Volume 10 No. 8
August 2010
CHANGES IN MICROSTRUCTURE, BETA CAROTENE CONTENT AND IN
VITRO BIOACCESSIBILITY OF ORANGE-FLESHED SWEET POTATO
ROOTS STORED UNDER DIFFERENT CONDITIONS
Tumuhimbise GA1, Namutebi A1 and JH Muyonga*2
John Muyonga
*Corresponding author email: muyongaj@agric.mak.ac.ug or hmuyonga@yahoo.com
1
Department of Food Science and Technology, Makerere University, P.O Box 7062,
Kampala-Uganda
3015
Volume 10 No. 8
August 2010
ABSTRACT
Orange-fleshed sweet potatoes {OFSP} (Ipomoea batatas (L.) Lam) contain high levels
of beta carotene, an important provitamin A carotenoid. Stored sweet potato roots
undergo many physiological changes that affect their beta carotene content and
bioaccessibility as well as the tissue microstructure. This study investigated the changes
in microstructure, beta carotene content and in vitro bioaccessibility of stored OFSP
roots. Roots of two varieties of OFSP, Ejumula and SPK004/6/6 were each stored under
the following conditions: in a pit (17-21 oC, RH 90-100%), saw dust (19-23oC, RH 86100%), dark room (24.5-28 oC, RH 68-100%) and ambient (24-27 oC, RH 68-100%).
Samples were drawn monthly from each of the storage treatments and analyzed for
changes in beta carotene content, in vitro bioaccessibility and tissue microstructure.
Stored roots of Ejumula variety contained significantly more (P ≤ 0.05) beta carotene
than those of the SPK004/6/6 variety. There was no significant difference (P ≥ 0.05)
between varieties in regards to beta carotene bioaccessibility. Roots stored in pits
retained higher beta carotene content compared to roots stored under other conditions. In
vitro bioaccessibility was significantly higher (P ≤ 0.05) in roots stored in pits compared
to roots stored under saw dust, dark room and ambient conditions. Samples of OFSP
roots stored under ambient and dark room conditions retained the least amount of beta
carotene and had the least amount of bioaccessible beta carotene. There was an increase
in the level of cell wall lignification during storage of OFSP. The extent of lignification
varied with storage method used. The roots stored under ambient and dark room
conditions showed higher levels of lignification compared to those stored under sawdust
and in pits. There were no differences in lignification between the different varieties
studied. The study shows that storage of OFSP roots using methods that maintain low
temperatures leads to higher retention of beta carotene and maintains higher in vitro
bioaccessibility.
Key words: Storage, beta carotene, bioaccessibility, microstructure
3016
Volume 10 No. 8
August 2010
INTRODUCTION
Sweet potato is one of the most important staple crops in developing countries [1].
Orange-fleshed sweet potatoes (OFSP) contain high levels of beta carotene, an important
provitamin A carotenoid [2-5]. Orange-fleshed sweet potatoes can, therefore, help
alleviate vitamin A deficiency [6]. However, carotenoids may be lost during potato root
storage [7]. Traditional storage methods such as storage in bags, pits and open ground
have not been evaluated to determine their impact on the retention of beta carotene
content as well as its bioaccessibility. Bioaccessibility gives an estimate of the amount
of beta carotene that would be potentially absorbed by the body after digestion [8].
Bioaccessibility of provitamin A carotenoids is known to be influenced by the tissue
microstructure, among other factors [9].
During storage, there are many changes that take place in the tissue microstructure of the
sweet potato roots. The physiological and compositional changes that take place include
loss of moisture/water and modification of texture [10, 11]. During storage of sweet
potato roots, starch is degraded into sugars by the action of endogenous amylase,
thereby affecting the microstructure of the sweet potato root tubers [12]. The extent of
these amylase moderated microstructural changes depend on temperature and water
content [13, 14]. These factors vary with storage time. High temperatures, in particular,
are known to increase respiration leading to lignification of the sweet potato cell walls
during storage [15]. The purpose of this study was to establish the effect of storing
OFSP roots under different conditions on their carotenoid content, microstructure and in
vitro bioaccessibility.
MATERIALS AND METHODS
Sweet potato varieties
Two varieties (Ejumula and SPK004/6/6) of OFSP (Ipomoea batatas (L) Lam) were
randomly harvested from a farm at Bombo, Luwero District of Uganda. The roots were
harvested at 4.5 months.
Storage of OFSP
After harvest, sweet potatoes of 200-250g were sorted to remove physically, and pest or
disease damaged roots. The sorted roots were cured naturally in the sun for four days by
spreading them on the ground (26-29 oC, RH 80-95%). The sweet potatoes from each
variety were divided into four portions. For each storage condition and variety, the roots
were divided into three portions, each containing 24 roots. Pit stores were constructed by
digging circular pits of 0.5m diameter and 0.5m depth. Pits were lined with dry spear
grass (Imperata cylindrica) before sweet potato roots were placed there [7]. The sweet
potatoes were then covered with dry spear grass before covering them with soil. The
grass acted as an insulating material and ensured cool conditions in the pits (17oC, RH
95-100%). The pits were then covered with grass-thatched roofing structures to prevent
rain water from entering the storage pits.
3017
Volume 10 No. 8
August 2010
The OFSP roots for dark room and ambient storage conditions were placed in woven
polypropylene sacks, which allowed air circulation. One set of the polypropylene sacks
was stored in a room at ambient conditions (24-28 oC, RH 78-100%) while another was
stored in a well ventilated dark room (24.5-27 oC, RH 77-100%). Another portion of the
OFSP roots was stored under sawdust. Sawdust was obtained from carpentries and then
dried in the sun to a moisture content of about 10%. The dry saw dust was placed in well
ventilated boxes (19-23 oC, RH 92%) containing the sweet potatoes and these were
stored in a well ventilated room.
Sample preparation for analyses
For each of the storage methods, four roots were randomly selected. The roots were cut
longitudinally and two opposite quarters of each removed. The sampled quarters were
cut into thin slices (1-2 mm) and freeze-dried using a Virtis Genesis (American
Lyophilizer, Inc., USA) freeze drier. The freeze-dried samples were packaged under
nitrogen in polythene bags (125 micron) before storage at -50 oC. Before analysis, the
freeze-dried OFSP samples were milled in a coffee grinder (Wagtech, UK) and made to
pass through a 0.2 mm mesh. From each of the four roots sampled for the four storage
methods, three samples were randomly picked for microscopic analysis.
Chemicals and standards
All chemicals, unless stated otherwise, were obtained from BDH (London, UK). The alltrans-beta carotene standard was obtained from CaroteNature GmbH (Lupisingen,
Switzerland). Enzymes porcine pancreatin and pepsin as well as porcine bile extract
were procured from Sigma Chemicals (St. Louis, MO). The water used for analytical
work was double- distilled.
Moisture content
Moisture content was determined by drying 10g of sample in a forced air oven
(Gallenkamp 300 Series, UK) at 105 oC to constant weight for about 20 hours.
Extraction of carotenoids
The OFSP dried samples (~0.2g) were weighed in triplicate into test tubes and
reconstituted with 1 ml of deionised water for 20 min followed by addition of 2 ml of
acetone containing 0.1% (w/v) butylated hydroxy toluene (BHT). Tubes were mixed by
vortex for 3 min and sonicated for 15 min and then centrifuged in a MicroR centrifuge
(Fisher Scientific, UK) for 3 min at 4750xg. The resulting supernatant was saved in a
new test tube. The residue was extracted with 2 ml of acetone and centrifuged again.
This was repeated up to 4 times until the residue was colorless. To the resulting acetone
extract, 3 ml petroleum ether (40-60 oC) was added together with 5 ml deionised water
to aid in the separation of the phases. The organic and water phases were separated by
centrifugation at 4750xg for 4 min and the organic phase was pipetted into a new test
tube. This step was repeated once. The pooled organic phases were collected in a roundbottomed flask and evaporated to dryness under nitrogen in a vacuum evaporator at 35
o
C. The residue was then dissolved in 10 ml mobile phase methanol: methyl-tert-butylether (1:1, v/v) in a flask and filtered through a 0.45
m por
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3018
Volume 10 No. 8
August 2010
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h70%,80%,90
%,96%,
100%,100%,100% f
or1½ h per concentration. Samples were later cleared in two
changes of xylene for 1 h and 1 ½ hours. Lastly, samples were impregnated using two
changes of molten paraffin wax at 50 oC for 2 h per change. After processing, the
samples were embedded in paraffin wax, blocked and sectioned using a Leica RM 2235
rotary microtome (Leica Microsystems, Germany). Sections of 5-7 µm were cut and
floated on a Leica H1120 water bath (Leica Microsystems, Germany). The wrinkle-free
sections were picked on grease-free slides and then dried in the oven at 53 oC. The cut
sections were de-waxed using two changes of xylene for 1-2 min per change. They were
then dehydrated using alcohol, starting with two changes of alcohol of 95% and 80% for
3-5 min per change. The breakdown of cell-wall material was studied using Periodic
Acid Schiffs (PAS)-reaction for visualization of totally insoluble carbohydrate. The
3019
Volume 10 No. 8
August 2010
sections were stained with PAS for 15 min and then dehydrated using ethanol in an
ascending order of concentration, starting with 95% and then two changes of absolute
ethanol for 3-5 min per change. The sections were cleared in two changes of xylene for
1-2 min and then mounted using depex. After mounting, the slides were allowed to air
dry and thereafter examined using a light microscope in objective 40 (Carl Zeiss,
Germany).
Statistical analysis
The data obtained for moisture content, beta carotene content and bioaccessibility were
analyzed using Stata statistical software (Stata Corporation, Texas, and USA).
Comparison between sample treatments was done using analysis of variance (ANOVA)
and means were separated using Bonferroni method. P-values ≤ 0.05 were considered
significant.
RESULTS
Moisture content
The results showed that there was a big drop in moisture content in the first month of
storage (Figure 1). The biggest drop of 3.9% in moisture content was observed in roots
stored under ambient conditions while the least was 1.5% recorded in roots stored in pits
in the first month of storage. There was no significant difference (P ≥ 0.05) between
moisture content of roots stored under ambient conditions and those stored in a dark
room. The OFSP roots stored in the pit maintained significantly (P ≤ 0.05) more
moisture content than any other storage method.
Ejumula
SPK004/6/6
Figure 1: Changes in moisture content of ejumula and SPK004/6/6 OFSP varieties
stored under different conditions
3020
Volume 10 No. 8
August 2010
The amount of beta carotene in roots stored under different conditions tended to increase
in the first month of storage. The amount of beta carotene in stored ejumula samples
increased from 380.5 ± 2.46 to 412.8 ± 2.11
g/
gdr
yma
t
t
e
r
)whi
l
ei
nSPK004i
t
i
nc
r
e
a
s
e
df
r
om 337.
1±15.
38t
o344
.
4±11.
1mg/
gdr
yma
t
t
e
ri
nt
h
ef
i
r
s
tmon
t
h
.
Howe
v
e
r
,t
h
ea
moun
tofb
e
t
ac
a
r
ot
e
n
ei
ns
t
or
e
dr
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sde
c
r
e
a
s
e
di
ns
ubs
e
que
n
tmon
t
h
s
(
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gur
e2)
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e
r
ewa
sn
os
i
gni
f
i
c
a
n
tdi
f
f
e
r
e
n
c
e(
P≥ 0.
05)b
e
t
we
e
nt
h
eb
e
t
ac
a
r
ot
e
n
e
c
on
t
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n
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e
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t
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t
.Th
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e
t
ac
a
r
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e
n
ec
on
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e
n
ti
n
OFSP r
oot
ss
t
or
e
d un
de
ra
mbi
e
n
ta
n
d da
r
kr
oom c
on
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ots
i
gni
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i
c
a
n
t
l
y
di
f
f
e
r
e
n
t(
P ≥ 0.
05
)
.Root
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t
or
e
di
npi
t
sma
i
n
t
a
i
n
e
d hi
gh
e
rbe
t
ac
a
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ot
e
n
ec
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e
n
t
c
ompa
r
e
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oot
ss
t
or
e
d un
de
ra
mbi
e
n
ta
n
d da
r
kr
oom c
on
di
t
i
on
s
.Th
e
r
ewa
sa
s
i
gni
f
i
c
a
n
tdi
f
f
e
r
e
n
c
e(
P ≤ 0.
05)be
t
we
e
nt
h
ebe
t
ac
a
r
ot
e
n
ec
on
t
e
n
ti
nejumula a
n
d
SPK004/
6/
6v
a
r
i
e
t
i
e
s
.
Ejumula
SPK004/6/6
Figure 2: Changes in the content of all-trans-beta carotene (
g/
gdr
ymat
t
e
r
)i
n
ejumula andSPK004/
6/
6OFSPvar
i
e
t
i
e
ss
t
or
e
dunde
rdi
f
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e
r
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ondi
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h
ee
n
doft
h
es
i
mul
a
t
e
d
ga
s
t
r
oi
n
t
e
s
t
i
na
ldi
ge
s
t
i
on
,a
n
dt
h
ei
ni
t
i
a
la
moun
ti
nt
h
ef
r
e
s
hr
oot
sb
e
f
or
es
t
or
a
ge
.In
vitro bi
oa
c
c
e
s
s
i
bi
l
i
t
yofb
e
t
ac
a
r
ot
e
n
ei
nr
oot
ss
t
or
e
di
npi
t
swa
ss
i
gni
f
i
c
a
n
t
l
yhi
gh
e
r(
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0.
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h
a
nt
h
a
tr
e
c
or
de
df
orr
oot
ss
t
or
e
d un
de
rs
a
wdus
t
,da
r
kr
oom a
n
da
mbi
e
n
t
c
on
di
t
i
on
s(
Fi
gur
e3)
.Th
e
r
ewe
r
en
os
i
gni
f
i
c
a
n
tdi
f
f
e
r
e
nc
e
si
nin vitro bi
oa
c
c
e
s
s
i
bi
l
i
t
yof
b
e
t
ac
a
r
ot
e
n
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mon
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or
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on
di
t
i
on
sf
ort
h
ef
i
r
s
tmon
t
hofs
t
or
a
ge
.In vitro
bi
oa
c
c
e
s
s
i
bi
l
i
t
yofb
e
t
ac
a
r
ot
e
n
ei
nr
oot
ss
t
or
e
di
ns
a
wdus
twa
ss
i
gni
f
i
c
a
n
t
l
yhi
gh
e
r(
P≤
0.
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h
a
ni
nr
oot
ss
t
or
e
dun
de
rda
r
kr
oom a
n
da
mbi
e
n
tc
on
di
t
i
on
swhi
l
et
h
e
r
ewa
sn
o
3021
Vol
ume10No.8
Augus
t2010
s
i
gni
f
i
c
a
n
tdi
f
f
e
r
e
nc
e(
P≥ 0.
05)i
nin vitro bi
oa
c
c
e
s
s
i
bi
l
i
t
yofb
e
t
ac
a
r
ot
e
n
ei
nr
oot
s
s
t
or
e
dun
de
rda
r
kr
ooma
n
da
mbi
e
n
tc
on
di
t
i
ons
.Bot
hEjumula a
n
dSPK004/
6/
6va
r
i
e
t
i
e
s
s
h
owe
dn
os
i
gni
f
i
c
a
n
tdi
f
f
e
r
e
n
c
e(
P ≤ 0.
05) i
n pe
r
c
e
n
tin vitro b
e
t
ac
a
r
ot
e
n
e
bi
oa
c
c
e
s
s
i
bi
l
i
t
y
.
Ejumula
SPK004/6/6
Fi
gur
e3:Change
si
nt
hein vitro bi
oac
c
e
s
s
i
bi
l
i
t
yofal
l
-transbe
t
ac
ar
ot
e
nei
n
ejumula andSPK004/
6/
6var
i
e
t
i
e
ss
t
or
e
dunde
rdi
f
f
e
r
e
ntc
ondi
t
i
ons
Th
es
t
or
a
ge pa
r
e
n
c
hyma oft
h
ef
r
e
s
h ejumula a
n
d SPK004/
6/
6 wa
sf
oun
dt
ob
e
c
ompos
e
dofpol
y
he
dr
a
lc
e
l
l
swi
t
hadi
a
me
t
e
rofa
ppr
oxi
ma
t
e
l
y98
m(
Fi
gur
e4a
,b
)
.
Th
ef
r
e
s
hOFSPr
ootc
e
l
l
sc
on
t
a
i
ne
ds
t
a
r
c
hgr
a
n
ul
e
sr
a
n
gi
ngf
r
om gl
ob
ul
a
rt
oe
l
l
i
ps
oi
d
a
n
dofv
a
r
yi
ngs
i
z
e
s
.Th
epa
r
e
nc
hy
maoft
h
es
we
e
tp
ot
a
t
oc
on
t
a
i
ne
ds
e
v
e
r
a
li
n
t
e
r
c
e
l
l
ul
a
r
s
pa
c
e
swhi
c
hwe
r
ea
ppr
oxi
ma
t
e
l
y6.
8
mi
ns
i
z
e
.Th
e
r
ewe
r
en
oma
r
ke
ddi
f
f
e
r
e
n
c
e
s
b
e
t
we
e
n mi
c
r
ogr
a
ph
s of f
r
e
s
h ejumula a
n
d SPK004/
6/
6s
t
or
e
d un
de
r di
f
f
e
r
e
n
t
c
on
di
t
i
on
s
.
3022
Vol
ume10No.8
Augus
t2010
Fi
gur
e4:Themi
c
r
ogr
aphsoff
r
e
s
h ejumula (
a
)and SPK004 (
b)s
t
ai
ne
d wi
t
h
Pe
r
i
odi
cAc
i
dShi
f
fRe
age
nt(
PAS)a
ndobs
e
r
ve
di
nl
i
ghtmi
c
r
os
c
ope
Fi
gur
e5:Themi
c
r
ogr
aphss
howi
ngt
hemi
c
r
os
t
r
uc
t
ur
eofs
t
or
e
dejumula t
ube
r
s
s
t
or
e
dunde
r(
a)pi
t(
b)s
awdus
t(
c
)dar
kr
oom (
d)ambi
e
ntc
ondi
t
i
ons
.
Thes
e
c
t
i
onswe
r
es
t
ai
ne
dus
i
ngPe
r
i
odi
cAc
i
dShi
f
fRe
age
nt(
PAS)and
obs
e
r
ve
dus
i
ngal
i
ghtmi
c
r
os
c
ope
3023
Vol
ume10No.8
Augus
t2010
Th
emi
c
r
ogr
a
ph
ss
h
owe
dt
h
a
ts
t
a
r
c
hgr
a
n
ul
e
sr
e
duc
e
di
nn
umbe
rdur
i
n
gt
h
es
t
or
a
ge
pe
r
i
od.Th
ec
e
l
lwa
l
loft
h
es
t
or
e
dr
oot
swa
st
hi
c
ke
n
e
da
si
tpi
c
ke
dupmor
eoft
h
ePAS
s
t
a
i
na
ss
t
or
a
get
i
mei
n
c
r
e
a
s
e
d.Root
ss
t
or
e
dun
de
ra
mbi
e
n
ta
n
dda
r
kr
oom c
on
di
t
i
on
s
h
a
dmor
et
hi
c
ke
n
e
dc
e
l
lwa
l
l
sc
ompa
r
e
dt
or
oot
ss
t
or
e
di
npi
t
sa
n
ds
a
wdus
t
.Root
ss
t
or
e
d
i
npi
t
sr
e
v
e
a
l
e
dmor
ei
n
t
a
c
ts
t
a
r
c
hgr
a
n
ul
e
st
h
a
nr
oot
ss
t
or
e
dun
de
rs
a
wdus
t
,da
r
kr
oom
ora
mbi
e
n
tc
on
di
t
i
ons
.St
or
a
gec
on
di
t
i
onsa
f
f
e
c
t
e
dt
h
emi
c
r
os
t
r
uc
t
u
r
eofejumula a
n
d
SPK004/
6/
6t
ot
h
es
a
mee
x
t
e
n
t
.
DI
SCUSSI
ON
Change
si
nal
lt
r
ansbe
t
ac
ar
ot
e
nec
ont
e
ntofejumula andSPK004/
6/
6s
t
or
e
dunde
r
di
f
f
e
r
e
ntc
ondi
t
i
ons
Ca
r
ot
e
n
oi
dsa
r
ekn
ownt
ode
c
r
e
a
s
edur
i
n
gs
t
or
a
geofpot
a
t
ot
ub
e
r
s[
20]
.Howe
v
e
r
,ot
h
e
r
s
t
udi
e
sha
v
er
e
por
t
e
da
ni
nc
r
e
a
s
ei
nbe
t
ac
a
r
ot
e
n
ec
on
t
e
n
twhi
c
hwa
sa
t
t
r
i
b
ut
e
dt
ot
h
e
ma
t
ur
i
n
goft
h
es
we
e
tpot
a
t
oe
s[
21,22]
.I
ti
sge
n
e
r
a
l
l
ykn
ownt
h
a
ti
ns
we
e
tpot
a
t
oe
s
,
b
e
t
a
c
a
r
ot
e
n
ei
ss
y
n
t
h
e
s
i
z
e
da
n
da
tt
h
es
a
met
i
mede
s
t
r
oy
e
di
nt
h
er
ooti
t
s
e
l
fdur
i
n
g
s
t
or
a
gea
n
d,t
h
e
r
e
f
or
e
,t
h
ef
i
na
la
moun
tde
pe
ndsont
h
ea
l
ge
b
r
a
i
cs
um oft
het
wo
pr
oc
e
s
s
e
s[
23]
.Th
es
we
e
tpot
a
t
or
oot
ss
t
or
e
di
npi
t
sma
i
n
t
a
i
ne
dahi
gh
e
ra
moun
tofbe
t
a
c
a
r
ot
e
n
ec
ompa
r
e
dt
ot
h
os
es
t
or
e
dun
de
ra
mbi
e
n
ta
n
dda
r
kr
ooms
t
or
a
gec
on
di
t
i
ons
,a
n
d
t
hi
sma
yb
ea
t
t
r
i
b
ut
e
dt
ot
h
el
ow t
e
mpe
r
a
t
ur
e
st
h
a
tp
r
e
v
a
i
l
e
di
nt
h
epi
ts
t
or
e
s
.Th
e
s
t
or
a
get
e
mpe
r
a
t
ur
e
si
nt
h
es
a
wdus
ts
t
or
a
gec
on
di
t
i
onwe
r
ec
l
os
et
ot
h
os
ei
nt
h
epi
t
s
.
Fa
c
t
or
ss
uc
ha
sh
e
a
ta
n
dl
i
gh
th
a
veb
e
e
nobs
e
r
ve
dt
opr
omot
ei
s
ome
r
i
s
a
t
i
onoftransc
a
r
ot
e
n
oi
dst
ot
h
ecisf
or
m[
24]
.Th
el
owe
rb
e
t
ac
a
r
ot
e
n
ec
on
t
e
n
ti
nt
h
er
oot
ss
t
or
e
d
un
de
ra
mbi
e
n
ta
n
d da
r
kr
oom c
on
di
t
i
ons ma
yh
a
ve r
e
s
ul
t
e
df
r
om t
h
e hi
gh
e
r
t
e
mpe
r
a
t
ur
e
s whi
c
hc
a
us
e
d mor
et
h
e
r
ma
lde
gr
a
da
t
i
on
.Howe
v
e
r
,a
l
lt
h
es
t
or
a
ge
c
on
di
t
i
on
sma
i
n
t
a
i
ne
dmor
et
h
a
n100
g/
gdr
yma
t
t
e
rofbe
t
ac
a
r
ot
e
n
e
.Thi
si
st
h
el
e
v
e
l
us
e
dbys
we
e
tp
ot
a
t
ob
r
e
e
de
r
st
os
c
r
e
e
nf
orv
a
r
i
e
t
i
e
st
h
a
tc
a
nr
e
t
a
i
ns
uf
f
i
c
i
e
n
tb
e
t
a
c
a
r
ot
e
n
ea
f
t
e
rp
r
oc
e
s
s
i
ng[
25]
.
Change
si
nt
hein vitro be
t
ac
ar
ot
e
nebi
oac
c
e
s
s
i
bi
l
i
t
yandmi
c
r
os
t
r
uc
t
ur
ei
ns
we
e
t
pot
at
or
oot
ss
t
or
e
dunde
rdi
f
f
e
r
e
ntc
ondi
t
i
ons
Th
er
e
duc
t
i
oni
nbi
oa
c
c
e
s
s
i
bi
l
i
t
yofb
e
t
ac
a
r
ot
e
n
ef
r
oms
t
or
e
dOFSPma
yb
ea
t
t
r
i
b
ut
e
dt
o
l
os
si
nmoi
s
t
ur
ec
on
t
e
n
tt
h
a
tma
yha
v
er
e
s
ul
t
e
di
nh
a
r
de
ni
ngoft
h
eOFSPc
e
l
lwa
l
l
s
.Th
e
OFSPr
oot
st
h
a
twe
r
eke
ptun
de
rl
owt
e
mpe
r
a
t
ur
ec
on
di
t
i
on
sh
a
dhi
gh
e
rpe
r
c
e
n
tin vitro
bi
oa
c
c
e
s
s
i
bi
l
i
t
yt
h
a
nt
h
e on
e
ske
pta
thi
gh
e
rt
e
mpe
r
a
t
ur
e
s
.Th
er
a
t
eofc
e
l
lwa
l
l
t
hi
c
ke
ni
ngi
skn
ownt
ov
a
r
ywi
t
hs
t
or
a
get
i
mea
ndt
e
mpe
r
a
t
ur
e[
26]
.Thi
si
sc
ons
i
s
t
e
n
t
wi
t
ht
h
ehi
gh
e
rin vitro bi
oa
c
c
e
s
s
i
bi
l
i
t
yr
e
c
or
de
di
ns
we
e
tpot
a
t
or
oot
ss
t
or
e
di
npi
t
s
un
de
rl
owe
rt
e
mpe
r
a
t
ur
e
st
h
a
nr
oot
ss
t
or
e
da
ta
mbi
e
n
tt
e
mpe
r
a
t
ur
e
s
.Th
ein vitro
bi
oa
c
c
e
s
s
i
bi
l
i
t
yofs
we
e
tpot
a
t
or
oot
ss
t
or
e
dun
de
rs
a
wdus
twa
sa
l
s
ohi
gh
,a
nob
s
e
r
v
a
t
i
on
a
t
t
r
i
b
ut
e
dt
ot
h
el
ow t
e
mpe
r
a
t
ur
ea
sc
ompa
r
e
dt
oa
mbi
e
n
tc
on
di
t
i
ons
.Th
ei
nc
r
e
a
s
e
d
t
r
a
n
s
pi
r
a
t
i
ona
ta
mbi
e
n
tt
e
mpe
r
a
t
ur
e
sr
e
s
ul
t
e
di
nl
os
sofmoi
s
t
ur
ef
r
om t
h
es
we
e
tpot
a
t
o
r
oot
s
,a
n
dt
hi
sma
yh
a
v
ec
on
t
r
i
b
ut
e
dt
ot
h
ei
nc
r
e
a
s
e
dl
i
gni
f
i
c
a
t
i
onob
s
e
r
v
e
di
nt
he
mi
c
r
os
t
r
uc
t
u
r
ea
n
a
l
y
s
i
s
.Si
mi
l
a
rr
e
s
ul
t
swe
r
er
e
por
t
e
df
ort
r
i
f
ol
i
a
t
ey
a
mt
ub
e
r
swhe
r
et
h
e
t
hi
c
ke
ni
ngoft
h
ec
e
l
lwa
l
la
n
dmi
ddl
el
a
me
l
l
ai
nc
r
e
a
s
e
dwi
t
ht
h
et
e
mpe
r
a
t
ur
eofs
t
or
a
ge
[
27]
.Th
el
os
sofmoi
s
t
ur
eofs
we
e
tpot
a
t
odur
i
n
gs
t
or
a
gema
yha
v
ei
nf
l
ue
nc
e
dt
h
e
3024
Vol
ume10No.8
Augus
t2010
oc
c
ur
r
e
n
c
eofpol
yme
r
i
z
a
t
i
ona
n
de
pi
me
r
i
z
a
t
i
onofc
e
l
lwa
l
lmi
c
r
of
i
br
i
l
sl
e
a
di
ngt
ot
h
e
t
hi
c
ke
ni
ng oft
h
ec
e
l
lwa
l
l
sa
n
ds
ubs
e
que
n
tr
e
l
e
a
s
eofc
a
r
ot
e
n
oi
dsdur
i
ng in vitro
di
ge
s
t
i
on
.Si
nc
et
h
er
a
t
eofmoi
s
t
ur
el
os
si
nr
oot
ss
t
or
e
dun
de
ra
mbi
e
n
tc
on
di
t
i
onswa
s
hi
gh
e
r
,t
h
et
hi
c
ke
ni
ngoft
h
ec
e
l
lwa
l
l
swa
sa
l
s
ohi
gh
e
ra
n
dt
e
n
de
dt
ol
i
mi
tt
h
er
e
l
e
a
s
eof
b
e
t
ac
a
r
ot
e
n
edur
i
n
gin vitro di
ge
s
t
i
on
.
CONCLUSI
ON
Th
el
os
sofb
e
t
ac
a
r
ot
e
n
edur
i
n
gs
t
or
a
geofOFSPc
a
nber
e
duc
e
dbyus
i
ngs
t
or
a
ge
t
e
c
h
ni
que
st
h
a
tma
i
n
t
a
i
nr
e
l
a
t
i
v
e
l
yl
ow t
e
mpe
r
a
t
ur
e
s
.Amon
gt
h
et
r
a
di
t
i
on
a
lme
t
h
ods
c
ommonl
yus
e
di
nEa
s
tAf
r
i
c
af
ors
we
e
tpot
a
t
os
t
or
a
ge
,pi
ts
t
or
a
gema
i
n
t
a
i
ne
db
e
t
a
c
a
r
ot
e
n
ec
on
t
e
n
tqui
t
ewe
l
lwhi
l
es
t
or
a
geun
de
ra
mbi
e
n
tc
on
di
t
i
on
ss
i
gni
f
i
c
a
n
t
l
yr
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e
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ac
a
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ot
e
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ec
on
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e
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ta
n
dbi
oa
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c
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s
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bi
l
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y
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ec
ha
n
ge
si
nbe
t
ac
a
r
ot
e
n
ebi
oa
c
c
e
s
s
i
bi
l
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t
y
s
e
e
mt
oc
or
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e
l
a
t
ewi
t
hc
h
a
n
ge
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nc
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l
lmi
c
r
os
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uc
t
ur
e
.Ce
l
lwa
l
ll
i
gni
f
i
c
a
t
i
ons
e
e
mst
ob
e
a
s
s
oc
i
a
t
e
dwi
t
hr
e
duc
t
i
oni
nb
e
t
ac
a
r
ot
e
n
ebi
oa
c
c
e
s
s
i
bi
l
i
t
y
.Thi
si
nf
or
ma
t
i
onc
oul
db
e
us
e
f
uli
nde
s
i
gni
ngs
t
or
a
ges
y
s
t
e
mst
h
a
te
n
s
ur
ehi
ghin vitro bi
oa
c
c
e
s
s
i
bi
l
i
t
ya
n
dc
on
t
e
n
t
ofb
e
t
ac
a
r
ot
e
n
ei
nOFSP.
ACKNOWLEDGEMENTS
Th
ea
ut
h
or
s woul
dl
i
ke t
oa
c
kn
owl
e
dge t
h
ef
i
na
n
c
i
a
ls
uppor
tf
r
om Ca
r
n
e
r
gi
e
Cor
p
or
a
t
i
onofNe
wYor
k,Nor
we
gi
a
nAge
n
c
yf
orDe
v
e
l
opme
n
tCoope
r
a
t
i
on(
NORAD)
a
n
dBTC/
CTB.
3025
Vol
ume10No.8
Augus
t2010
REFERENCES
1. Bove
l
l
Be
nj
ami
nAC andLTSt
e
veSwe
e
tPot
a
t
o:A r
e
vi
e
w ofi
t
spa
s
t
,pr
e
s
e
n
t
a
n
df
ut
ur
er
ol
ei
nh
uma
nn
ut
r
i
t
i
on
.Adv Food Nutr Res 2007;52:
159.
2. MwangaR,OdongoB,Ni
r
i
ngi
yeCandAAl
aj
oRe
l
e
a
s
eoft
woor
a
n
ge
f
l
e
s
h
e
d
s
we
e
t pot
a
t
oc
ul
t
i
va
r
s
,
'SPK004'(
'
Ka
ka
me
ga
'
)a
n
d'
Ej
umul
a
'
,i
n Uga
n
da
.
HortScience 2007;42:
17281730.
3. Fabe
rM andPJvanJaar
s
ve
l
dTh
epr
oduc
t
i
onofvi
t
a
mi
nAr
i
c
hv
e
ge
t
a
bl
e
si
n
h
ome
ga
r
de
n
sa
same
a
nsofa
ddr
e
s
s
i
ngvi
t
a
mi
nA de
f
i
c
i
e
nc
yi
nr
ur
a
lAf
r
i
c
a
n
c
ommuni
t
i
e
s
.J Sci Food Agric 2007;87:
366377
.
4. HuangAS,Tanudj
aj
aLa
ndDLum Con
t
e
n
tofa
l
ph
a
,b
e
t
ac
a
r
ot
e
n
ea
n
ddi
e
t
a
r
y
f
i
be
ri
n18s
we
e
tpot
a
t
ov
a
r
i
e
t
i
e
sgr
owni
nHa
wa
i
i
.J Food Comp Food Anal 1999;
12:
147151.
5. WuX,SunC,YangL,Ze
ngG,Li
uZandYLiBe
t
ac
a
r
ot
e
n
ec
on
t
e
n
ti
ns
we
e
t
pot
a
t
ov
a
r
i
e
t
i
e
sf
r
omChi
naa
n
dt
h
ee
f
f
e
c
tofpr
e
pa
r
a
t
i
ononb
e
t
ac
a
r
ot
e
n
er
e
t
e
n
t
i
on
i
nt
h
eYa
ns
h
uNo.5.
Inn Food Sci Em Tech 2008;9:
581586.
6. Low JW,Ar
i
mondM,Os
manN,Cunguar
aB,ZanoB andD Ts
c
hi
r
l
e
yA
f
oodb
a
s
e
da
ppr
oa
c
hi
n
t
r
oduc
i
n
gor
a
n
ge
f
l
e
s
h
e
ds
we
e
tpot
a
t
oe
si
n
c
r
e
a
s
e
dvi
t
a
mi
n
Ai
n
t
a
kea
n
ds
e
r
um r
e
t
i
n
olc
on
c
e
n
t
r
a
t
i
on
si
ny
oungc
hi
l
dr
e
ni
nr
ur
a
lMoz
a
mbi
que
.
J Nutr 2007;137:
13207.
7. Namut
e
biA,Nant
abi
r
wa H,Le
maga A,Kapi
nga R,Ma
t
ovu M and S
Tumwe
gamai
r
e Lon
gt
e
r
m s
t
or
a
ge ofs
we
e
tpot
a
t
o by s
ma
l
l
s
c
a
l
ef
a
r
me
r
s
t
h
r
oughi
mpr
ov
e
dpos
th
a
r
v
e
s
tt
e
c
h
n
ol
ogi
e
s
.Ug J Agric Sci 2004;9:
922930.
8. Tanumi
har
dj
oSA Fa
c
t
or
si
nf
l
ue
n
c
i
ngt
h
ec
onve
r
s
i
onofc
a
r
ot
e
n
oi
dst
or
e
t
i
n
ol
:
Bi
oa
va
i
l
a
bi
l
i
t
yt
oc
on
v
e
r
s
i
ont
obi
oe
f
f
i
c
a
c
y
.Int J Vit Res 2002;72:
4045.
9. Cas
t
e
nmi
l
l
e
rJM andCEWe
s
tBi
ov
a
i
l
a
bi
l
i
t
ya
ndbi
oc
onv
e
r
s
i
onofc
a
r
ot
e
n
oi
ds
.
An Nutr Rev 1998;18:
1938
.
10. HuW andSTanakaEf
f
e
c
t
sofhe
a
tt
r
e
a
t
me
n
ti
nt
h
equa
l
i
t
ya
n
ds
t
or
a
gel
i
f
eof
s
we
e
tp
ot
a
t
o.J Sci Food Agric 2007;87:
313319
.
11. Kat
unduGCM,He
ndr
i
c
ksSL,Bowe
rJPandM Si
we
l
aEf
f
e
c
toft
r
a
di
t
i
on
a
l
s
t
or
a
gepr
a
c
t
i
c
e
sofs
ma
l
l
s
c
a
l
eor
ga
ni
cf
a
r
me
r
sonpot
a
t
oqua
l
i
t
y
.J Sci Food
Agric 2007;87:
18201825.
12. Takahat
aY,Takahi
r
oN andSTe
t
s
uoCha
n
ge
si
nc
a
r
b
ohy
dr
a
t
e
sa
n
de
nz
y
me
a
c
t
i
vi
t
i
e
sofs
we
e
t
pot
a
t
ol
i
ne
sdur
i
n
gs
t
or
a
ge
.J Agric Food Chem 1995;43:
19231928.
3026
Vol
ume10No.8
Augus
t2010
13. Pi
c
haDH Ca
r
b
ohy
dr
a
t
ec
h
a
n
ge
si
ns
we
e
tpot
a
t
oe
sdur
i
n
gc
ur
i
n
ga
n
ds
t
or
a
ge
.J
Am Soc Hort Sci 1986;111:
8992.
14. Hage
ni
manaV,Si
mar
dE andLPVe
r
i
naAmyl
ol
y
t
i
ca
c
t
i
vi
t
yi
nge
r
mi
na
t
i
n
g
s
we
e
t
pot
a
t
o(
I
pomoea batatas L.
)r
oot
s
.J Am Soc Hort Sci 1994;119:
313320.
15. Re
e
sD,vanOI
r
s
c
hotQEA,Mbi
l
i
nyiLB,MuhannaM andKIToml
i
nsI
n
:
Re
e
sD,v
a
nOi
r
s
c
h
otQ,Ka
pi
ngaR,e
ds
.Swe
e
tpot
a
t
op
os
t
h
a
r
v
e
s
ta
s
s
e
s
s
me
n
t
:
Ex
pe
r
i
e
nc
e
sf
r
omEa
s
tAf
r
i
c
a
.Ch
a
t
h
a
m:Na
t
ur
a
lRe
s
our
c
eI
n
s
t
i
t
ut
e
,2003:
8592
.
16. He
dr
e
nE,Di
azVandUSve
r
nbur
gEs
t
i
ma
t
i
onofc
a
r
ot
e
n
oi
da
c
c
e
s
s
i
bi
l
i
t
yf
r
om
c
a
r
r
ot
sde
t
e
r
mi
ne
dbya
ni
nvi
t
r
odi
ge
s
t
i
onme
t
h
od.Eur J Clin Nutr 2002;56:
425430.
17. Oome
nAG,Rombe
l
be
r
gCJ,Br
ui
lMA,DobbeCJ,Pe
r
r
e
boom DPandAJ
Si
psDe
ve
l
opme
n
tofa
ni
nvi
t
r
omode
lf
ore
s
t
i
ma
t
i
n
gt
h
ebi
oa
c
c
e
s
s
i
bi
l
i
t
yofs
oi
l
c
on
t
a
mi
na
n
t
s
.Arch Env Cont Toxicol 2003;44:
28
17.
18. Ve
daS,Kamat
hA,Pl
at
e
lK,Be
gum K andK Sr
i
ni
vas
anDe
t
e
r
mi
na
t
i
onof
bi
oa
c
c
e
s
s
i
bi
l
i
t
yofβc
a
r
ot
e
n
ei
nv
e
ge
t
a
bl
e
sbyin vitro me
t
h
ods
.Mol Nutr Food
Res 2006;50:
10471052.
19. Ruz
i
nSE Mi
c
r
ot
e
c
hni
quea
n
dmi
c
r
os
c
opy
.Uni
v
e
r
s
i
t
yofCa
l
i
f
or
ni
a
,Be
r
ke
l
e
y
:
Oxf
or
dUni
ve
r
s
i
t
yPr
e
s
s
,1999.
20. Gr
i
f
f
i
t
hsDW,Dal
eMFB,Mor
r
i
sWLandG Rams
ayEf
f
e
c
tofs
e
a
s
ona
n
dpos
t
h
a
r
v
e
s
ts
t
or
a
geont
h
ec
a
r
ot
e
n
oi
dc
on
t
e
n
tofSolanum phureja pot
a
t
ot
ub
e
r
s
.J
Agric Food Chem 2007;55:
379385.
21. K’
os
amboLM,Car
e
yEE,Mi
s
r
aAK,Wi
l
ke
sJandV Hage
ni
manaI
nf
l
ue
n
c
e
ofa
ge
,f
a
r
mi
ngs
i
t
ea
n
db
oi
l
i
ngonpr
ovi
t
a
mi
nAc
on
t
e
n
tofs
we
e
tpot
a
t
o(
I
pomoea
batatas (L.) Lam.
)
.Food Comp Anal 1998;11:
305
321.
22. RaviVA,Ake
dJandCBal
agopal
anRe
vi
e
w ont
r
opi
c
a
lr
oot
sa
n
dt
ub
e
rc
r
ops
.
St
or
a
geme
t
h
odsa
n
dqua
l
i
t
yc
ha
n
ge
s
.Crit Rev Food Sci Nutr 1996;36:
661709
.
23. Yamamot
oYandYTomi
t
aSt
udi
e
sont
h
ebi
opi
gme
n
t
sa
n
dvi
t
a
mi
ns
:c
or
r
e
c
t
i
v
e
c
h
a
n
ge
si
nt
hec
a
r
ot
e
n
e
,t
ot
a
lc
a
r
ot
e
n
oi
dsa
n
dc
on
s
t
i
t
ue
n
t
sofs
we
e
tpot
a
t
oe
s
dur
i
n
gs
t
or
a
ge
.Ka
gos
hi
maUni
ve
r
s
i
t
yRe
pos
i
t
or
y1958;3:
6368.
24. Rodr
i
gue
z
Amaya DB Ca
r
ot
e
n
oi
ds a
n
df
ood pr
e
pa
r
a
t
i
on
:t
h
er
e
t
e
n
t
i
on of
pr
ovi
t
a
mi
nAc
a
r
ot
e
n
oi
dsi
npr
e
pa
r
e
d,pr
oc
e
s
s
e
da
n
ds
t
or
e
df
oods
.Ar
l
i
n
gt
on
,V.
A:
J
oh
nSn
owI
n
c
/
OMNIPr
oj
e
c
t
,1997.
25. Hage
ni
manaV,Car
e
yEE,Gi
c
huiST,Oy
ungaMAandJ
KI
mungiCa
r
ot
e
n
oi
d
c
on
t
e
n
t
si
nf
r
e
s
hdr
i
e
da
n
dpr
oc
e
s
s
e
ds
we
e
tpot
a
t
opr
oduc
t
s
.Ecol Food Nutr 1999;
37:
455473.
3027
Vol
ume10No.8
Augus
t2010
26. Af
oakwaEO andSSe
f
aDe
de
hCh
a
n
ge
si
nc
e
l
lwa
l
lc
on
s
t
i
t
ue
n
t
sa
n
dme
c
hni
c
a
l
pr
ope
r
t
i
e
sdur
i
n
gpos
t
h
a
r
v
e
s
th
a
r
de
ni
ngoft
r
i
f
ol
i
a
t
ey
a
m Dioscorea dumetorum
(
Kun
t
h
)pa
xt
ub
e
r
s
.Food Res Int 2002;35:
42943
4.
27. Af
oakwaEO andSSe
f
aDe
de
hTe
x
t
ur
a
la
n
dmi
c
r
os
t
r
uc
t
ur
a
lc
h
a
n
ge
sa
s
s
oc
i
a
t
e
d
wi
t
hpos
t
h
a
r
v
e
s
tha
r
de
ni
ngoft
r
i
f
ol
i
a
t
ey
a
m(
Dioscorea dumetorum)pa
xt
ub
e
r
s
.
Food Chem 2001;77:
279284.
3028