M Tech

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 (℃), treatment time (min). The optimised
treatment conditions were 30 % ozone concentration, 10 ℃ 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℃) 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.