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R.J. Bender, J.K. Brecht, D.J. Huber, and S.A. Sargent

Tree-ripe `Tommy Atkins' mangoes were not injured during storage in controlled atmospheres (CA) for 21 days at 8°C, and the fruit resumed ripening after transfer to air at 20°C (Bender et al., 1995). In our study, tree-ripe `Keitt' mangoes were stored at 5 and 8°C in either 10% or 25% CO2 combined with 5% O2 with control fruit maintained in air. Control fruit had higher percentages of electrolyte leakage than CO2-treated fruit at transfer from the CA and after 3 days in air at 20°C. Fruit stored in 25% CO2 at 5°C had significantly higher concentrations of 1-aminocyclopropane-1-carboxylic acid (ACC), over 0.5 nmol ACC/g fresh weight in mesocarp tissue. All the other treatments had similar ACC levels (<0.3 nmol/g fresh weight) after 21 days in CA. Ethylene production rates at both temperatures were significantly lower in the 10% CO2 treatment than in control fruit and were not detectable in 25% CO2. Ethylene production was similar in all treatments after transfer to air. Fruit from the 25% CO2 treatment at 5°C developed dull, green-grayish spots on the epidermis, but otherwise epidermal color, as determined by chroma and hue angles, did not differ among the treatments. There also were no differences in flesh color and flesh firmness.

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Elizabeth J. Mitcham

The produce industry faces a future with reduced access to postharvest fungicides. It has become increasingly important to reduce commodity susceptibility to decay and to develop non chemical methods for decay control. Heat therapy has been demonstrated to be effective for control of numerous decays and is currently practiced for control of anthracnose in mangoes and papayas and for decay control in oranges. The limitations to heat therapy include the often tine line between effectiveness and commodity injury and the lack of residual protection. Modified atmosphere has been used effectively for many years by the California strawberry and raspberry industry to allow cross-country shipment of a commodity on which no postharvest fungicides are used. It has been shown that CO2 concentrations of 15% and higher inhibit the growth of many fungi, including Botrytis cinerea, the main cause of strawberry decay. Many commodities cannot tolerate 15% CO2 for an extended period of time. However, the short term (1 to 3 weeks) tolerance has not been determined. With the loss of postharvest fungicides, we may find that many commodities could benefit from shipment under high CO2, as have strawberries. The combination of heat therapy and MA will also be discussed.

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Ahmed F. El-Shiekh and David H. Picha

Peaches stored in air for 40 days at OC developed severe internal breakdown and poor quality after transferring them to 20C to ripen. Comparable fruit stored under controlled atmosphere (1% O2 + 5% CO2) and then ripened at 20C had no breakdown and retained good quality. Fruit stored under CA had less reducing sugars but more sucrose than air stored fruit. Fruit pH increased and titratable acidity decreased over a 40 day storage period. Citric acid increased slightly while malic acid decreased during storage. Little or no differences in overall acidity and individual organic acids existed between CA and air storage. Little or no change in individual phenolic acid content occurred during storage or between CA and air storage. Internal color darkened and became redder with storage. CA stored fruit was significantly firmer than air stored fruit. Sensory evaluation indicated CA stored fruit was more acidic, sweeter, and had better overall flavor than air stored fruit.

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S.R. Drake and S.K. Ivanov

In 1989 and 1990, `Golden Delicious' apples from controlled-atmosphere (CA) storage (1% O2; 3% CO2) averaged 8.5 N firmer after 30 days and 13.5 N firmer after 60 days of storage than apples from regular-atmosphere (RA) storage. After 7 days of ambient storage, `Golden Delicious' apples from CA storage were 10.3 N firmer than apples from RA storage. Little change in color was evident in `Golden Delicious' apples from CA storage after 30 or 60 days, but a distinct increase in yellow color was evident in apples from RA storage after only 30 days. The quality (color, firmness, and acidity) of `Golden Delicious' apples stored for 30 days under CA and then 30 days under RA was superior to that of `Golden Delicious' apples after 60 days of RA storage and similar to that of `Golden Delicious' apples after 60 days of CA storage. `Granny Smith' apples, traditionally a very firm apple regardless of the type of storage, averaged 3.3 N firmer after 30 days of CA storage (1% O2; 1% CO2) and 5.8 N firmer after 60 days of CA storage when compared to apples from RA storage. Little change in color was evident in `Golden Delicious' apples regardless of storage length, but under ambient storage temperatures, `Golden Delicious' apples from CA storage maintained their green color longer. Titratable acidity of both `Golden Delicious' and `Granny Smith' apples depended on growing season, and neither `Golden Delicious' nor `Granny Smith' apples showed consistent trends in titratable acidity after either RA or CA storage.

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Angelos I. Deltsidis, Charles A. Sims, and Jeffrey K. Brecht

temperatures higher than those previously reported to be safe with regard to CI ( Bai et al., 2011 ; Maul et al., 2000 ). The use of other postharvest techniques that slow down the ripening process, such as controlled atmospheres (CA) or modified atmospheres

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Elizabeth Mitcham, Lisa Neven, and Bill Biasi

High-temperature, controlled-atmosphere treatments were explored for disinfestation of codling moths from `Bartlett' pear fruit. Fruit were freshly harvested in 1996 and 1997 and sorted for uniformity and absence of defects. Fruit were exposed to forced-heating at 46 °C for 1, 2 and 3 h in either air or a controlled atmosphere of 1% oxygen and 15% carbon dioxide. Fruit were evaluated during ripening at 20 °C immediately after treatment (1997 only) and after 3 weeks of cold storage at -1 °C. Fruit were ripened with and without an exogenous ethylene treatment in 1997. Heat treatments, and particularly heat plus CA treatments, slowed fruit ripening, even after fruit had been stored for 3 weeks. The longer the treatment, the greater the inhibition. Fruit from longer treatments were firmer than untreated fruit after 4 days of ripening, but treatment with exogenous ethylene did not overcome the inhibition in the rate of ripening, although fruit from all treatments softened faster. The mortality of codling moths following exposure to the same treatments was also determined. With the heat plus controlled-atmosphere treatments, 100% mortality was achieved in 2.5 h with the faster heating rate used in our 1996 experiment, while it took 3 h to achieve 100% mortality with the slower heating rate.

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Salah E. Youssef and Elizabeth J. Mitcham

Peaches and apricots were obtained at harvest. One-half were inoculated with the brown rot organism (Monilinia fructicola) and incubated overnight before immersion in 52C water for 2.5 and 2 minutes, respectively. Fruit were placed in storage at SC in air, 2% O2 and 15% CO2, or 17% O2 and 15% CO2 for 5 or 15 days before ripening at 20C. For peach, controlled atmosphere (CA) had no influence on decay while hot water significantly reduced decay incidence and severity. For apricot, after 15 days cold storage, both hot water and controlled atmosphere storage reduced decay incidence and severity. CA with 2% O2 and 15% CO2 controlled decay better than 17% O2 and 15% CO2. Growth and sporulation of Monilinia fructicola in air and CA was also evaluated in vitro. The combination of heat and CA controlled decay better than either treatment alone. The hot water treatment resulted in minor surface injury on peaches while apricots were not injured. Fruit were evaluated after storage for firmness, soluble solids, and titratable acidity. Accumulation of ethanol and acetaldehyde as a result of CA storage was monitored.

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C. Chervin, J. Raynal, N. André, A. Bonneau, and P. Westercamp

The effects of ethanol vapors, controlled atmosphere (CA) storage, and a combination of both on superficial scald development on `Granny Smith' apples (Malus ×domestica Borkh.) are reported. The major result was that ethanol vapors, applied in cold storage, prevented scald development over a week at 20 °C in apples that had been CA-stored for 4 months, then left for 1 month in cold air storage. Interrupting CA storage aimed to reproduce industry practices when fruit in part of storage rooms has to be sold and the remaining fruit is held in air for later sale. The estimated cost and further development of this method are discussed.

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K.C. Shellie, L.G. Neven, and S.R. Drake

Sweet cherries (Prunus avium `Bing') exposed to 113 or 117 °F (45 or 47 °C) in an atmosphere of 1% oxygen with 15% carbon dioxide (balance nitrogen) were heated to a maximum center temperature of 112 or 115 °F (44 or 46 °C) in 41 or 27 min, respectively. Heated cherries had similar incidence of pitting and decay, and similar preference ratings after 14 days of storage at 34 °F (1 °C) as nonheated or methyl bromide fumigated fruit. Heated cherries and methyl bromide fumigated cherries were less firm after 14 days of cold storage than nonheated, control fruit. The stems of methyl bromide fumigated cherries were less green than heated or nonheated cherries. Cherries exposed to 113 °F had lower titratable acidity than nonheated cherries, fumigated cherries, or cherries exposed to 117 °F. Cherry quality after 14 days of cold storage was not affected by hydrocooling before heating (5 min in water at 34 °F) or by method of cooling after heating (hydrocooling, forced air cooling, or static air cooling). Cherries stored for 14 days at 34 °F in 6% oxygen with 17% carbon dioxide (balance nitrogen) had similar market quality as cherries stored in air at 34 °F. Results suggest that `Bing' sweet cherry can tolerate heating in an atmosphere of low oxygen containing elevated carbon dioxide at doses that may provide quarantine security against codling moth (Cydia pomonella) and western cherry fruit fly (Rhagoletis cingulata).

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Stephen R. Drake

`Anjou' pears (Pyrus communis L.) were placed in controlled-atmosphere (CA) storage immediately after harvest (<24 hours) or after a 10-day delay in refrigerated storage, and held there for 9 months at 1C. Oxygen in all atmospheres was 1.5% and CO2 was at either 1% or 3%. Atmospheres in the flow-through system were computer-controlled at ±0.1%. After removal from CA storage, pears were evaluated immediately and after ripening at 21C for 8 days. Pears stored in 3% CO2 were firmer, greener, and displayed less scald, internal breakdown, and stem-end decay than pears stored in 1% CO2. In addition, no internal discoloration of `Anjou' pears was evident when held with 3% CO2. `Anjou' pears held in 3%. CO2 retained the ability to ripen after long-term storage. A 10-day delay in atmosphere establishment had little or no influence on the long-term keeping quality or ripening ability of `Anjou' pears.