Efecto de la aplicación postcosecha de ozono gaseoso sobre la tasa respiratoria y la calidad microbiológica de mora de Castilla (Rubus glaucus Benth)

Abstract

The fragile structure of Andean blackberries (Rubus glaucus Benth) influences in a relatively short shelf-life and limited by the microbial contamination. The aim of the present investigation was to study the effect of the postharvest application of gaseous ozone (0.5 and 0.7 ppm) on the respiratory rate and the activity of native microorganisms (aerobic mesophiles, psychotrophs, molds and yeasts) and inoculated pathogens (Botrytis cinerea, Escherichia coli, Salmonella enterica, Staphylococcus aureus). The results show that the treatment with ozone did not affect the respiratory rate of the berries. In addition, an antimicrobial effect of ozone was observed in aerobic mesophiles, psychotrophs and molds and yeasts with growth inhibition of up to 0,75; 1,9 y 2,25 logarithmic units respectively. Regarding to the inoculated microorganisms, the maximum growth inhibition of B. cinerea was 0.69 logarithmic units with the concentration of 0.5 ppm O3. In the case of E. coli and S. enterica, we worked with blackberry pulp, with adjusted pH at optimum values for the growth of each bacterium, and there was limited reduction of the microbial load due to the surface action of the ozone. Finally, there was no growth of S. aureus due to factors other than the ozone action.