BIOGENIC AMINE CONTENT AND MICROBIAL CONTAMINATION OF LEAFY VEGETABLES DURING STORAGE AT 5C

Biogenic amine content and microbial contamination of prepacked salad mixtures and the fresh leafy vegetables Chinese cabbage (Brassica pekinensis Rupr.), endive (Cichorium endivia L.), iceberg lettuce (Lactuca sativa var. capitata) and radicchio (Cichorium intybus var. foliosum) were examined during storage at 5C for 6 days. Putrescine, histamine, spermidine, spermine and tyramine were detected in concentrations ranging from 0.1 to 17 μg/g fresh weight. Only putrescine showed a progressive increase during storage, depending on the type of leafy vegetable; its level of increase ranged from 3- to 8-fold, with the most pronounced for Chinese cabbage. A relationship seems to exist between the Enterobacteriaceae population (representing up to 90% of the total microbial numbers determined by plate count methods) and the putrescine concentration.