Postharvest Handling of Berries

Abstract

Strawberries, raspberries, and blackberries are highly appreciated fruits due to their unique taste and high content in antioxidant and bioactive compounds. They are rich in phenolic compounds, mostly flavonoids and anthocyanins, which are responsible for fruit color and can exert antioxidant, antimicrobial, anti‐inflammatory, anticancer, and cardioprotective effects. However, berries have a short storage life, as a result of their high respiration and softening rate, and susceptibility to mechanical damages and decay. As berries are considered non‐climacteric fruit, they must be harvested at, or near to full maturity, because they will not continue to ripen normally once detached. At this stage, the fruit presents appropriate organoleptic attributes but may become softer and more sensitive to mechanical damage. Thus, it is crucial to be extremely careful during harvest and postharvest handling and to sort, grade, and pack the berries in the field, avoid‐ ing excessive manipulation of the fruit. The most extended methods to maintain quality during the postharvest period are prompt precooling and storage at low temperatures. Modified and controlled atmospheres with up to 20‐kPa CO 2 and 5–10‐kPa O 2 reduce microbial growth and delay senescence but can affect bioactive compounds with a culti‐ var‐dependent response observed for these technologies.

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Chapter 6
Postharvest Handling of Berries
Sandra Horvitz
Additional information is available at the end of the chapter
http://dx.doi.org/10.5772/intechopen.69073
Provisional chapter
© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,
and reproduction in any medium, provided the original work is properly cited.
DOI: 10.5772/intechopen.69073
Postharvest Handling of Berries
Sandra Horvitz
Additional information is available at the end of the chapter
Abstract
Strawberries, raspberries, and blackberries are highly appreciated fruits due to their
unique taste and high content in antioxidant and bioactive compounds. They are rich
in phenolic compounds, mostly avonoids and anthocyanins, which are responsible for
fruit color and can exert antioxidant, antimicrobial, anti‐inammatory, anticancer, and
cardioprotective eects. However, berries have a short storage life, as a result of their
high respiration and softening rate, and susceptibility to mechanical damages and decay.
As berries are considered non‐climacteric fruit, they must be harvested at, or near to full
maturity, because they will not continue to ripen normally once detached. At this stage,
the fruit presents appropriate organoleptic aributes but may become softer and more
sensitive to mechanical damage. Thus, it is crucial to be extremely careful during harvest
and postharvest handling and to sort, grade, and pack the berries in the eld, avoid‐
ing excessive manipulation of the fruit. The most extended methods to maintain quality
during the postharvest period are prompt precooling and storage at low temperatures.
Modied and controlled atmospheres with up to 20‐kPa CO2 and 5–10‐kPa O2 reduce
microbial growth and delay senescence but can aect bioactive compounds with a culti‐
var‐dependent response observed for these technologies.
Keywords: berries, maturity index, packaging, refrigeration, storage
1. Introduction
Berry fruits include, among others, strawberries (Fragaria ananassa), raspberries (Rubus idaeus),
and blackberries (Rubus spp.). These fruits are characterized by their acidic taste and can be
consumed fresh or frozen. Fresh fruits are mainly consumed locally and are available only in
the ripening season, except countries from South America, like Colombia or Ecuador, where
the production occurs all year round. Berries are also available as processed products like
refrigerated fruit pulp, jams, juices, and nectars [1]. What's more, due to their high content
in antioxidant and bioactive compounds, they can be considered as functional foods. In
© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.

eect, dierent studies conducted on berry fruits report antioxidant, antimicrobial, anti‐
inammatory, anticancer, and cardioprotective eects, which were aributed to their high
content in bioactive compounds, mainly dierent phenolic compounds [2].
However, the manipulation of these fruits presents a series of challenges: berries lack a pro‐
tective peel and are highly perishable, mainly because of their susceptibility to mechanical
damage, water loss, and fungal decay [3]. What's more, berries are considered non‐climacteric
fruit, which implies that they need to be harvested at, or near to, full maturity as most of them
will not continue to ripen normally once detached, and eating quality will not improve after
harvest. In some cases, they can color in storage but if they are harvested too early, texture,
sweetness, and acidity fail to fully develop [4].
Fruit quality for the market is largely determined by physicochemical parameters like size,
full color, gloss, rm and crisp texture, absence of decay, injuries and bruises, a balance
between sweetness and acidity, green sepals, and typical aroma. At the same time, the main
causes of loss and rejects include weight loss, presence of bruises and cuts, symptoms of mold
and decay, color changes, juice leakage, and sepal wilt.
To get the maximum quality at harvest and maintain this quality during transport and com‐
mercialization until the fruit is consumed, it is essential to harvest berries at the optimum
stage of maturity [5]. In this sense, the UNECE Standard FFV‐57 [6] concerning the market‐
ing and commercial quality control of berry fruit establishes that “Berry fruits must be suf‐
ciently developed and display satisfactory ripeness according to the species but must not be
overripe,” emphasizing the need to harvest at the appropriate maturity stage for each type
of fruit.
2. Harvest
In order to avoid excessive manipulation and damage to the fruit, berries for the fresh market
should be hand‐harvested, sorted, graded, and packed in the eld, directly into the nal con‐
tainer. Fruit ripeness at harvest and fruit handling are two critical factors in the postharvest
keeping quality. In fact, the stage of maturity at harvest largely aects the shelf‐life of berries,
their storage behavior, and sales probability [7]. Immature fruit may have a longer storage
capability but are unlikely to develop appropriate organoleptic characteristics while shelf‐life
of over‐mature fruit is generally very short as the susceptibility to decay also increases [8].
As berries ripen quickly but non‐uniformly (Figure 1), it is crucial to harvest frequently (daily,
or every 2–3 days, depending on weather conditions and area of production) and also train
pickers to identify the proper ripening stage and in the correct harvest practices to avoid dam‐
ages to the fruit.
Ideally, the fruit should be harvested early in the morning, after the dew is o the berries or
in the evening when the temperatures are cooler [9]. Berries should not be touched before har‐
vest because they are extremely fragile and easily damaged during harvest, for example, by
nger pressure. Only sound berries with good appearance should be placed in the packages,
Postharvest Handling108

and once harvested, fruit must be protected from exposition to direct sunlight. Roen fruit
must be picked o plants and discarded far from the marketable berries to avoid contamina‐
tion of the laer while small and overripe fruits can be used for processing [10].
2.1. Harvest maturity
Dierent maturity indexes can be used for determining berries’ optimum harvest date.
However, harvest maturity is mainly determined by fruit surface color and most standards
require for strawberries that more than one‐half to three‐fourth of the surface to be colored. In
the case of raspberries and blackberries, the fruit must present a completely red and a bright,
dark purple/black color, respectively. Color is also the main criterion used by the consumer
to judge fruit quality [11]. Besides color, blackberries, and raspberries should pull easily from
the receptacle yet being still rm. Regardless of the berry considered and in addition to color,
appearance (size, shape, and absence of defects), rmness, avor (soluble solids, titratable
acidity, and avor volatiles), and nutritional value (vitamin C) are all important quality char‐
acteristics that must be considered.
Several studies have shown that the color of these berries can change during storage even if
the fruit are harvested at early stages of color development [12–14]. However, the changes in
sugar and acid content of these unripe fruits are not enough to make them suitable for fresh
consumption [4]. On the other hand, Krüger et al. [7] reported that suitability for selling rasp‐
berries declined rapidly with increased ripening stage, and thus, the fruit should not be stored
and must be sold and consumed immediately after picking.
Figure 1. Fruit of blackberries showing dierent maturity stages.
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In any case, it is recommended to avoid mixing dierent ripening stages in the same pack, as
this practice is usually rejected by consumers at the marketplace. At an industrial level, fruit
selection is based both on external aributes such as intense red color and color distribution,
fruit size and shape, and absence of physiological defects and on internal quality parameters
including sweetness, acidity, and avor [15]. For an acceptable avor, a minimum of 7% solu‐
ble solids and/or a maximum of 0.8% titratable acidity are highly recommended for strawber‐
ries [16]. Similarly, the Ecuadorian Quality Standard NTE‐2427 [17] for Andean blackberries
(Rubus glaucus Benth) establishes a minimum of 9% soluble solids, a maximum of 1.8% titrat‐
able acidity and a minimum of 5 for the maturity index (total soluble solids/titratable acidity).
2.2. Packing
The containers most commonly used at the supermarket for raspberries and blackberries are
plastic clamshells containing 250 g of fruit. In the case of strawberries also, containers for 500,
1000, and even 2000 g of fruit are used, depending on fruit size (Figure 2a and b). Pulp and
wooden containers are also used, but they present the disadvantage that stain easily, and
wooden containers are also expensive. Regardless of the material, wide and shallow contain‐
ers are preferred to deep containers and no more than three layers of fruit should be included
in each package as the fruit in the boom may be crushed by the fruit on top.
Figure 2. Plastic clamshells of 250 (a) and 500 g (b) for the packing of raspberries and blackberries, and strawberries,
respectively.
Postharvest Handling110

Plastic clamshells present some advantages: they are solid and thus give protection to the fruit
from mechanical damage, they do not stain, they are inexpensive, and, as they are usually
clear or transparent, they allow consumers to inspect all the fruit at the time of purchasing.
The containers must be vented on top and sides and have a lid to reduce mechanical dam‐
age and moisture loss. On the other hand, the main disadvantage of these packages is plastic
disposal after use.
In some countries, it is still also a very common practice the use of baskets or buckets, some‐
times containing up to 12–15 kg of fruit (Figure 3). Customers pay for the rst basket and
bring them back in following purchases. This kind of containers are not appropriate as they
are usually not washed or disinfected before reuse and thus lack hygiene and can accumulate
fungal spores. Furthermore, the excessive weight of fruit causes damage to the fruit located
at the boom which usually collapses. In order to absorb the juice leaked from the fruit, non‐
food grade, periodic paper is frequently added at the boom of the baskets, underneath the
fruit, worsening the situation. Some eorts are being made to eliminate these kinds of prac‐
tices and to replace these containers by cartons containing plastic clamshells or cardboard
boxes (Figure 4a and b).
Figure 3. Baskets used for blackberries harvest.
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3. Precooling
Precooling, consisting in rapid removal of eld heat immediately after harvest, is essential to
maintain fruit quality and control decay [18]. For example, strawberries rapidly cooled down
to 0°C showed threefold the storage life of those fruit maintained at 10°C [19]. Field heat is
often removed using forced air cooling, where rapidly moving cold air is forced through
pallets of fruit to lower fruit temperature to 0 to 1°C within 2 h of picking. This method is
preferred to room cooling, as forced air can cool berries to 1°C within an hour, whereas room
cooling may take up to 9 h [9].
High relative humidity (85–95%) should be maintained within the refrigerated rooms, but
free moisture on the berries or in the containers must be kept to a minimum as, to reduce fruit
rot, the berries must be kept dry. Precooling conditions for blackberries are forced air cooling
to 5°C within 4 h and fruit should be transported at refrigeration temperatures of 5°C or less.
Raspberries should be forced air cooled to 1°C, no later than 12 h after harvest.
4. Storage
Strawberries, raspberries, and blackberries are highly perishable due to their relatively high
water content, high physiological postharvest activity, and susceptibility to fruit rot and
darkening. The high respiration rates of these fruits cause changes in texture, color, avor,
and nutritional content during storage, and such changes are crucial for the determination
of fruit quality and consumer's acceptability [20]. Their short storage life is also the result
of decay caused by rot‐causing pathogens and quick softening rates [21]. Botrytis cinerea,
a necrotrophic fungus that causes gray mold rot, is one of the main pathogens responsible
for postharvest decay in berries. The symptoms of disease are soft rot with a collapse and
water soaking of parenchyma tissues, followed by the appearance of gray masses of conidia
[22, 23] (Figure 5).
The presence of ethylene in storage can stimulate respiration rates and gray mold growth.
Moreover, color of raspberries can be adversely aected by ethylene as it causes darkening of
the red fruit to purple‐red [10].
Figure 4. Cartons containing plastic clamshells of 250 (a) and 500 g (b), for raspberries/blackberries and strawberries,
respectively.
Postharvest Handling112

Another physiological disorder that can aect berries during storage is water loss, which in
turn causes fruit shriveling, loss of gloss, and plays an important role in anthocyanin degrada‐
tion. Water loss accelerates senescence of the fruit and the maximum permissible amount of
water that can be lost (based on weight loss) from the fruit before becoming unmarketable is
6%. During postharvest handling of the berries, water loss can be reduced by prompt precool‐
ing and adequate packaging and storage at optimum temperature and relative humidity [24].
At present, the most extended methods used to maintain quality and bioactive compounds
stability and to control decay of fruits and vegetables are postharvest washing, rapid cooling
immediately after harvest, and storage at low temperatures [25, 26]. Furthermore, postharvest
diseases are normally controlled by the use of synthetic fungicides [27] and storing under con‐
trolled or modied atmospheres with high CO2 concentrations [28]. However, these methods
present some limitations. Berries washing before retail is not recommended because the skin
of the fruit may be damaged easily and the drying period delays precooling and enhances
infections by pathogenic microorganisms [27].
Likewise, chemical fungicides may exert several negative eects on food safety and the envi‐
ronment, and there are public concerns about environmental pollution, possible contamina‐
tion of berries by fungicide residues, and the inability to control fungal diseases because of the
appearance of fungicide‐tolerant strains of pathogens [29].
4.1. Temperature
One of the main factors aecting the storage shelf‐life and quality of fruit and vegetables is
temperature, as it regulates the rate of all the metabolic processes that occur in these products.
Figure 5. Botrytis cinerea growth on stored blackberries.
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Low temperatures slow down fungal growth and, at the same time, reduce respiration rate
and water loss and, therefore, delay ripening and senescence processes [30]. As these ber‐
ries are insensitive to chilling injury, extending the shelf‐life of berry fruit is often achieved
through low temperature with optimum storage conditions for strawberries, raspberries, and
blackberries being 0°C and 90–95% relative humidity [31].
Storage temperature is one of the key factors in suppressing fungal decay and inuencing the
stability of phenolic antioxidants in fruits during postharvest storage [32]. Also, temperature
management is the most important factor to be taken into account to retain the initial ascorbic
acid content during storage. Nevertheless, even when temperatures around 0°C are consid‐
ered the best for berries’ storage, the distribution in trucks and shops, the commercialization,
and the storage in consumer households usually occur at higher temperatures, which can
aect the berries shelf‐life and their physicochemical quality and nutritional value, in terms
of soluble sugars, vitamin C, and antioxidant compounds [33, 34].
Despite the already‐known positive eects of low temperatures on postharvest shelf‐life and
quality of fresh fruits and vegetables, contradictory results can be found in the literature.
Cooling of fruit at 0°C can be detrimental for short‐term sales, as fruit appearance may be
duller, and condensation of fruit during re‐warming might result in greater decay incidence
[35]. Jin et al. [36] indicated that strawberries stored at 10°C had higher antioxidant enzymes
activities, higher level of phenolics and anthocyanins contents, and stronger oxygen radical
scavenging capacities than those stored at 0 or 5°C, and Kalt et al. [32] found that low tem‐
peratures could aect anthocyanin synthesis during storage of small fruits. Similarly, antho‐
cyanin and ascorbic acid biosynthesis was delayed in three strawberry cultivars stored at 6°C
in comparison with storage at 16°C, while the contents of avonols, ellagic acid, and total
phenolics were not aected by the temperature lowering [33].
In blackberries, Joo et al. [37] found a reduction in total anthocyanin content (TAC) after 18
days at 3°C, while Wu et al. [38] did not see a clear tendency in the evolution of anthocyanins
during 7 days at 2°C. On the contrary, in Andean blackberries harvested at the light and dark‐
red maturity stages, we observed an increase in total anthocyanin content during 10 days of
storage at 8 ± 1°C and similar results were reported by Kim et al. [39] who observed that TAC
increased after 15 days of storage at 1 or after 13 days at 1 plus 2 days at 20°C.
On the contrary, Piljac‐Žegarac and Šamec [2] reported that the marketable quality of straw‐
berries was preserved at 4°C for a prolonged period of time in comparison with storage at
room temperature, while higher antioxidant capacity values were maintained at the lower
temperatures, as opposed to 25°C. Similarly, storage of strawberries at 1°C together with
moisture loss control reduced losses of total ascorbic acid by 7.5‐fold compared to fruit stored
at 20°C [40]. These authors concluded that even short periods at ambient temperature without
control of water loss could result in considerable losses of total AA in strawberries. Moreover,
Shin et al. [35] reported that the best temperature for visual appearance of strawberries was
0.5°C, but for short‐term storage periods (up to 4 days), it was also possible to use moderate
temperatures of 10°C. This temperature was useful to delay fruit ripening compared to room
temperature and, at the same time, provided a balance between sensory aributes and those
associated with the nutritional status of the fruit.
Postharvest Handling114

In Andean blackberries, we also observed that by storing the fruit in refrigerated storage,
weight and rmness loss were reduced and microbial growth was delayed in comparison
with storage at room temperature. What’s more, the refrigerated fruit presented higher scores
in the sensory analysis and, the total phenolic content and the antioxidant activity of the fruit
were not aected by the cold storage.
4.2. Modied and controlled atmospheres
Modied atmosphere (MA) and controlled atmosphere (CA) refer to any atmosphere dierent
from the normal air and usually involve atmospheres with reduced O2 and/or elevated CO2
levels. The dierence between them is that CA is strictly controlled during all time.
Both MA and CA can be used for the storage, transport, and packaging of dierent types of food
in compliment to low temperatures to extend their shelf‐lives after harvest. Exposure of fresh
horticultural crops to low O2 and/or elevated CO2 atmospheres within the range tolerated by each
commodity reduces their respiration and ethylene production rates and therefore results in sev‐
eral benecial eects such as delay of ripening and senescence and associated biochemical and
physiological changes, reduction of sensitivity to ethylene action, alleviation of certain physiolog‐
ical disorders such as chilling injury, direct, and indirect control of pathogens, and consequently
decay incidence and severity. On the contrary, if horticultural products are exposed to O2 con‐
centrations below, and/or CO2 concentrations above their optimum tolerable range, the initiation
and/or aggravation of certain physiological disorders, irregular ripening, increased susceptibility
to decay, development of o‐avors, and eventually the loss of the product can occur [41].
Modied atmospheres (MA) and controlled atmospheres (CA) with elevated (15–20%) carbon
dioxide and 5–10% oxygen concentrations reduce the growth of Botrytis cinerea (gray mold
rot) and other decay‐causing organisms. In addition, it reduces the respiration and softening
rates of berries, thereby extending postharvest life. Nevertheless, further reductions of O2
concentrations to 2 kPa had no benet and may cause fermentation of the fruit [42].
In addition, o odors can be produced if the fruits are kept under high CO2 atmospheres for
more than 4 days as a result of anaerobic respiration [43] and the eect on the avor preser‐
vation of these fruit is not clear. Several authors [28, 44, 45] reported changes in pH, titrat‐
able acidity, total soluble solids, sugars and organic acids, and fermentative metabolites after
storage under CO2‐enriched atmospheres. In eect, dierent fermentative volatiles (acetalde‐
hyde, ethanol, and ethyl acetate) were found after storage of strawberries in air + 20‐kPa CO2
at 2.8°C [46]. Among aroma compounds, esters are apparently the volatiles most aected by
CO2‐enriched atmospheres [47].
Anthocyanin synthesis continues after harvest, but it is inhibited in fruits stored in high CO2
concentrations. According to Holcroft and Kader [28], high CO2 concentrations together with
low O2 concentrations can also aect adversely total ascorbic acid and anthocyanin contents
and, thus, have a negative impact on fruit color and nutritional value. Conversely, the rm‐
ness, the external color, and the total phenolic compounds content of Selva strawberries were
not aected by storage atmospheres with up to 20‐kPa CO2 [28]. In both, strawberries and rasp‐
berries, a cultivar‐dependent response to changes in the storage atmosphere was observed.
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An atmosphere of 12.5‐kPa CO2 and 7.5‐kPa O2 was eective in reducing decay in red rasp‐
berries and elevated concentrations of CO2 together with reduced concentrations of O2 were
shown to inhibit mycelial growth and spore germination of B. cinerea and other fungi respon‐
sible for postharvest decay of fruit [42]. What's more, raspberries stored in 10/15‐kPa O2/CO2
presented a more aractive color in comparison with fruit stored in air.
Finally, Giovanelli et al. [48] reported that the use of high and medium barrier materials
delayed senescence and did not aect negatively the nutritional and antioxidant properties
of red raspberries stored at 4°C. However, fermentative volatiles were found for these fruits,
especially when an oxygen absorber was included in the packages.
5. Alternative methods for decontamination of strawberries
The need to minimize chemicals use has encouraged the rapid development of alternative
techniques [29]. One of the new approaches is the use of ‘generally recognized as safe’ (GRAS)
products, such as UV radiation and ozone, due to minimal concerns about their environmen‐
tal impact and low residues in the treated commodity.
5.1. UV‐C radiation
One strategy that can be an adjunct to refrigeration is the exposure of fruits to hormetic doses
of UV‐C radiation, a physical treatment that has been tested in strawberries and other fruits
to control postharvest diseases [43, 49, 50] and delay some ripening‐associated processes [51,
52]. Hormesis has been dened as the use of potentially harmful agents at low doses in order
to induce a benecial stress response [53].
UV‐C seems to have a direct germicide eect on pathogens and an indirect eect by inducing
defense mechanisms in the plant tissues [53–55]. Irradiation with UV‐C is known to stimulate the
phenylpropanoid pathway in several fruits, mainly by the induction of phenylalanine ammonia
lyase (PAL), a key enzyme in this pathway [56]. The compounds synthesized by this pathway are
implicated in a protective role against pathogens through reinforcement of plant cell walls, direct
inhibition of growth, and/or inactivation of enzymes that contribute to tissue maceration [57].
Particularly in strawberry fruit, dierent UV‐C doses increased enzyme activity, the antioxi‐
dant capacity and total phenolic content during storage, which correlated with lower fruit
decay observed in treated fruit [58]. The synthesis and accumulation of phenolic compounds
following irradiation with UV‐C could also play an additional indirect role in fruit protec‐
tion acting as natural substrates of polyphenol oxidase (PPO). One of the proposed roles of
the reaction products of PPO (quinones) in plant defense is their action as bactericidals and
fungicidals [59]. It was found that postharvest UV‐C treatment, a few hours prior to inocula‐
tion with B. cinerea, reduced the percentage of fruit infection in strawberries during storage
[60]. These authors also reported that irradiation of fruit with UV‐C increased expression and
activity of several enzymes (PAL, peroxidases, PPO, chitinases, and β‐1,3‐glucanases) which
are involved in defense mechanisms against pathogens and abiotic stressors. In another
Postharvest Handling116

experiment, photochemical treatment with UV‐C delayed the appearance of gray mold rot in
stored strawberries by up to 5 days at both 4 and 13°C [43]. These authors observed that the
treatment with UV‐C also enhanced the accumulation of anthocyanins, which in turn con‐
tributed to redder and visually more appealing fruit. In contrast, Erkan et al. [58] found lile
eect of UV‐C treatments on anthocyanin content in strawberries.
5.2. Use of ozone
Another emerging technology with potential application in the food industry is the use of
ozone as a sanitizer [61]. O3 can be used for the postharvest treatment of fresh fruits and veg‐
etables, in air or water, or as a continuous or intermient atmosphere throughout the storage
period. Gaseous ozone can be used to sanitize storage rooms and to prevent bacteria, molds,
and yeasts development on the food surfaces. It can also eliminate undesirable avors pro‐
duced by bacteria and chemically remove ethylene gas to slow down the ripening process [62].
Ozone gas ecacy to inactivate microorganisms is conditioned by the species considered,
its growth stage, the ions present in the air, the O3 concentration and exposure time, and, the
temperature and relative humidity of the room [63]. In air, the reactivity of ozone is greatest
with fungi, molds, and some odor‐causing chemicals and least with dry spores and bacteria.
For optimum eciency, it is also essential that the gas is thoroughly and evenly distributed
quickly. Otherwise, decomposition will occur before the O3 is able to contact its target [62].
Washing strawberries with ozonated water (0.3 ppm, 2 min) was an eective treatment to
reduce microbial counts and enhance anthocyanin and ascorbic acid retention of these fruits
during 13 days of refrigerated storage [64]. Similarly, Zhang et al. [65] reported greater ascor‐
bic acid retention in strawberries treated with gaseous O3 (4 ppm, 30 min/day) in compari‐
son with untreated fruit. Moreover, strawberries’ levels of biothiols were not aected by the
treatment with either gaseous‐phase or aqueous‐phase ozone [66]. Finally, while total pheno‐
lic and ellagitanin contents were similar in O3‐treated and untreated strawberry fruit after a
storage period of 12 days, the procyanidins and anthocyanins contents were reduced by the
exposure to this gas [67].
In addition to their antimicrobial power, O3 and UV‐C radiation gather other advantages,
which turn them into appealing and environmental friendly technologies [61]. Neither ozone
nor UV‐C leave undesirable residues on food or food‐contact surfaces nor create undesirable
disinfection by‐products [68]. Moreover, the application of these sanitizers in food processing
is approved by the code of Food and Drug Administration (FDA) in the USA and is allowed
by organic certication [69].
There are numerous studies in the literature reporting on the use of both, O3 and UV‐C light,
on several fruits and vegetables. However, results are sometimes contradictory and informa‐
tion about the eects of these decontamination treatments on sensory and nutritional quality
or health‐promoting composition of treated products is scarce. It should be taken into account
that while high doses of oxidizing agents may result in depletion of natural antioxidants,
moderate or low doses of oxidative stress were shown to cause a protective response, enhanc‐
ing the level of endogenous antioxidants [70, 71].
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6. Transport
Berries must be transported in clean and well‐maintained trucks, and it is crucial to maintain
the fruit cold and wrapped during loading, unloading, and transportation. In order to ensure
a proper circulation of the cold air, the ats or boxes must be stacked on pallets and with‐
out touching the truck walls. Frequently, rural roads are not in optimum conditions causing
bruises and abrasion due to the truck vibration and the impacts between the packed fruit and
between the fruit and the walls of the packs. These mechanical damages can be minimized
by stabilizing the load on every pallet, for example, by using stretch lm and by using trucks
with air suspension systems.
When refrigerated transport is used, it must be considered that trucks’ mechanical refrig‐
eration equipment is designed to maintain temperature but they do not have the capacity to
lower the temperature of the produce. So, it is very important to achieve the proper cooling
of the product before loading. Finally, to avoid condensation on the fruits, berries should be
allowed to warm only when they are ready for display to consumers and before removing the
plastic wrap over the ats [10].
Author details
Sandra Horvi
Address all correspondence to: sandra.horvi@unavarra.es
Food Science and Engineering Faculty, Technical University of Ambato, Ambato, Ecuador
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