Evaluation and Comparison of Postharvest
Cooling Methods on the Microbial Quality and
Storage of Florida Peaches
Jaysankar De1, Bruna Bertoldi1, Mohammad Jubair1,
Alan Gutierrez1, Jeffery K. Brecht2, Steven A. Sargent2,
and Keith R. Schneider1
ADDITIONAL INDEX WORDS. aerobic plate counts, forced-air cooling, hydrocooling,
room-cooling, yeast and mold counts
SUMMARY. Florida peaches (Prunus persica) typically are picked and placed in a cold
room on the day of harvest, then packed and shipped the next day. This room
cooling (RC) is slow, requiring 24 hours or more for the fruit to reach optimal
temperature (6 to 7 C). There is currently limited research on the effect of cooling
practices on microbial quality of peaches, yet this study is essential for decision
making in areas such as upgrading packing house facilities and the implementation
of improved handling procedures. This research compared the efficacies of postharvest cooling by RC, forced-air cooling (FAC), and hydrocooling with sanitizer
(HS) treatment of peaches to reduce their surface microbial population and to determine the effect on shelf life and microbial quality. Three trials for RC and two
trials each for FAC and HS were performed. Following cooling, fruit were stored at
1 C. The average aerobic plate count (APC) from field samples was 5.29 log cfu/
peach, which remained unchanged after RC or FAC but was reduced significantly
(P < 0.05) to 4.63 log cfu/peach after HS. The average yeast and mold counts
(Y&M) from field samples (6.21 log cfu/peach) were reduced highly significantly
(P < 0.001) to 4.05 log cfu/peach after HS. Hydrocooling significantly (P < 0.05)
reduced the APC and Y&M counts from the peaches and showed promise in
maintaining the microbiological quality of the fruit throughout storage. However,
at the end of the 21-day storage period, there was no significant difference in APC or
Y&M counts from peaches, irrespective of the cooling methods. Peaches that went
through the hydrocooling process and were subsequently packed showed an increase (P < 0.05) in both APC and Y&M counts, while fruit that were not hydrocooled showed no such increase. Information obtained will be used to recommend
the best temperature management practices for maintaining the postharvest quality
of peaches. A detailed cost-benefit analysis of different cooling methods and the
time interval between harvest and shipment are both necessary for a more conclusive
recommendation.
I
ncreasing awareness about healthy
eating drives health-conscious
consumers to eat peaches (Prunus persica) because this fruit is
a good source of antioxidants, including vitamin C (Hashem et al., 2019;
Noratto et al., 2014). The United
States occupied the fourth position in
peach production worldwide, with
638,020 tons of used production in
2018 with a value of $511,226 (U.S.
Department of Agriculture, 2019).
Peach acreage in Florida had increased
from 1231 in 2012 to 3000 in 2014
(Olmstead and Morgan, 2013; Olmstead et al., 2015; Singerman et al.,
2017), though there has been a slight
decrease with current estimates of
2000 acres (A. Sarkhosh, personal
communication). One of the main
drivers for increased production is
the availability of new peach cultivars
504
from the University of Florida/Institute of Food and Agriculture Sciences breeding programs that are
firmer, more flavorful, and better
adapted to Florida’s varied microclimates (Sarkhosh et al., 2016; Singerman et al., 2017). In addition, citrus
(Citrus sp.) growers, facing declining
production due to plant disease such
as citrus greening (also known as
Huanglongbing or HLB) caused by
the bacteria Candidatus Liberibacter
asiaticus, have started replacing citrus
acreage with peaches (Nickel, 2018).
During 2015, the Florida Department
of Agriculture and Consumer Services (FDACS) Division of Food,
Nutrition, and Wellness assisted 24
Florida school districts in procuring
an estimated 108,595 lb of peaches
and was responsible for their incorporation into school meal menus
(FDACS, 2015). Considering the
increasing demand for peaches, postharvest processes that extend shelf
life need further study for the benefit of the producer as well as the
consumer.
Peach, as a temperate, climacteric fruit (Guohua et al., 2012;
Hayama et al., 2006; Minas et al.,
2018; Tonutti et al., 1991; Zhang
et al., 2011) undergoes rapid ripening, which accounts for its short shelf
life and represents a serious constraint
for its efficient handling and transportation (Hussain et al., 2008). For
this reason, peaches are often picked
at a preclimacteric stage to withstand
the handling process. However, in
Florida, ripening initiated (‘‘treeripe’’) peaches can be picked due to
widespread planting of cultivars with
the nonmelting flesh trait that imparts
very firm texture (Sarkhosh et al.,
2016). Owing to rapid ripening after
harvest that results in a shortened
shelf life, refrigeration is often used
to store peaches. This has the beneficial effect of extending shelf life both
by maintaining fruit quality and by
reducing storage decay (Wang et al.,
2005; Xi et al., 2012). Conversely,
even though postharvest refrigeration
prolongs shelf life of peaches, this
fruit can easily suffer from chilling
injury (CI) and thereby become more
susceptible to microbial decay. CI,
commonly called ‘‘internal breakdown,’’ can cause flesh browning
and poor overall texture (‘‘mealiness’’) in the fruit (Anderson and
Penney, 1975; Artes et al., 2006;
Units
To convert U.S. to SI,
multiply by
U.S. unit
SI unit
To convert SI to U.S.,
multiply by
29,574
29.5735
2.54
0.4536
1
0.9072
(F – 32) O 1.8
fl oz
fl oz
inch(es)
lb
ppm
ton(s)
F
mL
mL
cm
kg
mLL–1
Mg
C
3.3814 · 10–5
0.0338
0.3937
2.2046
1
1.1023
(C · 1.8) + 32
•
August 2020 30(4)
Brovelli et al., 1998; Byrne, 2002;
Crisosto et al., 1995, 1996; Lurie and
Crisosto, 2005). As a result, several
nondestructive methods have been
developed that use acoustical or infrared (IR) energy to detect CI in
peaches (Byrne, 2002), as well as
irradiation treatment that inhibits ripening and decay (Hussain et al.,
2008). However, such treatments still
need more research before they can
become commercially viable.
Proper temperature management has been shown to be critical
in maintaining postharvest peach
quality (Crisosto and Valero, 2008;
Kader, 2003). However, current
cooling practices used by peach
growers often result in cooling delays
up to 24 h, compromising potential
quality. In many production areas,
peaches are typically picked and
placed in a cold room on the day of
harvest and packed and shipped on
the following day (De et al., 2017).
This form of cooling (room cooling)
is the slowest method and requires 20
h or more for fruit to achieve 7/8
cooling—a decrease in fruit temperature equal to 7/8 of the difference
between the initial fruit temperature
and the cooling medium temperature
(Sargent et al., 2017). Tree-ripe
peaches are already undergoing rapid,
climacteric ripening when they are
harvested, which makes them highly
perishable, thus making temperature
management critical for long distance
marketing to be successful. In addition to ripening, the longer the delay
Received for publication 13 Mar. 2020. Accepted for
publication 7 May 2020.
Published online 30 June 2020.
1
Department of Food Science and Human Nutrition,
Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
2
Horticultural Sciences Department, Institute of
Food and Agricultural Sciences, University of Florida,
Gainesville, FL 32611
This work was supported by the U.S. Department of
Agriculture, Florida Specialty Crop Block Grant Program, under the project ‘‘Temperature Management
for Quality and Safe Florida Blueberries and Peaches’’
(contract no. 00096305).
We thank the Florida peach growers for allowing use
of their facilities.
Current address for M.J.: University of Central Florida, Burnett School of Biomedical Sciences, College of
Medicine, 4110 Libra Drive, Biological Science Building, Suite 133, Orlando, FL 32816-2364.
K.R.S. is the corresponding author. E-mail: keiths29@
ufl.edu.
This is an open access article distributed under the CC
BY-NC-ND license (https://creativecommons.org/
licenses/by-nc-nd/4.0/).
https://doi.org/10.21273/HORTTECH04609-20
•
August 2020 30(4)
to cooling, the more moisture is lost,
and the more sensitive peaches are to
bruising (Ahmadi et al., 2010; Opara
and Pathare, 2014). The need exists
to investigate the impact of cooling
practices on postharvest quality and
shelf life of peaches. Locally grown
peaches have the potential to have far
better quality than imported product
during the harvest season. The increase in production of peaches and
the growing demand is leading
grower/shippers to explore alternative ways to expand their markets
while still maintaining quality. With
the increase in acreage and burgeoning markets for peaches comes a need
for Florida grower/shippers to expand packing and cooling capabilities
within the state. There is currently
a lack of research on effective cooling
practices, which is essential in decision making to assist in the upgrading
of these facilities and the implementation of improved handling procedures.
This research was performed to
compare and evaluate forced-air cooling (FAC) and hydrocooling by
chilled water with sanitizer (HS) as
alternatives to room cooling (RC).
Determination of microbial load from
the surface of untreated field (uncooled), and treated (cooled by RC,
FAC, and HS) peaches (pre- and postpack) were performed to compare the
efficacy of different postharvest cooling methods. In addition, the effect of
these cooling methods in maintaining
microbiological quality during a 21d storage was evaluated. The goal of
this research was to increase the competitiveness of growers, packers, and
shippers of fresh-market peaches by
improving and extending postharvest
quality and ensuring microbiological
safety by investigating the efficacy of
cooling methods and postharvest temperature management.
Materials and methods
FRUIT AND COOLING METHODS.
Freshly harvested ‘UF Sun’ peaches
from several different orchards in
Dundee, FL were collected in field
lugs, palletized, transported to a packinghouse, and cooled by either RC,
FAC, or HS. For RC, pallets were
placed in a commercial cold room
(3.8 C) and held overnight for
14–16 h until packing the next
morning. In FAC trials, pallets were
placed in the cold room and covered
with a large plastic sheet over the top
and two sides. A large fan pulled room
air through the pallets for 2 h, then
the pallets were left overnight in the
same room until packing the next
morning. For HS, pallets were individually loaded into a prototype
shower hydrocooler with commercial
water flow rate and capacity to maintain the chilled water at 2 to 5 C for
1 h. The cooling water was maintained at 150–200 ppm free chlorine
(Cl) at pH 7.0–7.3 during cooling.
Water temperature and pH were measured by a combination pH and oxidation-reduction potential (ORP)
meter (Hanna Instruments USA,
Smithfield, RI); and free Cl concentrations were measured using colorcoded strips (Aquacheck; Hach Co.,
Loveland, CO). Free chlorine levels
were adjusted using a 5.7% to 6%
sodium hypochlorite (NaOCl) solution (Fisher Scientific, Fair Lawn,
NJ), and the pH was adjusted using
muriatic acid (Hach Co.). Duration
for the FAC and HS were chosen to
achieve 7/8 cooling.
Peaches for microbiological analyses were sampled from pallets (field,
uncooled) and after cooling. Each
sample was a composite of five peaches
(diameter 6.5 cm) and was collected
in sterile plastic bags (Stomacher; Seward, Bohemia, NY). Peaches were also
sampled and microbiologically analyzed before and after packing to see
if there was any effect of handling
before they were packed for shipment.
While packing was performed by professional workers, all sampling and
microbiological analyses were performed by trained laboratory personnel. All peach samples, collected either
from pallets or after cooling at the
packing house, were transported in
insulated coolers to the laboratory in
Gainesville, FL and immediately analyzed for aerobic plate counts (APC)
and yeast and mold counts (Y&M).
Cooled peaches were stored at 1.1 C
for 21 d for the shelf-life study. Representative samples were withdrawn
on days 0, 1, 7, 14, and 21. At each
sampling time, three replicates were
sampled. Each sample consisted of five
fruits. Peaches collected from the pallets for microbiological analyses were
not included in the shelf-life experiments. Three trials for RC and two
trials each for FAC and HS were
conducted. Different trials were run
concurrently. All trials were conducted
between 11 Apr. and 10 May 2016.
505
Except the sampling day in early May
2016 for the third trial, the weather
was sunny, hot, and humid. There was
a heavy rainfall on the day before the
sampling day for the third trial.
MICROBIOLOGICAL ANALYSIS. A
100-mL aliquot of 0.1% (w/v) sterile
peptone water (PW) (Thermo Fisher
Scientific, Waltham, MA) was added
to the sterile sample bags and each
peach was rubbed for 30 s to remove
surface bacteria. Bacterial enumeration was performed by 10-fold serial
dilution in 0.1% (w/v) PW. A 100-mL
portion of each dilution was spreadplated onto plate count agar (PCA)
(Difco; Becton, Dickinson and Co.,
Sparks, MD) to determine total mesophilic APC and on potato dextrose
agar (PDA) (Difco; Becton, Dickinson and Co.) for Y&M counts.
Peaches from the post-packing line
were stored at 1.1 C for 21 d.
Representative samples were withdrawn on days 0, 1, 7, 14, and 21;
each were processed for microbiological analysis in the same manner as
described above.
STATISTICAL ANALYSIS. Triplicate
sets of samples, each set containing
five peaches, were collected at each
time point starting from the field
pallets through to the end of the
storage experiment. The RC experiment was repeated three times (n =
3), whereas the FAC and HS experiments were performed twice (n = 2).
Bacterial counts were log (log10)
transformed before statistical analysis.
The limit of detection (LOD) for
colony counts was set to log 1.3
cfu/peach. Multifactorial regression
analysis of the response variables
(APC and Y&M) for treatment (RC,
FAC, HS), day (0, 1, 7, 14, and 21),
and trial (1, 2, 3, and 4) were performed. One-way analysis of variance,
F-test (two-sample for variances), and
t test for individual sample set with
unequal variance were performed to
determine the effects of different
cooling methods on the microbial
quality of peaches during postharvest
cooling, handling, and storage.
Means were calculated and comparisons for all pairs were performed
using the Tukey–Kramer honestly
significant difference analysis. The
level of confidence (a) was set at
0.05. All statistical analysis was performed using JMP Pro (version 14;
SAS Institute, Cary, NC) and Microsoft Excel (version 1808, Microsoft
506
Office 365 ProPlus; Microsoft Corp.,
Redmond, WA).
Results
Pulp temperatures of the freshly
harvested fruit were 29 to 32 C and
the fruit were cooled to 6.7 and
3.8 C after FAC and HS, respectively. There were differences between trials for APC and Y&M
counts from peaches. Field samples
were compared among four trials,
whereas RC samples were compared
among three trials. The FAC and HS
samples were compared among the
last two trials (Tables 1 and 2) because they were not performed in the
first two trials. The APC in field and
RC samples were the highest in the
third trial (Table 1). There was no
significant difference (P > 0.05)
among trials in Y&M counts from
field samples or in FAC or HS samples, but the RC samples had significantly higher Y&M counts in the
third trial (Table 2). The average
APC from field samples was 5.29 log
cfu/peach, which remained almost
unchanged after RC or FAC, but it
was significantly (P < 0.05) reduced
to 4.63 log cfu/peach after HS (Table
3). The average Y&M counts from
field samples (6.22 log cfu/peach)
was reduced highly significantly (P <
0.001) to 4.05 log cfu/peach after
HS (Table 4).
Sorting and packing significantly
increased both APC and Y&M counts
on hydrocooled peaches (P < 0.05),
while these activities showed no such
effect on RC or FAC peaches. The
APC on RC peaches remained unchanged (5.20 log cfu/peach) before
and after packing. These counts increased slightly (P > 0.05) on FAC
peaches, from 5.35 to 5.60 log cfu/
peach, before and after packing, respectively. The APC on HS peaches
increased significantly (P < 0.05),
from 4.63 to 5.18 log cfu/peach,
before and after packing, respectively.
The Y&M counts on RC peaches
was reduced from 6.11 to 6.02 log
cfu/peach from before to after packing. These counts increased slightly
(P > 0.05) on FAC peaches, from
6.07 to 6.14 log cfu/peach, from
before to after packing. The Y&M
Table 1. Comparison of aerobic plate counts (APC) on uncooled peaches and
those cooled by room cooling (RC), forced-air cooling (FAC), and hydrocooling
with sanitizer (HS).
Treatmentz
Field
Trial no.
1
2
3
4
RC
FAC
APC [least square mean ±SE (log cfu/peach)]y
4.73 ± 0.17 bx
4.73 ± 0.17 b
6.16 ± 0.17 a
5.57 ± 0.17 a
4.33 ± 0.13 c
5.03 ± 0.13 b
6.20 ± 0.13 a
NT
NT
NT
4.63 ± 0.03 b
6.06 ± 0.03 a
HS
NT
NT
4.37 ± 0.06 b
4.90 ± 0.06 a
z
RC treatment was 14–16 h. FAC and HS treatments were 2 and 1 h, respectively.
Reported values are of APC from four individual trials. RC was performed three times (n = 3); FAC and HS were
performed two times each (n = 2); NT = not tested.
x
Values with the same letters within columns for the same treatment are not significantly different (P > 0.05) via
Tukey–Kramer honestly significant difference analysis.
y
Table 2. Comparison of yeast and mold counts (Y&M) on uncooled peaches and
those cooled by room cooling (RC), forced-air cooling (FAC), and hydrocooling
with sanitizer (HS).
Treatmentz
Field
Trial no.
1
2
3
4
RC
FAC
Y&M [least square mean ±SE (log cfu/peach)]y
6.43 ± 0.17 ax
6.03 ± 0.17 a
6.27 ± 0.17 a
6.17 ± 0.17 a
6.00 ± 0.05 b
5.96 ± 0.05 b
6.33 ± 0.05 a
NT
NT
NT
6.01 ± 0.10 a
6.10 ± 0.10 a
HS
NT
NT
3.97 ± 0.21 a
4.13 ± 0.21 a
z
RC treatment was 14–16 h. FAC and HS treatments were 2 and 1 h, respectively.
Reported values are of APC from four individual trials. RC was performed three times (n = 3); FAC and HS were
performed two times each (n = 2); NT = not tested.
x
Values with the same letters within columns for the same treatment are not significantly different (P > 0.05) via
Tukey–Kramer honestly significant difference analysis.
y
•
August 2020 30(4)
Table 3. Effect of postharvest room cooling (RC), forced-air cooling (FAC), and
hydrocooling with sanitizer (HS) on aerobic plate counts (APC) during peach
storage.
Treatmenty
Field
RC
FAC
APC [mean ±SE (log cfu/peach)]x
Storage (d)z
5.29 ± 0.11 aw
NT
NT
NT
NT
0
1
7
14
21
5.19 ± 0.23 a Aw
5.18 ± 0.23 a A
5.23 ± 0.23 a A
5.24 ± 0.23 a A
4.90 ± 0.23 a A
5.35 ± 0.19 a A
5.62 ± 0.19 a A
5.15 ± 0.19 a A
5.23 ± 0.19 a A
4.85 ± 0.19 a A
HS
4.63 ± 0.16 b B
5.18 ± 0.16 ab AB
5.50 ± 0.16 a A
4.75 ± 0.16 b B
4.80 ± 0.16 b B
z
Day 0 values were obtained immediately after harvesting (field) and cooling treatments. Day 1 values were
obtained from packed samples.
y
RC treatment was 14–16 h. FAC and HS treatments were 2 and 1 h, respectively.
x
Reported values are of APC from all trials. RC was performed three times (n = 3); FAC and HS were performed
two times each (n = 2); NT = not tested.
w
Values with the same letters within columns (a, b, c) for the same treatment, or within rows (A, B, C) for the same
day, are not significantly different (P > 0.05) via Tukey–Kramer honestly significant difference analysis.
Table 4. Effect of postharvest room cooling (RC), forced-air cooling (FAC), and
hydrocooling with sanitizer (HS) on yeast and mold counts (Y&M) during peach
storage.
Treatmenty
RC
FAC
Y&M [mean ±SE (log cfu/peach)]x
Field
Storage
(d)z
6.22 ± 0.11 aw
NT
NT
NT
NT
0
1
7
14
21
6.11 ± 0.06 a Aw
6.03 ± 0.06 a A
6.06 ± 0.06 a A
6.20 ± 0.06 a A
6.17 ± 0.06 a A
6.08 ± 0.07 ab A
6.17 ± 0.07 a A
5.95 ± 0.07 b AB
5.90 ± 0.07 bc AB
5.73 ± 0.07 c B
HS
4.05 ± 0.16 c C
5.21 ± 0.16 b B
5.95 ± 0.16 a A
5.23 ± 0.16 b B
5.83 ± 0.16 ab AB
z
Day 0 values were obtained immediately after harvesting (field) and cooling treatments. Day 1 values were
obtained from packed samples.
y
RC treatment was 14–16 h. FAC and HS treatments were 2 and 1 h, respectively.
x
Reported values are of Y&M from all trials. RC were performed three times each (n = 3); FAC and HS were
performed two times each (n = 2); NT = not tested.
w
Values with the same letters within columns (a, b, c) for the same treatment, or within rows (A, B, C) for the same
day, are not significantly different (P > 0.05) via Tukey–Kramer honestly significant difference analysis.
counts on HS peaches increased
significantly (P < 0.05), from 4.05
to 5.21 log cfu/peach, from before
to after packing.
Cooling peaches by HS significantly reduced (P < 0.05) the APC
from 5.29 log cfu/peach on uncooled (field) peaches to 4.63 log
cfu/peach on day 0 samples. There
was no such effect noted for RC nor
FAC, where the APC on peaches
remained almost the same until day
14. At the end of the 21-d storage
period, there was no significant effect
of different cooling methods on the
APC (Table 3). The average Y&M
counts significantly (P < 0.05) declined, from 6.22 log cfu/peach on
uncooled (field) peaches to 4.05 log
cfu/peach on HS peaches. Reduction
of Y&M counts were not significant
for RC (6.11 log cfu/peach) nor FAC
(6.08 log cfu/peach) peaches (Table
•
August 2020 30(4)
4). At the end of the 21-d storage
period, the Y&M counts on RC
peaches were 6.17 log cfu/peach,
which was significantly higher (P <
0.05) than the FAC (5.73 log cfu/
peach) or HS (5.83 log cfu/peach)
peaches (Table 4).
Discussion
The quality of peaches after harvest can only be maintained, not
improved, a situation that makes temperature management crucial for reducing the rate of losses of quality.
Similarly, effective temperature management contributes to the microbial
quality of peach fruit by reducing the
rate of microbial proliferation during
storage and marketing. Peaches can
be damaged by rough handling, especially when picked at an advanced
(tree ripe) stage of development.
Peaches are highly perishable after
harvest, and cold storage is required
to minimize deterioration rates and
delay softening. For this reason,
packers and shippers emphasize
means to maintain firm fruit to aid
in maximizing the storage, shipping,
and retail market life potential (Crisosto and Costa, 2008). Cooling fruit
to 7/8 cool before packing and shipping can extend shelf life. It has been
recommended that peaches picked at
the preclimacteric stage should be
cooled to 5 to 10 C within 6 to 8
h, and to 0 C within 24 h of harvest,
whereas tree-ripe peaches should be
cooled to near 0 C within 6 to 8 h of
harvest (Crisosto et al., 1995). In the
present study, uncooled field samples
were used only to determine initial
microbial loads and were not included in the storage experiment.
These initial microbial loads were
compared with those taken from
peaches following cooling to determine the effects of cooling method on
microbial populations.
Postharvest loss of stone fruits to
decay-causing fungi is considered
the greatest deterioration problem
(Crisosto et al., 1995). Worldwide,
the most important pathogen of fresh
stone fruits is grey mold or botrytis
rot, caused by the fungus Botrytis
cinerea. In southern Florida, though
not to a greater extent, cause of loss
due to decay is caused by the brown
rot fungi Monilinia fructicola, Monilinia laxa, or Monilinia fructigena
(Bernat et al., 2017; Garcia-Benitez
et al., 2017). These fungi have different survival potentials and can proliferate during refrigerated storage
(Garcia-Benitez et al., 2017) or at
higher temperatures (30 to 33 C)
(Bernat et al., 2017). During the 21d storage there was a significant increase in Y&M counts on HS peaches,
though their identification was beyond the scope of the current study.
In this study APC counts on the
fruit did not increase significantly
during storage—thus maintained microbiological quality irrespective of the
cooling method used. The APC on
incoming field fruit was significantly
higher (P < 0.05) in the third trial than
in the other two trials (Table 1),
possibly due to heavy rainfall before
harvest. The HS in this experiment
resulted in rapid cooling of the fruit
and significantly greater reduction
of the postharvest loads of APC and
Y&M on the peaches and showed
507
promise in maintaining the microbiological quality of the fruit throughout the storage. Both RC and FAC
also were able to keep the microbiological load of the peaches under
control; though, unlike the HS, they
did not reduce the initial loads on
the peaches. However, at the end of
the 21-d storage period there was no
difference in microbiological quality
of the peaches, irrespective of the
cooling method used. An important
factor to be considered here is the
time involved in the three different
cooling methods. In that regard, RC
took overnight, FAC took 2 h,
whereas HS took about 1 h to reach
the target 7/8 cooling temperature.
Peaches that were hydrocooled (HS)
and subsequently packed showed an
increase (P < 0.05) in both APC and
Y&M counts, while fruit that were not
hydrocooled showed no such increase. This increase could possibly
be due to handling of the wet peaches
during packing, negating the benefits
seen in peaches sampled directly post
HS. Initial sanitation during hydrocooling (only used on the HS) reduced microbial load compared with
RC and FAC. However, the benefits
rapidly disappeared during cold storage. Thus, this result demonstrated
that sanitation must be enforced and
supervised during all packing process.
While considering the efficacy of
these cooling methods, a detailed economic analysis comparing all the three
methods is necessary to reach any
conclusion and make a recommendation to peach handlers. Peaches cooled
by HS had lower microbial loads compared with the peaches cooled by the
other two methods. Moreover, HS
peaches, owing to shorter cooling
time, could also be available for packing and shipping on the day of harvest,
which would reduce the delay in
shipment and market distribution of
peaches.
Literature cited
Ahmadi, E., H.R. Ghassemzadeh, M.
Sadeghi, M. Moghaddam, and S.Z.
Neshat. 2010. The effect of impact and
fruit properties on the bruising of peach.
J. Food Eng. 97:110–117.
Anderson, R.E. and R.W. Penney. 1975.
Intermittent warming of peaches and
nectarines stored in a controlled atmosphere or air. J. Amer. Soc. Hort. Sci.
100:151–153.
508
Artes, F., P.A. G
omez, and F. ArtesHernandez. 2006. Physical, physiological
and microbial deterioration of minimally
fresh processed fruits and vegetables.
Food Sci. Technol. Intl. 13:177–178.
Bernat, M., J. Segarra, C. Casals, N.
Teixid
o, R. Torres, and J. Usall. 2017.
Relevance of the main postharvest handling operations on the development of
brown rot disease on stone fruits. J. Sci.
Food Agr. 97:5319–5326.
Brovelli, E.A., J.K. Brecht, W.B. Sherman, and C.A. Sims. 1998. Quality of
fresh-market melting- and nonmeltingflesh peach genotypes as affected by
postharvest chilling. J. Food Sci. 63:730–
733.
Byrne, D.H. 2002. Peach breeding trends:
A world wide perspective. Acta Hort.
592:49–59.
Crisosto, C.H. and D. Valero. 2008.
Harvesting and postharvest handling of
peaches for the fresh market, p. 575–596.
In: D.R. Layne and D. Bassi (eds.). The
peach: Botany, production and uses. CAB
Intl., Wallingford, UK.
Crisosto, C.H., F.G. Mitchell, and S.
Johnson. 1995. Factors in fresh market
stone fruit quality. Postharvest News Inf.
6:17N–21N.
Crisosto, C.H., E.J. Mitcham, and A.A.
Kader. 1996. Peaches and nectarines.
Recommendations for maintaining postharvest quality. Perishables Handling
Nwsl. 86:17–18.
Crisosto, C.H. and G. Costa. 2008. Preharvest factors affecting peach quality, p.
536–549. In: D.R. Layne and D. Bassi
(eds.). The peach: Botany, production
and uses. CAB Intl., Wallingford, UK.
De, J., B. Bertoldi, A. Gutierrez, J.
Mohammad, S. Sargent, and K.R. Schneider.
2017. Effect of postharvest cooling on
the microbial quality and storage of
Florida peaches. Intl. Assn. Food Protection
(IAFP) Annu. Mtg., 9–12 July 2017,
Tampa, FL. P1-44. J. Food Prot. Supplement p. 98.
Florida Department of Agriculture and
Consumer Services (FDACS). 2015. Annual
report. 25 Dec. 2019. <https://www.
freshfromflorida.com/content/download/
68787/1616663/2015-FDACS-AnnualReport.pdf>.
Garcia-Benitez, C., P. Melgarejo, and A.
De Cal. 2017. Fruit maturity and postharvest environmental conditions influence the pre-penetration stages of
Monilinia infections in peaches. Intl. J.
Food Microbiol. 241:117–122.
Guohua, H., W. Yuling, Y. Dandan, D.
Wenwen, Z. Linshan, and W. Lvye. 2012.
Study of peach freshness predictive
method based on electronic nose. Food
Control 28:25–32.
Hashem, M., S.A.M. Alamri, M.S.A.
Alqahtani, and S.R.Z. Alshehri. 2019. A
multiple volatile oil blend prolongs the
shelf life of peach fruit and suppresses
postharvest spoilage. Scientia Hort.
251:48–58.
Hayama, H., M. Tatsuki, A. Ito, and Y.
Kashimura. 2006. Ethylene and fruit
softening in the stony hard mutation in
peach. Postharvest Biol. Technol. 41:16–
21.
Hussain, P.R., R.S. Meena, M.A. Dar, and
A.M. Wani. 2008. Studies on enhancing
the keeping quality of peach (Prunus
persica Bausch) cv. Elberta by gamma-irradiation. Radiat. Phys. Chem. 77:473–
481.
Kader, A.A. 2003. A perspective on
postharvest horticulture (1978–2003).
HortScience 38:1004–1008.
Lurie, S. and C.H. Crisosto. 2005.
Chilling injury in peach and nectarine.
Postharvest Biol. Technol. 37:195–208.
Minas, I.S., T. Georgia, and A. Molassiotis. 2018. Environmental and orchard
bases of peach fruit quality. Scientia Hort.
235:307–322.
Nickel, A. 2018. Growers optimistic for
Florida crop. 25 Dec. 2019. <https://
www.thepacker.com/article/growersoptimistic-florida-peach-crop>.
Noratto, G., W. Porter, D. Byrne, and L.
Cisneros-Zevallos. 2014. Polyphenolics
from peach (Prunus persica var. Rich
Lady) inhibit tumor growth and metastasis of MDA-MB-435 breast cancer cells
in vivo. J. Nutr. Biochem. 25:796–800.
Olmstead, M. and K. Morgan. 2013. Orchard establishment budget for peaches
and nectarines in Florida. 25 Dec. 2019.
<http://edis.ifas.ufl.edu/hs1223>.
Olmstead, M.A., J.L. Gilbert, T.A. Colquhoun, D.G. Clark, R. Kluson, and H.R.
Moskowitz. 2015. In pursuit of the perfect peach: Consumer-assisted selection of
peach fruit traits. HortScience 50:1202–
1212.
Opara, L.U. and B.P. Pathare. 2014.
Bruise damage measurement and analysis
of fresh horticultural produce—A review.
Postharvest Biol. Technol. 91:9–24.
Sargent, S.A., A.D. Berry, J.K. Brecht, M.
Santana, S. Zhang, and N. Ristow. 2017.
Studies on quality of southern highbush
blueberry cultivars: Effects of pulp temperature, impact and hydrocooling. Acta
Hort. 1180:497–502.
•
August 2020 30(4)
Sarkhosh, A., M.A. Olmstead, J.X. Chaparro, P. Andersen, and J. Williamson. 2016.
Florida peach and nectarine varieties. 25 Dec.
2019. <http://edis.ifas.ufl.edu/mg374>.
Singerman, A., M. Burani-Arouca, and M.
Olmstead. 2017. Establishment and production costs for peach orchards in Florida:
Enterprise budget and profitability analysis. 25 Dec. 2019. <https://edis.ifas.ufl.
edu/pdffiles/FE/FE101600.pdf>.
Tonutti, P., P. Casson, and R. Ramina.
1991. Ethylene biosynthesis during peach
fruit development. J. Amer. Soc. Hort.
Sci. 116:274–279.
•
August 2020 30(4)
U.S. Department of Agriculture. 2019.
Noncitrus Fruits and Nuts: 2018 Summary.
June 2019. <https://www.nass.usda.gov/
Publications/Todays_Reports/reports/
ncit0619.pdf>.
Wang, Y.-S., S.-P. Tian, and Y. Xu. 2005.
Effects of high oxygen concentration on
pro- and anti-oxidant enzymes in peach
fruits during postharvest periods. Food
Chem. 91:99–104.
Xi, W.-P., B. Zhang, L. Liang, J.-Y. Shen,
W.-W. Wei, C.-J. Xu, A.C. Allan, I.B.
Ferguson, and K.-S. Chen. 2012. Postharvest temperature influences volatile
lactone production via regulation of acylCoA oxidases in peach fruit. Plant Cell
Environ. 35:534–545.
Zhang, L., Z. Yu, L. Jiang, J. Jiang, H.
Luo, and L. Fu. 2011. Effect of postharvest heat treatment on proteome
change of peach fruit during ripening. J.
Proteomics 74:1135–1149.
509