Microbial Contamination in Peeled Chestnuts and the Efficacy of Postprocessing Treatments for Microbial Spoilage Management

Abstract

High undesirable spoilage of peeled chestnuts after thawing prompted a 2006–2007 survey in which chestnuts were quantitatively examined for microbial contaminants after harvest and peeling. Chestnuts (C. sativa × C. crenata cv. “Colossal”) were collected after harvest from seven Michigan farms, and peeled using a commercial-brulage-peeler. Average mesophilic aerobic bacteria (MAB), yeast and molds populations in peeled chestnuts were 2.70, 2.74 and 2.51 after harvest; 3.46, 3.27 and 2.40 during peeling; and 5.39, 3.09 and <1.70 log CFU/g after peeling, respectively. Two bacteria Rahnella sp., and Curtobacterium sp. and the yeast Candida sp. were the primary causes of spoilage. With the objective of reducing microbial contamination, six postprocessing sanitizer treatments, as well as X-ray irradiation and warm water (65C) were evaluated (18 days of storage at 4C). X-ray irradiation, 3 min immersion in 92 ppm hydrogen dioxide and 65C water were most effective in reducing MAB and yeast. Practical Applications High undesirable spoilage of peeled chestnuts after thawing prompted a 2006–2007 survey in which chestnuts were quantitatively examined for microbial contaminants after harvest and peeling. Two bacteria Rahnella sp., and Curtobacterium sp. and the yeast Candida sp. were the primary causes of spoilage. With the objective of reducing microbial contamination, six postprocessing sanitizer treatments, as well as X-ray irradiation and warm water (65C) were evaluated (18 days of storage at 4C). X-ray irradiation, 3 min immersion in 92 ppm hydrogen dioxide and 65C water were most effective in reducing MAB and yeast. This treatments can be practically used to reduce microbial decay and enhance peeled chestnut quality.