to CI and quality rapidly deteriorates—this requires appropriate safe postharvest treatments and storage techniques to extend storage and shelf life. Heat treatment can be used postharvest for many different fruits ( Lurie and Pedresch, 2014 ). A
Hui-juan Zhou, Zheng-wen Ye, Ming-shen Su, Ji-hong Du, and Xiong-wei Li
Michael Lay-Yee and Kellie J. Rose
`Fantasia' nectarine fruit [Prunus persica (L.) Batsch var. nectarina (Ait.) Maxim.], held at 0C for ≤ 1 week following harvest, were forced-air heated either immediately after removal from cold storage or after an overnight pretreatment at 20C. Fruit were heated to 41,43, or 46 ± lC for 24,36, or 48 hours. Following treatment, fruit were stored for 3 weeks at 0C, held at 20C for 1 or 5 days, and then assessed for quality. No significant damage, relative to nonheated controls, was observed in pretreated fruit subjected to 41C for 24 hours. Nonpretreated fruit given the same treatment showed only a slight increase in damage relative to controls. Higher temperatures and longer treatment times, however, were associated with an increased incidence of fruit damage (scald, internal browning, or decay). Heat treatment was associated with reduction in ethylene production and titratable acidity of the fruit following storage.
Michael Lay-Yee, Graeme K. Clare, Robert J. Petry, Robert A. Fullerton, and Anne Gunson
Papaya fruit (Carica papaya L. cv. Waimanalo Solo), at color break ripeness, were either not heated (controls) or forced-air heated to center temperatures of 47.5, 48.5, or 49.5 °C, and held at these temperatures for 20, 60, 120, or 180 minutes. Following heat treatment, fruit were hydrocooled until reaching a center temperature of 30 °C, treated or not treated with prochloraz, allowed to ripen at 26 °C and then assessed for quality. Treatment at 48.5 °C or 49.5 °C for ≥60 minutes was associated with skin scalding. No significant scald was observed in other treatments or in the controls. Both control and heat-treated fruit had relatively high levels of decay. Heat treatment increased the incidence of body rots but did not affect the incidence of stem-end rots. Prochloraz treatment significantly reduced the incidence of decay. With the inclusion of a prochloraz treatment to control postharvest decay, fruit tolerated treatments of 47.5 °C for up to 120 minutes, and 48.5 °C and 49.5 °C for 20 minutes with no significant damage. Chemical name used: 1-N-propyl-N-(2-(2,4,6-(trichlorophenoxy)ethyl)-1H-imidazole-1-carboxamide (prochloraz).
Ibrahim I. Tahir, Eva Johansson, and Marie E. Olsson
should be developed. Postharvest heat treatment has been used to reduce fungal rots in apples ( Ferguson et al., 2000 ; Saftner et al., 2003 ; Sholberg et al., 2000 ). Decay caused by P. expansum can be avoided by heating fruits at 38 °C for 4 d
Michael J. Mahovic, Rajya Shukla, Renée M. Goodrich-Schneider, Michael V. Wood, Jeffrey K. Brecht, and Keith R. Schneider
Infantis (F4319), when treated with hot water at 70 or 97 °C for 60 s, resulted in a 2.0- or 3.4 log 10 cfu/cm 2 reduction of Salmonella , respectively. Any heat treatment used to reduce microbe populations on produce must be effective without exceeding
Valeria Sigal Escalada and Douglas D. Archbold
; Halder-Doll and Bangerth, 1987 ; Mir et al., 1999 ; Stover et al., 2003 ). Heat treatment after harvest has shown potential for inhibiting ripening and extending cold storage life. In climacteric fruit, heat might act through its effect on enzymes
Harvey T. Chan Jr. and Eric Jang
Heat treatments have been used to control diseases and insect infestation of fruit. The development of heat treatments have been the result of empirical experiments based on the efficacy on the insects coupled with parallel experiments on the phytotoxicity of host fruit. Such heat treatments while approved as quarantine treatments have occasionally produced fruit of poor quality. Thermal processing of foods, an established science, employs kinetics of enzyme inactivation, thermal death times evaluation of various time-temperature relationships to determine the adequacy of the heat process to ensure the safety of the product as well as minimize over-processing to preserve the products quality. There is a need to develop thermo-processing guidelines in the development of quarantine heat treatments and also to enhance product quality. We will report methods that we have developed to determine the thermal death kinetics of insects, fruit pathogens and kinetics for thermotolerance of the fruit.
T. Gregory McCollum, Salvatore D'Aquino, and Roy E. McDonald
`Keitt' mango (Mangifera indica L.) were kept at 38C for 0, 24, or 48 hours before storage at 5C for 11 days. Nonheated fruit developed severe rind pitting and discoloration, whereas chilling injury symptoms decreased with increased duration at 38C. Respiratory rates were slightly higher in nonheated than in heated fruit. Nonheated fruit produced a transient burst of ethylene evolution following transfer to 21C; heated fruit did not produce a similar burst. Firmness was similar in nonheated and heated fruit at the time of transfer to 21C for ripening, but was slightly higher in nonheated fruit after 3 and 6 days of ripening. Soluble solids concentration was higher in heated than in nonheated fruit at the time of transfer to 21C, but was similar after 9 days at 21C. Commission Internationale de l'Eclairage a* and b* flesh values were higher in heated than in nonheated fruit. Results of this study indicate that mango tolerance to chilling temperatures may increase after prestorage heat treatment.
Guy J. Hallman
`Arkin' carambolas (Averrhoa carambola L.) were subjected to the fruit fly quarantine treatments of hot water immersion at 43.3 to 43.6C for 55 or 70 rein, 46.0 to 46.3C for 35 or 45 rein, or 49.0 to 49.3C for 25 or 35 rein, or vapor heat at 43.3 to 43.6C for 90 to 120 rein, 46.0 to 46.3C for 60 or 90 rein, or 49.0 to 49.3C for 45 or 60 min. Marketability, color, weight loss, internal appearance, flavor, total acids, and soluble solids content were determined. The 49.0 to 49.3C treatments resulted in excessive damage to the carambolas 2 to 4 days after treatment. There were no statistically significant differences in the variables measured among the other treatments and control; however, heat-treated carambolas appeared duller in color than control fruits. Overall, fruit treated at 46.0 to 46.3C lost significantly more weight than that treated at 43.3 to 43.6C.
John S. Hu, Diane M. Sether, H. Michael Harrington, and Diane E. Ullman
Thermotolerance of pineapple crowns (`Champaka 153') to 50C and above was increased with a 30-min first treatment at 30, 35, or 40C. Pineapple crowns receiving a 30-min heat treatment, before a second heat treatment at 50 or 55C, exhibited significantly less leaf damage than controls receiving no first treatments (P ≤ 0.05). The degree of thermotolerance was dependent upon the season in which crowns were harvested; greater thermotolerance occurred in crowns harvested in April than those harvested in October. Maximum thermotolerance occurred after an interval of at least 8 h between the first treatment and the higher temperature heat treatment. Thermotolerance was stable for at least 24 h.