Postharvest quality of apple predicted by NIR-spectroscopy: Study of the effect of biological variability on spectra and model performance

The effect of cultivar, season, shelf-life and origin on the accuracy of near infrared (NIR) calibration models for the soluble solids content (SSC) and firmness of apple was studied based on a large spectral data set based on approximately 6000 apple fruit from different cultivars, origins, shelf-life exposure time and seasons. To interpret the variance in the spectra with respect to biological variability, functional analysis of variance (FANOVA) was used. From the FANOVA analysis it was concluded that the effects of cultivar, origin and shelf-life exposure time on the NIR spectra were all significant. The largest differences in the spectra were found around the water absorption peaks (970, 1170 and 1450 nm). External validations using independent data sets showed that the accuracy of the models increased considerably when more variability was included in the calibration data set. In general the RMSEP for predictions of the SSC were in the range 0.6–0.8 °Brix, while for Magness Taylor firmness it was 5.9–8.8 N, depending on the cultivar. It was shown that atypical data can lead to large validation errors. It is, therefore, important to collect a calibration data set which is sufficiently representative for future samples to be analyzed with the developed calibration models and to develop simple procedures for model adaptation during practical use.     

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.     

Combination of electrolysed water,UV-C and superatmospheric O2 packaging for improving fresh-cut broccoli quality

The effects of neutral electrolysed water (NEW), ultraviolet light C (UV-C) and superatmospheric O₂ packaging (HO), single or combined, on the quality of fresh-cut kailan-hybrid broccoli for 19 days at 5 °C were studied. As controls, washing with water and sanitation with NaClO were both used. Electrolyte leakage, sensory, microbial and nutritional quality changes throughout shelf-life were studied. At day 15, the combined treatments achieved lower mesophilic and psychrophilic growth compared to the single ones. Single treatments produced higher ascorbate peroxidase (APX) reductions just after its application, while superoxide dismutase (SOD) showed the opposite behaviour. After 5 days at 5 °C, a great increase of APX and guaiacol peroxidase (GPX) activity was observed, NEW + UV-C + HO and HO-including treatments achieving the highest and the lowest APX increases, respectively. UV-C-including treatments produced the highest α-linolenic acid (ALA) decreases ranging 35–38% over control contents on the processing day. NEW-including treatments greatly reduced, throughout shelf-life, ALA and stearic acid (SA) content by 27–44% and 31–61%, respectively. Total phenolic content and antioxidant capacity (1415 mg ChAE kg⁻¹ fw and 287 mg AAE kg⁻¹ fw, respectively) remained quite constant during shelf-life. In general, the treatments and their possible combinations seem to be promising techniques to preserve, or even enhance, the quality of fresh-cut kailan-hybrid broccoli and, probably, other vegetables.     

Impact of a decontamination step with peroxyacetic acid on the shelf-life,sensory quality and nutrient content of grated carrots packed under equilibrium modified atmosphere and stored at 7 °C

Peroxyacetic acid (PAA) is a strong oxidizer and exerts antimicrobial properties. The effect of a decontamination step with 80 and 250 mg L⁻¹ PAA on shelf-life of grated carrots stored under equilibrium modified atmospheric packaging at 7 °C was determined and compared with the shelf-life of unwashed and water-washed carrots. Microbial parameters, including total aerobic plate count, numbers of lactic acid bacteria, Lactobacillae and yeasts, and sensory quality were evaluated. Next to these parameters, atmospheric gas composition, pH and nutrient content were also monitored. The suggested packaging configuration prevented CO₂ accumulation, but at the end of the study anoxic conditions were reached for unwashed carrots and carrots washed with 80 mg L⁻¹ PAA. The microbial shelf-life of water-washed carrots was 4 d based on the yeast count, whereas the flavour was not acceptable after 5 d. The total aerobic plate count and the yeast count determined the shelf-life of carrots treated with 80 mg L⁻¹ PAA on 5 d, whereas the flavour was unacceptable after 7 d. None of the microbial parameters determined the shelf-life of carrots washed with 250 mg L⁻¹ PAA. However, this treatment had already a pronounced adverse effect on the initial sensory quality. Water washing already decreased the content of all individually studied nutrients (−16 to −28%), except for lutein content and the antioxidant capacity. Additional losses after adding PAA on day 0 were found for α-tocopherol and phenols. Regardless of the applied treatment, α- and β-carotene remained stable during storage, whereas ζ-carotene, lutein and α-tocopherol were unstable. The phenol content and the antioxidant capacity of unwashed, water-washed and 80 mg L⁻¹ PAA-treated carrots increased significantly at the end of the storage period, whereas no changes were found in carrots treated with 250 mg L⁻¹ PAA.On the condition that carrots were packed under an adequate EMA, the 80 mg L⁻¹ PAA treatment showed possibilities for extending shelf-life without pronounced effects on nutrient content.     

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).     

Postharvest shelf-life extension of green chillies (Capsicum annuum L.) using shellac-based edible surface coatings

Shellac-based coatings were developed in combination with starch, EDTA and sodium alginate and were evaluated for shelf-life extension of fresh green chillies during storage at ambient temperature (26 ± 2 °C, RH 68 ± 4%) for 12 days. The developed composite coatings were found to be effective in extending the shelf-life of chillies. The control samples showed a higher weight loss (12.35%) compared to coated ones (5.60-6.90%). The coated samples showed significantly (p < 0.05) higher retention of ascorbic acid, firmness and chlorophyll content, whereas, total phenolic content was found to be significantly (p < 0.05) higher in uncoated samples after 12 days of storage. Shellac-sodium alginate based coating was found to be the most effective in maintaining the quality of fresh green chillies during ambient storage as compared to other coatings.     

Extending the shelf life of fresh-cut eggplant with a soy protein–cysteine based edible coating and modified atmosphere packaging

The effect of a soy protein-based edible coating with antioxidant activity, and conventional and superatmospheric modified atmosphere (MA) packaging, on the quality of fresh-cut ‘Telma’ eggplants, was evaluated during storage. In a first experiment, eggplant pieces were dipped in either a coating composed of soy protein isolate (SPI) and 0.5% cysteine (Cys), or water as an uncoated control. Samples were packed in trays under atmospheric conditions to reach a passive MA (MA-P) or two gas mixtures (MA-A: 15 kPa CO₂ + 5 kPa O₂; MA-B: 80 kPa O₂) and were stored at 5 °C. Atmospheric conditions were used as the control conditions (Control). The coated samples packed under MA-B and Control conditions resulted in the highest whiteness index (WI) values during storage, whereas MA-A did not improve the shelf-life of minimally processed eggplants and had the lowest WI values. The MA-B and atmospheric control conditions helped to maintain firmness, whereas the coating helped to maintain the weight loss under MA-A and MA-B. The maximum commercial shelf-life was reached on day 6 for the coated samples packed under atmospheric conditions. In a second experiment, the commercial shelf-life of fresh-cut eggplants was extended to 8 and 9 storage days by increasing the Cys content in the edible coating from 0.5 to 1% under MA-B and Control storage conditions, respectively.     

Hot water and ethanol treatments can effectively inhibit the discoloration of fresh-cut sunchoke (Helianthus tuberosus L.) tubers

The main problem affecting the quality of fresh-cut sunchoke tubers is cut surface discoloration. Pre- and post-cutting hot water and ethanol treatments were evaluated for their potential to inhibit discoloration, color changes, and associated phenolic metabolism in tuber slices stored in air at 5 °C. Some of the treatments tested inhibited discoloration and changes in a* and hue color values. Slices that were post-cut treated with hot water at 50 °C for 6–8 min or 55 °C for 3–4 min and pre-cut treated with water at 50 °C for 20–25 min maintained good color for 8–12 days at 5 °C. Post-cut ethanol fumigation (150–750 μL/L for 5 h at 5 °C) can prevent discoloration for 30 d at 5 °C. Post-cut dips with ethanol solutions (3, 5, 8 or 10% for 5 min) increased shelf-life twofold or longer compared to untreated slices. Ethanol fumigation retarded the onset of wound-induced respiration rates as well as reducing maximum rates. A post-cut 10% ethanol dip also reduced respiration rates and reduced PAL activity and total phenolics. Ethanol dips had no effect and hot water treatments had no persistent effect on microbial loads over 12 d.     

Conventional and emergent sanitizers decreased Ectomyelois ceratoniae infestation and maintained quality of date palm after shelf-life

Several methods have been used to prevent pest diseases and microbial contamination of dates, although their use is being restricted due to harmful effects on humans and/or to the environment. Sustainable sanitation techniques for keeping overall quality and safety of harvested dates should be developed and implemented. The current work studied the effect of NaClO, UV-C, ozonated water and alkaline and neutral electrolyzed water (NEW) on natural infestation by Ectomyelois ceratoniae or moth of pyrale, and on overall quality of ‘Deglet Nour’ dates stored for 30 days at the commercially used temperature of 20 °C. As controls, untreated samples were used. The skin color, firmness, pH, titratable acidity, total soluble solids content, sugar content, total polyphenols, antioxidant activity, microbial counts, sensory quality and moth infestations were monitored. Phenolics content increased after shelf-life. As expected, all sanitizers lowered microbial counts and moth infestation. A dose of 6 kJ UV-C m⁻² was the most efficient treatment against yeast and molds (without differences with NaClO and O₃), and coliforms, maintaining overall quality of dates after shelf-life. UV-C and NEW (pH 7.2, ORP 814 mV, and 300 mg L⁻¹ of free chlorine) were the most effective against moth proliferation, and could be considered as promising useful tools for commercial disinfection of fresh dates and extending shelf-life. As far as we know, no other comparative studies on these postharvest sanitizers on dates have been reported.     

Improvement of quality and shelf-life of strawberries with edible coatings enriched with chitosan

Strawberry fruit have a very short shelf-life and senescent period due to their high degree of perishability and infection caused by several pathogens that can rapidly reduce fruit quality. The aim of this study was to determine the efficacy of carboxymethyl cellulose (CMC), hydroxypropylmethyl cellulose (HPMC) and composites with chitosan (CH) coatings on the shelf-life and overall quality of strawberry fruit. Strawberry fruit dipped for 2 min in solutions of CMC (1%), HPMC (1%), CMC (1%) + CH (1%) and HPMC (1%) + CH (1%) were stored at 11 ± 1 °C, 70–75% RH, while the uncoated fruit served as controls. Fruit coated with edible coatings showed significant delays in the change of weight loss, decay percentage, titratable acidity (TA), pH, total soluble solids (TSS) and ascorbic acid content as compared to uncoated control fruit. In addition, the edible coatings had a positive effect on maintaining higher concentrations of total phenolics and total anthocyanins, which decreased in control fruit due to over-ripening and senescence processes. Compared to the controls, all the coatings had positive effects on the inhibition of cell wall degrading enzymes and among all the tested coatings, CMC + CH and HPMC + CH was superior in inhibiting enzyme activity. These findings suggest that the use of CMC 1% + CH 1% and HPMC 1% + CH 1% coatings are useful for extending the shelf-life and maintaing quality of strawberry fruit.     

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.     

Effect of 1-MCP treatment and N2O MAP on physiological and quality changes of fresh-cut pineapple

The effects of both 1-MCP treatment of pineapples and packaging of their fresh-cut products with an alternative modified atmosphere (MA: 86.13 kPa N₂O, 10.13 kPa O₂ and 5.07 kPa CO₂) on physiological and quality changes of these minimally processed products were investigated. Fresh-cut fruit treated or not with 1-MCP were packed in Air or in MA and were stored at 4 °C for 10 d. The following parameters were monitored during storage: ripening index; O₂, CO₂ and C₂H₄ in the package headspace; firmness and colour. Microbial spoilage of MP pineapple samples was also investigated and a mathematical model based on the Zwietering modified Gompertz equation was used to obtain growth parameters of mesophilic bacteria, yeasts and moulds.The results showed that 1-MCP treatment and MAP in a N₂O enriched atmosphere had a positive combined effect on the inhibition of respiration and ethylene production of fresh-cut pineapple and on its softening delay, confirming previous findings about 1-MCP and N₂O preservative effects on fresh-cut fruit quality. This combined effect was not extended to the ripening index and colour maintenance, as MAP at 86.13 kPa of N₂O did not add any benefit to that of the 1-MCP treatment. From a microbiological point of view, N₂O MAP extended the shelf-life of the products of 3–4 d by increasing the lag phase of microbial growth.     

Physicochemical measurements in ‘Mondial Gala®’ apples stored at different atmospheres: Influence on consumer acceptability

Standard quality parameters, consumer acceptability, emission of volatile compounds and ethylene production of ‘Mondial Gala^®’ apples (Malus × domestica Borkh.) were determined in relation to storage atmosphere, storage period and shelf-life period. Fruit were harvested at the commercial date and stored in AIR (21 kPa O₂:0.03 kPa CO₂) or under three different controlled atmospheres (CAs): LO (2 kPa O₂:2 kPa CO₂), ULO1 (1 kPa O₂:1 kPa CO₂), or ULO2 (1 kPa O₂:2 kPa CO₂). Fruit samples were analysed after 12 and 26 weeks of storage plus 1 or 7 d at 20 °C.Apples stored in CA maintained better standard quality parameters than AIR-stored fruit. The volatile compounds that contributed most to the characteristic aroma of ‘Mondial Gala^®’ apples after storage were butyl, hexyl and 2-methylbutyl acetate, hexyl propanoate, ethyl butanoate, ethyl hexanoate, ethyl, butyl and hexyl 2-methylbutanoate. Data obtained from fruit analysis were subjected to principal component analysis (PCA). The apples most accepted by consumers showed the highest emission of ethyl 2-methylbutanoate, ethyl hexanoate, tert-butyl propanoate and ethyl acetate, in addition to the highest titratable acidity and firmness values.     

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.     

Sensory and analytical characteristics of a novel hybrid muskmelon fruit intended for the fresh-cut industry

A novel hybrid muskmelon has been bred specifically for use by the fresh-cut industry in winter. Quality characteristics of fresh-cut pieces from the hybrid were compared to those of its inbred parental lines and to those of a commercial netted muskmelon (cantaloupe) and a non-netted muskmelon (honeydew) fruit available in winter. Pieces from hybrid and female line fruit had higher soluble solids content (SSC) and firmness, and lower aromatic volatile concentrations compared to those from the male line fruit. Pieces from hybrid fruit also had higher SSC (>3%) and were firmer (>5 N) than commercial fruit available during the winter, and had twice the aromatic volatile concentration of commercial honeydew and a more intense orange hue than commercial muskmelon. Consumers rated the flavor, texture, sweetness and overall eating quality of the hybrid higher than its inbred parents and winter-available honeydew and as well as or better than winter-available muskmelon. Hybrid fruit stored 5 weeks at 1 °C under modified atmospheric conditions, then fresh-cut and stored 14 d in air at 5 °C maintained good quality (firmness = 51 N, SSC > 12%, β-carotene and ascorbic acid concentrations = 18 and 182 mg kg^?1, respectively), and showed no signs of tissue translucency or surface pitting despite microbial populations >11 log₁₀ kg^?1. The results indicate that the novel hybrid muskmelon is a promising new melon type for fresh-cut processing and marketing, at least during the winter season.     

Blueberry leaf extracts incorporated chitosan coatings for preserving postharvest quality of fresh blueberries

The phenolic compounds in blueberry (Vaccinium spp.) fruit and leaf extracts (BLE) were determined based on HPLC analysis. Antimicrobial assays against Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium and Escherichia coli, as well as fungi isolated from the rotting blueberry fruit were conducted. The effects of chitosan coating incorporating different concentrations of BLE on the quality of fresh fruit during postharvest storage at 2 ± 1 °C and 95 ± 2% relative humidity (RH) for 35 d and then at room conditions for 3 d were also investigated. Five different coating treatments were applied including 2% (w/v) chitosan coating (T1), 2% (w/v) chitosan coating containing 4% (w/v, T2), 8% (w/v, T3), or 12% (w/v, T4) BLE, and 2% (w/v) chitosan coating containing 12% BLE plus modified atmosphere packaging (MAP at 3 kPa O₂ + 12 kPa CO₂) (T5). A sample of blueberries dipped into distilled water was used as control (T0). BLE had a greater variety of phenolic compounds than fruit extracts with syringic acid the highest concentration (0.259 ± 0.003 g kg⁻¹), but the total phenolic content in BLE was lower (P < 0.05) than in fruit extracts. BLE showed good antimicrobial activity against all tested microorganisms, with a minimum inhibition concentration from 25 to 50 g L⁻¹. The 2% chitosan coating that incorporated 8% or 12% BLE showed some degree of decreasing decay rate of fruit compared with the control, and the coating with BLE plus MAP had more effective control of fruit decay. All treated samples maintained higher total phenolic content and radical scavenging activity than the control. This study suggested that chitosan coating incorporating BLE can be employed to extend shelf-life and maintain high nutritional value of fresh blueberries during postharvest storage.     

Effect of new sanitizing formulations on quality of fresh-cut iceberg lettuce

In the present study, three recently patented decontamination agents: peroxyacetic acid combined with lactic acid, and two different combinations of hydrogen peroxide with citric acid (with and without propylene glycol), were compared with sodium hypochlorite and tap water washing regarding their effect on equilibrium modified atmosphere packaged (EMAP) fresh-cut iceberg lettuce. Effects of these sanitizers on respiration rate, electrolyte leakage, microbial levels, and sensory quality of the product after decontamination and during storage (3 d at 4 °C followed by 4 d at 7 °C) were elucidated. Hydrogen peroxide based sanitizers provoked a significant increase in the respiration rate and the electrolyte leakage of fresh-cut iceberg lettuce compared with tap water washing. Peroxyacetic acid combined with lactic acid resulted in similar results to those of tap water washing for all the parameters analyzed. However, other aspects of the combination of peroxyacetic and lactic acids (e.g. efficacy for cross-contamination avoidance) should be assessed in the future in order to determine its suitability for fresh-cut iceberg lettuce processing.     

Optimization of postharvest ultrasonic treatment of strawberry fruit

Freshly harvested strawberry fruit were treated at ultrasonic powers from 250 to 450 W at a constant frequency of 40 kHz for different times (5–15 min). Response surface methodology (RSM) based on a two factors three level central composite design was applied to optimize ultrasonic treatments on decay incidence, microbial population and quality maintenance of strawberries. According to response surface analysis, the optimal treatment parameters were an ultrasonic power of 250 W and treatment time of 9.8 min. Decay incidence and quality parameters of strawberries treated at the determined optimum conditions were compared with a water treatment during storage for 8 d at 5 °C. An ultrasonic treatment was found to be effective in inhibiting decay incidence and preserving quality in strawberries, and these results suggest that such a treatment may provide an alternative for extending shelf-life and maintaining quality of strawberry fruit.     

Preharvest application of methyl jasmonate (MeJA) in two plum cultivars. 2. Improvement of fruit quality and antioxidant systems during postharvest storage

‘Black Splendor’ (BS) and ‘Royal Rosa’ (RR) plums were treated preharvest with methyl jasmonate (MeJA) at three concentrations (0.5, 1.0 and 2.0 mM) along the on-tree fruit development: 63, 77 and 98 days after full blossom (DAFB). Both control and treated fruit were harvested at the commercial ripening stage and stored in two temperature conditions: 9 days at 20 °C or at 2 °C + 1 day at 20 °C for 50 days. Preharvest MeJA at 2.0 mM significantly accelerated whereas 0.5 mM delayed the postharvest ripening process for both cultivars, since ethylene production, respiration rate and softening were reduced significantly at the two storage conditions for 0.5 mM. In these fruit, total phenolics, total antioxidant activity (hydrophilic fraction, HTAA) and the antioxidant enzymes peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were found at higher levels in treated than control plums during postharvest storage, which could account for the delay of the postharvest ripening process and the extension of shelf-life.