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.     

A new strain of Metschnikowia fructicola for postharvest control of Penicillium expansum and patulin accumulation on four cultivars of apple

The efficacy of three antagonistic yeasts, Metschnikowia pulcherrima strain MACH1, M. pulcherrima strain GS9, and Metschnikowia fructicola strain AL27, against Penicillium expansum and patulin accumulation was evaluated on apples stored at room (22 ± 1 °C for 7 days) and cold temperatures (1 ± 1 °C for 56 days). To increase the potential range of application of the biocontrol agents (BCAs), their efficacy was evaluated on four cultivars of apple, i.e. ‘Golden Delicious’, ‘Granny Smith’, ‘Red Chief’ and ‘Royal Gala’. AL27 was more effective than MACH1 and GS9 in the control of blue mold rot and in the reduction of patulin accumulation. The efficacy of AL27 was in most cases similar to the chemical control used, making the antagonist as competitive as chemical fungicides. In vitro experiments showed that AL27 reduced the conidial germination and germ tube length of P. expansum more than the other strains. The three BCAs were more effective in the control of blue mold rot on ‘Golden Delicious’ apples than on the other tested cultivars.     

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 preharvest nitric oxide treatment on ethylene biosynthesis and soluble sugars metabolism in ‘Golden Delicious’ apples

In order to examine the influence of preharvest nitric oxide (NO) treatment on ethylene biosynthesis and soluble sugar metabolism in ‘Golden Delicious’ apples, apple trees were sprayed with 50 μM sodium nitroprusside (SNP) (a donor of NO) 14 days before harvest. The results indicated that preharvest SNP treatment can increase the NO content and the NOS activity in apple fruit, therefore, delay the accumulation of ethylene due to its inhibition on the activities of 1-aminocyclopropane-1-carboxylate synthase (ACS) and 1-aminocyclopropane-1-carboxylate oxydase (ACO). Fructose is the main sugar in ‘Golden Delicious’ apple. The synthesis of sucrose was stimulated and the decomposition of sucrose was inhibited by this treatment, thus causing the accumulation of sucrose. We can draw a conclusion that pre-harvest SNP (50 μM) treatment can increase the NO content of fruit during storage, while higher NO content can further regulate fruit ripening through its effect on ethylene and sugar metabolism in ‘Golden Delicious’ apple fruit during storage at 18 °C.     

Control of blue mold of apple by combining controlled atmosphere,an antagonist mixture,and sodium bicarbonate

‘Golden Delicious’ apples were wound-inoculated with Penicillium expansum and treated with various combinations of sodium bicarbonate and two antagonists (Metschnikowia pulcherrima, Cryptococcus laurentii), and then stored in air or controlled atmosphere (CA = 1.4 kPa O₂ and 3 kPa CO₂) for 2 or 4 months at 1 °C. The antagonists survived and their populations increased during both air and CA storage. The antagonists alone reduced blue mold but were more effective when combined. Sodium bicarbonate tended to reduce lesion size when used with these antagonist, either when they were used alone or combined. Storage under CA conditions also increased the effectiveness of both antagonist, when used alone or in combination. The only treatment that completely eliminated P. expansum-incited decay was the combination of the two antagonists and sodium bicarbonate on fruit stored under CA conditions. The proper combination of alternative control measures can provide commercially acceptable long-term control of fruit decay and could help reduce our dependency on fungicides.     

Effects of repeated 1-methylcyclopropene (1-MCP) treatments on ripening and superficial scald of ‘Cortland’ and ‘Delicious’ apples

Postharvest 1-MCP can maintain fruit quality and inhibit development of superficial scald, a physiological storage disorder found in apple fruit, but the extent of the inhibition can vary by cultivar. In this study, we investigated whether multiple applications of 1-MCP, which are now permitted by a label modification of the commercial 1-MCP product, SmartFresh™, might improve scald control. ‘Cortland’ and ‘Delicious’ apples were untreated, treated on the day of harvest with the antioxidant inhibitor of scald, diphenylamine (DPA), or with 1 μL L⁻¹ 1-MCP at different intervals after harvest. Treatment times (days) were 1, 4, 7, 1 + 4, 4 + 7, 1 + 4 + 7, 7 + 14, 7 + 28, 7 + 42, and 7 + 84. Internal ethylene concentrations (IECs), flesh firmness, and accumulations of α-farnesene and conjugated trienols (CTols) were measured at harvest, at the time of treatment, and at intervals during air storage at 0.5 °C for up to 36 weeks. Scald was completely inhibited by DPA and all 1-MCP treatments in ‘Delicious’. However, effective control of scald in ‘Cortland’ was obtained with 1-MCP treatments within the first 4 days of harvest, either alone or in combination. Scald control with delayed 1-MCP treatments resulted in poorer scald control that was comparable to that obtained with DPA. IECs and α-farnesene accumulation were similar in untreated and DPA treated fruit, but inhibited by 1-MCP. However, differences among 1-MCP treatments became more evident with increasing storage periods. Inhibition of IECs and α-farnesene accumulation was greater in fruit treated on days 1, 4, 1 + 4, 4 + 7, 1 + 4 + 7, than on day 7 alone. A second application of 1-MCP on day 14 to fruit treated on day 7 increased inhibition of IECs, α-farnesene and CTol accumulations, but increasing delays before the second 1-MCP treatment resulted in progressively less inhibition of these factors. Similar effects of treatment on IECs, α-farnesene and CTol accumulations were found for both cultivars, even though no scald was detected in treated ‘Delicious’ apples. The results indicate that initial 1-MCP treatments should be applied to faster ripening cultivars such as ‘Cortland’ within a few days of harvest.     

Inhibition of browning on the surface of apple slices by short term exposure to nitric oxide (NO) gas

Freshly cut slices of apple (Malus x domestica Borkh cv. Granny Smith) were fumigated with nitric oxide (NO) gas at concentrations between 1 and 500 μl l⁻¹ in air at 20 °C for up to 6 h followed by storage at 0, 5, 10 and 20 °C in air. Exposure to nitric oxide delayed the onset of browning on the apple surface with the most effective treatment being fumigation with 10 μl l⁻¹ NO for 1 h. While nitric oxide inhibited browning in slices held at all temperatures, it was relatively more effective as the storage temperature was reduced with the extension in postharvest life over the respective untreated slices increasing from about 40% at 20 °C to about 70% at 0 °C. In a smaller study on ‘Royal Gala’, ‘Golden Delicious’, ‘Sundowner’, ‘Fuji’ and ‘Red Delicious’ slices stored at 10 °C, 10 μl l⁻¹ NO for 1 h was found to be effective in inhibiting surface browning in all cultivars.     

Influence of the combination of different atmospheres on diphenylamine,folpet and imazalil content in cold-stored ‘Pink Lady®’ apples

‘Pink Lady^®’ apples were harvested at commercial maturity, treated with three different agrochemical products, and stored at 1 °C under either air or controlled atmosphere conditions (2 kPa O₂ + 2 kPa CO₂ and 1 kPa O₂ + 1 kPa CO₂) for 13 and 27 weeks, followed by 4 weeks storage in air at 1 °C. Diphenylamine, folpet and imazalil contents in both the skin and flesh were simultaneously determined after cold storage plus simulated marketing periods of 1 and 7 d at 20 °C. After 27 weeks plus 7 d, diphenylamine and folpet levels in apple skin were lower for fruit stored in low O₂ (2 kPa) or air than for those kept under ultra-low O₂ (1 kPa). An additional storage period of 4 weeks in air reduced diphenylamine and folpet contents in whole apples stored for 13 weeks in the low O₂ controlled atmosphere. For imazalil, the same result was obtained in apple skins stored for 27 weeks under an ultra-low O₂ controlled atmosphere. Differences in diphenylamine and folpet contents were found for skin and flesh samples throughout the simulated marketing period, but there were observable differences in imazalil contents only for flesh samples.     

Relationship of IAD index to internal quality attributes of apples treated with 1-methylcyclopropene and stored in air or controlled atmospheres

The research was conducted to evaluate the relationship between I_AD index (index of absorption difference between 670 and 720 nm) values and internal quality attributes of apples treated with 1-methylcyclopropene (1-MCP) and stored in air and controlled atmospheres (CA). Apples of ‘8S6923’ (Aurora Golden Gala™), ‘Fuji’ and ‘Royal Gala’ were tested. The results with Aurora Golden Gala™ show that I_AD index values were maintained at higher levels if the fruit were stored in CA and that 1-MCP had no significant effect on retaining at-harvest values. The I_AD values correlated with chlorophyll a content in the peel (R² = 0.95, P < 0.0001), but not with chlorophyll b content, internal ethylene levels, firmness or titratable acidity. ‘Royal Gala’ apples showed a similar response to Aurora Golden Gala™ apples, showing no correlation between I_AD index values and internal quality attributes of those apples when treated with 1-MCP and/or CA. In contrast, ‘Fuji’ apples showed a relationship between I_AD index value changes and internal ethylene concentrations (R² = 0.67, P < 0.05) and titratable acidity changes (R² = 0.89, P < 0.01), but not firmness. These results suggest that when 1-MCP and/or CA are applied to apples after harvest, that I_AD index values do not consistently correlate to any internal quality attributes other than peel chlorophyll a content.     

NIR spectroscopy for the optimization of postharvest apple management

Apples can be stored for long time under controlled temperature and atmosphere conditions, and therefore, non-destructive and rapid tools are required to assess fruit quality and to monitor changes during the postharvest period. The aim of this study was to evaluate the feasibility of NIR spectroscopy to optimize postharvest apple management and to follow changes in fruit quality during storage. An FT-NIR system operating in diffuse reflectance in the range 12,500–3600 cm⁻¹ was used to evaluate the physico-chemical (dry matter, soluble solids, colour and firmness) and some nutraceutical characteristics (total phenolics, total flavonoids and antioxidant activity) of ‘Golden Delicious’ apples, which were stored for about six months at 1 °C in controlled atmosphere, over two subsequent years. Spectral data were elaborated by PLS regression and LDA classification techniques. Good correlation models between spectral data and chemical and physical parameters were obtained for soluble solids, a* colour coordinate and firmness (0.81 < R² < 0.90 in calibration and 0.79 < R² < 0.89 in cross validation). Even higher correlation values (0.89 < R² < 0.95 in calibration and 0.86 < R² < 0.92 in cross validation) were obtained for indexes correlated to the antioxidant capacity of apples. The classification technique Linear Discriminant Analysis was applied to spectral data, in order to discriminate apples on the basis of storage time. Average correct classification was higher than 93% in validation and close to 100% in calibration, indicating high potential of NIR spectroscopy for the estimation of storage time of apple lots.     

Modeling the effect of preharvest weather conditions on the incidence of soft scald in ‘Honeycrisp’ apples

‘Honeycrisp’ apples show a high susceptibility to physiological disorders such as soft scald. The objective of this study was to identify weather parameters during fruit development that influence soft scald development in ‘Honeycrisp’ apples. Soft scald susceptibility of ‘Honeycrisp’ has been linked to weather conditions during specific periods of the growing season, referenced by given phenological stages. Using weather data and fruit quality analysis data from three sites in Ontario, two sites in Quebec and one site in Nova Scotia for three seasons (2009–2011) and four additional sites in Ontario from 2002–2006, a model for soft scald incidence (SSI) was built to predict the susceptibility of ‘Honeycrisp’ apples prior to storage. This model used primarily two weather variables during three sub-periods of fruit development to accumulate a SSI index (%) during the growing season, from full bloom to harvest time. Relatively wet conditions during phenological stages from full bloom until 10 mm diameter (precipitation > 0.5 mm) and from 10 mm until 50% of final caliber (precipitation > 6.0 mm), cool conditions (temperature < 15 °C) from full bloom until 10 mm diameter, and warm conditions (temperature > 20 °C) from 50 to 80% of final size are conditions that resulted in increased soft scald susceptibility for ‘Honeycrisp’ apples. The SSI model may be used by producers to establish more appropriate marketing and storage strategies depending on levels of susceptibility to soft scald development predicted prior to storage.     

Dynamics of ascorbic acid in ‘Braeburn’ and ‘Gala’ apples during on-tree development and storage in atmospheres conducive to internal browning development

The underlying causes as well as chemical and biochemical alleviation for CO₂-induced browning in apple fruit are poorly understood. Ascorbic acid (AsA) dynamics in ‘Braeburn,’ a susceptible cultivar, and ‘Gala’, a resistant cultivar, were evaluated during on-tree development and storage at 0.5 °C in air or controlled atmospheres (CA) containing 1 kPa O₂ and 1, 3 or 5 kPa CO₂. ‘Braeburn’ fruit treated with diphenylamine (DPA) was also stored for 1 month to determine effects on browning incidence and AsA concentration. ‘Braeburn’ apples had significantly higher (p ≤ 0.05) AsA levels than ‘Gala’ during on-tree development, and storage. No correlation between AsA and maturity/ripening indices for ‘Braeburn’ or ‘Gala’ was apparent. Histochemical localization of fruit AsA showed a staining intensity consistent with the quantity analytically determined, and showed that AsA is diffusely distributed throughout the cortex in both cultivars during on-tree development. During storage, AsA was localized to the periphery of brown tissue in ‘Braeburn’ and to the coreline and cortex proximal to the peel in ‘Braeburn’ and ‘Gala’ tissues. DPA decreased browning development during storage, however, no correlation between DPA treatment and AsA quantity in healthy or brown cortex tissue was observed. The results indicate AsA quantity alone is not an indicator of CO₂ sensitivity in these two cultivars.     

Controlled atmosphere storage of guava (Psidium guajava L.) fruit

The effects of controlled atmospheres (CA) on respiration, ethylene production, firmness, weight loss, quality, chilling injury, and decay incidence of three commercially important cultivars of guava fruit were studied during storage in atmospheres containing 2.5, 5, 8, and 10 kPa O₂ with 2.5, 5, and 10 kPa CO₂ (balance N₂) at 8 °C, a temperature normally inducing chilling injury. Mature light green fruit of cultivars, ‘Lucknow-49’, ‘Allahabad Safeda’ and ‘Apple Colour’, were stored for 30 days either in CA or normal air, and transferred to ambient conditions (25–28 °C and 60–70% R.H.) for ripening. CA storage delayed and suppressed respiratory and ethylene peaks during ripening. A greater suppression of respiration and ethylene production was observed in fruit stored in low O₂ (≤5 kPa) atmospheres compared to those stored in CA containing 8 or 10 kPa O₂ levels. High CO₂ (>5 kPa) was not beneficial, causing a reduction in ascorbic acid levels. CA storage was effective in reducing weight loss, and maintaining firmness of fruit. The changes in soluble solids content (SSC), titratable acidity (TA), ascorbic acid, and total phenols were retarded by CA, the extent of which was dependent upon cultivar and atmosphere composition. Higher amounts of fermentative metabolites, ethanol and acetaldehyde, accumulated in fruit held in atmospheres containing 2.5 kPa O₂. Chilling injury and decay incidence were reduced during ripening of fruit stored in optimal atmospheres compared to air-stored fruit. In conclusion, guava cultivars, ‘Lucknow-49’, ‘Allahabad Safeda’, and ‘Apple Colour’ may be stored for 30 days at low temperature (8 °C) supplemented with 5 kPa O₂ + 2.5 kPa CO₂, 5 kPa O₂ + 5 kPa CO₂, and 8 kPa O₂ + 5 kPa CO₂, respectively.     

Internal ethylene concentrations in apple fruit at harvest affect persistence of inhibition of ethylene production after 1-methylcyclopropene treatment

Factors that affect the efficacy of 1-methycyclopropene (1-MCP) treatment of apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] include cultivar and maturity. In this study, ‘McIntosh’, ‘Cortland’ and ‘Empire’ apples were categorized by internal ethylene concentrations (IECs) at harvest, treated with 1 μL L⁻¹ 1-MCP, and the IECs of individual fruit followed at 30 d intervals during air storage at 0.5 °C for 90 d. IECs at harvest ranged from <0.5 μL L⁻¹ to ≥100 μL L⁻¹, 51 < 100 μL L⁻¹, and 10 < 50 μL L⁻¹ for ‘McIntosh’, ‘Cortland’ and ‘Empire’, respectively. 1-MCP treatment resulted in a decrease of IECs in fruit of all cultivars by day 30 after harvest. During subsequent storage IECs remained low in fruit with <1 μL L⁻¹ at harvest, but in ‘McIntosh’, ‘Cortland’ increased in proportion to IECs at harvest, but not in ‘Empire’. The importance of initial IECs in fruit on the persistence of 1-MCP inhibition of ethylene production was confirmed in a further experiment, in which IECs in untreated and 1-MCP treated ‘McIntosh’ and ‘Empire’ apples were measured for up to 194 d. 1-MCP also decreased 1-aminocyclopropene-1-carboxylic acid (ACC) concentrations in fruit. The results of our study are consistent with the hypothesis that IEC modulates the sensitivity of climacteric fruit to 1-MCP.     

Multivariate analysis of modifications in biosynthesis of volatile compounds after CA storage of ‘Fuji’ apples

Emission of aroma volatile compounds and some related enzyme activities (LOX, PDC, ADH, and AAT) were assessed in ‘Fuji’ apples (Malus × domestica Borkh.) during shelf life at 20 °C following cold storage under air or under three different CA conditions (3 kPa O₂:2 kPa CO₂; 1 kPa O₂:1 kPa CO₂; or 1 kPa O₂:2 kPa CO₂). Data were used for principal component analysis (PCA) and partial least-square regression (PLSR) analysis of results. LOX activity was partly inhibited by hypoxic conditions, and thus could have contributed to differentiation between air- and CA-stored fruit. Accordingly, emission of straight-chain esters was also higher in air- than in CA-stored fruit. In contrast, PDC activity was responsible for part of the differences between low (3 kPa) and ultra-low (1 kPa) O₂ storage conditions, probably by providing substrates for AAT action. AAT activity afforded no satisfactory differentiation between samples, and therefore it is suggested that substrate availability is a more decisive factor than enzyme activity for volatile production after storage. The PCA and PLSR models developed in this work were not useful for discrimination between the two studied ultra-low O₂ conditions.     

Hyperspectral laser-induced fluorescence imaging for assessing apple fruit quality

Chlorophyll fluorescence is a promising technique for postharvest quality research, and reported studies were mainly based on the fluorescence kinetic analysis method, which has not been quite satisfactory for measuring fruit quality. This paper reports on using a hyperspectral imaging technique for measurement of laser-induced fluorescence from apple fruit for predicting multiple fruit quality parameters. A continuous wave blue laser (408 nm) was used as an excitation source for inducing fluorescence in apples. Fluorescence scattering images were acquired from ‘Golden Delicious’ apples by a hyperspectral imaging system at the instance of laser illumination (0 min) and after 1, 2, 3, 4, and 5 min of illumination. The hyperspectral fluorescence image data were represented by mean, maximum, and standard deviation spectra. Standard tests were performed on measuring fruit skin and flesh color, firmness, soluble solids content, and titratable acid. A hybrid method of combining principal component analysis and neural network modeling was used for developing prediction models to predict fruit quality parameters for each of the six illumination time periods. Fluorescence emission decreased steadily during the first 3 min of illumination and was stable within 5 min. The 0-min fluorescence prediction models had somewhat poorer prediction results for individual quality parameters except skin hue than did the models of longer illumination time. The differences were minimal in the model prediction results from the fluorescence data at 1, 2, 3, 4 or 5 min of illumination. Overall, excellent predictions were obtained for apple skin hue with the correlation coefficient of prediction of 0.94. Relatively good predictions were obtained for fruit firmness, skin chroma, and flesh hue with values for the correlation coefficient being equal to or greater than 0.74 for 1 min of illumination or longer times, and poorer correlations were found for soluble solids content, titratable acid, and flesh chroma. Hyperspectral laser-induced fluorescence imaging is potentially useful for assessing selected quality parameters of apple fruit and further research is needed to improve fluorescence measurement for better prediction of fruit quality.     

Relationships between the instrumental and sensory characteristics of four peach and nectarine cultivars stored under air and CA atmospheres

‘Big Top’ and ‘Venus’ nectarines and ‘Early Rich’ and ‘Sweet Dream’ peaches were picked at commercial maturity and stored for 20 and 40 d at −0.5 °C and 92% RH under either air or one of the three different controlled atmosphere regimes (2 kPa O₂/5 kPa CO₂, 3 kPa O₂/10 kPa CO₂ and 6 kPa O₂/17 kPa CO₂). Physicochemical parameters and volatile compounds emission were instrumentally measured after cold storage plus 0 or 3 d at 20 °C. Eight sensory attributes were assessed after cold storage plus 3 d at 20 °C by a panel of 9 trained judges, in order to determine the relationship between sensory and instrumental parameters and the influence of storage period and cold storage atmosphere composition on this relationship.A principal component analysis (PCA) was undertaken to characterize the samples according to their sensory attributes. PCA results reflected the main characteristics of the cultivars: ‘Big Top’ was the nectarine cultivar with the highest values for sweetness, juiciness and flavor; ‘Sweet Dream’ was the sweetest peach and was characterized by high values for crispness and firmness, while ‘Venus’ and ‘Early Rich’ were characterized by their sourness. To assess the influence of storage period and CA composition on sensory properties, a PLS model of the flavor of the different samples was constructed using standard quality attributes and volatile concentrations as the X-variables. The model with 2 factors accounted for more than 80% of flavor variance. PLS results indicated that the main influence on flavor perception was storage period. Atmosphere composition also had an influence on flavor perception: flavor perception decreased from samples stored in a 2/5 O₂/CO₂ atmosphere composition to those of 3/10 and 6/17. These results can be qualitatively extended to juiciness and sweetness since all these sensory properties were strongly correlated.     

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.     

High oxygen combined with high carbon dioxide improvesmicrobial and sensory quality of fresh-cut peppers

The effects of high O₂ and high CO₂ throughout storage on the microbial and sensory quality of fresh-cut bell peppers from two commercial ‘California’ cultivars grown under different climatic conditions were studied. The ‘Meteor’ cultivar was minimally processed in Leuven (Belgium) and the ‘Requena’ cultivar in Cartagena (Murcia, Spain). The storage conditions were (kPa O₂/kPa CO₂/kPa N₂) 100/0/0, 80/15/5, 60/0/40, 50/15/35, 20/15/65 and 21/0.03/≅79 as control. Bell peppers freshly-cut in cubes were stored at 5 °C up to 9–10 days. Changes in total counts of mesophilic, psychrotrophic, yeasts and mould as well as Enterobacteriaceae were monitored. Individual and total sugars and organic acids contents, visual appearance, color, shriveling, off-aroma, crunchiness, flavor and overall quality were also evaluated. The results in both experiments showed that 80 or 50 kPa O₂ combined with 15 kPa CO₂ maintained the main sensory quality attributes and inhibited growth of the spoilage microorganisms and Enterobacteriaceae in minimally processed bell peppers.     

Changes in respiration of fresh-cut butterhead lettuce under controlled atmospheres using low and superatmospheric oxygen conditions with different carbon dioxide levels

The effect of different O₂ levels from 0 to 100 kPa in combination with 0, 10 and 20 kPa CO₂ on the respiration metabolism of greenhouse grown fresh-cut butter lettuce was studied. Controlled atmospheres of 20 or 75 kPa O₂ with 0 or 10 kPa CO₂ showed a constant respiration rate during the first 2–4 days at different temperatures (1, 5 and 9 °C). Therefore, constant respiration rates during a short period of 2–4 days could be considered as valid for a large part of the commercial life of, for instance, a modified atmosphere package development. The fresh-cut lettuce exposed to low O₂ levels (2–10 kPa) combined with moderate to high CO₂ levels (10 and 20 kPa) had a higher respiration rate than when 20–100 kPa O₂ were used. Moderate CO₂ levels (10 kPa) reduced the respiration rates of fresh-cut lettuce 20–40% at 9 °C. This effect was less noticed at lower temperatures. Gas composition with high CO₂ levels (20 kPa) probably caused a metabolic disorder increasing the respiration rate of fresh-cut butter lettuce. It was concluded that 80 kPa O₂ must be used in modified atmosphere packaging (MAP) to avoid fermentation of fresh-cut butter lettuce in combination with 10–20 kPa CO₂ for reducing their respiration rate.