Application of a microbial sensor to the quality control of meat freshness

Samples of fresh meat stored at 5 degreesC a ere periodically removed from storage and washed with water for periods of up to 2 weeks. The amount of a mino acids, polyamines and viable counts (number of bacteria) in the washed water were measured by using an HPLC system and a colony counting method, At the same lime, the washed water was charged into a flow injection analys is (FIA) system combined a microbial sensor using yeast (Trichosporon cutan eum), which was developed in this work for monitoring the freshness of meat . A relationship between the sensor signals obtained by the FIA system and the amounts of polyamines and amino acids produced from the meat and the nu mber of bacteria which had multiplied in the meat during the aging process was investigated The sensor signal was found to correspond to increases in amino acid levels and viable counts in the meat with the storage time in th e course of the first stage of aging. This is due to the fact that amino ac ids produced initially by enzymes in the meat serve as a source of nutritio n for septic bacteria during the aging process, and as a result, the level of bacterial cells increases with increasing amounts of amino adds with the passage of days. ii good correlation, with a correlation factor of 0.908, was obtained between the sensor signal and viable counts obtained by the co lony counting method. The present sensor method was more sensitive than the colony counting method at the early stage of the aging process, where viab le counts were in the vicinity of 10(4) g(-1). (C) 2001 Elsevier Science B. V. All rights reserved.