|Sanderson, Peter - WA TREE FRUIT RES. COMM.|
Submitted to: Journal of Food Processing and Preservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 13, 1999
Publication Date: March 1, 1999
Citation: DRAKE, S.R., SANDERSON, P., NEVENS, L. RESPONSE OF APPLE AND WINTER PEAR FRUIT QUALITY TO IRRADIATION AS A QUARANTINE TREATMENT. JOURNAL OF FOOD PROCESSING AND PRESERVATION. 23(3):203-216. 1999. Interpretive Summary: Export of agricultural commodities to foreign markets is a major interest to the United States. Fumigation of fruit products with methyl bromide is a requirement by most countries. The future of methyl bromide as a fumigant is in doubt. This research was conducted to identify an alternative to methyl bromide to meet quarantine requirements. Apples ('Fuji', 'Gala', 'Granny Smith') and winter pears ('Anjou' and 'Bosc') were exposed to various doses (1000 Grays or less) of irradiation. Irradiation at doses between 300 and 900 Gy's reduced apples firmness. Doses of <300 Gy had no effect on apples firmness. Firmness lost due to irradiation was cultivar dependent. Acidity of 'Gala' apples was reduced at irradiation doses of 600 Gy and above. No loss of acidity due to irradiation dose was evident for 'Fuji' or 'Granny Smith' apples. 'Bosc' pears lost firmness due to irradiation and firmness loss was dose dependent. Both, 'Anjou' and 'Bosc' pears ripened normally after irradiation exposure. There was and increase in scald for 'Anjou' pears that was dose dependent. Decay reduction was observed, in winter pears, with the exposure to 900 Gy's of irradiation. Irradiation at doses of 1000 Gy's or less is a viable alternative to methyl bromide to meet quarantine requirements for the exportation of fruit.
Technical Abstract: Irradiation at doses between 0.30 and 0.90 kGy reduced apple firmness. Doses of <0.30 kGy had no effect on apple firmness. Firmness lost due to irradiation was cultivar dependent. Titratable acidity (TA) of 'Gala' apples was reduced at irradiation doses of 0.60 kGy and above. No loss of TA due to the irradiation dose was evident for 'Fuji' or 'Granny Smith' apples. Irradiation did not influence the external color of apples, but change in the internal color of 'Gala' and 'Granny Smith' apples due to irradiation exposure was present. 'Bosc' pears lost firmness due to irradiation, and the firmness loss was dose dependent. Both 'Anjou' and 'Bosc' ripened normally after irradiation exposure. There was an increase in scald for 'Anjou' that was dose dependent. Disease incidence of 'Fuji' and 'Granny Smith' apples caused by P. expansum was reduced from about 80% of wounds with lesions to 30% after irradiation exposure. Irradiation had no effect on number of lesions caused by either B. cinerea or M. piriformis. No effect was observed on decay of 'Anjou' pear fruit naturally infected with P. expansum and B. cinerea. However, a reduction in decay as observed in naturally infected 'Bosc' pear fruits treated with 0.90 kGy.