Air-stored Fruit Research Articles

Controlled atmosphere storage impacts fruit quality and flavor chemistry of five cultivars of highbush blueberry (Vaccinium corymbosum)

Changes in highbush blueberry fruit quality and flavor chemistry following air or controlled atmosphere storage was determined for five blueberry cultivars. ‘Duke’, Aurora’, ‘Brigitta’, ‘Jersey’ and ‘Liberty’ fruit were stored for six weeks at 1 °C in chambers containing air or 0, 10.0, 12.5, 15.0, 17.5, or 20.0 kPa CO2 with 10.0 kPa O2. Elevated concentrations of CO2 reduced decay but did not affect fruit splitting, which differed among cultivars. Fruit firmness increased 36% in air-stored fruit, but decreased as CO2 concentration increased being 110% and 83% of initial values in fruit stored in 10 and 20 kPA CO2, respectively. Flesh discoloration increased following storage and in response to CO2 concentration. Sugar and acid content tended to increase in fruit stored in elevated CO2 concentrations but sugar/acid ratio declined. Volatile compounds were monitored using headspace solid phase microextraction-2 dimension gas chromatography-time of flight-mass spectroscopy. Concentrations of aldehydes did not change following storage regardless of atmosphere. Monoterpenoids and ketones declined after storage, but were not effected by storage atmosphere. Alcohols and esters increased after storage and in response to CO2 concentration. Ethanol, acetaldehyde and ethyl acetate increased in response to elevated concentrations of CO2 and were 1,100-, 90- and 150-fold greater in fruit stored in 20 kPa CO2 than in fruit prior to storage. Other ethyl and acetate esters also increased in response to elevated CO2 atmospheres. Differences in CO2 tolerance were observed among cultivars with ‘Liberty’ showing the least expression of fermentation-induced volatiles and ‘Aurora’ the least flesh discoloration. While storage of blueberries in elevated concentrations of CO2 is effective to reduce decay, its effects on fruit flavor must be considered in optimizing storage atmospheres.

EFFECT OF TEMPERATURE AND 1-METHYLCICLOPROPENE ON THE STORABILITY OF ‘ALEXANDER LUCAS’ PEAR

ABSTRACT The storage life of ‘Alexander Lucas’ pear is limited by the occurrence of internal storage disorders during controlled atmosphere (CA). 1-Methylcyclopropene (1-MCP) can be used to delay pear ripening, however, its interaction with CA conditions is not well understood. ‘Alexander Lucas’ fruit were treated with 1-MCP at 300 nL L-1 for 24 h in air at-0.5 or 1.0 °C before being stored. Fruit were kept at-0.5 or 1.0 °C in normal air or CA (2.0 kPa O2 plus <0.7 kPa CO2). After six months of storage, superficial scald did not develop in fruit. The highest incidence of flesh browning (72.2 %) was found in air-stored fruit at-0.5 °C without 1-MCP treatment. Storage in air at 1.0 °C plus 300 nL L-1 1-MCP produced 88.8 % of healthy fruit. In contrast, 1-MCP increased the incidence of flesh and core browning under CA conditions. 1-MCP and CA maintained greener skin color and higher titratable acidity. No significant differences were found for fruit firmness, total soluble solids and ascorbic acid content between the treatments. In conclusion, the quality of ‘Alexander Lucas’ pear was best maintained during six months storage under normal air at 1.0 °C combined with 300 nL L-1 1-MCP treatment.

Avoiding Chilling Damage in ‘Hass’ Avocado Fruit by Controlled Atmosphere Storage at Higher Temperature

Sea-freight distribution of ‘Hass’ avocado (Persea americana) is by refrigerated containers, sometimes supplemented by controlled atmosphere (CA). With both refrigeration and CA prolonging the storage life of the fruit, there is a question as to whether the technologies can be traded. That is, by using CA at warmer temperatures to extend storage without the risk of chilling damage. In this project, the potential to avoid chilling damage by storing fruit at 7 °C in 2% O2/2% CO2 CA instead of 5 °C in 2% O2/2% CO2 CA or air has been investigated for fruit stored for 4 or 6 weeks. Increasing the storage temperature from 5 °C to 7 °C did not affect the quality of fruit immediately out of CA storage, with no significant difference in skin color, firmness, or skin disorders. Both CA storage regimes, at 5 °C or 7 °C, resulted in better fruit quality than for fruit that had been stored in air at 5 °C. Overall, CA at 7 °C was less effective at retarding the progression of ripening in storage than CA at 5 °C, although after 4 weeks of storage, fruit from both CA regimes took longer to ripen than the air-stored fruit. After 6 weeks of storage, there was no difference in ripening time between fruit that had been stored in CA at 7 °C or in air at 5 °C, with fruit that had been in CA at 5 °C still taking longest to ripen. However, the incidence of diffuse flesh discoloration (DFD) in the air-stored fruit was high compared with that in fruit from CA at 7 °C or 5 °C. The main negative aspect to storing fruit in CA at 7 °C rather than at 5 °C was the higher incidence of rots in ripe fruit. While it was lower in the air-stored fruit, the incidence in fruit that had been stored in CA at 7 °C tended to be higher than that of the fruit stored in CA at 5 °C. It therefore appears that the potential for using CA at slightly higher temperatures to avoid chilling damage rests on the storage duration required and the risk of rots in the fruit.

Textural changes in ‘Hayward’ kiwifruit during and after storage in controlled atmospheres

Storage of kiwifruit in controlled atmospheres (CA) is a common practice to extend the marketing window. An investigation into the softening of CA-stored ‘Hayward’ kiwifruit is described. Fruit softening during and after CA was recorded by standard penetrometer and also for specific tissue zones: outer pericarp, inner pericarp and core. In addition, when making standard penetrometer measurements, the degree of displacement of the fruit surface prior to penetration was recorded. The data have been used to describe the rate of post-CA softening and the relative softening of the outer pericarp, inner pericarp and core tissue zones.Results confirmed the benefit of CA storage in maintaining fruit firmness. Firmness retention in a 5% CO2 CA was better than in a 2% CO2 CA. The effect of 5% CO2 was maintained for a couple of weeks after transfer from CA- to air-storage. The rate of softening on transfer from CA- to air-storage increased to a rate equivalent to that of a fruit of similar firmness stored in air. The softening patterns of the inner and outer pericarp tissues were exponential whilst the core was closer to linear. Whilst the softening of all tissue zones was slowed by CA, the outer pericarp appeared to be slowed to a greater extent than the inner pericarp. A consequence of the differential effect of CA on the two pericarp tissue zones was that after CA storage the inner pericarp had become relatively softer than the outer pericarp when compared with air-stored fruit at the same fruit firmness value. This may account for the observed greater deformation of the fruit before tissue rupture for CA-stored fruit than air-stored fruit at the same firmness when making a penetrometer measurement.

Relationships between fruit composition and storage life in air or controlled atmosphere of red raspberry

Fruit of 9 genotypes of red raspberry (Rubus idaeus L.) were assessed for market-life when held at 1°C in air or controlled atmosphere (CA, 12.5kPa CO2/7.5kPa O2) with 95% RH over 2 harvest years. Fruit were assessed for firmness, soluble solids and titratable acids as well as sugar, acid and volatile composition immediately after harvest. Groups of 16 fruit were individually assessed for decay and physiological breakdown (PB) every 2–3 d. The lag period of decay and PB development was the number of days until the first sign of deterioration. The rate of fruit loss was the linear rate of deterioration following the lag period. CA storage strongly suppressed fruit decay of all genotypes with the lag period extended to >45 d compared to 19–29 d for genotypes stored in air. The lag of PB, which was expressed as juice leakage, ranged from 6 to 28 d in air-stored fruit and increased by −1.0 to 9.7 d in CA-stored fruit depending on genotype. Loss of fruit firmness was similar during storage in air and CA. Sugar content of fruit averaged 51% fructose, 26% glucose and 23% sucrose. Acids averaged 75% citric, 13% quinic, 6% succinic and 6% malic. Both sugar and acid composition varied among genotypes. The majority of fruit volatiles were composed of C13 norisoprenoids, which totaled 65–93% of the total volatile content. Monoterpenes comprised 2.6–20.2% of total volatiles. Firmness prior to storage correlated with resistance to PB during storage. The development of PB negatively correlated with C13 norisoprenoid content, while correlations with other volatiles had no significant correlation with decay or PB development. No relationship between sugar and acid content and fruit storage-life was found.

Deficit irrigation strategies combined with controlled atmosphere preserve quality in early peaches.

Due to the water scarcity in the Mediterranean countries, irrigation must be optimized while keeping fruit quality. The effect of deficit irrigation strategies on changes in quality parameters of the early "Flordastar" peaches was studied. The deficit irrigation was programmed according to signal intensity of the maximum daily trunk shrinkage; deficit irrigation plants were irrigated to maintain maximum daily trunk shrinkage signal intensity values close to 1.4 or 1.3 in the case of DI1 or DI2 plants, respectively. Results were compared to a control watered at 150% crop evapotranspiration. Fruits were stored up to 14 days at 0 ℃ and 95% Relative Humidity (RH) in air or in controlled atmosphere (controlled atmosphere; 3-4 kPa O2 and 12-14 kPa CO2), followed by a retail sale period of 4 days at 15 ℃ and 90-95% Relative Humidity in air. Weight losses were lower in controlled atmosphere stored peaches from deficit irrigation. Air-stored fruits developed a more intense red color due to a faster ripening, which was not affected by the type of watering. At harvest, deficit irrigation peaches showed higher soluble solids content, which provided a better sensory evaluation. The soluble phenolic content was initially higher (55.26 ± 0.18 mg gallic acid equivalents/100 g fresh weight) and more stable throughout postharvest life in DI1 fruits than in those from the other irrigation treatments. Concerning vitamin C, control fruits at harvest showed higher ascorbic acid than dehydroascorbic acid content (5.43 versus 2.43 mg/100 g fresh weight, respectively), while water stressed peaches showed the opposite results. The combination of DI2 and controlled atmosphere storage allowed saving a significant amount of water and provided peaches with good overall quality, maintaining the bioactive compounds analyzed.

Regulation of L-ascorbic acid content in strawberry fruits.

Plants have several L-ascorbic acid (AsA) biosynthetic pathways, but the contribution of each one to the synthesis of AsA varyies between different species, organs, and developmental stages. Strawberry (Fragaria×ananassa) fruits are rich in AsA. The pathway that uses D-galacturonate as the initial substrate is functional in ripe fruits, but the contribution of other pathways to AsA biosynthesis has not been studied. The transcription of genes encoding biosynthetic enzymes such as D-galacturonate reductase (FaGalUR) and myo-inositol oxygenase (FaMIOX), and the AsA recycling enzyme monodehydroascorbate reductase (FaMDHAR) were positively correlated with the increase in AsA during fruit ripening. Fruit storage for 72 h in a cold room reduced the AsA content by 30%. Under an ozone atmosphere, this reduction was 15%. Ozone treatment increased the expression of the FaGalUR, FaMIOX, and L-galactose-1-phosphate phosphatase (FaGIPP) genes, and transcription of the L-galactono-1,4-lactone dehydrogenase (FaGLDH) and FAMDHAR genes was higher in the ozone-stored than in the air-stored fruits. Analysis of AsA content in a segregating population from two strawberry cultivars showed high variability, which did not correlate with the transcription of any of the genes studied. Study of GalUR protein in diverse cultivars of strawberry and different Fragaria species showed that a correlation between GalUR and AsA content was apparent in most cases, but it was not general. Three alleles were identified in strawberry, but any sequence effect on the AsA variability was eliminated by analysis of the allele-specific expression. Taken together, these results indicate that FaGalUR shares the control of AsA levels with other enzymes and regulatory elements in strawberry fruit.

The emission of flavour-contributing volatile esters by ‘Golden Reinders’ apples is improved after mid-term storage by postharvest calcium treatment

Calcium treatment of apple ( Malus × domestica Borkh.) fruit is a widely used practice aimed mainly at avoiding the development of bitter pit. However, very few studies have reported the effects of such treatments on the production of flavour-related volatile compounds, despite the relevance of aroma and taste for overall quality. In this study, commercially mature ‘Golden Reinders’ apples were dipped in 2% (w/v) calcium chloride prior to storage at 1 °C and 92% RH under either air, standard controlled atmosphere (SCA; 3 kPa O 2:2 kPa CO 2) or ultra-low oxygen atmosphere (ULO; 1 kPa O 2:2 kPa CO 2) for 19 or 31 weeks, and subsequent removal to 20 °C for 7 d, after which the emission of aroma-related volatile compounds and a number of maturity and standard quality parameters were assessed. Calcium treatment notably enhanced the production of aroma volatile compounds after mid-term storage under air and, to a lesser extent, under SCA. Retention of titratable acidity (TA) was also improved in air-stored fruit in response to calcium treatment, while no effects on firmness were observed. Although ULO-stored samples showed the highest firmness and TA values under storage, aroma volatile production was severely depleted, and calcium treatment could not overcome this inhibition. It is therefore suggested that calcium applications allow improving aroma quality while preserving adequate levels of key standard quality parameters after mid-term storage of ‘Golden Reinders’ fruit, and are thus a simple and economical alternative to CA storage of this apple cultivar.

EFFECT OF STORAGE CONDITIONS ON QUALITY ATTRIBUTES OF FRESH-CUT MANGOSTEEN

Fresh-cut mangosteen (Garcinia mangostana L.) is highly susceptible to quality losses due to damaged cells and tissues and lack of protective skin. The appropriate use of storage condition has extensively been reported to be an effective approach to maintain quality of fresh-cut fruits. The objective of this study was to investigate changes in some quality attributes of fresh-cut mangosteens as affected by storage conditions. Mangosteens were peeled and dipped in a solution consisting of 2% sodium erythorbate + 0.2% calcium chloride for 30 min, and then drained prior to storage under three different conditions, including modified atmosphere packaging (MAP; 5% O 2 + 9% CO 2 ), vacuum packaging (VAC) and air (AIR). In all treatments, moisture content, total soluble solids, pH, titratable acidity, color, firmness and sensory acceptance of fresh-cut mangosteens were monitored at 2-day intervals during 14 days of storage at 4°C. During storage, total soluble solids of fresh-cut fruits stored in AIR sharply increased and were considerably higher than those stored in MAP and VAC. Losses of moisture content and firmness were retarded by storage in MAP and VAC, whereas a rapid decline of both quality attributes was found in fruits stored in AIR. Titratable acidity of MAP and VAC-treated fruits gradually decreased, compared with the slight change in AIR-treated fruits as a result of a greater extent of dehydration. However, pH of fruits in all treatments remained somewhat stable during storage. Lightness (L*) decreased to a larger extent in VAC and AIR-stored fruits, whereas a small decrease in MAP-treated fruits were detected. Fresh-cut fruits with MAP treatment obtained the highest sensory scores, compared with other treatments, throughout the entire period of storage. MAP resulted in the best overall retention of quality attributes of fresh-cut mangosteens during postharvest storage.

CELL WALL-MODIFYING ENZYME ACTIVITIES AFTER CONTROLLED ATMOSPHERE STORAGE OF CALCIUM-TREATED 'FUJI' APPLES

In this work, 'Fuji Kiku-8' apples were treated with 2% (w/v) CaCl 2 and stored at 1°C and 92% RH under either air or two different controlled atmosphere (CA) regimes for 7 months. Different cell wall-modifying enzyme activities were determined 7 d after removal from storage in order to assess relationships, if any, to changes in fruit firmness and cell wall composition induced by CaCl 2 treatment and/or storage atmosphere. Applied calcium was effective in preserving firmness of air-stored fruit but no significant differences in this attribute were found for samples kept under CA regardless of calcium treatment. Results showed high correlation between firmness and covalently-bound pectin content. To a lesser extent, non covalently-bound pectin content was also related to firmness. Solubilisation of pectins, which leads to loss of fruit firmness, may require a previous release of neutral sugar residues from the side-chains of wall-bound pectins by the action of a number of glycosidases such as β-galactosidase (β-Gal) or β-xylosidase (β-Xyl), which in turn was partially inhibited by CA-conditions during cold storage.

Developmentally dependent responses of detached cucumber ( Cucumis sativus L.) fruit to exogenous ethylene

Previous studies of the postharvest physiological and developmental behavior of cucumber ( Cucumis sativus L.) fruit have examined fruit at a single developmental stage corresponding to commercial harvest maturity. The present study investigated the postharvest storage and ethylene responses of cucumber fruit at defined developmental stages based on growth and surface color parameters. Plants of a greenhouse cucumber (cv. Manar) were grown using current commercial practices. Fruit size and surface color were monitored during fruit development. Fruit were harvested at four stages of development: Immature (4–8 d after anthesis (DAA), commercial harvest maturity), Mature (10–14 DAA), Breaker (16–20 DAA) and Yellow (35–40 DAA). Fruit were stored in air or in either 10 μL L −1 ethylene or 1300 μL L −1 propylene for 12 d at 15 °C. The data indicate that cucumber fruit undergo marked changes in ethylene responses during development. Ethylene-treated Immature fruit exhibited mesocarp watersoaking and epidermal sloughing, slight degreening, and declines in mesocarp pH and firmness compared with air-stored fruit after 6 d of storage. Mature fruit behaved similarly to Immature fruit, but exhibited a lower incidence of watersoaking and greater fruit degreening. In sharp contrast, Breaker and Yellow fruit rapidly degreened and became orange due to chlorophyll degradation and β-carotene accumulation, softened, and produced ‘fruity’ aromatic compounds after 9 d of ethylene exposure. Ethylene increased respiration in fruit of all stages of development; however, ethylene production was detectable only in decaying fruit. The data indicate that the postharvest response of mini-cucumber fruit to ethylene is highly developmentally dependent, with older fruit exhibiting climacteric-like responses and younger fruit exhibiting tissue watersoaking and general fruit deterioration.

Antioxidant contents and activity of 1-methylcyclopropene (1-MCP)-treated ‘Empire’ apples in air and controlled atmosphere storage

The effect of 1-MCP on ripening and concentrations of total phenolics, flavonoids, anthocyanins and total antioxidant activity of ‘Empire’ apples ( Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.) was studied. Fruit were stored in air for up to 5 months, and in controlled atmosphere (CA) of 2 and 3 kPa O 2 (2 kPa CO 2) at 0.5 and 2.2 °C for 4.5 and 9 months. Ripening was delayed by 1-MCP treatment in both air and CA storage as indicated by lower internal ethylene concentrations and slower softening than in untreated fruit. Overall, total phenolic, flavonoid and anthocyanin concentrations as well as antioxidant activity were relatively stable during air and CA storage. In air-stored fruit, total phenolic concentrations were higher in the peel of 1-MCP treated fruit than in the control fruit, but slightly lower in the flesh of 1-MCP treated fruit. In CA-stored fruit, interactions between O 2 partial pressures, temperature and storage duration were detected but overall, few consistent trends were observed. However, flavonoid concentrations were higher in the flesh of 1-MCP treated than untreated fruit kept in 2 kPa O 2 while anthocyanin concentrations, only measured in the peel, were not affected by 1-MCP treatment. There were no correlations found between total phenolics and antioxidant activity. Ascorbic acid concentrations declined in both peel and flesh tissues of untreated and 1-MCP treated fruit stored in air, while changes of ascorbic acid concentrations in CA-stored fruit were inconsistent.

Long-Term Storage of Pink Lady Apples Modifies Volatile-Involved Enzyme Activities: Consequences on Production of Volatile Esters

Pink Lady apples were harvested at commercial maturity and stored at 1 degrees C and 92% relative humidity under either air or controlled atmosphere conditions (2 kPa O 2:2 kPa CO 2 and 1 kPa O 2:1 kPa CO 2) for 27 weeks. Data on the emission of volatile compounds and on the activity of some related enzymes in both skin and flesh tissues were obtained during subsequent shelf life at 20 degrees C. Major effects of storage atmosphere and poststorage period were observed on the emission of volatile esters and their precursors. Changes in the production of volatile esters were partly due to alterations in the activity of alcohol o-acyltransferase, but the specific esters emitted by fruit after storage also resulted largely from modifications in the supply of the corresponding substrates. Samples stored under air were characterized by higher availability of acetaldehyde, whereas those stored under CA showed enhanced emission of the alcohol precursors ethanol and 1-hexanol (2 kPa O 2) and 1-butanol (1 kPa O 2), with accordingly higher production of ethyl, hexyl, and butyl esters. Multivariate analysis revealed that a large part of the observed differences in precursor availability arose from modifications in the activity of the enzymes considered. Higher pyruvate decarboxylase activity in air-stored fruit possibly accounted for higher acetaldehyde levels in these samples, while storage under 1 kPa O 2 led to significantly decreased lipoxygenase activity and thus to lessened production of 1-hexanol and hexyl esters. Low acetaldehyde availability together with enhanced hydroperoxide lyase and alcohol dehydrogenase levels in these fruits are suggested to have led to higher emission of 1-butanol and butyl esters.

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 O 2:0.03 kPa CO 2) or under three different controlled atmospheres (CAs): LO (2 kPa O 2:2 kPa CO 2), ULO1 (1 kPa O 2:1 kPa CO 2), or ULO2 (1 kPa O 2:2 kPa CO 2). 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.

Fruit Quality, Antioxidant Contents and Activity, and Antiproliferative Activity of Strawberry Fruit Stored in Elevated CO2 Atmospheres

The effects of CO2 in the storage atmosphere on color, firmness, ascorbic acid (AA), anthocyanins, flavonoids, phenolics, total antioxidant activity, and antiproliferative activity of strawberry fruit have been investigated. "Northeaster" and "Earliglow" strawberries were stored in air or in 20% CO2 (in air) at 3 degrees C for 20 d. Color changes in Northeaster were delayed more by CO2 treatment than in Earliglow. Firmness of CO2-stored fruit increased slightly compared with those stored in air. The increases in total and reduced AA concentrations during air storage were usually prevented by CO2 storage in both cultivars. Dehydroascorbic acid (DHA) concentrations increased during CO2 storage. Anthocyanins and flavonoids, and total antioxidant activity of both cultivars were higher in air-stored fruit than in CO2-stored fruit. The total phenolic concentration was lower in CO2-stored Earliglow fruit than in air, but storage treatment did not affect that of Northeaster. A 40 mg/mL concentration of Northeaster strawberry extract inhibited about 80% of HepG2 human liver cancer cell proliferation. CO2 treatment did not affect the antiproliferative activity of strawberry fruits, but antiproliferative activity was greater at harvest than after storage.

The effect of delays in establishment of a static or dynamic controlled atmosphere on the quality of ‘Hass’ avocado fruit

The effect of delays of 1, 5, 10 or 15 d after harvest in establishing a static controlled atmosphere (SCA) or dynamic controlled atmosphere (DCA) on the quality of ‘Hass’ avocados ( Persea americana Mill.) was investigated. Fruit were stored at 5 °C in SCA (5% O 2/5% CO 2) or DCA (<3% O 2/0.5% CO 2) for 6 weeks and compared with fruit stored in air. In addition, to determine whether increasing the CO 2 in the DCA would affect the fruit quality, DCA-stored fruit were compared with fruit held in a DCA with 5% CO 2 (DCA + CO 2) established 1 d after harvest. The quality of fruit was assessed at the end of storage and after ripening at 20 °C. DCA-stored fruit ripened in 4.6 d compared with 7.2 d for SCA-stored fruit, or 4.8 d for air-stored fruit. In addition, the incidences of stem end rot (SER), body rot (BR) and vascular browning (VB) were lower in DCA-stored fruit (35%, 29% and 29%, respectively) than in SCA-stored fruit (57%, 52% and 49%, respectively), or air-stored fruit (76%, 88% and 95%, respectively). Delaying the establishment of both SCA and DCA for 15 d resulted in significantly more advanced skin colour at the end of storage (average rating score 11.9) compared with other delay periods (4.6–5.1). There was no significant effect of delay on the time to ripen, skin colour when ripe or any ripe fruit disorder incidence. The incidence of diffuse flesh discolouration (DFD) was not only <1% when averaged over all delays but only occurred at >0.5% incidence in the 15 d delay treatment in DCA (4.8%) and not in SCA. The incidence of diffuse flesh discolouration was 62% in air-stored fruit. Inclusion of 5% CO 2 in DCA retarded fruit ripening from 4.7 to 6.9 d and increased the incidence of rots at the end of storage from 5% to 14%, and increased the incidence in ripe fruit of SER from 30% to 56% and of BR from 27% to 55%. It is concluded that fruit quality was better after CA storage than after air storage, and that DCA storage was better than SCA. The effect of DCA is to independently reduce the time to ripen after storage and the incidence of rots when ripe. Delaying the application of SCA or DCA did not affect the expression of rots, but may increase the incidence of DFD. Inclusion of CO 2 at 5% in CA retarded fruit ripening but stimulated rot expression and should not be used for CA storage of New Zealand grown ‘Hass’ avocados.

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 O 2 with 2.5, 5, and 10 kPa CO 2 (balance N 2) 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 O 2 (≤5 kPa) atmospheres compared to those stored in CA containing 8 or 10 kPa O 2 levels. High CO 2 (>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 O 2. 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 O 2 + 2.5 kPa CO 2, 5 kPa O 2 + 5 kPa CO 2, and 8 kPa O 2 + 5 kPa CO 2, respectively.

Changes in volatile constituents of blackcurrants ( Ribes nigrum L. cv. ‘Titania’) following controlled atmosphere storage

Blackcurrants ( Ribes nigrum L. cv. Titania) were stored for 6 weeks under air and the following controlled atmosphere (CA) storage conditions: 12:18; 18:18; 6:2 and 18:2 (kPa CO 2:kPa O 2). The emission of volatiles was assessed after 3 and 6 weeks (prolonged storage) and analyzed by GC/MS. Fifty-three volatile compounds were quantified through calibration curves. Fruit that were stored in air, for either 3 or 6 weeks, did not differ significantly from freshly harvested fruit with respect to total terpene volatiles. However, decreasing O 2 levels and increasing CO 2 levels retarded the capacity of 3-week stored fruit to synthesize terpenes, although prolonged storage under these conditions led to a partial recovery. Differential changes among the various groups of terpenes were more important, where terpene alcohols reached a peak in 6-week air-stored fruit, and storing berries under a high CO 2 level (18 kPa) and/or decreasing O 2 level (2 kPa) resulted, in most cases, in lower biosynthesis of these alcohols compared to 6-week air-stored fruit. Non-terpene compounds, mainly esters and alcohols, were also increased in air-stored fruit. CA storage conditions led to a transitory reduction in the emission of alcohols but a recovery was recorded with prolonged storage. Non-terpene esters differed greatly in storage, in particular the ester ethyl butanoate. Air-stored fruit at both sampling dates synthesized significantly higher amounts of esters than freshly harvested fruit but a significant decline was observed for branched butyl substances (2-methylbutanoate) after 6 weeks storage.

Carbon Dioxide-induced Flesh Browning in Pink Lady Apples

To investigate a flesh browning (FB) disorder in Pink Lady apple [Malus ×sylvestris (L.) Mill. var. domestica (Borkh.) Mansf. cv. Cripps Pink], fruit were harvested from the same orchard each year from 2002 to 2005, at two or three maturity stages each year. Fruit were kept in air or controlled atmosphere (CA) storage (1.5- to 2-kPa O2 in combination with 1-, 3-, or 5-kPa CO2) at 0.5 °C. Additional subsets of fruit were exposed to 1 μL·L−1 1-methylcyclopropane (1-MCP) for 24 hours and dipped in 2200 μL·L−1 diphenylamine (DPA) for 5 min or held in air at 0.5 °C for 2 or 4 weeks before CA storage. Flesh browning was not seen in air-stored fruit but appeared in CA-stored fruit as soon as 2 months after harvest. Flesh browning incidence did not increase after longer storage times. Flesh browning increased with increasing CO2 concentration and decreasing O2 concentration in storage. 1-MCP did not significantly affect FB incidence, while delaying CA by 2 or 4 weeks reduced it. Diphenylamine eliminated FB incidence. When similar storage atmospheres were compared for the four seasons, FB incidence was high in 2002 and 2004 and low in 2003 and 2005. Concentrations of B, Ca, and Mg in apple flesh and seasonal field temperatures during the growing and harvest periods were related to FB incidence in 2002, 2003, and 2004 but not in 2005. The relationship of these pre- and postharvest factors to FB susceptibility are discussed.

Quality of Pink Lady Apples in Relation to Maturity at Harvest, Prestorage Treatments, and Controlled Atmosphere during Storage

Apple [Malus ×sylvestris (L.) Mill. var. domestica (Borkh.) Mansf. ‘Cripps Pink’] fruit were harvested yearly, at two or three maturity stages, from the same California orchard in 2002 through 2005. Fruit firmness, soluble solids, titratable acidity, background color, and percent blush were correlated with the starch pattern index at harvest. Fruit from each harvest were stored at 0.5 ºC in air or in a controlled atmosphere (CA) with 1.5 or 2 KPa O2 in combination with 1, 3, and 5 KPa CO2. Subsets of fruit were treated with 1 μL·L−1 1-methylcyclopropane for 24 hours at 0 ºC or 2200 μL·L−1 diphenylamine (DPA) for 5 minutes. Ethylene production was measured for 30 days after harvest. Ethylene concentration in the storage atmosphere was also monitored during storage. Fruit quality was evaluated after storage plus 5 days of ripening at 20 ºC. Fruit in a CA with 1 or 3 KPa CO2 maintained firmness and green background color, and produced less ethylene during ripening at 20 ºC than fruit stored in a CA with 5 KPa CO2; however, quality of all CA-stored fruit was better than air-stored fruit. Flesh browning developed only in CA storage, appearing by 2 months and not increasing in incidence with further storage periods. 1-Methylcyclopropane conserved fruit quality in air as well as CA during 4 months of storage, and DPA-treated fruit were firmer after CA storage, but similar after air storage, compared with untreated fruit. Diphenylamine did not control a stem-end scald disorder, which increased with time in storage and affected more than 80% of the fruit after 6 months of air storage.