LWT - Food Science and Technology 75 (2017) 243e250

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LWT - Food Science and Technology

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Evolution of cherries texture in brine: Impact of harvest conditions

during long-time storage
Wael Wahib a, b, c, d, *, Jean François Maingonnat a, b, Ulrich Fleury d,
Mohamed El-Maataoui c, Catherine M.G.C. Renard a, b
a
INRA, UMR408 SQPOV, Avignon, France
b
Universit

e d'Avignon, UMR408 SQPOV, Avignon, France
c
Universit

e d'Avignon, UMR Qualisud, Avignon, France
d
Aptunion Industrie, Apt, France

a r t i c l e i n f o a b s t r a c t

Article history: Texture is a primary quality attribute of brined sweet cherries (Prunus avium L.) and its preservation is a
Received 8 June 2016 major objective for candying industry. In order to identify the harvest factors influencing textural
Received in revised form changes during long period brine storage, different itineraries were applied: harvest at two different
10 August 2016
maturity stages, treatment or not with ethephon, manual or mechanical harvest, removal or not of pe-
Accepted 30 August 2016
duncles. The cherries were immersed in brine and examined over a 12-months period for firmness,
Available online 31 August 2016
calcium and total soluble solids diffusion and cytohistological remodelling. Mechanical harvesting,
harvest at late maturity stage and storage with peduncle decreased firmness while ethephon treatment
Keywords:
Prunus avium L.
had no effect. However, only presence or absence of peduncles influenced salt and total soluble solids
Firmness diffusion, suggesting that peduncle removal promotes osmotic exchanges.
Candied cherries Brine storage led to a texture gain in the first two months in most cases compared to fresh cherries, as
Brine confirmed by a beneficial reshuffle at cytohistological level. This explains why it can allow storage of
Cytohistology cherries for candying over the whole duration between two harvest seasons.
Cell wall © 2016 Published by Elsevier Ltd.

1. Introduction that initiates a signal transduction leading to acceleration of cell-

wall degrading enzymes and cell death in the abscission zone
Sweet cherries (Prunus avium L. cv. Napole
on) produced in (Estornell, Agusti, Merelo, Talon, and Tadeo (2013); Hall., Shakeel, &


Vaucluse (South France) are mainly intended for processing to glace Schaller (2007)). In the case of cherries, approximately 80% fruits
cherries, represented 10.000 tons of final product, with 70% fall without peduncle. However, this harvesting method is not a
destined for more than 60 countries. They must be harvested rule and manually harvested cherries still represent 20% of total
within a short time (3e4 weeks) and are then stored in brine for quantity delivered to industry (Ulrich Fleury, personal
candying all along the year. The narrow window of harvesting communication).
prompted growers to adopt mechanical methods based on the use Between harvest and candying, cherry fruits are stored in brine
of ethephon (2-chloroethyl phosphonic acid) and harvesting at an containing sulfur dioxide and calcium salts. Acidity and sulphites
earlier stage. The ethylene released by Ethephon induces a decrease protect fruit from microorganism proliferation due to SO2 anti-
of the pedicel-fruit retention force in sweet cherry (Smith & septic effects (Dupuy, 1959; Julien, 1972). Calcium salts act on
Whiting, 2007). This is mediated by its binding to receptor sites cherries firmness, as also noted to improve texture for pickled cu-
cumbers (Hudson & Buescher, 1985). Sulfur dioxide and calcium are
directly related to brined cherry quality. Improper use of these
* Corresponding author. INRA, UMR408 SQPOV, Avignon, France. e Universite
chemicals may result in cherries that are soft, poorly bleached, or
d’Avignon, UMR408 SQPOV, Avignon, France. e Universite
d’Avignon, UMR
spoiled due to fermentation (Payne, Beavers, Cain, & Station
Qualisud, Avignon, France. e Aptunion Industrie, Apt, France.
E-mail addresses: wael.wahib@aptunion.com (W. Wahib), jean-francois.
(1969)). Atkinson and Strachan (1962) pointed out other advan-
Maingonnat@avignon.inra.fr (J.F. Maingonnat), ulrich.fleury@aptunion.com tages of sulfur dioxide as a preservative. It is inexpensive and
(U. Fleury), mohamed.elmaataoui@univ-avignon.fr (M. El-Maataoui), catherine. provides a quick method of handling large quantities of fruit. The
renard@avignon.inra.fr (C.M.G.C. Renard).

http://dx.doi.org/10.1016/j.lwt.2016.08.059
0023-6438/© 2016 Published by Elsevier Ltd.
244 W. Wahib et al. / LWT - Food Science and Technology 75 (2017) 243e250

product may be placed in bulk containers for shipment, and the Aptunion, Apt, France) for storage with 50/50 ratio fruit/brine.
preservative is effective for a sufficient period of time to allow for Fruits (1) and (3) were stored in brine with their peduncle and fruits
storage and remanufacture. In addition, most of the sulfur dioxide (2) and (4) without peduncle (Table 1).
can be removed easily and inexpensively before candying, so that Samples were taken at 0, 2, 5, 8, and 15 days and at 1, 2, 3, 4, 5, 6,
this allergen is absent (Aptunion, internal analysis) in the glace
7, 8, 10 and 12 months in brine.
cherries. Moreover, storing for a long period without loss of fruit
quality is one of industries objectives. 2.2. Fruit texture characterization
Firmness loss during fruit development is associated with cell-
wall polysaccharide turnover (Brummell & Harpster, 2001). Cher- For each treatment, 62 cherries (randomly chosen) were placed
ry cell walls are modified in harvesting, whether after chemical in holes, with the peduncle scar on top (Fig. 1). They were pitted
ethephon treatment (Batisse, Coulomb, Coulomb, and Buret (1998)) with a texture analyser TA Plus (Ametek, Lloyd Instruments Ltd,
or natural ripening-overripening mechanism (Batisse, Filslycaon, Fareham, UK) using an 8 mm diameter probe moving at 20 mm s1
and Buret (1994)) leading to softness. Some of the genotypic vari- for a course of 40 mm after first contact. The maximum load
ations in fruit firmness have been linked with differences in the (Newton) during pitting, captured by a 250 N load cell, is our cri-
patterns of cell-wall disassembly. For example, Cheol, Toivonen, terion to define the texture quality. It was chosen as the texture test
Wiersma, and Kappel (2002) reported that soft varieties present as it is representative of the actual process, pitting being a critical
lower total cell wall contents in fresh fruit. Taillan, Ambid, Pech, and point in the processing to glace
cherries, and presented a good
Raynal (1992) demonstrated that pectic fractions were the main correlation with a compression test such as routinely applied to
cell wall component modified during cherries storage in aluminium other fruits, e.g. in Grotte, Duprat, Loonis, and Pietri (2001);
or calcium brines; fruits stored in calcium brine present a better Missang, Maingonnat, Renard, and Audergon (2011).
firmness than in aluminium brine leading industry to continually
improve brine formulation to increase the quality of stored fruits. 2.3. Physico-chemical characterizations
However, other factors have been reported to be important
modulators for cherry post harvest behaviour. Richardson et al. The total soluble solids (TSS) or Brix were measured in the brine
(1998) reported that some harvest factors are susceptible to affect with an ATAGO PR-1 Digital Refractometer (Atago Co., LTD, Tokyo,
sweet cherries P. avium cv. Royal Ann texture, such as machine Japan). Indeed, brine TSS is complementary to fruit TSS due to the
factors (pattern of tree shaking, duration of shakes, etc.), climatic diffusion phenomenon that leads to an equilibrium state.
conditions, crop loads, tree sizes or their spacing. Since this early Calcium concentration in the brine was measured by Atomic
work, no studies have attempted to evaluate the consequences of absorption spectroscopy on a Varian AA 55 (Agilent technologies,
other harvest itineraries on the evolution of the quality of cherries Santa Clara, USA) equipped with an acetylene/nitrous oxide burner.
in brine. Understanding the impact of the harvest conditions on
cherry texture evolution during storage is of major importance for 2.4. Microscopy
the industry. In the present study, evolution of firmness during
brine storage was quantified according to the fruits maturity stage, Cytohistological analyses were performed using tissue samples
the harvesting method, the ethephon application and the peduncle excised from median part of fruits going from exocarp to endocarp
presence. Cytohistological investigations have been performed to (Fig. 2). Immediately after excision all specimens were immersed in
follow the gross structural alterations during storage in brine. fixative solution consisting of 10% Acetic acid 10% Formalin and 80%
Ethanol. To promote good penetration of the fixative product
2. Materials and methods samples were subjected to vacuum for 20 min. After 48 h fixation at
room temperature, the specimens were rinsed in distilled water
2.1. Plant material and stored in 70% ethanol until required. They were then dehy-
drated in a graded ethanol series (80e100%) and embedded in

on) for industry
Fruit of sweet cherry (Prunus avium L., cv. Napole methacrylate resin (Kit Technovit 7100, Heraeus-Kulzer GmbH,
were harvested in Provence (Lagnes 43
530 3900 N and 5
060 5500 ) in
June 2013. Table 1 summarizes the different treatments and harvest
conditions. Ethephon (PRM12, Bayer S.A.S, Lyon, France) was
applied at 0.36 g L1 on vigorous trees [conditions (1) and (2)], by
high humidity and 20
C (standard treatment). Untreated trees
were also included in the study (conditions (3) and (4)). Cherries
were picked at 10 “early” and 20 “late” days after treatment with
ethephon corresponding to the beginning and end of the harvest.
The fruits were harvested mechanically [condition (2)] or manually
(1), (3) and (4) then immediately immersed in brine tanks (Type

Table 1
: Summary of the different treatments and harvest conditions for the different sweet
cherry samples. Ethephon was applied at 0.36 g l1; mechanical harvest stored in
industrial container and manual harvest stored in bucket for practically. Each sample
was picked at to maturity stage “early” and “late”.

Sample 1 2 3 4

Ethephon þ þ e e
Peduncle þ e þ e
Harvest method Manual Mechanical Manual Manual
Container (m3) 0.025 3 0.025 0.025
Fig. 1. Sweet cherry disposition and orientation for firmness measurements.
 W. Wahib et al. / LWT - Food Science and Technology 75 (2017) 243e250 245

darkfield, phase contrast and UV illuminations. Images were

captured using Leica DFC 300 FX digital camera and processed
using LAS software (Leica, Wetzlar, Germany). At least 6 fruits were
analysed per treatment.

2.5. Statistics

All statistics were performed using R i386 3.1.2 software (R

Foundation for Statistical Computing, Vienna, Austria). Prior to
analysis data were tested using Shapiro-Wilk normality test to
verify the distribution. Mean and Sd were calculated and one-way
analysis of variance (ANOVA) and the Tukey post-hoc test were
applied to verify the significance of differences between firmness,
TSS and calcium levels in fruits from different harvest conditions.

3. Results and discussion

Fig. 2. Cherry fruit pericarp with the 3 zones of cytohistological interesting: exocarp,
middle mesocarp and deep mesocarp.
3.1. General evolution of texture during storage

Wehrheim, Germany). Sections (3 mm thickness) were serially cut During storage in brine, evolution of cherry texture was char-
using a retraction microtome (Supercut 2065; Reichert-Young, acterized by a first stage of rapid increase in firmness, up to about
Wien, Austria), and collected on microscope slides. They were 10 days. This was followed by a second stage (10 dayse2 months) of
stained to visualise polysaccharides and proteins using periodic texture stabilisation, and between 2 and 12 months texture
acid-Schiff's reagent and naphthol blue-black procedures, respec- remained constant or showed limited decreasing trend (Fig. 3C and
tively (El Maa^taoui & Pichot, 1999). Observations were performed D). Storage in brine thus increased fruit firmness with a maximum
using Leica DMR photomicroscope equipped for brightfield, reached in about 2 months. Thereafter comparison will concern
only D0, D8, M2 and M12 conservation stages as those present

Fig. 3. Initial cherry texture according to A maturity stage and B harvest type and their texture evolution during storage in brine C according to maturity stage: early, late
and D harvest type: manual, mechanical. Each point corresponds to 248 randomly selected fruits. Average and standard deviation are represented.
246 W. Wahib et al. / LWT - Food Science and Technology 75 (2017) 243e250

characteristics points during cherries evolution in brine. This can be remained stable at about 34 N after one year. The difference in
compared to the short shelf life of fresh cherries, with both texture firmness thus increased to reach 15 N, which was significant and
loss and material degradation. For example Wei, Qi, Guan, and Zhu corresponded to the quality differential observed industrially, with
(2011) maintained firmness for 30 days after 1- soft fruit and increased loss for mechanically harvested cherries
methylcycloproprene (1-MCP) treatment combined with 0
C after prolonged storage. However they remained above the limit of
storage and 8 days for untreated sweet cherry ‘Summit’. Preserva- processability, which has been assessed at 17 N. The mechanical
tion effects in sulfur dioxide brine are mainly due to the inhibition harvest, in spite of its great advantages in cost and speed, was
of deleterious enzymatic activity thanks to brine and by the calcium deleterious to fruit quality, probably by increasing mechanical
complexation in different fruit tissues. Conservation by brine- damage and decreasing fruit firmness, as also observed by Timm
process confers a stable firmness to pickled capers (Capparis spp.) and Guyer (1998) for tart cherries. Storing in brine over a long
in brine (Ozcan & Akgul, 1999) and allows improving texture in first period conferred a texture gain, improving effectively the fruit
stage and stabilization for some months in pickled cucumbers (Bell quality for a manual harvest whereas the gain was minimal after a
& Etchells, 1961; Hudson & Buescher, 1985). mechanical harvest with fruits that remained above the limit of
processability.

3.2. Maturity stage and harvest method

3.3. Ethephon application
The cherries picked at different maturity stages had different
initial firmness: fresh “early” cherries presented a median firmness Mechanized harvest is dependent on ethephon application.
of 25 N at harvest, and “late” fruit 18 N (Fig. 3A). They reached 35 N Ethephon application had a slight impact on initial texture (24 N for
for “early” and 25 N for “late” after 2 months and firmness then untreated, 28 N for treated) (Fig. 4) i.e. on average a gain of about
remained constant over one year storage (Fig. 3C). Indeed matu- 15%. This effect was at the opposite to what Smith and Whiting
ration is characterized by loss of firmness, as has been reported by (2009) reported, i.e. ethephon application leads to a decrease of
Batisse et al. (1994) and Filslycaon and Buret (1990) for sweet firmness by about 20% in both “Chelan” and “Bing” fresh cherries
cherries including ‘Napole
on’ cultivar. The initial loss observed here harvested 22 days after ethephon treatments. Initial firmness dif-
was of 38% of the firmness, with a mean difference of 6e7 N that ference disappeared during brine soaking (31 N at 2 months for
persisted throughout brine storage but the gap becomes 19% of the both batches) and cherry had almost the same firmness (30.5 N for
firmness after 12 months. untreated against 29.5 N for treated) after 12 months. Ethephon
Harvesting modalities had an impact on initial texture (25 N for application had a positive impact on fresh cherries firmness but
manual, 18 N for mechanical) (Fig. 3B), at 2 months (35 N for brine storage led to texture equalization. Ethephon is known to
manual, 24 N for mechanical), but more important also on texture have different consequences on texture depending on plant spe-
evolution after 1 year storage in brine (Fig. 3D). Mechanically har- cies; it decreases firmness in both kiwifruit and muskmelon
vested cherries showed a trend for texture loss reaching 19 N after (Yamaguchi, Hughes, Tyler, Johnson, & May, 1977; Zhang, Li, Liu,
12 months, while the texture of manually harvested cherries Song, & Liu, 2012), does not impact texture in cucumber (Miller &

Fig. 4. Evolution of cherries firmness in brine with/without ethephon application; D0 ¼ fresh fruit and D008, D060, D365 corresponding to period storage of 8, 60, and 365 days,
respectively. Each boxplot represents 248 randomly selected cherries stored in brine. Statistical significance at P  0.01 represented with different letters after Tukey (HSD) post-hoc
test.
 W. Wahib et al. / LWT - Food Science and Technology 75 (2017) 243e250 247

Lower, 1972) or induces a better ripening of fruits with uniform changes in cherries, even mechanically harvested, thus allowing
colour, pleasant flavour, desirable firmness and acceptable sensory their utilisation for processed candied-fruits until the next crop
quality in guava (Mahajan, Gagandeep, & Dhatt, 2008). year.

3.4. Peduncle effect 3.5. TSS and calcium evolution in brine

Removing peduncle before soaking in brine improved texture of During storage in brine, the sugars and organic acids that
fruits. Starting from the same firmness level (23 N), cherries constitute most of the TSS of sweet cherries diffuse to the brine by
without peduncle presented higher firmness than integrals cher- osmotic phenomenon and, inversely, the brine components like
ries ones immersed in brine (29 N and 24 N, respectively) after 8 calcium diffuse from brine to sweet cherries (Karel, 1975; Taillan,
days (Fig. 5). Then, the firmness reached 34 N against 31 N after 2 1991). Accordingly, the measures were performed only in brine,
months storage and between 2 and 12 months texture remained assuming the remainder was in the fruits. The cherries without
constant with the same gap. This suggests that absence of peduncle peduncle released more TSS after 8 and 60 days in brine than those
leads to fruit with a better texture. The peduncle-abscission zone immersed with peduncle. After 1 year storage, TSS in brine was
might be a preferential circuit of exchange between cherries and higher for the fruits without peduncle (Fig. 6A). This difference in
brine salts. The pedicel of a sweet cherry fruit is a useful indicator of TSS content of the brine after 1 year (i.e. equilibration complete)
its postharvest freshness (Drake & Elfving, 2002; Sekse & Lyngstad, starting from identical initial fruit (16.5
B) and brine (same batch)
1993; Wani, Singh, Gul, Wani, & Langowski, 2014). Although studies soluble solids might be an artefact from fruit packing in the bins.
have been carried out on molecular composition of peduncle Indeed, while a 50/50 ratio (weight/weight) was initially aimed for,
(Khalid, Gellert, Szendrei, & Duddeck, 1989) and transpiration fruits with peduncle occupied more volume per weight so that
mechanism (Athoo, Winkler, & Knoche, 2015) in sweet cherries or more brine had to be added to cover them.Calcium evolution in the
abscission and physical zone separation in rabbiteye blueberry brine (Fig. 6B) was faster for cherries without peduncle; after 8 days
(Vashisth & Malladi, 2013), little is known about impact of peduncle cherries without peduncle had absorbed about 10% more calcium
removal. Here we show for the first time that peduncle removal had than cherries with peduncle.
a marked effect on texture of cherry during brine storage leading to Calcium is well known to enhance texture of fruit and particu-
improved fruit texture, mostly by increasing the firmness gain larly of fruit stored in brine, as has been studied for pickled cu-
between crop days and 2 months. cumbers (Howard & Buescher, 1990; McFeeters, 1985). It limits the
Table 2 summarizes the variations in firmness in our experi- softening of pickles during heating or storage under different
mental system. It appears that the best combination was a manual conditions (Tang & McFeeters, 1983). The impact of calcium on
harvesting thus not requiring ethephon, in the early maturation texture is due to formation of calcium cross-links between pectin
stage and immersing in brine without peduncle. However, this is molecules in the cell wall (Van Buren, 1979). Garcia, Brenes, and
not practical economically as mechanical harvest is highly effective Garrido (1994) reported that the monovalent sodium ions Naþ
in terms of cost and rapidity. Storage in brine promotes textural does not show any action on firmness while calcium Ca2þ improves

Fig. 5. Evolution of cherries firmness in brine with/without peduncle; D0 ¼ fresh fruit and D008, D060, D365 corresponding to period storage of 8, 60, and 365 days respectively.
Each boxplot represent a variation of 248 randomly selected cherries stored in brine. Statistical significance at P  0.01 represented with different letters after Tukey (HSD) post-hoc
test.
248 W. Wahib et al. / LWT - Food Science and Technology 75 (2017) 243e250

Table 2
Firmness (N) per sample itineraries at harvesting (fresh cherries) and variation gain in percentage (%) during brine storage compared to fresh fruit at harvest. Each value
represents an average (bold text) of 62 randomly selected fruits and standard deviation is represented (±).

Maturity stage Harvest method Ethephon Peduncle Fresh cherries 15 days in brine 2 months in brine 1 year in brine

Early Manual Yes Pþ 28 ± 4.9 34 ± 5.1 37 ± 4.8 30 ± 3.4

24% 34% 8%
Mechanical Yes P 22 ± 4.2 29 ± 5 28 ± 3.8 22 ± 4.2
29% 27% 0%
Manual No Pþ 24 ± 4.7 32 ± 4.9 36 ± 4.2 33 ± 5
31% 50% 34%
Manual No P 24 ± 4.7 34 ± 4.8 41 ± 5.1 37 ± 5.4
39% 68% 54%
Late Manual Yes Pþ 20 ± 4.5 24 ± 4 25 ± 4.4 25 ± 3.8
22% 24% 25%
Mechanical Yes P 15 ± 4.3 21 ± 3.8 20 ± 5 17 ± 4.6
38% 32% 10%
Manual No Pþ 23 ± 4.5 25 ± 4.1 25 ± 4.8 28 ± 4.5
15% 10% 26%
Manual No P 23 ± 4.5 28 ± 4.8 29 ± 3.6 30 ± 4.2
28% 27% 33%

Total Calcium
soluble (g/L)
solids 12 A 4 B
a
a
9 3
a
b b
c b
6 2
c d
ef
d e
3 1
e f

0 0
D0 D8 D60 D365 D0 D8 D60 D365
Storage (Days) Storage (Days)

Fig. 6. Evolution of A total soluble solids (
B) and B calcium (g/l) in brine during storage of cherries with ( ) and without peduncle ( ). Different letters within the means and
standard deviation of each date signify statistical separation at P  0.05.

firmness and use of both can lead to competition between them in 3.6. Microscopy
the cross-linked de-esterified pectin thereby weakening the pectin-
calcium-based network. Cytohistological observations were performed by light micro-
Further, Taillan et al. (1992) demonstrated that residual pectin scopy to better understand the impact of the studied harvest con-
methyl esterase (PME) activity is present during brine storage of ditions on cherry fleshy tissues during brining. Applied to all
cherry fruit, and that calcium concentration modulates the stimu- conditions, this approach globally revealed that brined fruits
lation of PME activity. The pedicel-abscission zone allowed an display similar tendencies of cell and tissue structural behaviour.
earlier transfer of brine components thus potentially enhancing the These tendencies will be described here taking as example sections
PME-calcium interaction and conferring improved texture. In of tissue fragments excised from fruits harvested mechanically
contrast, the removal of Ca2þ bound to middle lamella-cell wall (without peduncle) at early stage, and brined either for 2 or 12
material enhances the rate and magnitude of galacturonan degra- months. Fig. 7 presents typical micrographs illustrating main
dation by polygalacturonase (Buescher & Hobson, 1982), and may changes in comparison with samples from fresh fruits.
cause softening. Loss of textural integrity can be controlled by the In fresh fruits, the peripheral pericarp tissues showed cohesive,
formation of intermolecular links between Ca2þ and pectin ach- normally shaped cells exhibiting intact cell walls (Fig. 7A). In
ieved by the addition of calcium salts (Barrett, Garcia, & Wayne, contrast, middle mesocarp and to a greater extent inner mesocarp
1998) and/or boosting the endogenous PME activity (Anthon, tissues displayed profound cytomorphological alterations charac-
Blot, & Barrett, 2005). The positive impact of peduncle removal teristic of ripening cherries (Batisse et al. 1998). These mainly
observed in our conditions might thus be due to increased and consisted of cell plasmolysis and cell wall loosening giving the cells
accelerated calcium availability for pectin cross-linking in the a shrunk, distorted contour (Fig. 7B and C). The natural mechanisms
cherry fleshy tissues. of cherries maturation (Barrett & Gonzalez, 1994) paired to me-
chanical harvesting may have caused cell wall alterations. After 2
 W. Wahib et al. / LWT - Food Science and Technology 75 (2017) 243e250 249

Fig. 7. Evolution of cherry cv. Napole
on tissues structure during brine storage. Sections were stained to visualise polysaccharides (pink) and proteins (blue) in fresh fruit (A, B, C),
fruits brined 2 months (D, E, F) and fruits brined 1 year (G, H, I) at 3 levels of tissues; exocarp (A, D, G), middle mesocarp (B, E, H) and deep mesocarp around endocarp (C, F, I). Scale
bars ¼ 100 mm. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

and 12 months in brine, the peripheral mesocarp cell layers treatment only impacted positively fresh fruit firmness and allowed
appeared to be structurally similar to those of fresh fruits (compare to maintain acceptable cherries quality for processing over one
Fig. 7A, D and G). But surprisingly, in middle and inner mesocarp, year.
cells exhibited regular contour giving them a turgescent-like state The harvest modalities that impacted texture of cherries were,
(Fig. 7E, F, H and I). This apparent morphological rescue may be in order of importance, harvest type, maturity stage, and presence
interpreted as cell wall stabilising effects of the brine via pectin- of peduncle.
calcium interactions. Alonso, Tortosa, Canet, and Rodríguez However, presence of an abscission zone accelerated osmotic
(2005) described a synergic effect of thermal treatment (70
C) exchange and also improved penetration of brine salts rate,
and immersion in calcium solution to decrease the degree of conferring high texture gain with cell wall remodelling. Optimal
esterification of water-soluble and EDTA-soluble pectins, thereby textures were obtained for fruit harvested manually (to avoid me-
favouring the formation of calcium bridges and preventing the chanical damage) an early stage (to avoid over-ripening) and stored
depolymerization of pectins in sweet cherry cv Pico Colorado. in brine without peduncle (to promote brine diffusion within fruit
Other authors (Roy, Jauneau, & Vian, 1994) observed high contents tissues). Since mechanical harvesting is unavoidable and fruit
of non-esterified homogalacturonan sequences in the same spaces growers aim to shorten the harvest period, fruit quality enhance-
in accordance with the presence of calcium ions. Calcium pectate ment may be established at post-harvest level. In addition to
plays a role as a last barrier before total cell disaggregation and had peduncle and its relevance for calcium diffusion, temperature and/
an important function in maintaining firmness during brine stor- or pressure might modulate residual endogenous PME activity
age. One-year storage in brine further consolidated the cellular (Taillan et al. 1992). This leads to release a significant proportion of
architecture with an intercellular space rich in polysaccharides. free carboxyl groups from pectin polymers that might then interact
with calcium salt to form secondary cross-bridges thus improving
4. Conclusion cell wall strength, and consequently, a higher quality final product.
This will be the object for further work.
In this work, we characterized the different harvest factors
involved in the evolution of cherries texture during brine storage. Acknowledgements
Overall, brine increased texture, thus alleviating slightly the initial
damage due to harvest itineraries. Among these factors, ethephon The research was funded by research contracts n
21000533 and
250 W. Wahib et al. / LWT - Food Science and Technology 75 (2017) 243e250

n
C-14-PFL-06 between Aptunion and respectively INRA and Alimentaires et Agricoles (Doctoral dissertation).
Karel, M. (1975). Osmotic drying. FENNEMA, O. Principles of Food Science. New York:
Avignon University. ANRT partly covered the salary of authors WW
[sn], part 2: 348e357.
under CIFRE grant n
2013/0673. Khalid, S. A., Gellert, M., Szendrei, K., & Duddeck, H. (1989). Prunetin 5-0-beta-d-
glucopyranoside, an isoflavone from the peduncle of Prunus avium and Prunus
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