Effects of temperature abuse on the growth and survival of Listeria monocytogenes on a wide variety of whole and fresh-cut fruits and vegetables during storage

Abstract

Twenty types of fruits and vegetables representing a broad range of fresh produce categories were assessed for the growth potential and growth kinetics of Listeria monocytogenes under conditions reflecting commercial practices for storage and distribution and conditions reflecting sustained temperature abuse. Whole and fresh-cut produce was obtained from various commercial sources and inoculated with L. monocytogenes strains to evaluate the survival and growth for up to 25 days, depending on the projected commercial storage or retail shelf life for each commodity. The L.monocytogenes populations showed a sustained decline on all tested whole fruits, including avocado, blueberry, grape, mango, peach, green pepper, and tomato. Under “normal” storage conditions (defined as those reflective of common commercial practices), significant L. monocytogenes growth was only observed on fresh-cut cantaloupe (∼0.8 log) and fresh-cut mango (∼0.6 log). Exposure to temperature abuse conditions did not change the overall trends of L. monocytogenes survival on the whole fruits but did result in significant growth on several fresh-cut products, including celery, cauliflower, mango, onion, romaine lettuce, and cantaloupe. After inoculation on certain products (e.g., fresh-cut carrot and whole peach), L. monocytogenes seemed to lose cultivability rapidly but did retain viability as determined by the maintenance of cell membrane integrity.