Air-stored Fruit Research Articles

Volatile compound production by Bisbee Delicious apples after sequential atmosphere storage

Bisbee Delicious apples were stored for 6 months in controlled atmosphere (CA) where oxygen concentration was increased from 1 to 2% after 3, 4, or 5 months. Volatile emission after storage was highest in late-harvest apples. Increasing the oxygen concentration during storage did not increase loss of firmness, soluble solids content, or titratable acidity, and volatile emission was not enhanced. All CA treatments reduced volatile emission compared to that of air-stored fruit. Esters were the majority of volatiles detected. Emission of lipid-derived esters was inhibited more by CA treatments than were esters resulting from amino acid metabolism

Pectic polymer changes in nectarines during normal and abnormal ripening

Nectarines ( Prunus persica, cv Fiesta Red) were harvested and either ripened for five days at 20° or stored for eight weeks at 0° in air or in a controlled atmosphere (CA) of 10% CO 2 and 15% O 2 before ripening. Air-stored fruit developed the flesh disorder of mealiness, while CA-stored fruit did not. During storage, the degree of esterification of the cell wall decreased in air- but not CA-stored fruits. Air-stored fruits retained more pectin in the sodium carbonate fraction after ripening and the polymers in the trans-1,2-diaminocyclohexane- N, N, N′, N′-tetraacetic acid (CDTA) and water-soluble fractions were of smaller M, than unstored or CA-stored fruits. Air storage also led to loss of arabinose from the sodium carbonate and guanidine thiocyanate fractions, and a lower arabinose content was also found in the CDTA fraction when air-stored fruits were ripened. The size distribution of componentsof the pectic fractions from air-stored fruits differed from fruits after harvest or CA-storage. In comparison with air-stored fruit, the CA-stored fruit showed changes in cell wall components which were very similar to those in fruit ripened immediately after harvest.

714 PB 394 CHANGES IN AVOCADO FRUIT MEMBRANE LIPIDS DURING CONTROLLED ATMOSPHERE STORAGE AND RIPENING

California grown `Hass' avocado fruit were stored at 5C, in air or a controlled atmosphere (CA) of 2% oxygen and 5% carbon dioxide. Fruit were evaluated at 0, 3, 6, and 10 weeks, both immediately upon removal from storage and after 5 days at 20C. Severe chilling injury developed in the air-stored fruit after six weeks, while only moderate symptoms were observed in CA stored avocado fruit after 10 weeks. Lipid peroxidation breakdown products increased during storage and ripening in both air and CA treatments. Sterols, sterol esters, glycolipids, and phospholipids were analyzed. There was a shift in composition during storage towards increasingly saturated fatty acids. The fatty acid shift was greater in air, than in CA stored fruit. Results will be discussed concerning their relevance to chilling injury development.

373 MITOCHONDRIAL RESPIRATlON OF `HASS' AVOCADOS IN RESPONSE TO ELEVATED CO, CONCENTRATIONS

Carbon dioxide-enriched atmospheres can be effective in the retardation of ripening and in the reduction of decay of horticultural commodities. However, concentrations in excess of the tolerance level may cause physiological damage. The goal of our research is to elucidate the specific regulatory mechanisms of CO2 actions. Cytochrome oxidase (CytOx) in vitro activity in preclimacteric avocado fruit stored in air or 40% CO2 + 12.6% O2 was evaluated at 20C. Activities were determined during treatment and also after a transfer to air. Fruit treated with 40% CO2 + 12.6% O2 had elevated CytOx in vitro activity when compared to air-stored fruit. Immunoblot analysis was performed to determine if the increase in CytOx activity could be due to an increase in enzyme concentration. The decline in respiration rate of CO,-treated fruit was most likely due to the decrease in intracellular pH and its effect on the activities of important respiratory enzymes, including CytOx. The regulatory mechanisms of other mitochondrial respiratory enzymes in `Hass' avocados exposed to elevated CO2 atmospheres are also under investigation.

Correlation of Reduced Softening and Increased Polyamine Levels during Low-oxygen Storage of ‘McIntosh’ Apples

Abstract The rate of postharvest softening of ‘McIntosh’ apples (Malus domestica Borkh.) was reduced by storage in a 1% O2 atmosphere at 1 or 3.5C. Apples stored in controlled atmosphere (CA) also maintained higher levels of the polyamines putrescine (PUT), spermidine (SPD), and spermine (SPN) in both skin and flesh tissues than those stored in air. The levels of putrescine and spermidine increased by 2- to 6-fold in CA-stored apples, while spermine decreased, but remained 2- to 5-fold higher than in air-stored fruit at both temperatures. Polyamines were also found to inhibit the in vitro activity of the cell wall-degrading enzyme polygalacturonase (PG). SPD and SPN were more effective than PUT, with SPN possessing the greatest inhibitory activity. These results are consistent with a hypothesis that increased polyamine levels are involved in the beneficial effects of CA storage and that polyamine activity could include the inhibition of cell wall degradation.

Storage quality of Cox’s Orange Pippin apples in relation to fruit mineral composition during development

SummaryThe extent to which mineral composition of fruits sampled in mid-July, early and late-August, and at harvest was correlated with the firmness and susceptibility of apples to physiological storage disorders was determined in a three-year study. Bitter pit incidence in air-stored fruit correlated well with Ca concentration and the K/Ca ratio of fruits analysed in late August or at harvest but rarely in mid-July or early August. Although there were seasonal effects on the threshold concentrations of Ca and K/Ca at which no bitter pit was expected, a reasonably accurate prediction could be made in late August or at harvest, but not earlier in the growing season. Firmness of fruit stored in 1.25% O2 and to a lesser extent 2% O2 was related predominantly to fruit P concentration in late August and harvest samples. However, regression lines of fruit P against firmness differed in the three years of the study which precluded the establishment of a fruit P threshold for minimum acceptable firmness ex-store....

ACC and Ethylene Levels in ‘d’Anjou’ Pears in Air and Controlled-atmosphere Storage

Abstract ‘d’Anjou’ pear fruit (Pyrus communis L.) stored at −1°C for 125 days in 3% O2, or 153 days in 1% O2 storage had internal ethylene levels equal to those of air-stored fruit. Fruit softened faster during subsequent ripening at 20° after 1% or 3% O2 storage than after air storage. Endogenous ACC levels were 20 times higher in fruit stored in 1% or 3% O2 compared to air-stored fruit. Exogenous application of 5 mm ACC stimulated at 2-fold increase in ethylene production from 1% O2-stored fruit and a 4-fold increase in air-stored fruit. When 5 mm ACC, in combination with 0.05 mm cycloheximide (CHI), an inhibitor of protein synthesis, were supplied exogenously to disks cut from pears stored in air or 1% O2, the air-stored fruit produced 100 times more ethylene than 1% O2-stored fruit. Increased internal ethylene levels and accelerated softening during ripening of 1% or 3% O2-stored fruit suggests the need for rapid marketing of this fruit as compared to air-stored fruit. Chemical names used: 1-aminocyclopropane-l-carboxylic acid (ACC), 3-[2(3,5-dimethyl-2-oxocyclohexyl)-2-hydroxyethyl glutarimide (cycloheximide).

Changes in Water Soluble Polyuronides in the Pulp Tissue of Ripening ‘Bosc’ Pears following Cold Storage in Air or in 1% Oxygen

Abstract ‘Bosc’ pears (Pyrus communis L.) harvested at an optimum maturity, based on flesh firmness (about 62 N), were stored either in air or 1% O2 (plus <0.03% CO2) at −1°C. Fruit stored in air for 1 to 3 months softened rapidly after 2 days of ripening at 20°C and reached ripeness with flesh firmness of 20 N or lower by the 9th day. Ripening was associated with a reduction in extractable juice (EJ) and an apparent increase in water soluble polyuronides (WSP). Fruit stored in air for 4 to 5 months also softened rapidly after 2 days of ripening, but flesh firmness was still between 26 and 30 N after 9 days; however, EJ and WSP of fruit did not change appreciably during 9 days of ripening. The WSP content in fruit stored in either air or 1 % O2 increased substantially during 6 months of storage at −1°C. Increased WSP content during storage did not affect the quantity of EJ. Fruit stored at 1% O2 showed a reduction in EJ and an increase in WSP during the 9-day ripening period, whereas, in long-term air-stored fruit, EJ did not decline while WSP was degraded. Correlation of EJ and WSP during each ripening period provided an estimation of storage life. Increased WSP after ripening might be responsible for the increase in hygroscopic binding capacity of the ripened pulp tissue.

Effects of Delays in Establishing Controlled Atmospheres on Kiwifruit Softening during and Following Storage

Abstract Establishment of a controlled atmosphere (CA) of 2% O2 + 5% CO2 within one day of harvest (no delay) or after a one-week delay in 0°C air retarded rapid softening of CA-stored kiwifruit (Actinidia chinensis Planch. ‘Hayward’) during the 1st 6 weeks of 0° storage, relative to those kept in air or in CA established after a 2-week delay. Between the 6th and 24th week of storage, further softening in air-stored fruit was suppressed in all CA treatments, and the 2-week delay CA fruit always were significantly softer than those placed in CA within one day of harvest. The one-week delay treatment resulted in an intermediate flesh firmness. The rates of fruit softening at 0°-air after 12, 16, or 24 weeks of CA storage were comparable to those of fruit stored continuously in 0° air.

Ethylene Production by ‘Flamekist’ Nectarines as Influenced by Exposure to Ethylene and Propylene

Abstract ‘Flamekist’ nectarine fruit [Prunus persica (L.) Batsch] picked during the slow-growth phase exhibited reduced C2H4 production in response to 1250 and 12,500 ppm C3H6 while fruit picked during the 2nd rapid-growth phase did not. Ethylene production by mature, preclimacteric nectarines during ripening in air at 20°C was stimulated by prior storage in air at 0° or exposure to 100 ppm C2H4 at 0° or 20°. Storage in air + C2H4 at 0° for longer than 4 days, however, nullified the stimulative effect. Subsequent peak-level C2H4 production was reduced by one-half compared to air-stored fruit. Concentration of 1-aminocyclopropane-1-carboxylic acid (ACC) increased along with C2H4 production rates during ripening. In mature fruit showing reduced C2H4 production, ACC accumulated above the expected level relative to control fruit. The data indicates that the inhibition of C2H4 production by C3H6 in developing nectarine fruit during the slow-growth phase is due to low availability of ACC, while in mature fruit the reduction in C2H4 production results from slowed conversion of ACC to C2H4.

Bitter pit reduction in ‘Cox's Orange Pippin’ apples by controlled and modified atmosphere storage

Controlled and modified atmospheres reduced bitter pit in New Zealand ‘Cox's Orange Pippin’ apples stored for 5 weeks at 2°C. Fruit from orchards that had received calcium sprays during the season were stored in an integral container maintained with a gas atmosphere of 3% CO 2 plus 3% O 2, and had less than 6% bitter pit. In comparison, air-stored fruit from the same orchards had up to 26% bitter pit. Polyethylene bags containing different numbers of 9-mm holes were tested for their effectiveness in influencing bitter pit development. The incidence of bitter pit that developed during storage was progressively reduced from 50% to less than 5% as the number of holes per bag decreased. Fruit in polybags had less weight loss, higher firmness and improved quality compared with air-stored fruit. Practical problems relating to commercial use of polybags for bitter pit control are discussed.

Interaction of temperature and oxygen level on the respiration rate and storage quality of Idared apples

SummaryRates of CO2 production by cv Idared apples were progressively reduced by lowering O2 levels from 21% to 2% and 1%. Although lowering the temperature from 4° to 2°C also reduced the respiration rate, fruits stored in 1% and 2% O2 were respiring faster after 100 days at 0°C than at 2° or 4°C. After 192 days the air-stored fruit also showed an increase in respiration rate at 0°C. These higher respiration rates preceded the development of low temperature breakdown in fruit stored in air, 2% and 1% O2 at 0°C and in 1% 02 at 2°C. Progressively lower O2 concentrations reduced ethylene production whilst increasing the retention of acid (expressed as malic), soluble solids, chlorophyll and firmness. In the absence of low temperature breakdown the effects of reduced temperature on fruit ripening were similar to those of lowered O2 concentrations. The quality of apples stored at 4°C in 1% O2 was markedly better than in 2%; the fruits were also free of core flush (brown core) and other physiological disorders.

Stem-end Decay and Quality of Low Oxygen Stored ‘d’Anjou’ Pears1

Abstract Stem-end decay caused by several several fungi was less in ‘d’Anjou’ pears (Pyrus communis L.) stored in a low O2 (1% O2 + 0.05% CO2, −1.1°C) room than in ones stored in −1.1° air. Ethylene concentration in the low O2 room was about 120 times higher than in the air room hut did not cause fruit softening or peel degreening after 8 months storage at −1. 1°. The 1% O2-stored fruit softened faster than the air-stored fruit during ripening and also ripened with better dessert quality. Juice binding capacity of ripened fruit pulp from 1 % O2-stored pears was greater than that of air-stored fruit; the texture of ripe fruit from the 1% O2 storage was buttery and juicy while that of air-stored fruit was coarse and dry. The high performance liquid chromatographic analysis revealed that organic acids in 1% O2-stored and air-stored fruits were qualitatively identical.

Keeping Qualities of ‘Stayman’ and ‘Delicious’ Apples Treated with Calcium Chloride, Scald Inhibitors, and other Chemicals1

Abstract ‘Stayman’ apples (Malus domestica Borkh.) dipped in 4% CaC12 were firmer after 5–6 months storage in air at 0°C and developed less senescent breakdown than untreated fruit. Use of the thickener Keltrol with CaC12 or vacuum infiltrating (VI) CaC12 resulted in the firmest fruit after storage and the highest flesh Ca levels. ‘Stayman’ stored 5 or 6 months in CA at 0°C were 1.5 kg firmer than air-stored fruit. Dipping apples in CaC12 prior to CA storage provided little additional benefit. Liquid concentrate formulations of diphenylamine (DPA) and ethoxyquin used alone or in combination with 4% CaC12 gave excellent scald control on ‘Stayman’ stored 5 or 6 months at 0° + 6 days at 20°. However, the same chemicals gave poor scald control for ‘Starkrimson Delicious’ picked early to midseason. The antioxidants BHT and BHA evaluated as postharvest dips at 2,000 ppm were less effective than DPA or ethoxyquin in controlling scald on ‘Stayman’. ‘Delicious’ apples were not significantly firmer after 6 months storage in air at 0°C when dipped in 3% CaC12 alone or with Keltrol, or when CaC12 was VI. When CaC12 was contaminated with Penicillium expansum spores, VI of the solution greatly increased decay of both ‘Delicious’ and ‘Stayman’.