Submitted to: HortScience
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/15/2005
Publication Date: 8/1/2005
Citation: Obenland, D.M., Neipp, P.W., Mackey, B.E., Neven, L.G. 2005. Peach and nectarine quality following treatment with high temperature forced air combined with controlled atmospheres. Hortscience 40(5):1425-1430. Interpretive Summary: Peaches and nectarines often must be fumigated with methyl bromide prior to export. The continued availability of methyl bromide is, however, uncertain due to environmental concerns. Forced air heating combined with low oxygen and high carbon dioxide is being investigated as a non-chemical alternative to methyl bromide for peaches and nectarines. Treated fruit had slightly higher amounts of surface injury, although the increase in surface injury was only an important factor to marketability in cultivars that had high amounts of surface injury prior to treatment. Juiciness following extended cold storage was enhanced in treated fruit while soluble solids, acidity, weight loss and color were not significantly affected. Taste panelists slightly preferred untreated over treated fruit although the differences may not be noticeable to the average consumer. Forced air heating combined with low oxygen and high carbon dioxide shows promise as an alternative to methyl bromide fumigation.
Technical Abstract: Yellow- and whited-fleshed peach [Prunus persica (L.) Batsch] and nectarine [Prunus persica (L.) Batsch var. nectarina (Ait) Maxim.] cultivars of mid- and late-season maturity classes were subjected to combined controlled atmosphere high temperature forced air (CATTS) treatments using heating rates of either 12 C/h (slow rate) or 24 C/h (fast rate) with a final chamber temperature of 46 C, while maintaining a controlled atmosphere of 1% oxygen and 15% carbon dioxide. Fruit seed surface temperatures generally reached 45 C within 160 min and 135 min for the slow and fast heating rate, respectively. The total duration of the slow heating rate treatment was 3 h, while 2.5 h was required for the fast heating rate treatment. Following treatment the fruit were stored at 1 C for either 1, 2 or 3 weeks followed by a ripening period of 2 to 4 d at 23 C and subsequent evaluation for fruit quality. Fruit quality was similar for both heating rates. Compared to the untreated controls, CATTS-treated fruit displayed higher amounts of surface injury, although the increase in surface injury was only an important factor to marketability in cultivars that had high amounts of surface injury prior to treatment. The percentage of free juice in the flesh was slightly less in CATTS-treated fruit early in storage but was often greater in treated fruit toward the end of the storage period. Slower rates of softening during fruit ripening were apparent in CATTS-treated fruit. Soluble solids, acidity, weight loss and color all were either not affected or changed to a very small degree as a result of CATTS treatment. Members of a trained sensory panel preferred the taste of untreated fruit over fruit that had been CATTS-treated but the ratings of treated and non-treated fruit were generally close together and it is unclear whether an average consumer could detect the difference. Although further work needs to be done regarding the influence of CATTS on taste, it otherwise appears that CATTS treatment does not adversely affect the marketability of good quality fruit and therefore shows promise as a non-chemical quarantine treatment for peaches and nectarines.