Microbiological and physical-chemical aspects of strawberry exposed to ozone gas at different concentrations during storage

Abstract

The objective of this work was to evaluate microbiological and physical-chemical quality of strawberries, Portola variety, exposed to ozone gas at different concentrations and stored for six days under refrigeration. Ozone concentrations equivalent to 0, 4, 9, 14 and 18 mg·L ^-1, flow rate of 1 L min^-1, at 25 °C, were evaluated for 30 min. Regarding microbiological quality, the presence of Salmonella spp. was evaluated, and total coliforms, E. coli, molds and yeasts and aerobic mesophiles were quantified. Regarding the physical-chemical quality, the following parameters were evaluated: mass loss, titratable total acidity, total soluble solids, pH, total soluble solids ratio, besides the color of the fruits. Completely Randomized Design was used in Factorial Scheme 5 x 4, with five treatments and four storage periods (0, 2, 4 and 6 days), with three replications. No presence of Salmonella spp. was detected in fruits submitted or not to ozonation. For E. coli, the count was below the detection limit. The low and irregular count of total coliforms in the fruits did not allow inferring about the ozone capacity to inactivate microorganisms of this group. Ozone was effective in controlling mold and yeast and aerobic mesophiles in strawberries during storage. In general, ozone did not affect negatively the physical-chemical quality of strawberries. On the other hand, it was observed that, the higher the gas concentration, the lower was the fruits loss of mass. It was concluded that ozone is an important antimicrobial agent, and there was a reduction of undesirable microorganisms under the adopted conditions in this work. In general, ozone did not interfere with the evaluated physical-chemical variables.

Keywords:
Fragaria x ananassa Duch.; Ozonation; Microbiological quality; Physical-chemical quality; Storage; Conservation