Influence of process operations on shelf-life and microbial population of fresh-cut vegetables

Cut lettuce salads and shredded carrots were prepared according to four different procedures in order to determine the influence of various operations on the shelf-life of these "minimally processed' foods. In particular, the level of active chlorine used or its residue after washing as well as the processing time were considered. The results emphasize the role of free chlorine in reduction of the contamination level and its effectiveness toward Pseudomonadaceae and Enterobacteriaceae. Moreover a 12-h delay without refrigeration, after pre-washing or removal of ends, caused a lengthening of the processing time, enough to allow microbial proliferation and subsequent shortening of shelf-life. Shelf-life extension and the improvement of safety and quality of these products can be obtained by means of adequate processing operations.