POSTHARVEST ANTIMICROBIAL TREATMENTS WITH ORGANIC ACIDS TO IMPROVE THE SHELF LIFE OF TOMATOES

Abstract

Tomato (Lycopersicon esculentum Mill.) is one of the most economically important fruit vegetable facing greater problems in storage because of its perishable nature and reduction of quality. They are susceptible to various microbial infections, both pre- and postharvest. The present research was conducted to investigate the effects of postharvest treatments with citric (2%), benzoic (0.2%) and sorbic (0.2%) acids on physicochemical, biochemical and microbiological evolution of fresh tomatoes. Samples were evaluated initially at 3-day interval for maintained better quality in terms of water loss, titratable acidity (TA), total soluble solids (TSS), pH, lycopene, ascorbic acid content, and surface microbial load for two weeks storage time. Chemical treatments significantly reduced the microbial growth on the fruit surface throughout the storage period as compared to the control samples, but they caused a significant increase in moisture loss (sorbic acid > citric acid > benzoic acid > water). Antimicrobial effects of chemical treatments were more noticeable than their biochemical effects. The total titratable acidity, total ascorbic acid content and total lycopene content of fruits increased continuously in the first 9 days of storage but decreased thereafter. At the end of the storage period, the citric acid treated tomatoes had significantly higher titratable acidity, ascorbic acid and lycopene activity as compared with the control samples. Sorbic acid which allowed only the growth of the Rhizopus mold during two weeks of room temperature storage compere to other organic acids. However, at the end of the storage period, samples treated with citric acid is the best preservatives as compared with control samples.