Effects of hot water treatment on the storage stability of satsuma mandarin as a postharvest decay control

Satsuma mandarins (Citrus unshiu Marc., cv. Gungchun) of an early harvesting cultivar were treated by hot water dipping at 52 °C for 2 min, 55 °C for 1 min, and 60 °C for 20 s, and then stored at 5 °C for 3 weeks and subsequently at 18 °C for 1 week (simulated shelf-life) to examine the possible use of hot water treatment (HWT) as an environmentally benign method to maintain mandarin quality characteristics during postharvest storage and sale. The initial respiration rate, just after heat treatment, was significantly higher in the treated fruit than in the untreated controls. During storage, however, the respiration rate was at a similar level in all treatments. HWT also had no adverse effects on quality attributes, including pH, titratable acidity, soluble solids contents, weight loss, firmness and peel color. The development of stem-end rots, mold decay, and black rots was manifestly lower in heat-treated fruit than in untreated controls. Sensory evaluation showed that HWT at 60 °C for 20 s markedly improved fruit appearance, making them cleaner and glossier. The results confirmed that hot water dipping could be applied to satsuma mandarin as an effective pretreatment to maintain postharvest quality during storage and marketing.     

Hot water dipping treatments on Tarocco orange fruit and their effects on peel essential oil

The most common and serious diseases which affect citrus fruit after harvest in Italy are induced by Penicillium digitatum Sacc. and Penicillium italicum Weh., responsible respectively for green and blue mold rots. This paper deals with the effectiveness of hot water dipping (HWD) treatments as alternative means to control postharvest decay on Tarocco orange fruit [Citrus sinensis (L.) Osbeck], and their effect on fruit quality with special regard to peel essential oils. Selected treatments were HWD at 52 °C for 180 s and at 56 °C for 20 s. These treatments were compared with an effective fungicide standard treatment (Imazalil) and an untreated control. The results showed that HWD at 56 °C for 20 s was more effective in inhibiting P. digitatum spore germination than HWD at 52 °C for longer exposure time. In addition, HWD treatment at 56 °C significantly increased the level of alcohols, esters and aliphatic (fatty) aldehydes. Therefore, the lowest values of decay incidence recorded in HWD fruit treated at 56 °C may be due to the increase in oxygenated monoterpenes, esters and aldehydes. Finally, HWD treatments did not cause surface damage or color change and did not influence internal quality parameters.     

Control of Monilinia rots on fruit naturally infected by hot water treatment in commercial trials

In recent years, safer methods for the control of fruit postharvest pathogens have been investigated and heat treatment could represent an effective and safe approach for managing postharvest decay such as Monilinia rots. In the present study, the effect of hot water treatment (HWT) (60 °C for 30 and 60 s) on brown rot was investigated. More specifically, the influence of HWT was determined in in vitro trials on conidial germination of Monilinia laxa, Monilinia fructicola and Monilinia fructigena and in peach and nectarine fruit, naturally infected. The effect of hot water application on fruit quality was also assessed. M. fructicola showed a greater resistance to heat than M. laxa and M. fructigena, however conidia germination of all three species was completely inhibited by a dipping in hot water for 1 min at 55 °C. The results of a large scale experiment under commercial conditions and several pilot trials showed a good antifungal activity of HWT in naturally infected fruit. After 6 days at 0 °C and 3 days at 20 °C, in both semi-commercial and commercial trials, the inhibition of decay was higher than 78% in four trials out of six. In addition, the treated fruit showed an acceptable commercial quality and no visual damage was observed as a consequence of HWT. The results demonstrated that HWT is a promising method to control Monilinia rots of peach and nectarine, and is safe and readily available for conventional and organic production under commercial conditions.     

Postharvest ethylene conditioning as a tool to reduce quality loss of stored mature sweet oranges

Ethylene is related to senescence but also induces protective mechanisms against stress in plants. The citrus industry only applies the hormone to induce fruit degreening. The aim of this work was to determine the effect of ethylene on the quality of colored citrus fruit stored under commercial conditions to extend postharvest life, since it protects them from stress causing postharvest disorders such as chilling injury (CI) and non-chilling peel pitting (NCPP). The effect of conditioning mature Navelate and Lane Late sweet oranges (Citrus sinensis L. Osbeck) for 4 days with 2 μL L⁻¹ ethylene at 12 °C, rather than at higher temperatures used for degreening, on the quality of fruit stored at 2 or 12 °C, was examined. The ethylene conditioning (EC) treatment did not increase color but reduced calyx abscission and NCPP in fruit of both cultivars stored at 12 °C, and also CI in Navelate fruit at 2 °C. Lane Late fruit did not develop CI but showed a new disorder in EC fruit held at 2 °C. This disorder began as scalded areas around the fruit stem end and extended over the fruit surface during storage. EC had no deleterious effect on the quality of Navelate oranges stored at either 2 or 12 °C. Similar results were found in Lane Late fruit although EC slightly increased off-flavor perception at 2 °C and the maturity index at 2 and 12 °C. Moreover, EC slightly increased the content of bioactive flavonoids in the pulp of Navelate fruit but significant differences between control and EC fruit were only found after prolonged storage at 2 °C. In Lane Late fruit, EC avoided the initial decrease in flavonoid content found in control samples. Results show, therefore, that EC at 12 °C may be a tool to extend postharvest life of NCPP and CI-sensitive oranges, and that the tolerance of citrus cultivars to the combined effect of EC and non-freezing low temperature (2 °C) should be tested to select the proper storage temperature.     

Temperature and relative humidity effects on quality,total ascorbic acid,phenolics and flavonoid concentrations,and antioxidant activity of strawberry

The physical qualities and antioxidant components of ‘Jewel’ strawberry fruit stored in 75, 85 or 95% relative humidity (RH) at 0.5, 10 and 20 °C for 4 days were studied. Overall fruit quality declined more rapidly at 20 °C, especially at 95% RH. Weight loss of fruit was negligible for 2 days at all temperatures but it increased at 10 °C in the lowest RH and increased rapidly from day 3 at 20 °C especially with lower RH. Firmness was maintained, or even increased, at 0.5 or 10 °C, while soluble solids concentrations (SSC) decreased at higher storage temperatures. Red color, assessed using chroma, hue and lightness, and anthocyanin concentrations were relatively unchanged at 0.5 or 10 °C but increased rapidly at 20 °C as fruit ripened. Firmness, SSC and color were not affected by RH. Total phenolic compounds were slightly higher at 20 °C than at other temperatures at all RHs. Total ascorbic acid concentrations of the fruit remained similar for the first 2 days of storage, then declined in fruit stored at 0.5 and 20 °C, but remained unchanged at 10 °C at all RHs. Total flavonoid content of fruit did not change over time at all temperatures. The total antioxidant activity of fruit was higher at 10 °C than at 0.5 and 20 °C on day 3, and no effect of RH was detected. In conclusion, while the best temperature for long-term storage is 0.5 °C, quality could be maintained at 10 °C for acceptable periods of time for marketing and may be associated with better nutritional quality.     

Use of hot water treatment to control codling moths in harvested California ‘Bing’ sweet cherries

Preharvest gibberellic acid-treated California ‘Bing’ sweet cherries (Prunus avium L.) were treated with hot water baths (46–58 °C for 0.25–18 min), followed by hydrocooling. The fruit were then stored to simulate either air shipment or sea shipment to overseas markets, both followed by 15 h of shelf life at 20 °C. In separate experiments, cherries were also infested with codling moth larvae and subjected to similar hot water bath heating. The quality attributes showed different sensitivity to the combinations of temperature and time used for hot water bath treatment. Pitting was more common in fruit treated at lower temperatures for longer times, while stem browning was more common in fruit treated at high temperatures. Berry browning, stem color, and pitting were the quality attributes most affected by heat treatment. Browning of cherry stem color was a crucial factor in determining whether a combination of temperature and time for hot water bath treatment was successful. All cherries stored at 0 °C for 14 days to simulate sea shipment were of unacceptable quality after shelf life. Hot water bath treatments that provided 100% codling moth mortality and maintained overall acceptable fruit quality were very limited and included treatments at 50 °C for 10 min and at 54 °C for 6 min. Delaying the hot water bath treatment after fruit harvest, even if the cherries were kept at 0 °C, resulted in a greater loss in fruit quality compared with those treated on the harvest day. Using hot water baths as a quarantine treatment for codling moths (Cydia pomonella) on sweet cherries may be feasible if fruit are air shipped at 5 °C for 2 days, but not suitable if fruit are sea shipped at 0 °C for 14 days.     

Cold quarantine responses of ‘Tarocco’ oranges to short hot water and thiabendazole postharvest dip treatments

This study investigated the effects of brief hot water and thiabendazole (TBZ) postharvest dip treatments on ultrastructural changes of fruit epicuticular wax (ECW), TBZ residues, decay development and quality traits of ‘Tarocco’ oranges [Citrus sinensis (L.) Osbek] subjected to cold quarantine, subsequent simulated transport and shelf-life. Commercially mature fruit were submerged in water at 20 °C (control fruit) or TBZ at 1000 mg/L and 20 °C for 60 s, or in hot water without or with TBZ at 300 mg/L and 53, 56, or 59 °C for 60, 30, and 15 s respectively. Following treatments, fruit were stored for 3 weeks at 1 °C (simulated quarantine conditions for fruit disinfestations against Mediterranean fruit fly, Medfly), followed by 4 days at 3 °C (simulated long distance transport), and finally kept at 20 °C for 3 days (shelf-life, SL). Scanning electron microscopy (SEM) analysis of ‘Tarocco’ orange surface showed that the typical wax platelets, lifting around edges of wax plates and areas free of epicuticular wax (ECW), that disappeared after hot water dips at 53–59 °C for 60–15 s, become visible again after storage for 21 days at 1 °C (quarantine conditions), and changes involving the appearance of rough ultrastructure, presence large curled plates, fissured wax crusts, and areas with ECW deficiencies, became much more pronounced after shelf-life. These occurrences were related to the transient effect of hot water treatment in decay control. Conversely, treatments with 300 mg/L TBZ 53 °C for 60 s or 56 °C for 30 s effectively reduced decay after quarantine. These treatments were as effective as standard treatment with 1000 mg/L TBZ at 20 °C and produced similar TBZ residue levels in fruit, without impairing fruit quality traits such as visual appearance, weight loss, compression test, sensory attributes, juice color parameters (a*, b*, h, L*, and Chroma), and juice chemical characteristics (soluble solids content, titratable acidity, ascorbic acid, glucose, sucrose, citric acid, total phenols, total anthocyanins, and total antioxidant activity).     

1-Methylcyclopropene (1-MCP) delays senescence,maintains quality and reduces browning of non-climacteric eggplant (Solanum melongena L.) fruit

Ethylene action can be counteracted by 1-methylcyclopropene (1-MCP), which has been used during postharvest storage to maintain quality. In this work, we evaluated the effect of 1-MCP treatments on eggplant quality and phenolic metabolism during refrigerated storage. Eggplants (cv. Lucía) were harvested at commercial maturity, treated with 1-MCP (1 μL/L, 12 h at 20 °C), stored at 10 °C for 21 d and subsequently held at 20 °C for 2 d. Corresponding controls were stored at 10 °C and then transferred to 20 °C for 2 d. During storage calyx color, damage and chlorophyll content, fruit weight loss and firmness, pulp sugar content, acidity, browning and total phenolics were measured. In addition, polyphenol oxidase (PPO), pyrogallol peroxidase (POD), and phenylalanine ammonia-lyase (PAL) activities were evaluated. Fruit calyxes showed reduced damage and remained greener in 1-MCP treated than in control fruit. 1-MCP treated eggplants showed lower weight loss. Pulp browning was clearly prevented as a consequence of 1-MCP exposure, and this was associated with delayed senescence, lower accumulation of total phenolics and reduced activity of PAL. The activity of the enzymes PPO and POD involved in the oxidation of phenolics compounds was also decreased in 1-MCP treated fruit. Results suggest that 1-MCP treatments delay senescence, prevent browning and are beneficial to complement low temperature storage and maintain quality of non-climacteric eggplant fruit.     

Postharvest conditioning of Satsuma mandarins for reduction of acidity and skin puffiness

Postharvest temperature and relative humidity (RH) treatments were tested for their capacity to increase the soluble solids content:titratable acidity ratio (SSC:TA ratio) and/or reduce skin puffiness of New Zealand grown ‘Miho’ Satsuma mandarin. Fruit of low SSC:TA (approximately 6.8:1) harvested in 2001 and 2002 were held at 18 or 30 °C at low (approximately 65%) or high (>95%) RH for 3 or 5 days, followed by 2 days at 10 °C (88–92% RH). In 2002, an additional treatment of high and low RH at 10 °C was examined. Treatments at 30 °C, irrespective of RH, resulted in increased SSC:TA ratios in the fruit as a result of a decrease in titratable acidity, largely a decrease in citric acid. There was little effect of temperature on SSC and the levels of individual sugars. There was no significant effect of RH on either TA or SSC. The altered metabolism was also seen in an elevated respiratory CO₂ output at 30 °C, but a decreased CO₂ output once these fruit were transferred to 10 °C, in comparison with fruit treated at lower temperatures.At 30 °C, weight loss was up to 8.5% after 5 days under low RH, but <4% under high RH. Fruit with >4% weight loss tended to have an unacceptable level of dehydration of the skin. After 5 days at 30 °C and low RH, skin puffiness, quantified from magnetic resonance images taken before and after treatment, was reduced, although fruit tended to have soft skin that could be more prone to damage.It is concluded that short high temperature treatments such as 3–5 days at 30 °C can significantly raise the SSC:TA ratio in Satsuma mandarin through a reduction in TA, and conducting these treatments under a RH >90% minimises the risk of excessive weight loss and softening of the skin.     

Internal browning disorder and fruit quality in modified atmosphere packaged ‘Bartlett’ pears during storage and transit

Internal browning (IB) can be a serious problem with the use of modified atmosphere packaging (MAP) for ‘Bartlett’ pears (Pyrus communis L.) grown in the Pacific Northwest during storage and transit to distant markets. To investigate this disorder, ‘Bartlett’ pears harvested at commercial maturity were packed in a commercial MAP (MAPc), an experimental MAP (MAPe) and commercial perforated plastic bags (control) and stored in air at −1.1 °C. After 1 and 3 months of storage, samples of MAPc and control fruit were transferred to rooms at temperatures of 2, 4.5, 7.5, and 10 °C for 3 weeks to simulate transit temperatures and the time required to reach distant markets. MAPc maintained an average internal atmosphere of 12.3% O₂ + 5.6% CO₂ and significantly extended ‘Bartlett’ pear storage life with high eating quality and without IB and other disorders for up to 4 months at −1.1 °C. The internal gas atmosphere of MAPe equilibrated at 2.2% O₂ + 5.7% CO₂, which resulted in fruit with 25.5 and 62.3% IB after 3 and 4 months of storage, respectively. During simulated transit conditions of 2, 4.5, 7.5, and 10 °C, the CO₂ level in MAPc was maintained at 5.6–7.9%, while O₂ was reduced dramatically to 10.5, 5.0, 2.5, and 1.0%, respectively. IB developed at 7.5 and 10 °C but not at 2 and 4.5 °C, regardless of pre-transit storage duration (1 and 3 months) at −1.1 °C. The longer the storage duration and the higher transit temperature, the higher the incidence and severity of IB. The MAP-related IB disorder observed in this study included two types of symptoms: classic pithy brown core and wet brown flesh. The MAPc storage gas atmospheres maintained fruit firmness, color and higher eating quality after ripening, eliminated senescent scald and core breakdown, suppressed the loss of ascorbic acid (AsA) and titratable acidity, and slowed the accumulation of malondialdehyde (MDA) during storage at −1.1 °C for up to 4 months or 3 months + 3 weeks at simulated transit temperatures of 2 and 4.5 °C. In contrast, fruit held in MAP with low O₂ levels (1.0–2.5%) developed IB that appeared to be associated with a reduction in AsA, accumulated MDA and exhibited an increase in membrane leakage. MAP inhibited ripening at high CO₂ + high O₂ but lead to IB when the packaging material or elevated temperatures resulted in high CO₂ + low O₂ conditions. The incidence of IB closely correlated with lipid peroxidation and appeared to be related to fruit AsA concentration. The MAPc designed for pears appears to be suitable for ‘Bartlett’ fruit stored at −1.1 °C for up to 4 months or storage for 3 months and a transportation duration of up to 3 weeks at 0–4.5 °C during the early season and at 0–2 °C during the late packing season. These conditions yielded fruit of high eating quality and without IB or over-ripening upon arrival at distant markets.     

Effect of 1-methylcyclopropene (1-MCP) on storage life of durian fruit

Fruit of cv. Monthong durian (Durio zibethinus) were treated with 0 (control) or 500 nL L⁻¹ 1-MCP for 12 h at 25 °C. Fruit were then stored at 15 °C. To determine storage life, every 3 days a batch of fruit was transferred to 25 °C. The time to ripeness (adequate eating quality) at 25 °C in controls (no 1-MCP) decreased from 5 days in freshly harvested fruit to 3 days after 18 days of storage at 15 °C. Storage life was considered adequate if the time to ripeness was ≥3 days. The storage life at 15 °C of control fruit (no 1-MCP) was therefore 18 days. After the 1-MCP treatment the time to ripeness at 25 °C was 7 days in fresh fruit, while in fruit stored at 15 °C for 30 days it was about 3 days. The storage life at 15 °C of 1-MCP-treated fruit was therefore 30 days. Pulp firmness and pulp total soluble solids (TSS) were determined after 3 day storage intervals at 15 °C and when the fruit was ripe at 25 °C. These parameters were only slightly affected by the 1-MCP treatment. Furthermore, 1-MCP had no effect on pulp color, but delayed yellowing of the fruit exterior. It is concluded that treatment with 1-MCP before storage at 15 °C extended storage life from 18 to 30 days.     

Effect of oxalic acid on ripening attributes of banana fruit during storage

The effect of exogenous oxalic acid treatment on ripening attributes of banana fruit during storage was investigated. Banana fruit were dipped into solutions of 0 (control) or 20 mM oxalic acid for 10 min and then stored at room temperature (23 ± 2 °C) and 75–90% relative humidity. The application of oxalic acid reduced fruit deterioration during storage. The oxalic acid treatment also reduced the rates of respiration and ethylene production, and delayed the decreases in firmness, hue angle, and maximal chlorophyll fluorescence (Fv/Fm) of banana fruit during storage. Furthermore, fruit treated with oxalic acid exhibited higher superoxide dismutase activity and antioxidant capability with a lower production of reactive oxygen species at the late storage period compared with non-oxalic acid-treated fruit. Overall, the oxalic acid treatment was effective in inhibiting postharvest ripening of banana fruit and exhibited the potential for commercial application to store the bananas at room temperature. It can be concluded that the delay in banana fruit ripening associated with oxalic acid treatment could be due to inhibition of respiration and ethylene production rates, and reduction of oxidative injury caused by reactive oxygen species through increased antioxidant activity.     

Physiology of fresh-cut ‘Galia’ (Cucumis melo var. reticulatus) from ripe fruit treated with 1-methylcyclopropene

‘Galia’ (Cucumis melo var. reticulatus L. Naud. cv. Galia) fruit were harvested at the three-quarter slip stage and treated with 1 μL L⁻¹ 1-methylcyclopropene (1-MCP) at 20 °C for 24 h. The fruit were processed and stored as fresh-cut cubes and intact fruit for 10 d at 5 °C. Ethylene production of fresh-cut cubes was approximately 4–5-fold higher than intact fruit at day 1. Afterward, the ethylene production of fresh-cut cubes declined significantly whereas that of intact fruit remained relatively constant at about 0.69–1.04 ng kg⁻¹ s⁻¹. 1-MCP delayed mesocarp softening in both fresh-cut and intact fruit and the symptoms of watersoaking in fresh-cut fruit. Continuously stored fresh-cut cubes and cubes derived from intact fruit not treated with the ethylene antagonist softened 27% and 25.6%, respectively, during 10 d storage at 5 °C while cubes derived from 1-MCP-treated fruit softened 9% and 17%, respectively. Fresh-cut tissue from 1-MCP-treated fruit exhibited slightly reduced populations of both total aerobic organisms and Enterobacterium, although the differences did not appear to be sufficient to explain the differences in keeping quality between 1-MCP-treated and control fruit. Based primarily on firmness retention and reduced watersoaking, 1-MCP treatment deferred loss of physical deterioration of fresh-cut ‘Galia’ cubes at 5 °C by 2–3 d compared with controls.     

Ethylene synthesis,ripening capacity,and superficial scald inhibition in 1-MCP treated ‘d’Anjou’ pears are affected by storage temperature

A continuing challenge for commercializing 1-methylcyclopropene (1-MCP) to extend the storage life and control superficial scald of ‘d’Anjou’ pear (Pyrus communis L.) is how to initiate ripening in 1-MCP treated fruit. ‘D’Anjou’ pears harvested at commercial and late maturity were treated with 1-MCP at 0.15 μL L⁻¹ and stored either at the commercial storage temperature −1.1 °C (1-MCP@−1.1 °C), or at 1.1 °C (1-MCP@1.1 °C) or 2.2 °C (1-MCP@2.2 °C) for 8 months. Control fruit stored at −1.1 °C ripened and developed significant scald within 7 d at 20 °C following 3–5 months of storage. While 1-MCP@−1.1 °C fruit did not develop ripening capacity due to extremely low internal ethylene concentration (IEC) and ethylene production rate for 8 months, 1-MCP@1.1 °C fruit produced significant amounts of IEC during storage and developed ripening capacity with relatively low levels of scald within 7 d at 20 °C following 6–8 months of storage. 1-MCP@2.2 °C fruit lost quality quickly during storage. Compared to the control, the expression of ethylene synthesis (PcACS1, PcACO1) and signal (PcETR1, PcETR2) genes was stable at extremely low levels in 1-MCP@−1.1 °C fruit. In contrast, they increased expression after 4 or 5 months of storage in 1-MCP@1.1 °C fruit. Other genes (PcCTR1, PcACS2, PcACS4 and PcACS5) remained at very low expression regardless of fruit capacity to ripen. A storage temperature of 1.1 °C can facilitate initiation of ripening capacity in 1-MCP treated ‘d’Anjou’ pears with relatively low scald incidence following 6–8 months storage through recovering the expression of certain ethylene synthesis and signal genes.     

Effect of initial hermetic sealing on quality of ‘Kyoho’ grapes during storage

Experiments of initial hermetic sealing using high barrier film were carried out on ‘Kyoho’ grapes (Vitis vinifera L. × V. Labrusca L. cv. Kyoho) in the 2008 and 2009 fruit seasons, to investigate their potential to enhance quality and extend storage life of the fruit. In the 2008 season, grapes were packaged in high barrier film bags for 1, 2, 3, 4 and 5 weeks, and a modified atmosphere (MA) of low oxygen and high carbon dioxide was formed after sealing. After packaging, fruit were removed from bags and stored in air for up to 90 d at 0 °C. In the 2009 season, grapes were packaged in perforated bags, or in high barrier film bags for 2 weeks and subsequently perforated bags to avoid further anoxia and excessive CO₂ accumulation. After treatment, fruit were stored for up to 90 d at 0 °C, followed by shelf-life at 20 °C for 7 d. Non-packaging air storage was used as a control in both seasons. Fruit quality attributes including soluble solids, titratable acidity, stem browning, berry drop and decay incidence were measured. The results indicated that short-term initial MAP (≤2 weeks) had potential for improving appearance of bunches and maintaining the quality of berries during long-term storage, and significantly reduced quality deterioration. Stems were greener and berry drop and decay incidence were more effectively controlled when fruit were sealed in high barrier film bags for 2 weeks and the bags were subsequently perforated.     

Ethanol vapor prior to processing extends fresh-cut mango storage by decreasing spoilage,but does not always delay ripening

This study was undertaken to optimize ethanol vapor application as a ripening inhibitor on whole mangoes to extend fresh-cut mango shelf life. Freshly harvested mangoes were first subjected to hot water (+HW) at 46 °C for 60 or 90 min to simulate quarantine heat treatments, or remained untreated (−HW). Fruit of each batch (+ or −HW) were then held at 20–25 °C for 4 or 7 d (D4 and D7) after the hot water treatment before being exposed to ethanol vapors [0 h (E0), 10 h (E10), or 20 h (E20)]. Fruit were then peeled and cut into slices, packed in plastic clamshells, and stored at 7 °C for 15 d. Only slices from +HW-D4-E20-treated fruit maintained higher firmness, hue angle, and titratable acidity (TA) in storage. The +HW-D7-E10- or E20-treated fruit had higher hue angle than E0, but firmness, total soluble solids, TA, pH, and respiration rate did not differ. Internal ethanol and acetaldehyde were very high in slices from +HW, D4 and D7, E20 and −HW-D7-E20-treated fruit. A sensory panel could perceive higher firmness and acidity in slices from fruit treated with ethanol. However, E20 induced off-flavor, and these fruit were least preferred.Ethanol exposure on fruit was repeated with purchased mangoes that had been subjected to a commercial quarantine heat treatment. A second heat treatment of 18 h at 38 °C and 98% relative humidity was added to one batch of fruit in this experiment. Ethanol vapors did not result in delayed ripening in those mangoes. However, this treatment inhibited microbial growth. The second heat treatment did not improve fresh-cut mango shelf life, and further, microbial growth increased compared to other treatments. It is concluded that, due to inconsistent results, ethanol vapor applied for 20 h to whole mangoes prior to processing for fresh-cut is not a practical approach to delay ripening; however, at lower doses (10 h), it could be used as a safe microbial control in a fresh-cut production sanitation system.     

Benzyl-aminopurine (BAP) treatments delay cell wall degradation and softening,improving quality maintenance of refrigerated summer squash

Round summer squash are harvested before reaching full maturity and even though they are highly perishable, fruit postharvest handling is mostly based on storage at non-chilling temperatures. Finding complementary treatments minimizing deterioration and reducing postharvest losses would be extremely useful. In this work we evaluated the effect of postharvest cytokinin (CK) treatments on refrigerated round soft rind squash. Fruit were harvested at commercial maturity and sprayed with 1 mmol L⁻¹ benzylaminopurine (BAP) or water (control) prior to storage at 5 °C for 0, 13 or 25 days. Quality was assessed upon removal from cold storage as well as after a 2 day shelf-life period at 20 °C. CK-treated fruit showed slower deterioration and dehydration and remained firmer than the control. BAP sprays did not affect color, respiration or sugar-acid balance. The treatments prevented phenolic compound accumulation, and decreased pectin solubilization. By the end of the storage period BAP-treated squash had higher levels (45%) of tightly-bound polyuronides than untreated controls, indicating a substantial delay in cell wall dismantling. CK sprays also reduced neutral sugar solubilization from pectin-rich fractions, but no changes were found in the cross-linking glycans or cellulose. To our knowledge, this is the first work showing that CK can regulate pectin disassembly in developing fruit. Postharvest BAP sprays preventing texture deterioration may be a simple treatment to complement refrigeration of round, soft rind, summer squash.     

Increasing maturity reduces wound response and lignification processes against Penicillium expansum (pathogen) and Penicillium digitatum (non-host pathogen) infection in apples

Penicillium expansum is the main postharvest pathogen of pome fruit and is a necrotrophic fungus that requires wounds to infect the fruit. Therefore, injuries caused during harvest and postharvest handling provide an optimal locus for infection. In this study, the effect of wound response in apples harvested at three different maturity stages and stored at two different temperatures (20 and 0 °C) infected with P. expansum (pathogen) and Penicillium digitatum (non-host pathogen) was evaluated. The effect of wounding and pathogen inoculation on lignin content was also quantified. At 20 °C, less decay incidence and severity were observed when time between wounding and inoculation increased, and these differences were more important in fruit from immature and commercial harvests. However, at 0 °C, wound response was too slow to prevent P. expansum infection. Lignin content was highest in fruit from the immature harvest. Our results indicated that maturity and storage temperature play an important role in apple wound response. This is the first report demonstrating that P. digitatum, a non-host pathogen, was able to develop rots in over-mature apples.