Package Headspace Composition Changes of Chill-Stored Perishable Foods in Relation to Microbial Spoilage
Hwan Ki Kim, Duck Soon An, Kit L. Yam, Dong Sun Lee
Department of Food Science and Biotechnology, Kyungnam University, Changwon, South Korea.
In order to find a convenient way to monitor and control the microbial quality and shelf life of chill-stored perishable foods, microbial growth and package headspace gas concentration changes were measured during storage of three foods (seasoned pork meat, Manila clam and seasoned spinach) at 10°C, and their interrelationship was investigated. Aerobic bacterial count was the highest among the measured counts of microbial groups including specific spoilage organisms and thus may be potentially used as an index of microbial spoilage of the foods. Spoilage bacterial growth on the foods accompanied O2 depletion and CO2 build-up in package headspace with some delay. There was a wide variation among the foods in the headspace package atmospheric change resulting from or related to microbial spoilage. Except for CO2 production of Manila clam, lag times of the O2 and CO2 changes, determined by applying logistic function, amounted to 105.1–107.3 CFU/g, which is in the range of the microbial quality limit commonly used for shelf life determination. Overall, lag times of gas concentration changes may be used as an indicator of shelf life periods of perishable foods to a limited extent.