QUALITY OF PACKED AND BIN STORED 'ANJOU' PEARS AS INFLUENCED BY STORAGE ATMOSPHERE AND TEMPERATURE

Packed pears (Pyrus communis‘d’‘Anjou’) were stored under four individual controlled atmosphere (CA) storage conditions (#1: CA of 1.5% O₂ and < 1% CO₂ at −1.5C; #2: CA of 1.5% O₂ and < 1% CO₂ at + 1.5C; #3: CA of 1.5% O₂ and 3.0% CO₂ at −1.5C; #4: CA of 1.5% O₂ and 3.0% CO₂ at + 1.5C). Loose pears in bins were stored under three CA storage conditions (#1: CA of 1.5% O₂ and <1% CO₂ at −1.5C; #2: CA of 1.5% O₂ and 3.0% CO₂ at −1.5C; #3: CA of 1.5% O₂ and 3.0% CO₂ at +1.5C). For packed pears, increased CO₂ in the storage atmosphere resulted in retention of peel color, reduced firmness loss and enhanced subjective scores, particularly for finish and stem condition. Pears stored loose in bins, prior to packing in late January in an atmosphere containing 3.0% CO₂ aided firmness retention, reduced scald and greatly enhanced subjective quality scores for appearance, finish and scuffing. Storing ‘Anjou’pears in a 3.0% CO₂ atmosphere allows for storing pears loose in bin and packing in late January with little or no quality losses compared with using the standard 1.0% CO₂ in the storage atmosphere.     

QUALITY OF 'ANJOU' PEARS FROM VARIABLE OXYGEN AND HIGH CARBON DIOXIDE CONTROLLED ATMOSPHERE STORAGE

Loss of ‘Anjou’ pear quality after 90 days of storage (60 days at 1.5% O₂ and <1.0% CO₂ then 30 days at 4% O₂) wasapparent in this study. Distinct color changes from green to yellow in the peel and a more yellow flesh, coupled with a loss of firmness, for ‘Anjou’ pears even afteronly a short period (30 days) in elevated O₂ was evident. Use of elevated CO₂ (3%), in CA storage, resulted in a greener peel and firmer pears with less change in flesh color, and superior stem condition after 150, or 210, days of storage compared with pears from 1.5% O₂ and <1% CO₂. After controlled atmosphere and an addition 30 days of storage in regular atmosphere, quality differences in ‘Anjou’ pears from the different atmospheres (1.5% O₂ and 1.0% CO₂; variable O₂;1.5% O₂ and 3.0% CO₂) was even more manifest. Pears in elevated O₂, displayed reduced firmness, finish and stem condition and enhanced shrivel. Pears in 3.0% CO₂, compared favorably in all quality considerations with pears from a normal (1.5% O₂ and <1.0% CO₂) atmosphere. No pithy brown core was evident in ‘Anjou’ pears regardless of storage atmosphere.     

QUALITY OF 'ANJOU' PEARS AFTER DIFFERENT TYPES OF CONTROLLED ATMOSPHERE STORAGE

‘Anjou’ pears (Pyrus communis, L) were subjected to seven different controlled atmosphere (CA) storage practices and stored at 1C, for 90, 150 or 210 days plus 30 days at regular air atmosphere (RA). CA storage treatment conserved pear qualities to a certain extent regardless of storage treatment. Establishment of CA conditions (2% O₂ and < 1 % CO₂ on warm pears (20C), prior to cooling, resulted in reduced firmness, finish and color and increased amount of scald, shrivel and physiological disorders. Pears held in CA storage (2% O₂ and < 1 % CO₂) for 90 days and an additional 30 days in RA storage maintained good quality. When held for longer storage periods, firmness, finish and color decreased, and scald, shrivel and physiological disorders increased.     

QUALITY OF ‘GALA’ APPLES AS INFLUENCED BY HARVEST MATURITY,STORAGE ATMOSPHERE AND CONCOMITANT STORAGE WITH ‘BARTLETT’ PEARS1

Controlled atmosphere (CA) storage for 45 or 90 days following harvest reduced quality losses for both ‘Gala’apples and ‘Bartlett’pears compared with fruit from regular atmosphere (RA) storage. Fruit stored in CA were firmer, had higher acidity and less color change than fruit from RA storage. Apples and pears stored together in CA maintained good quality and compared favorably with apples or pears stored separately. There was no difference in fruit quality between fruit stored at 1% O₂ and 1% CO₂ compared with fruit stored in 2% O₂ and 3% CO₂. Fruit harvested at a more advanced stage of maturity deteriorated more quickly in storage than earlier harvested fruit. A combination of 45 days in CA followed by 30 days RA resulted in apples that were superior in quality to apples stored for 75 days in RA alone.     

CHANGES OF SOME ODOR-ACTIVE VOLATILES IN CONTROLLED ATMOSPHERE-STORED APPLES

The effect of controlled atmosphere (CA) storage on the production of 22 odor-active volatiles in ‘McIntosh’ and ‘Cortland’ apples was studied. Volatiles were analyzed periodically during ripening in air after harvest, during refrigerated air and CA storage, and during ripening in air after CA storage. Production of most volatiles at a lower rate during ripening after CA storage than during ripening immediately after harvest cannot be attributed entirely to the action of CA. Under the conditions of this study (3% O₂+ 3% CO₂+ 94% N₂ at 0°C for 19 weeks) CA storage caused a “residual suppression” effect on the production of propyl butanoate, butyl hexanoate, and hexyl hexanoate. Results indicate that CA might have altered the normal metabolism of the fruit by blocking the normal production of some volatiles either temporarily or permanently and either partially or completely.     

Sensorial and physicochemical quality responses of pears (cv Rocha) to long‐term storage under controlled atmospheres

Pears (cv Rocha) kept under controlled atmospheres (CA) and air were evaluated after long‐term storage in terms of sensory attributes and physicochemical parameters, namely colour, firmness, polyphenoloxidase (PPO) activity and concentration of hydroxycinnamic compounds. The CA conditions were all combinations of 2 and 4% (v/v) O₂ with 0.5 and 1.5% (v/v) CO₂. Storage under CA conditions produced a beneficial effect on ‘Rocha’ pears in maintaining their quality and, consequently, in extending their shelf life and acceptability. Clear differences in sensorial attributes, colour parameters and PPO activity were found between CA‐ and air‐stored pears. The effect provided by the CA conditions persisted throughout the time of exposure to the open air. The 2% O₂ concentration produced a more beneficial effect than its 4% counterpart on the sensorial and physical characteristics of the pears. The former concentration of O₂ prevented yellowing and allowed regular softening, hence keeping a high flavour quality. No clear effects could be associated with CO₂ levels. Empirical models were developed that describe the effects of O₂ and CO₂ concentrations, as well as time at room temperature on physicochemical parameters pertaining to ‘Rocha’ pears. Copyright © 2004 Society of Chemical Industry     

QUALITY OF MODIFIED ATMOSPHERE PACKAGED "BARTLETT" PEARS AS INFLUENCED BY TIME AND TYPE OF STORAGE

Commercially mature “Bartlett” pears for this study were obtained from local commercial packing facilities. In the first year, pears were packed in modified atmosphere bags and placed in boxes or packed normally (control) with an individual paper wrap around each pear plus a polyethylene liner in the box. Boxed pears from both types of packaging were stored in regular atmosphere (RA) storage at 1C for 30 or 90 days. In the second year, pears were packed normally and stored in both RA or controlled atmosphere (CA) storage for 45 or 90 days, or packed in modified atmosphere bags and stored in RA at 1C. After 45 days, normally packed pears from both RA and CA were removed from their initial storage, placed in modified atmosphere bags and returned to RA storage for an additional 45 days. Pears stored in modified atmosphere bags were superior in quality to normally packed pears stored only in RA storage and equal in quality to pears stored in CA for periods of 90 days. The quality of pears held in modified atmosphere bags under CA conditions deteriorated after only short periods of time (<45 days). Pears in modified atmosphere bags should be stored only in RA. Little or no quality advantage was evident if use of modified atmosphere bags was delayed regardless of prior storage type.     

QUALITY ATTRIBUTES OF D'ANJOU PEARS AFTER DIFFERENT WAX DRYING TEMPERATURES AND REFRIGERATED STORAGE

Half-cooling times for hot (60°C) and cold (0°C) dried waxed pears in boxes, were identical and equal to 17 h. Waxed hot dried pears required an additional 21 h to equilibrate to holding room temperature. Waxing of pears modified the ripening pattern dependent upon whether the waxed pears were hot or cold dried. Waxed hot and cold dried pears exhibited lower external, but higher internal concentrations of CO₂ than nonwaxed fruit. After prolonged storage waxed cold dried pears required more time to develop the characteristic ripe yellow color and retained firmness longer than either waxed hot dried or non-waxed pears. Waxed hot dried pears were slower to develop yellow color and retained firmness longer than nonwaxed pears. Pears waxed immediately after harvest or after 90 days of cold storage demonstrated increased ripening time compared to nonwaxed fruit.     

Effect of different levels of CO2 on the antioxidant content and the polyphenol oxidase activity of ‘Rocha’ pears during cold storage

Pears (Pyrus communis L. cv. ‘Rocha’) were exposed to air or controlled atmosphere (CA) containing various concentrations of CO₂: 0, 0.5 and 5 kPa, all with 2 kPa O₂. After 4 months of storage at 2 °C, the fruits were transferred to air at room temperature, and assessed in terms of soluble solids, titratable acidity, pH, incidence of brown heart and flesh browning, phenolic content, vitamin C content and polyphenol oxidase activity. By 4 months of storage, soluble solids and pH increased, and acidity decreased relative to harvest, but no differences were detected between pears stored under air or any of the CA tested. Higher contents of hydroxycinnamic derivatives and flavan‐3‐ols in the peel than in the flesh were recorded. However, the content of arbutin was higher in the flesh than in the peel, whereas flavonols were only detected in the peel. In general, hydroxycinnamic derivatives and flavonols were stable throughout storage, but flavan‐3‐ols decreased in concentration under air or CA. Arbutin was the only phenolic compound that increased in concentration as time elapsed. No clear relation was found between the storage conditions tested and the phenolic concentration in pears. Regarding ascorbic acid (AA) and dehydroascorbic acid (DHA), their concentrations were higher in the peel than in the flesh. Furthermore, AA and DHA were strongly affected by storage: the former decreased, whereas the latter increased in content. A decrease in PPO activity was apparent after harvest and during storage, particularly under higher levels of CO₂. The combination 2 kPa O₂ + 5 kPa CO₂ increased the incidence of internal disorders (viz. brown heart and flesh browning) after storage. Copyright © 2005 Society of Chemical Industry     

SHORT-TERM CONTROLLED ATMOSPHERE STORAGE FOR SHELF-LIFE EXTENSION of APRICOTS1

Shelf-life of ‘Perfection’ and ‘Rival’ apricots can be enhanced with the use of controlled atmosphere (CA) storage. Apricots were harvested at commercial maturity and immediately stored in CA at 1 or 2% 0₂ and 3, 6, 9, 12 or 15% C0₂ for 30, 45 and 60 days. No differences in fruit quality were evident between 02 atmospheres of 1 and 2%, except that fruit stored in 1 % 02 displayed less rot development and higher acid content. Apricots stored in 9% or less C0₂ displayed reduced external and internal color, inadequate finish, increased internal breakdown and more rot development with unacceptable firmness retention for additional handling. Apricots stored in 12 or 15% CO₂ retained firmness and displayed enhanced finish with reduced rots and very little internal breakdown with storage duration of 60 days. Color was much slower to develop in apricots stored in 12 or 15% CO₂ for all storage periods.     

Postharvest Physiology and Quality Maintenance of Sliced Pear and Strawberry Fruits

Sliced strawberries (cvs.‘Pajaro’ and 'G-3′) and partially ripe pears (cv.‘Bartlett’) were dipped in various solutions (citric acid, ascorbic acid, and/or calcium chloride) and stored in air or in controlled atmospheres (CA) for 7 days at 2.5°C followed by one day at 20°C. Fruit slices respired at a higher rate than whole fruits at both temperatures. CA storage suppressed respiration and ethylene production rates of sliced fruits. Firmness of strawberry and pear slices was maintained by storage in air + 12% CO₂ and in a 0.5% O₂ atmosphere, respectively, or by dipping in 1% calcium chloride. These treatments also resulted in lighter colored pear slices than the air control treatment.     

SHORT‐TERM CONTROLLED ATMOSPHERE STORAGE FOR STORAGE‐LIFE EXTENSION OF WHITE‐FLESHED PEACHES AND NECTARINES1

Abstract Response of white‐fleshed peaches (‘Sugar Lady’, ‘Snow Giant’, ‘White Lady’and ‘Snow King’) and nectarines (‘Arctic Queen’and ‘Arctic Rose’) to controlled‐atmosphere (CA) storage is cultivar dependent. Samples of fruit of these six cultivars were collected just prior to commercial harvest and held in either regular‐atmosphere (RA) storage at 1C or controlled‐atmosphere (CA) storage at 2% O₂ and 6, 12 or 18% CO₂, all at 1C. Four of the six cultivars (‘Snow Giant’, ‘White Lady’, ‘Snow King’and ‘Arctic Queen’) displayed excessive internal browning and poor flesh color after only 30 days of storage and should not be considered for long storage (+30 days). While ‘Sugar Lady’and ‘Arctic Rose’performed better and are possible candidates for CA storage, they should not be stored more than 45 days after harvest. The value of CA storage to extend the marketing of white‐fleshed peaches and nectarines is questionable at best. If CA storage is to be used for storage‐life extension of white‐fleshed peaches and nectarines, O₂ level should be maintained at 2% or less and CO₂ level maintained at 12% or higher.     

Controlled and modified atmospheres influence chilling injury,fruit quality and antioxidative system of Japanese plums (Prunus salicina Lindell)

Our objective was to compare the effects of controlled atmosphere (CA) and modified atmosphere packaging (MAP) on fruit quality, chilling injury (CI) and pro‐ and antioxidative systems in ‘Blackamber’ Japanese plums. Matured fruit were stored for 5 and 8 weeks at 0–1 °C in normal air, CA‐1 (1% O₂ + 3% CO₂), CA‐2 (2.5% O₂ + 3% CO₂) and MAP (~10% O₂ and 3.8% CO₂). CA was more effective than MAP in retention of flesh firmness and titratable acidity during cold storage. Fruit stored in CA‐1 showed reduced CI and membrane lipid peroxidation after 5 and 8 weeks of cold storage. Low O₂ atmospheres appeared to limit the generation of reactive oxygen species (ROS) and their efficient scavenging through the concerted action of superoxide dismutase and peroxidase. The role of ascorbate–glutathione (AsA–GSH) cycle in the regulation of oxidative stress was also studied during and after storage in different atmospheres. In conclusion, optimum CA conditions delayed fruit ripening and CI through augmentation of antioxidative metabolism and suppression of oxidative processes.     

Control of internal browning and quality improvement of ‘Fuji’ apples by stepwise increase of CO2 level during controlled atmosphere storage

To control internal browning injury and to reduce quality loss in ‘Fuji’ apples during storage, a stepwise controlled atmosphere (CA) method was applied in this study. Both non‐bagged and bagged apples during maturation were stored at 0 °C under 1% O₂ + 1% CO₂, 1% O₂ + 3% CO₂ or air for 10 months, and 1% O₂ + 1% CO₂ for 2 months followed by 1% O₂ + 3% CO₂ for 8 months (stepwise CA). The concentrations of internal ethylene and carbon dioxide in apples kept for 24 h at 20 °C after storage under CA conditions were maintained at low level, but there was no effect of stepwise CO₂ increase on internal gas concentrations. The non‐bagged and bagged apples stored under stepwise CA were not significantly different from those stored under 1% O₂ + 3% CO₂ continuously for 10 months in term of flesh firmness, titratable acidity and yellowing index. However, the apples stored under stepwise CA were firmer, more acid and greener than those stored under 1% O₂ + 1% CO₂ continuously for 10 months. Internal browning injury occurred in apples stored under 1% O₂ + 3% CO₂ continuously for 10 months, but it was suppressed completely by stepwise CA storage. The stepwise CA, increasing of CO₂ level after holding at 1% CO₂ for the first 2 months of storage, was effective in maintaining the quality and controlling the internal browning injury in non‐bagged and bagged ‘Fuji’ apples. Copyright © 2005 Society of Chemical Industry     

Control of Superficial Scald on 'ďAnjou' Pears by Ethoxyquin: Effect of Ethoxyquin Concentration, Time and Method of Application, and a Combined Effect with Controlled Atmosphere Storage

‘d'Anjou’ pears (Pyrus communis, L.) without ethoxyquin developed superficial scald upon ripening after 3 months of storage. Ethoxyquin at 1,000 ppm controlled scald for 4 months and did not cause phy-totoxicity to the fruit. Ethoxyquin at 2,700 ppm controlled scald for 5 months but caused phytotoxicity to the fruit. Fruit drenched with 1,000 ppm ethoxyquin within 2 days after harvest plus an additional line spray of 1,700 ppm ethoxyquin after 1 to 3 months of storage developed minimal scald incidence and did not suffer phytotoxicity after 5 months. Pre-storage drench of ethoxyquin at 500 ppm to ‘d'Anjou’ fruit was sufficient to control the scald disorder for up to 7 months in a controlled atmosphere (2% O₂+ 1% CO₂) storage.     

Loss of ascorbic acid during storage of Conference pears in relation to the appearance of brown heart

To investigate the causes of brown heart (BH) in Conference pears, the contents of ascorbic acid (AA) and dehydroascorbic acid (DHAA) in fruits were studied during the first period of storage. AA was studied in 1999 and 2000, DHAA in 1999 only. Pears from normal and very late harvest stored immediately or after a delay in a controlled atmosphere with 2% O₂ and low (0.7%) or high (5%) CO₂ were compared. DHAA content did not change during storage in any treatment. AA decreased in storage according to an exponential model. The rate of AA loss was different in the two years and was higher in late‐harvest fruits and in those stored in 5% CO₂. BH appeared in different treatments when AA decreased below a threshold, which was about 2 mg kg^?1 fresh weight, corresponding to 5% of the AA content at harvest. The frequency and severity of symptoms depended linearly on the time spent by fruits in low‐ascorbate conditions. Advanced maturity at harvest and storage in high CO₂ determine the appearance of BH and increase the rate of AA loss, probably through a reduction in the turnover of antioxidants. © 2002 Society of Chemical Industry     

QUALITY OF PINK TOMATOES (cv. BUFFALO) AFTER STORAGE UNDER CONTROLLED ATMOSPHERE AT CHILLING AND NONCHILLING TEMPERATURES

Greenhouse-grown pink tomatoes (cv. Buffalo) were stored in air or in a controlled atmosphere (CA) of 4% O₂ plus 2% CO₂, to study the effect of CA at chilling and nonchilling temperatures on fruit quality characteristics. Tomatoes could be stored in CA at 12C for three weeks with no major changes in fruit appearance. CA was effective in delaying color development and ripening at this temperature. The soluble solids content was lower after CA storage, but no significant differences in firmness, pH or titratable acidity were observed between storage in air or CA. Storage in CA at 12C was also effective in reducing decay. However, at 6C, fruit showed high incidence of decay after both air and CA storage. CA did not alleviate chilling injury symptoms relative to air-stored samples and may have caused CO₂ injury. Water loss was greater under CA at both temperatures.     

Effects of controlled atmosphere (CA) storage on pectinmethylesterase (PME) activity and texture of ‘Rocha’ pears

Firmness and pectinmethylesterase (PME) activity were evaluated in pears (cv Rocha) after 9 months of storage in controlled atmosphere (CA) followed by various periods of exposure to air at room temperature. The free calcium content was also evaluated in tissues. Fruit firmness decreased with increasing time of air exposure for all four different CA storage conditions tested. After 9 days of air exposure, fruits stored in 2% O₂ + 1.5% CO₂ were less firm than control fruits (stored in air) and showed higher PME activity. In spite of normal textural changes being observed with increasing time of exposure to air at room temperature, the underlying metabolism might have been affected by CA storage. © 2001 Society of Chemical Industry     

Shelf Life of Mature Green Tomatoes Stored in Controlled Atmosphere and High Humidity

Freshly harvested mature green tomatoes were washed, sorted and treated with 125 ppm chlorine water. The treated tomatoes were stored at 85% or 98% RH under controlled atmosphere (CA) storage for periods up to 8 wk. The controlled atmosphere was 2.5% O₂, 5.0% CO₂, and N₂ as the balance gas at 12°C. After storing 40 days, the tomatoes were allowed to ripen in air at 23°C. Samples of tomatoes were tested every 3 days to examine changes in quality as determined by visual observation, weight loss, titratable acidity, pH, color and firmness. Weight loss was reduced significantly by CA storage of tomatoes at 98% RH. Tomatoes remained green up to 40 days of storage and changed in color gradually during consecutive storage in atmospheric conditions. Appearance of the tomatoes was acceptable after ripening.     

CHANGES IN THE ACTIVITY AND SUBCELLULAR DISTRIBUTION OF PPO IN 'DELICIOUS' APPLES DURING CONTROLLED ATMOSPHERE STORAGE

Polyphenol oxidase (PPO) activity in 4, 000 × g, 100, 000 × g, 200 × g and soluble fractions of ‘Delicious’ apples was monitored during 28 weeks of controlled atmosphere storage. PPO activity in 4, 000 × g and 100, 000 × g fractions decreased, while that in soluble and 200 × g fractions increased. These shifts in subcellular location occurred sooner in apples which were stored under high CO₂ conditions (2.5–6% O₂, 8–12% CO₂) than those under normal CA conditions (2% O₂, 3% CO₂). Polyacrylamide gel electrophoresis of 4, 000 × g fractions isolated from ‘Delicious’ apples at harvest showed 2 bands with PPO activity, while stored samples all had 3 bands. Isoenzyme patterns were found to vary in different subcellular fractions.