OZONE TREATMENTS FOR IMPROVING THE QUALITY PARAMETERS AND SURFACE DECONTAMINATION OF TOMATO

Abstract

Minimising pathogenic and spoilage microorganisms in fruits, vegetables and their products are of prime importance in food safety. The consumption of fresh horticultural products is significant as they form an integral part of a perfectly balanced diet due to the presence of numerous essential nutrients, phytochemicals etc which lower the risk of diseases. The superiority in quality has led to its increased consumption, but this surge in usage is accompanied by a rise in food borne outbreaks which in turn makes it important to maintain microbial safety in all activities related to the handling of fresh fruits and vegetables. Tomato (Solanum lycopersicum), an edible berry belonging to the Solanaceae family, is one of the most versatile and a widely consumed fruit due to its abundance in carotenoids, phenolic compounds, ascorbic acid etc. However, they are highly susceptible to the attack of numerous microorganisms. Conventionally, thermal processing methods viz. pasteurisation, sterilisation, frying, cooking etc. are used to inhibit pathogens. Nonetheless, thermal processing methods is found to have a negative impact on various quality characteristics of fresh horticultural produce. Ozone technology is an emerging non-thermal processing method which is highly effective in disinfection of food products with a great potential for enhancing the shelf stability of food products. Ozone destroys pathogens by the progressive oxidation of vital cellular components wherein microbial cell surface is the primary target. The impact of gaseous ozone treatment on various quality characteristics of tomato and its efficacy in removing surface microflora from tomato samples were evaluated. A treatment chamber specifically for treating tomatoes were designed and developed simultaneously. In addition, the optimised samples were packed in perforated PP and perforated PET packets and was stored in room temperature and refrigerated storage for shelf-life analysis. Consequently, response surface methodology was explored to optimise the ozone treatments with three independent variables: ozone concentration (% weight/weight), temperature (°C), treatment time (min). The optimised treatment conditions were 30 % ozone concentration, 10 °C temperature and a time of 11.7 min. During storage weight loss, total soluble solids and total plate count of the samples increased whereas, hue angle, firmness, β-carotene, lycopene, and ascorbic acid decreased. However, ozone treated samples stored in perforated PET boxes stored at refrigerated conditions (8 ±2°C) were acceptable till 21 days with better quality attributes, lower weight loss and reduced microbial load. Thus, ozonation treatment retained all the quality parameters of tomato along with a significant reduction in the count of surface microorganisms.