
hydrothermal process is rich in sugars that can be reused as raw material for the production
572
of other valuable products, which would give additional value to spent coffee grounds into
573
a bio-refinery concept. Furthermore, the cellulose and hemicellulose fractions of SCG have
574
potential applications in sorbitol, hydroxymethylfurfural, levulinic acid, formic acid,
575
xylitol, arabitol, mannitol, galactitol, furfural and, emulsificant production (Mussato et al.,
576
2011a). High pressure and temperature hydrolysis of SCG generates MOS, already
577
marketed in Japan as a functional food primarily as a probiotic for digestive health
578
(Fukami, 2010).
SC
RI
PT
570
Waste from brewing coffee could be a valuable resource for the production of
580
hydrophilic bioactive antioxidants for dietary supplements according to Spanish researchers
581
(Bravo et al., 2012). All spent coffee (from filter, plunger and espresso-type coffee makers)
582
had relevant amounts of total caffeoylquinic acids, mainly dicaffeoylquinic acids that were
583
4–7-fold higher than their respective coffee brews. Solvent mixture of isopropanol and
584
water can selectively extract phenolic antioxidant adjunct for food processing from SCG
585
and other coffee by-products (Murthy & Naidu, 2012b). Melanoidins, another antioxidant
586
component exert bacteriostatic activity at low concentration decreasing pathogenic
587
virulence and may be good candidates as natural antimicrobial agents in thermally
588
processed foods (Rufián-Henares & De La Cueva, 2009). The anti-tumor and anti-
589
allergenic (inhibition of histamine release) activities of SCG extract (Ramalakshmi, Rao,
590
Takano-Ishikawa, & Goto, 2009) provides yet another new opportunities for its
591
pharmaceutical use.
EP
TE
D
M
AN
U
579
Current available technologies enable the complete integrated use/exploitation of SCG
593
adding value to an already abundant low-cost product simultaneously reducing the
594
environmental footprint of the coffee industry. The accumulated body of knowledge
595
generated since 1950 and earlier has now been refined and there is an urgent need for
596
practical and innovative ideas to use this low cost SCG and exploit its full potential
597
increasing the overall sustainability of the coffee agro-industry.
AC
C
592
21
ACCEPTED MANUSCRIPT
References
Acevedo, F., Rubilar, M., Scheuermann, E., Cancino, B., Uquiche, E., Garcés, M., et
Journal of Biobased Materials and Bioenergy, 7(3), 420-428.
RI
PT
al. (2013). Spent coffee grounds as a renewable source of bioactive compounds.
Ahangari, B., & Sargolzaei, J. (2013). Extraction of lipids from spent coffee grounds
SC
using organic solvents and supercritical carbon dioxide. Journal of Food Processing
and Preservation, 37(5), 1014-1021.
M
AN
U
Al-Hamamre, Z., Foerster, S., Hartmann, F., Kröger, M., & Kaltschmitt, M. (2012). Oil
extracted from spent coffee grounds as a renewable source for fatty acid methyl ester
manufacturing. Fuel, 96, 70-76.
Andrade, K. S., Gonçalvez, R. T., Maraschin, M., Ribeiro-do-Valle, R. M., Martínez, J.,
& Ferreira, S. R. (2012). Supercritical fluid extraction from spent coffee grounds and
D
coffee husks: Antioxidant activity and effect of operational variables on extract
TE
composition. Talanta, 88, 544-552.
Andrade, K.S., & Ferreira, R.S. (2013). Cost manufacturing of oil extraction of spent
grounds
EP
coffee
obtained
by
supercritical
AC
C
technology.http://iufost.org.br/sites/iufost.org.br/files/anaid/03671.pdf
Asano, I., Nakamura, Y., Hoshino, H., Aoki, K., Fujii, S., Imura, N., et al. (2001). Use
of mannooligosaccharides from coffee mannan by intestinal bacteria. Nippon
Nogeikagaku Kaishi, 75(10), 1077-1083.
Baechler, R. (2002). Process for extracting terpens from spent coffee grounds. E.P.
Patent 0819385 B1.
22
ACCEPTED MANUSCRIPT
Balasundram, N., Sundram, K., & Samman, S. (2006). Phenolic compounds in plants
and agri-industrial by-products: Antioxidant activity, occurrence, and potential uses.
Food Chemistry, 99(1), 191-203.
RI
PT
Belitz, H. D., Grosch, H., Schieberte, P. (2004). Food Chemistry; Springer: Berlin,
Germany; pp 939−969.
Bicho, N. C., Leitão, A. E., Ramalho, J. C., & Lidon, F. C. (2011). Identification of
SC
chemical clusters discriminators of the roast degree in Arabica and Robusta coffee
beans. European Food Research and Technology, 233(2), 303-311.
M
AN
U
Bradbury, A. G., & Halliday, D. J. (1990). Chemical structures of green coffee bean
polysaccharides. Journal of Agricultural and Food Chemistry, 38(2), 389-392.
Bradbury, A. G., & Halliday, D. J. (1990). Chemical structures of green coffee bean
polysaccharides. Journal of Agricultural and Food Chemistry, 38(2), 389-392.
D
Bravo, J., Juániz, I., Monente, C., Caemmerer, B., Kroh, L. W., De Peña, et al. (2012).
TE
Evaluation of spent coffee obtained from the most common coffeemakers as a source of
hydrophilic bioactive compounds. Journal of Agricultural and Food Chemistry, 60(51),
EP
12565-12573.
AC
C
Bravo, J., Monente, C., Juániz, I., De Peña, M. P., & Cid, C. (2013). Influence of
extraction process on antioxidant capacity of spent coffee. Food Research
International, 50(2), 610-616.
Caetano, N. S., Silva, V. F., & Mata, T. M. (2012). Valorization of coffee grounds for
biodiesel production. Italian Association of Chemical Engineering, 26.
Calixto, F., Fernandes, J., Couto, R., Hernández, E. J., Najdanovic-Visak, V., &
Simões, P. C. (2011). Synthesis of fatty acid methyl esters via direct transesterification
23
ACCEPTED MANUSCRIPT
with methanol/carbon dioxide mixtures from spent coffee grounds feedstock. Green
Chemistry, 13(5), 1196-1202.
Campos-Vega, R., Oomah, B. D., Loarca-Piña, G., & Vergara-Castañeda, H. A. (2013).
RI
PT
Common beans and their non-digestible fraction: cancer inhibitory activity—an
overview. Foods, 2(3), 374-392.
Campos-Vega, R., Reynoso-Camacho, R., Pedraza-Aboytes, G., Acosta-Gallegos, J. A.,
SC
Guzman-Maldonado, S. H., Paredes-Lopez, O., et al. (2009). Chemical composition and
of Food Science, 74(7), T59-T65.
M
AN
U
in vitro polysaccharide fermentation of different beans (Phaseolus vulgaris L.). Journal
Carrera, F., León-Camacho, M., Pablos, F., & González, A. G. (1998). Authentication
of green coffee varieties according to their sterolic profile. Analytica Chimica Acta,
370(2), 131-139.
D
Casal, S., Oliveira, M. B. P. P., Alves, M. R., & Ferreira, M. A. (2000). Discriminate
TE
analysis of roasted coffee varieties for trigonelline, nicotinic acid, and caffeine content.
Journal of Agricultural and Food Chemistry, 48(8), 3420-3424.
EP
Couto, R. M., Fernandes, J., da Silva, M. D. R., & Simões, P. C. (2009). Supercritical
fluid extraction of lipids from spent coffee grounds. The Journal of Supercritical
AC
C
Fluids, 51(2), 159-166.
Cruz, M. V., Paiva, A., Lisboa, P., Freitas, F., Alves, V. D., Simões, P., et al. (2014).
Production of polyhydroxyalkanoates from spent coffee grounds oil obtained by
supercritical fluid extraction technology. Bioresource Technology.
Cruz, R., Cardoso, M. M., Fernandes, L., Oliveira, M., Mendes, E., Baptista, P., et al.
(2012). Espresso coffee residues: a valuable source of unextracted compounds. Journal
of Agricultural and Food Chemistry, 60(32), 7777-7784.
24
ACCEPTED MANUSCRIPT
da Cruz Pradella, J. G., Ienczak, J. L., Delgado, C. R., & Taciro, M. K. (2012). Carbon
source pulsed feeding to attain high yield and high productivity in poly (3-
Biotechnology Letters, 34(6), 1003-1007.
RI
PT
hydroxybutyrate)(PHB) production from soybean oil using Cupriavidus necator.
De Azevedo, A. B. A., Kieckbush, T. G., Tashima, A. K., Mohamed, R. S., Mazzafera,
P., & Melo, S. A. B. (2008). Extraction of green coffee oil using supercritical carbon
SC
dioxide. The Journal of Supercritical Fluids, 44(2), 186-192.
de Souza, AL., Garcia, R., Cabral’, L., Bernardino, FS., Zervoudakis, JT., Rocha, FC.,
M
AN
U
et al. (2004). Coffee hulls in diets of dairy cows: nitrogenous compounds balance.
Poultry Science, 83, p. 51.
Delgado, P. A., Vignoli, J. A., Siika-aho, M., & Franco, T. T. (2008). Sediments in
coffee extracts: Composition and control by enzymatic hydrolysis. Food Chemistry,
D
110(1), 168-176.
TE
Diaz, L. F., De Bertoldi, M., & Bidlingmaier, W. (Eds.). (2011). Compost Science and
Technology (Vol. 8). Elsevier.
EP
Elbl, J., Plošek, L., Kintl, A., Přichystalová, J., Záhora, J., & Friedel, J. K. (2014). The
effect of increased doses of compost on leaching of mineral nitrogen from arable land.
AC
C
Polish Journal of Environmental Studies, 23(3), 697-703.
Elías, L.G. (1979) Chemical composition of coffee-berry by-products. In J.E. Brahman
& R. Bressani (Eds.), Coffee Pulp Composition, Technology, and Utilization.
International Development Research Centre (IDRC-108e), Ottawa, Canada, pp 11-16.
Esquivel, P., & Jiménez, V. M. (2012). Functional properties of coffee and coffee byproducts. Food Research International, 46(2), 488-495.
Fan, L., Pandey, A., Mohan, R., & Soccol, C. R. (2000). Use of various coffee industry
25
ACCEPTED MANUSCRIPT
residues for the cultivation of Pleurotusostreatus in solid state fermentation. Acta
Biotechnologica, 20(1), 41-52.
Fiol, N., Escudero, C., & Villaescusa, I. (2008). Reuse of Exhausted Ground Coffee
RI
PT
Waste for Cr (VI) Sorption.Separation Science and Technology, 43(3), 582-596.
Freitas, S. P., Monteiro, P. L., & Lago, R. C. A. (2000). Extração do óleo da borra de
café solúvelcom etanol comercial. Simpósio de Pesquisa dos Cafés do Brasil, 740-743.
SC
Fukami, H. (2010). Functional Foods and Biotechnology in Japan. In D. Bagchi, F. C.
Lau., & D.K. Ghosh (Eds.), Biotechnology in Functional Foods and Nutraceuticals (pp.
M
AN
U
29-49). Taylor and Francis Group, LLC. Boca Raton, FL.
Givens, D. I., & Barber, W. P. (1986). In vivo evaluation of spent coffee grounds as a
ruminant feed. Agricultural Wastes, 18(1), 69-72.
Gottesman, M. (1985) Simultaneous coffee hydrolysis and oil extraction.U.S.Patent
D
4544567, issued October 1, 1985.
TE
Grembecka, M., Malinowska, E., & Szefer, P. (2007). Differentiation of market coffee
and its infusions in view of their mineral composition. Science of the Total
EP
Environment, 383(1), 59-69.
Illy, A., Viani, R. Roasting. In Espresso Coffee: The Chemistry of Quality, 1st ed.;
AC
C
Academic Press: New York, 1995; pp 105−106.
Jenkins, R. W., Stageman, N., Fortune, C., & Chuck, C. J. (2014). Effect of the type of
bean, processing and geographical location on the biodiesel produced from waste coffee
grounds. Energy Fuels, 28, 1166-1174.
26
ACCEPTED MANUSCRIPT
Jooste, T., García-Aparicio, M. P., Brienzo, M., van Zyl, W. H., & Görgens, J. F.
(2013). Enzymatic hydrolysis of spent coffee ground. Applied Biochemistry and
RI
PT
Biotechnology, 169(8), 2248-2262.
Jung, W. K., Park, P. J., Ahn, C. B., & Je, J. Y. (2014). Preparation and antioxidant
potential of maillard reaction products from (MRPs) chitooligomer. Food Chemistry,
SC
145, 173-178.
Kan, T., Strezov, V., & Evans, T. (2013). Catalytic Pyrolysis of Coffee Grounds Using
M
AN
U
NiCu-Impregnated Catalysts. Energy & Fuels.
Kante, K., Nieto-Delgado, C., Rangel-Mendez, J. R., & Bandosz, T. J. (2012). Spent
coffee-based activated carbon: Specific surface features and their importance for H2S
separation process. Journal of Hazardous Materials, 201, 141-147.
Karr-Lilienthal, L. K., Kadzere, C. T., Grieshop, C. M., & Fahey Jr, G. C. (2005).
D
Chemical and nutritional properties of soybean carbohydrates as related to
TE
nonruminants: A review. Livestock Production Science, 97(1), 1-12.
Khan, N. A., & Brown, J. B. (1953). The composition of coffee oil and its component
EP
fatty acids. Journal of the American Oil Chemists Society, 30(12), 606-609.
AC
C
Kondamudi, N., Mohapatra, S. K., & Misra, M. (2008). Spent coffee grounds as a
versatile source of green energy. Journal of Agricultural and Food Chemistry, 56(24),
11757-11760.
Kondamudi, N., Mohapatra, S. K., & Misra, M. (2008). Spent coffee grounds as a
versatile source of green energy. Journal of Agricultural and Food Chemistry, 56(24),
11757-11760.
27
ACCEPTED MANUSCRIPT
Koutinas, A.A., Kopsahelis, N., Stamatelatou, K., Dickson, F., Thankappan, S.,
Mohamed, Z., et al. (2013). Food waste as a valuable resource for the production of
chemicals, materials and fuels. Current situation and global perspective. Energy &
RI
PT
Environmental Science, 6(2), 426-464.
Lago, R.C.A., Antoniassi, R., & Freitas, S.C. (2001). Centesimal composition and
SC
amino acids of raw, roasted and spent ground of soluble coffee. In II Simpósio de
Pesquisa dos Cafés do Brasil Vitoria, ES. Resumos, (p. 104)
M
AN
U
Lu, J.H., & Lee, W.H. (2013) Process of manufacturing powedered coffee carbons from
spent coffee grounds. U.S. Patent 8513159 B2, issued August 20, 2013.
Misra, M., Mohapatra, SK., Kondamudi, & NV. (2013). Methods, systems, and
apparatus for obtaining biofuel from coffee and fuels produced therefrom. U.S. Patent
D
8591605 B2, issued November 26, 2013.
TE
Moreira, A. S., Nunes, F. M., Domingues, M. R., & Coimbra, M. A. (2012). Coffee
melanoidins: structures, mechanisms of formation and potential health impacts. Food &
EP
Function, 3(9), 903-915.
Murthy, P. S., & Naidu, M. M. (2012a). Sustainable management of coffee industry by-
58.
AC
C
products and value addition—A review. Resources, Conservation and recycling, 66, 45-
Murthy, P. S., & Naidu, M. M. (2012b). Recovery of phenolic antioxidants and
functional compounds from coffee industry by-products. Food and Bioprocess
Technology, 5(3), 897-903.
Mussatto, S. I., Ballesteros, L. F., Martins, S., & Teixeira, J. A. (2011b). Extraction of
antioxidant phenolic compounds from spent coffee grounds. Separation and
28
ACCEPTED MANUSCRIPT
Purification Technology, 83, 173-179.
Mussatto, S. I., Carneiro, L. M., Silva, J., Roberto, I. C., & Teixeira, J. A. (2011a). A
study on chemical constituents and sugars extraction from spent coffee grounds.
RI
PT
Carbohydrate Polymers, 83(2), 368-374.
Mussatto, S. I., Machado, E., Carneiro, L. M., & Teixeira, J. A. (2012). Sugars
metabolism and ethanol production by different yeast strains from coffee industry
SC
wastes hydrolysates. Applied Energy, 92, 763-768.
Nunes, F. M., & Coimbra, M. A. (2010). Role of hydroxycinnamates in coffee
M
AN
U
melanoidin formation. Phytochemistry Reviews, 9(1), 171-185.
Obruca, S., Marova, I., Snajdar, O., Mravcova, L., & Svoboda, Z. (2010). Production of
poly (3-hydroxybutyrate-co-3-hydroxyvalerate) by Cupriavidus necator from waste
rapeseed oil using propanol as a precursor of 3-hydroxyvalerate. Biotechnology Letters,
D
32(12), 1925-1932.
TE
Obruca, S., Petrik, S., Benesova, P., Svoboda, Z., Eremka, L., & Marova, I. (2014).
Utilization of oil extracted from spent coffee grounds for sustainable production of
EP
polyhydroxyalkanoates. Applied Microbiology and Biotechnology, 1-8.
AC
C
Oestreich-Janzen, S. (2010). Chemistry of coffee In L. Mander, & H-W. Liu (Eds.),
Comprehensive Natural Products II Chemistry and Biology, Volume 3: Development &
Modification of Bioactivity (pp. 1085-1117). Elsevier, Oxford, UK.
Oliveira, L. S., Franca, A. S., Camargos, R. R., & Ferraz, V. P. (2008). Coffee oil as a
potential feedstock for biodiesel production. Bioresource Technology, 99(8), 32443250.
Oomah, B. D. (2001). Flaxseed as a functional food source. Journal of the Science of
29
ACCEPTED MANUSCRIPT
Food and Agriculture, 81(9), 889-894.
Panusa, A., Zuorro, A., Lavecchia, R., Marrosu, G., & Petrucci, R. (2013). Recovery of
natural antioxidants from spent coffee grounds. Journal of Agricultural and Food
RI
PT
Chemistry, 61(17), 4162-4168.
Passos, C. P., & Coimbra, M. A. (2013). Microwave superheated water extraction of
polysaccharides from spent coffee grounds. Carbohydrate Polymers, 94(1), 626-633.
SC
Pavlović, M. D., Buntić, A. V., Šiler-Marinković, S. S., & Dimitrijević-Branković, S. I.
(2013). Ethanol influenced fast microwave-assisted extraction for natural antioxidants
M
AN
U
obtaining from spent filter coffee. Separation and Purification Technology, 118, 503510.
Pfaltzgraff, L. A., Cooper, E. C., Budarin, V., & Clark, J. H. (2013). Food waste
biomass: a resource for high-value chemicals. Green Chemistry, 15(2), 307-314.
D
Prajapati, V. D., Jani, G. K., Moradiya, N. G., Randeria, N. P., Nagar, B. J., Naikwadi,
TE
N. N., & Variya, B. C. (2013). Galactomannan: a versatile biodegradable seed
polysaccharide. International Journal of Biological Macromolecules, 60, 83-92.
EP
Preethu, D. C., BhanuPrakash, B. N. U. H., Srinivasamurthy, C. A., & Vasanthi, B. G.
(2007). Maturity indices as an index to evaluate the quality of compost of coffee waste
AC
C
blended with other organic wastes. In Proceeding of International Conference on
Sustainable Solid Waste Management, Chennai, India (pp. 270-275).
Pujol, D., Liu, C., Gominho, J., Olivella, M. À., Fiol, N., Villaescusa, I., et al. (2013).
The chemical composition of exhausted coffee waste. Industrial Crops and Products,
50, 423-429.
Ramalakshmi, K., Rao, L., Takano-Ishikawa, Y., & Goto, M. (2009). Bioactivities of
low-grade green coffee and spent coffee in different in vitro model systems. Food
30
ACCEPTED MANUSCRIPT
Chemistry, 115(1), 79-85.
Ratnayake, W. M. N., Hollywood, R., O'Grady, E., & Stavric, B. (1993). Lipid content
Toxicology, 31(4), 263-269.
RI
PT
and composition of coffee brews prepared by different methods. Food and Chemical
Ravindranath, R., Khan, R., Obi Reddy, T., ThirumalaRao, S. D., & Reddy, B. R.
(1972). Composition and characteristics of Indian coffee bean, spent grounds and oil.
SC
Journal of the Science of Food and Agriculture, 23(3), 307-310.
Rogers, W. J., Bézard, G., Deshayes, A., Meyer, I., Pétiard, V., & Marraccini, P.
M
AN
U
(1999). Biochemical and molecular characterization and expression of the 11S-type
storage protein from Coffea Arabica endosperm. Plant Physiology and Biochemistry,
37(4), 261-272.
Rudel, L. L., Parks, J. S., & Sawyer, J. K. (1995). Compared with dietary
D
monounsaturated and saturated fat, polyunsaturated fat protects African green monkeys
TE
from coronary artery atherosclerosis. Arteriosclerosis, Thrombosis, and Vascular
Biology, 15(12), 2101-2110.
EP
Rufian-Henares, J. A., & de la Cueva, S. P. (2009). Antimicrobial Activity of Coffee
Melanoidins: A Study of Their Metal-Chelating Properties. Journal of Agricultural and
AC
C
Food Chemistry, 57(2), 432-438.
Saldaña, M. D., Mohamed, R. S., Baer, M. G., & Mazzafera, P. (1999). Extraction of
purine alkaloids from mate (Ilex paraguariensis) using supercritical CO2. Journal of
Agricultural and Food Chemistry, 47(9), 3804-3808.
Sampaio, A., Dragone, G., Vilanova, M., Oliveira, J. M., Teixeira, J. A., & Mussatto, S.
I. (2013). Production, chemical characterization, and sensory profile of a novel spirit
31
ACCEPTED MANUSCRIPT
elaborated from spent coffee ground. LWT-Food Science and Technology, 54(2), 557563.
Sikka, S. S., & Chawla, J. S. (1986). Effect of feeding spent coffee grounds on the
RI
PT
feedlot performance and carcass quality of fattening pigs. Agricultural Wastes, 18(4),
305-308.
Sikka, S.S., Bakshi, M.P.S., & Ichhponani, J.S. (1985). Evaluation in vitro of spent
SC
coffee grounds as a livestock feed. Agricultural Wastes, 13, 315-317.
Silva, M. A., Nebra, S. A., Machado Silva, M. J., & Sanchez, C. G. (1998). The use of
M
AN
U
biomass residues in the Brazilian soluble coffee industry. Biomass and Bioenergy,
14(5), 457-467.
Silva, V. M., Vieira, G. S., & Hubinger, M. D. (2014). Influence of different
combinations of wall materials and homogenisation pressure on the microencapsulation
green
coffee
oil
by
spray
drying.
Food
Research
International.
D
of
TE
http://dx.doi.org/10.1016/j.foodres.2014.01.052
Simões, J., Madureira, P., Nunes, F. M., do Rosário Domingues, M., Vilanova, M., &
EP
Coimbra, M. A. (2009). Immunostimulatory properties of coffee mannans. Molecular
Nutrition & Food Research, 53(8), 1036-1043.
AC
C
Simões, J., Nunes, F.M., Domingues, M.R., & Coimbra, M.A. (2013). Extractability
and structure of spent coffee ground polysaccharides by roasting pre-treatments.
Carbohydrate Polymers, 97, 81-89.
Spiller, M. A. (1998). The chemical components of coffee. In G. A. Spiller (Ed.),
Caffeine (pp. 97-161). CRC Press, Boca Raton, FL.
Stahl, H., Bayha, R., & Fulger, C.V. (1984). Production of mannitol and higher mannosaccharide alcohols. U.S. Patent 4484012, issued November 20, 1984.
32
ACCEPTED MANUSCRIPT
Takao, I., Fujii, S., Ishii, A., Han, L., Kumao, T., Ozaki, K., et al. (2006). Effects of
mannooligosaccharides from coffee mannan on fat storage in mice fed a high fat diet.
Journal of Health Science-Tokyo-, 52(3), 333.
RI
PT
Tello, J., Viguera, M., & Calvo, L. (2011). Extraction of caffeine from Robusta coffee
(Coffeacanephora var. Robusta) husks using supercritical carbon dioxide. The Journal
of Supercritical Fluids, 59, 53-60.
SC
Todaka, M., Kowhakul, W., Masamoto, H., Shigematsu, M., & Onwona-Agyeman, S.
(2013). Thermal decomposition of biodiesel fuels produced from rapeseed, jatropha,
M
AN
U
and coffee oils with different alcohols. Journal of Thermal Analysis and Calorimetry,
113(3), 1355-1361.
Tsai, W. T., Liu, S. C., & Hsieh, C. H. (2012). Preparation and fuel properties of
biochars from the pyrolysis of exhausted coffee residue. Journal of Analytical and
D
Applied Pyrolysis, 93, 63-67.
TE
Udenigwe, C. C., & Aluko, R. E. (2010). Antioxidant and angiotensin converting
enzyme-inhibitory properties of a flaxseed protein-derived high Fischer ratio peptide
EP
mixture. Journal of Agricultural and Food Chemistry, 58(8), 4762-4768.
Urgert, R., Schulz, A. G., & Katan, M. B. (1995). Effects of cafestol and kahweol from
AC
C
coffee grounds on serum lipids and serum liver enzymes in humans. The American
Journal of Clinical Nutrition, 61(1), 149-154.
Vardon, D. R., Moser, B. R., Zheng, W., Witkin, K., Evangelista, R. L., Strathmann, T.
J., et al. (2013). Complete utilization of spent coffee grounds to produce biodiesel, biooil, and biochar. ACS Sustainable Chemistry & Engineering, 1(10), 1286-1294.
Vergara-Castañeda, Oomah B. D., & Campos-Vega R. (2013). Pulses Facing the New
Age: Functional Compounds on Gene Expression and Health Connection. In A.
33
ACCEPTED MANUSCRIPT
Robinson & D. Emerson (Eds.), Functional Foods: Sources, Biotechnology
Applications and Health Challenges. New York, NY, Nova SciencePublishers, Inc.
ISBN-10:1624174353 | ISBN-13: 978-1624174353.
RI
PT
Wei, F., Furihata, K., Koda, M., Hu, F., Miyakawa, T., & Tanokura, M. (2012).
Roasting process of coffee beans as studied by nuclear magnetic resonance: time course
of changes in composition. Journal of Agricultural and Food Chemistry, 60(4), 1005-
SC
1012.
White, E., & Burns, A. (2013). Coffee grounds-based fuel and method of manufacture.
M
AN
U
U.S. Patent 8439988 B2, issued May 14, 2013.
Yen, W. J., Wang, B. S., Chang, L. W., & Duh, P. D. (2005). Antioxidant properties of
roasted coffee residues. Journal of Agricultural and Food Chemistry, 53(7), 2658-2663.
Zuorro, A., & Lavecchia, R. (2012). Spent coffee grounds as a valuable source of
AC
C
EP
TE
D
phenolic compounds and bioenergy. Journal of Cleaner Production, 34, 49-56.
34
ACCEPTED MANUSCRIPT
Table 1. Amino acid content (% protein) and characteristics of coffee protein and by
products
Min
4.8
0.1
0.2
nd
11.5
2.4
0.1
5.1
10.6
1.9
1.0
0.5
3.1
0.9
0.3
2.9
6.0
Max
5.4
0.2
1.9
5.1
13.8
7.9
5.3
5.3
10.9
2.3
1.9
6.7
4.7
1.2
2.2
4.0
6.8
Instant
4.0
0.5
3.0
0.3
12.9
4.7
1.6
4.2
8.5
1.4
1.2
5.2
5.6
1.6
2.6
3.1
5.7
Pulp
3.5
2.8
7.1
0.3
7.7
4.2
2.5
3.3
4.7
3.4
0.3
3.0
3.7
3.3
3.1
1.9
3.7
11S
3.5
8.4
4.0
1.0
8.6
5.0
2.1
4.3
8.7
6.4
0.3
7.3
4.3
4.5
2.9
2.8
5.7
BCAA
AAA
Fischer ratio
Lys/Arg
Arg+Glu+His
Met+Cys
EAI (%)
21.7
0.9
24.1
19.0
11.8
1.0
79.3
23.0
8.9
2.6
11.5
19.3
7.0
128.8
18.4
7.8
2.4
2.8
15.0
1.5
94.6
11.7
6.1
1.9
1.2
13.0
0.6
74.7
18.7
10.2
1.8
0.8
19.1
1.3
117.3
SC
M
AN
U
D
TE
a
Soymeal
2.3
4.0
6.3
0.8
9.8
2.3
1.4
2.3
4.2
3.3
0.8
2.6
3.0
3.1
1.7
1.8
2.4
RI
PT
Amino Acids
Alanine
Argininea
Aspartic acid
Cystine
Glutamic acid
Glycine
Histidinea
Isoleucinea
Leucinea
Lysinea
Methioninea
Phenylalaninea
Proline
Serine
Threoninea
Tyrosine
Valinea
8.9
4.3
2.1
0.8
15.2
1.6
58.2
AC
C
EP
Essential amino acid
BCAA (Val+Leu+Ile)
AAA (Phe+Tyr)
Fischer ratio (BCAA/AAA)
nd, not detected
Data calculated from Lago et al., (2001)
Data from http://www.feedipedia.org/node/11612
Data from Rogers, Bézard, Deshayes, Meyer, Pétiard, & Marraccini, (1999)
Soymeal data from Karr-Lilienthal et al. (2005)
ACCEPTED MANUSCRIPT
Table 2. Caffeine content of SCG and roasted coffee
RI
PT
10 ± 3
Reference
Andrade et al., (2012)
SC
H2O(92 ± 5 °C/6 h)
Medium roast
Medium roast
Content (%)
0.007
0.378
0.314
0.039
0.28
0.177
0.248
0.434
0.5
M
AN
U
SCG (Robusta-Rb)
Roasted Coffee (Ar)
Roasted Coffee (Rb)
SCG
SCG (espresso)
D
SCG (Arabica-Ar)
Yield (%)
9
9.9
12.2
12
10.8
15
9.1
10.5
TE
SFE CO2
(µg/mg extract)
0.734
38.2
25.7
3.27
25.9
11.8
27.2
41.3
25 ± 2
EP
Soxhlet
Solvent/Condition
Hexane
Dichloromethane
Ethanol
Hexane
Dichloromethane
Ethanol
200 bar/331.15 K
300 bar/331.15 K
H2O(92 ± 5 °C/6 h)
AC
C
Extraction
Ultrasound
0.2
1.6
2.4
0.02 ± 0.1
0.18
Ramalakshmi, Rao, TakanoIshikawa, & Goto, (2009)
Murthy & Naidu, (2012)
Cruz et al., (2012)
ACCEPTED MANUSCRIPT
Table 3. Fatty acid composition of SCG
C18:1
9.00
8.31
10.30
6.70
24.00
8.18
12.90
0.60
nd
nd
nd
nd
4.36
2.42
35.78
37.48
34.04
35.86
36.86
41.87
6.25
6.02
5.45
5.26
11.32
10.4
nd
9.53
5.45
7.56
15.87
15.79
C18:2
45.04
44.67
44.20
22.00
49.90
32.35
56.90
24.90
C18:3
4.12
1.42
1.50
nd
1.40
1.31
8.50
5.50
46.53
44.52
25.83
35.35
44.15
41.19
C20:0
nd
1.16
2.60
0.00
1.50
2.39
9.80
37.80
SFA
41.0
45.6
42.5
42.1
56.4
58.2
21.7
69.0
PUFA
50.0
46.1
45.7
22.0
51.3
33.7
65.4
30.4
PUFA/SFA
1.22
1.01
1.08
0.52
0.91
0.58
3.01
0.44
AI
0.55
0.69
0.58
1.23
0.55
1.32
0.03
0.07
TI
1.26
1.44
1.25
2.93
1.49
2.15
0.01
0.33
nd
1.46
1.89
1.53
6.91
4.29
42.2
45.0
41.4
42.7
71.1
66.4
49.1
45.5
25.8
9.9
46.3
46.7
1.16
1.01
0.62
0.24
0.65
0.91
0.62
0.68
1.09
0.84
1.06
1.00
1.32
1.45
2.52
1.92
1.43
1.91
RI
PT
C18:0
8.35
7.07
7.10
6.70
13.50
6.55
0.30
28.00
SC
C16:0
32.45
37.37
32.80
35.40
41.40
43.64
0.50
1.00
M
AN
U
C14:0
0.05
nd
0.1
nd
nd
2.00
0.4
0.3
D
References
C12:0
Acevedo et al. (2013)
nd
De Melo et al. (2014)
nd
Cruz et al. (2014)
nd
Jenkins et al. (2014)
nd
Jenkins et al. (2014)
nd
Ahangari & Sargolzaei(2013) 3.58
Todaka et al. (2013)(Hex)Drip nd
Todaka et al. (2013)(Hex)Esp nd
Supercritical Fluid Extraction (SFE)
Acevedo et al. (2013)
nd
De Melo et al. (2014)
nd
Ahangari & Sargolzaei(2013) nd
Couto et al. (2009)
nd
Ahangari & Sargolzaei(2013) 11.69
Couto et al. (2009)
7.4
2.02
0.99
nd
nd
2.16
1.88
AC
C
EP
TE
SFA, saturated fatty acids; PUFA, polyunsaturated fatty acids; AI, atherogenic index; TI, thromogenic index;
nd, not determined.
ACCEPTED MANUSCRIPT
SCG2
20.34
1.37
Coffee 1
5.84
1.23
Coffee 2
5.74
0.79
16.08
21.75
52.66
5.30
1.65
1.42
18.36
22.48
48.00
9.07
0.62
0.80
15.66
22.82
52.27
4.05
2.01
1.74
16.83
21.94
48.78
8.81
1.68
0.70
AC
C
EP
TE
D
Data derived from Lago, Antoniassi, & Freitas (2001)
SC
SCG1
26.74
2.12
M
AN
U
Sterols
Oil content (%)
Unsaponifiables (% DW)
Sterols (% oil)
Campesterol
Stigmasterol
Sitosterol
Δ5 Avenasterol
Δ7 Stigmastenol
Δ7 Avenasterol
RI
PT
Table 4. Sterol (%) composition of SCG and their sourced roasted coffee
ACCEPTED MANUSCRIPT
Table 5. Products and/or processes innovation using SCG or coffee products including SCG
SC
RI
PT
Claim
References
Aromatic flavor components (diacetyl and acetaldehyde) are recovered from an aroma stream Cale et al. (1990)
generated by thermal hydrolysis of a partially extracted roasted and ground coffee. The flavor can
be used as a natural ingredient and/or in soluble coffee processing.
Antioxidant-rich biofuel is produced by transesterifying triglycerides extracted from coffee Misra et al. (2013)
products including SCG. Glycerin resulting from the transesterification process can be isolated,
purified and used in foods, pharmaceuticals, cosmetics and other products.
D
M
AN
U
A process is described for manufacturing powdered coffee carbons as an environmentally friendly Lu & Lee (2013)
activated carbon source
SCG is converted to an alternative solid combustible fuel-a wax-less fire log
White & Burns
(2013)
Coffee oil is recovered from hydrolyzed SCG simultaneously using the residual aqueous Gottesman (1985)
hydrolyzate as an economically valuable soluble coffee solids in soluble coffee processing
A process for preparing low-cost high yield manno-saccharide alcohols such as mannitol (a value Stahl et al. (1984)
added expensive specialty food, chemical, and pharmaceutical ingredient)
Terpenes containing kahweol and cafestol (10.7 and 14.7 mg/g coffee oil, respectively) are Baechler &
extracted from SCG.
Hirsbrunner (2002)
TE
Component
Spent grounds
volatile
compounds
Ground/Green/
Whole
roasted/spentcoffee beans
Spent coffee
grounds
Dried spent
coffee grounds
Spent coffee
grounds
Coffee extraction
residue
Spent coffee
grounds
AC
C
EP
1
ACCEPTED MANUSCRIPT
The Coffee Cherry (Fruit)
RI
PT
Skin
5-10 %
M
AN
U
Mucilage
90 %
total waste
45-50 %
Spent coffee ground
EP
TE
D
Parchment
(Hull)
Silverskin
Bean
AC
C
45-50 %
SC
Pulp
Figure 1. The coffee cherry fruit wastes (With information of: Murthy & Naidu, 2012a; Esquivel & Jiménez, 2012)
Brown(colored$compounds$
Browning,index,0.155,
16%,melanoidins,,!
,,
$Caffeine$$
Carbohydrates$
galactomannans,and,
arabinogalactans,
,
Mannooligosaccharides,
,
An-oxidant,dietary,fiber,,
Non(protein$nitrogeneous$compounds$
Carbon/nitrogen,ra-o,of,19.8:1,(wt):,microbial,ac-vity,,
Soil,amendment,impact,$
SCG$
Minerals$
K,,Mg,,P,,Ca,,Na,,Fe,,Mn,,and,Cu,$
Phenolic$compounds$
Natural,phenolic,an-oxidants,
1–1.5%,total,polyphenols,
Chlorogenic,acid,,,(12%,solids)$
$
Lipids$
Oil,manufacturing,cost,US$,48.60/kgL,earning,up,to,US$,460/kg,
Polyunsaturated/saturated,ra-o,>,1,,
Mix,linoleic,,palmi-c,,and,oleic,acids/,polyhydroxylalkanoatesLbiodegradable,synthe-c,polymer,
$
Figure$2.$ValueLadded,products,/sustainability,of,the,coffee,agroLindustry,,
ACCEPTED MANUSCRIPT
Highlights
Most of the polysaccharides remain as insoluble material bound to the SCW
RI
PT
The essential amino acids comprise almost half (~ 49%) of the total SCW amino acid
Caffeine obtained from SCW is equivalent up to 48% of those extracted from coffee beans
Lipids (90.2%) mainly remained in SCW
AC
C
EP
TE
D
M
AN
U
SC
Innovative ideas are needed to use this low cost SCW and exploit its full potential