Preservation of fresh strawberries in an ozone-enriched atmosphere

Strawberries fruit are highly appreciated by consumers due to their high nutritive value, sweet taste, and fruity flavour. However, strawberries are highly perishable fresh produce, with very short storage period and rapidly are deteriorated mainly by fungal diseases. In the present study, strawberry fruit were purchased at a local market. Examining fruit microflora after 5 days of storage at 12°C and 95% relative humidity (RH), in an ozone-enriched atmosphere (0.05-0.2-1.0 ppm), a decrease of colonies of bacteria (at 1.0 ppm of ozone), and of fungi and yeast (at ≥0.05 ppm ozone) was observed. In another batch of strawberries, fruit were inoculated with 20 μL of spore suspensions (106 spores mL-1) of Botrytis cinerea and subjected to either clear air or ozone-enriched air (0.05-0.2-1.0 ppm) at 12°C and 95% RH. Fungal lesion growth decreased at the high ozone levels, after the 3rd day of storage. Fungal spore production was decreased up to 32, 48.3 and 60.9% for 0.05, 0.2 and 1.0 ppm of ozone concentrations, respectively. In vitro studies performed on fungal raised on Potato Dextrose Agar (PDA) for 6-7 days at 12°C and 95% RH revealed no direct effects of ozone on fungal growth (no great effects on colony growth) per se, implying that suppression of pathogen development was due in a large part to the impacts of ozone on fruit-pathogen interactions. Indeed, the reproductive phase of the pathogen was greatly affected by the ozone application, with decreased spore production up to 56% in .0.2 ppm of ozone or complete inhibition at 1.0 ppm of ozone. Therefore, ozone is considered as an alternative sanitizer for the fresh produce preservation.