Influence of pre-harvest ozone exposure on quality of strawberry fruit under simulated retail conditions

Strawberries (Fragaria × ananassa Duch.) were grown under an ozone-enriched atmosphere, and fruit yield, quality, and postharvest behavior under simulated retail storage conditions were investigated. The more ozone sensitive cv. Korona and the less sensitive cv. Elsanta, according to previous studies, were exposed for 2 months to 156 μg m⁻³ ozone on average, or air without ozone, in controlled-environment chambers. The influence of ozone depended significantly on the cultivar and its susceptibility to oxidative stress. Generally, ozone decreased the contents of ascorbic acid, caused higher lipid peroxidation and lowered sweetness of the fruit. In the case of lipid peroxidation, the effect was strengthened under retail conditions. The ozone stress did not influence yield, size, antioxidative capacity, anthocyanins, or phenolic compounds of fruit. In the more sensitive cv. Elsanta, ozone-induced sepal injuries were detected and the appearance of fruit was thus impaired; glutathione content of fruit also decreased. In contrast, fruit quality of the less sensitive cv. Korona remained almost constant. In general, retail conditions impaired quality of strawberry fruit and in the case of an effect on quality by ozone during fruit development, quality was slightly worse after storage due to the high perishability of the strawberry fruit.     

Distribution center and retail conditions affect the sensory and compositional quality of bulk and packaged slicing cucumbers

During distribution and retail display, fruits and vegetables are often exposed to undesirable temperature and humidity conditions which often result in increased waste due to weight loss and objectionable appearance. Unwaxed fresh-market slicing cucumbers (cv. Calypso) were harvested from a commercial operation and shipped to a distribution center (DC) in Florida. At the DC, 2 d after harvest, cucumbers were sorted and either commercially machine packaged in expanded polystyrene trays covered with a polyvinylchloride film or remained unpackaged for bulk retail display. Cucumbers were transported the next day by truck to a retail store in Gainesville, collected from the store, and stored under optimum (10 °C and 90% RH) or simulated retail display conditions (4 °C or 14 °C and 90–92% RH). Sensory (visual and instrumental color, firmness, shriveling, chilling injury and decay) and compositional quality (pH, titratable acidity, soluble solids and chlorophyll contents) were evaluated initially at the DC and after a 4-d simulated retail display period. Overall, bulk cucumbers were softer, appeared more shriveled, and were more affected by pitting and decay than packaged cucumbers. Bulk cucumbers also appeared lighter green and more yellowish than packaged fruit. Hue angle was less in bulk than in packaged cucumbers, but no consistent differences were observed in the L*, chroma, and hue values between the different temperatures. Small variations in the L*, hue, and chroma values compared to significant losses in chlorophyll content suggest that insufficient chlorophyll degradation occurred to cause major visual color changes. The greater weight loss in bulk cucumbers compared to packaged fruit was associated with accelerated chlorophyll degradation, lower acidity, and lower soluble solids content. Although packaged cucumbers had better visual quality than bulk cucumbers, there was higher RH inside the packages and greater development of decay on packaged fruit. Overall, after the 4-d simulated retail display, the appearance of the cucumbers used in this study was considered to be objectionable due to either yellowing, loss of firmness, shriveling or decay, regardless of the treatment. Results from this study demonstrate the importance of using an appropriate protective package in addition to maintaining the optimum temperature during distribution and retail display. Moreover, initial quality evaluation should be performed upon reception at the DC, and before cucumbers are displayed at the retail store, in order to estimate the remaining shelf life before this product becomes unacceptable for sale.     

Environmental conditions during root development: Drought constraint on cassava starch quality

Cassava has the reputation of being a drought tolerant crop, however, when deprived of water, plant and root development are affected. This ultimately will translate to an altered starch synthesis expressed by variation of starch quality. The magnitude of which, is influenced by the severity of stress conditions and stage of plant maturity. During early plant development,water stress retards growth, which will only be resumed after the immature plant has received sufficient water. Despite of an increased starch yield, the effect of initial water stress on starch quality is still sustained. In mature plants, starch quality is affected by environmental conditions prior to root harvest, especially the onset of rain after a stress period as indicated by a reduced starch paste. This paper presents the argument for extending the scope of traditional breeding programs beyond selecting for plant growth under drought conditions, to strategies that place greater emphasis on stabilizing starch quality. This revised version was published online in July 2006 with corrections to the Cover Date.     

Volatile compounds,quality parameters and consumer acceptance of ‘Pink Lady®’ apples stored in different conditions

Standard quality parameters, consumer acceptance, and volatile compound emission of ‘Pink Lady^®’ apples (Malus × domestica Borkh.) were measured at harvest and after 14 and 25 weeks of cold storage in three different atmospheres. After storage, fruit were left to ripen for 1 and 7 days at 20 °C before instrumental and sensory measurements were performed. Data were subjected to principal component analysis (PCA) and partial least square regression (PLSR). PLSR results indicated that the parameters positively influencing acceptability were soluble solid content, titratable acidity, background colour, and emission of hexyl 2-methylbutanoate, hexyl hexanoate, hexyl propanoate, butyl 2-methylbutanoate, 2-methylbutyl acetate and butyl propanoate. Results of sensory analyses revealed the treatments considered in this work could be split into two levels of acceptability.     

Colour development and quality of mangosteen (Garcinia mangostana L.) fruit during ripening and after harvest

The colour of mangosteen (Garcinia mangostana L.) fruit changes from green to purple black after harvest as the fruit ripens, and is used as a quality guide for growers and consumers. We determined the relationship between anthocyanin composition and content during fruit colour development in relation to fruit maturity and postharvest quality. Fruit at different stages of maturity (light greenish yellow with 5% scattered pink spots to purple black) were harvested and kept at 25 °C (85–90% RH). Fruit from each maturity stage all developed to the final purple black stage. During the postharvest period, hue angle values and pericarp firmness decreased significantly, while soluble solids contents increased. Anthocyanin contents in the outer pericarp were higher than in the inner pericarp and increased to a maximum at the final colour stage. Sensory evaluation and fruit quality (hue angle values, soluble solids and titratable acidity) of fruit harvested at the different stages did not differ once the fruit had finally developed to the purple black stage. The anthocyanins in the outer pericarp mainly consisted of five compounds, identified by HPLC/MS as cyanidin-sophoroside, cyanidin-glucoside, cyanidin-glucoside-pentoside, cyanidin-glucoside-X, cyanidin-X₂ and cyanidin-X, where X denotes an unidentified residue of m/z 190, a mass which does not correspond to any common sugar residue. Cyanidin-3-sophoroside and cyanidin-3-glucoside were the major compounds and the only ones that increased with fruit colour development.     

Interaction of temperature control deficiencies and atmosphere conditions during blueberry storage on quality outcomes

Southern hemisphere blueberry producers often export their products through extended supply chains to Northern hemisphere consumers. During extended storage, small variations in temperature or atmosphere concentrations may generate significant differences in final product quality. In addition, relatively short delays in establishing cool storage temperatures may contribute to quality loss. In these experiments a full factorial analysis was done of the effects of three cooling delays (0, 12 or 24 h at 10 °C), three atmosphere concentrations (air, 10% CO₂ + 2.5% O₂ and 10% CO₂ + 20% O₂) and two storage temperatures (0 °C and 4 °C) which were assessed for their impact on final quality, measured as weight loss, firmness and rot incidence. Two blueberry cultivars were studied: ‘Brigitta’, a highbush cultivar, and ‘Maru’, a rabbiteye. Delays in cooling had a small effect on final product weight, whereas variation in storage temperature and atmosphere during simulated transport influenced both firmness and rot incidence. Atmospheres with 10% CO₂ reduced decay incidence, particularly at low oxygen concentration (2.5% O₂), although the latter conditions tended to soften fruit. In order to achieve optimal postharvest storage for blueberries, minimising temperature variability in the supply chain is important, as is finding the potentially cultivar-specific optimal combination of high CO₂ and low O₂ concentration that results in simultaneously minimising rot incidence and induced softening.     

Effectiveness of pre- and post-veraison calcium applications to control decay and maintain table grape fruit quality during storage

A two year research was carried out on a table grape vineyard, cv. Italia, to evaluate the effectiveness of pre- and post-veraison calcium applications for controlling postharvest table grape rots and maintaining high fruit quality during cold storage. Two calcium application timings (from fruit set to veraison and from veraison to harvest) were compared to an untreated control. Clusters were sprayed with calcium chloride as Ca EDTA 44%. After each calcium application, bunch samples were collected and Ca²⁺ concentration was measured in berry compartments (skin, flesh and seeds). The main mechanical and chemical characteristics were measured on bunch samples at harvesting and during storage. In addition, the incidence of Botrytis cinerea rots, computed as McKinney index, was evaluated in field on natural inoculum and after harvesting on bunches artificially inoculated and maintained at room temperature. The highest Ca²⁺ concentrations were detected in skin tissues and after pre-veraison applications. Calcium accumulation in skin and flesh tissues stopped after veraison, whereas it continued up to ripening in seeds since the axial flow, differently from the peripheral, remains functional. In both years, calcium applications to bunches were effective both in maintaining postharvest fruit quality, as shown by flesh firmness and berry breaking force, and in reducing B. cinerea rots during storage. The applications were particularly efficacious if carried out between fruit set and veraison when stomata are functional and the re-translocation of calcium not directly absorbed by the bunches may occur via xylem transport.     

Calcium chloride extends the keeping quality of fig fruit (Ficus carica L.) during storage and shelf-life

The effects of postharvest application of fruit hardening chemical agents on fig (Ficus carica L. cv. Poona) fruit were compared with untreated figs during storage. The impact of calcium chloride (4%) was notable in terms of retention of fruit color, texture and increased accumulation of ascorbic acid, compared to untreated control figs. Pretreatment with calcium chloride (4%) was found to be most effective in checking the growth of both mesophilic aerobic bacteria and yeast and molds at low temperature (1 ± 0.5 °C; 95–98% RH) storage and it further delayed ripening and senescence of figs and was beneficial in prolonging the postharvest life twofold. Treated figs without microbial spoilage could be used for short term storage, transportation, distribution and marketing for long distance domestic markets in India.     

The kinetics of acetaldehyde and ethanol accumulation in ‘Hass’ avocado fruit during induction and recovery from low oxygen and high carbon dioxide conditions

The kinetics of acetaldehyde (AA) and ethanol (EtOH) accumulation and pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activities were studied in pre-climacteric ‘Hass’ avocado fruit flesh during induction and recovery from hypoxic conditions at 6 °C. Oxygen levels <0.5% resulted in a rapid accumulation of AA and EtOH. The pattern of AA and EtOH accumulation could be described by a hyperbolic model, although the initial 96 h of EtOH accumulation was linear. The accumulation of EtOH and AA was coincident with a doubling of the extractable ADH and PDC activities after 120 h exposure. Exposure of the fruit to up to 20% CO₂ concentrations resulted in an increase in tissue levels of AA, but not EtOH. The pattern of AA accumulation under high CO₂ was similar to that under low O₂, with the level of AA being higher at higher CO₂ concentrations.The AA and EtOH induced by low O₂ declined to basal levels in an exponential manner when O₂ was increased from ≤0.5 to ≥2%. The longer the duration of hypoxic induction, the longer the time required for AA and EtOH to decline to basal levels. When low O₂ induction was 48 h or less, the time required for AA and EtOH to decline to basal levels was not affected by O₂ concentrations >2%. However, after 96 h induction, the initial rate of decline in AA or EtOH was slower at lower O₂ concentrations. Including 20% CO₂ in the recovery atmosphere decreased the initial rapid rate of AA and EtOH decline, affecting EtOH levels more than AA, although both compounds reached pre-induction levels at approximately the same time. The rate of decline of ADH and PDC activity following low O₂ induction was accelerated by the presence of CO₂ in the atmosphere.Based on the rapid induction of AA and EtOH in response to low O₂ stress, and the comparable rapid recovery to basal levels after removal of the stress atmosphere, together with a seemingly high tolerance to O₂ atmospheres <2% and the similar but relatively smaller effect of CO₂ compared with O₂, it is concluded that preclimacteric ‘Hass’ avocados are physiologically well suited to dynamic CA storage.     

High-pressure water washing and continuous high humidity during storage and shelf conditions prolongs quality of red capsicums (Capsicum annuum L.)

In order to develop practical sea freight and marketing options for high quality red capsicums, we have investigated washing treatments that can minimize deterioration when fruit are subsequently stored under high humidity packaging conditions, at cool (6–8 °C) and warm (20 °C) temperatures. In small-scale trials using vented plastic bags to provide high humidity, fruit washed with unheated high-pressure water (517 kPa) had reduced incidence of flesh rots and deterioration of the calyx and stem compared to controls (unwashed or passed through a commercial packing line) or hot water drenched fruit (55 °C for 30 s) following a high humidity storage regime of 2 weeks at 6–8 °C and a further 14 d at 20 °C. In a more extensive trial where 5 kg boxes of fruit were used as replicates, washing with high-pressure water, packing in unperforated plastic box-liners and storing at 6–8 °C for 2 weeks, then 21 d at 20 °C resulted in 84% acceptability. In contrast, acceptability of fruit treated in a commercial packing line stored under regular (uncontrolled humidity) conditions or inside box liners (high relative humidity) declined rapidly at 20 °C after 2 weeks cool storage, with final acceptabilities of 10% and 39% after 21 d, respectively. We conclude that high-pressure water washing is an effective cleaning step, permitting high humidity to be used to prevent shrivel during cool-storage and subsequent ambient conditions, while minimizing the incidence of flesh rots or calyx/stem deterioration. Extended capsicum quality in high humidity at room temperature suggests that (a) cool-storage during transport to some markets may not be necessary if fruit are cleaned to a high standard and (b) fruit could remain within a box liner right up until the product is displayed on the supermarket shelves.     

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.     

Expression of expansin genes during postharvest lignification and softening of ‘Luoyangqing’ and ‘Baisha’ loquat fruit under different storage conditions

Four expansin cDNA fragments, EjEXPA1, EjEXPA2, EjEXPA3 and EjEXPA4, were isolated and characterized from loquat (Eriobotrya japonica Lindl.) fruit. EjEXPA1 mRNA accumulated consistently with the increase in fruit firmness in 0 °C storage of ‘Luoyangqing’ (LYQ) fruit, where chilling injury with increased fruit firmness due to lignification was observed. EjEXPA1 mRNA levels were lower in fruit that underwent low temperature conditioning (LTC, 6 d at 5 °C then 4 d at 0 °C), and in 1-methylcyclopropene (1-MCP) treated fruit, in both cases where chilling injury was alleviated. Fruit of the ‘Baisha’ (BS) cultivar soften after harvest rather than increase in firmness, and high expression levels of EjEXPA1 and EjEXPA4 accompanied the softening of BS fruit stored at 20 °C; such mRNA accumulation was much lower when fruit were stored at 0 °C, where softening was significantly inhibited by the low temperature. Very low expression of EjEXPA2 and EjEXPA3 was observed during storage of both LYQ and BS fruit under the different storage conditions. Our results showed that of the four genes characterized, EjEXPA1 might be associated with chilling-induced lignification while both EjEXPA1 and EjEXPA4 were closely related to softening of loquat fruit during the postharvest period.