|Authors: ||M.A. Gatto, L. Sergio, M. Pieralice, V. Linsalata, L. Spremulli, D. Di Venere|
|Keywords: ||tomato, intermediate moisture foods, sensory quality, sugars, lycopene, polygalacturonase, microbiological safety|
High water activity (aw) can affect maintenance and quality of semi-dry products during storage.
In the present work, the evolution of physico-chemical, biochemical, and microbiological parameters of semi-dry tomato in different conditions of packaging and storage is reported.
Tomato fruits, 'Ikram', were washed with sodium hypochlorite 0.01% and cut into quarters; slices were sprinkled with a solution of 2% (w/v) ascorbic acid and 4% (w/v) sodium chloride.
The semi-dry product was obtained using a heat pump dehydration system, up to 75% weight loss and 21.0±0.5% dry matter.
Semi-dried tomato slices were packed in air or in modified atmosphere (MA, 30% CO2 + 70% N2), packed in PP trays with a OPA+PP/EVOH/PP cover film, and stored at 4 or 12°C for 30 days.
Dry matter, aw, pH, colour, texture, content in sugars (glucose, fructose) and lycopene, polygalacturonase activity, and total microbial load were evaluated every 10 days during storage.
As this latter, it was assessed to be much below the limit established for spoilage microorganisms in food products (5 log CFU g-1 FM). The semi-dry product stored in MA at 4°C maintained the best quality characteristics and good microbiological stability.
In particular, after 20 days of storage, a slight increase in the fungal component (i.e., Botrytis cinerea, Mucor spp., and Cladosporium spp.) compared to the starting level (from 3 to 4 log CFU g-1 FM) was observed.
Moreover, the bacterial component remained on the initial levels (3 log CFU g-1 FM) during the whole storage period.
The results showed that the used MA conditions are able to preserve quality and hygienic properties of the product for 20 days at 4°C.
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