Suppression of growth of putrefactive and food poisoning bacteria by lactic acid fermentation of kitchen waste

In order to produce lactic acid, from kitchen waste, which is a raw material for biodegradable plastic production, it is necessary to store waste for some days in the system of kitchen waste collection and transportation through disposers and pipes. The changes of counts of viable cells in kitchen waste during storage were observed. In spite of seasonal variations, lactic acid bacteria (LAB) became preferential bacteria after the kitchen waste had been stored for 24 h. In contrast, coliforms and Clostridium spp. which are the indices of putrefaction and contamination decreased. Coliforms were not detected after 72 or 96 h storage. None of food poisoning bacteria, such as Staphylococcus aurens and Bacillus cereus, were detected after 24 h storage. The results of adding S. aureus to waste indicated that LAB also easily became preferential even if food poisoning bacteria gained predominance at the beginning of storage. This study clearly indicated that lactic acid fermentation during the storage process inhibits the growth of putrefactive bacteria and food poisoning bacteria, which as a result, enables the preservation and deodorization of the kitchen waste to be realized with case. (C) 2001 Elsevier Science Ltd. All rights reserved.