Efecto del ozono gaseoso sobre la calidad microbiológica de moras de Castilla (Rubus glaucus Benth)

Abstract

Castilla blackberry is a fruit without external layer that protects it from physical, mechanical and microbiological damages. The attack of microorganisms in this fruit generates high percentages of losses and being Tungurahua a province with high Castilla blackberry productive capacity, it is necessary to study the antimicrobial effect of ozone gas (O3) (0,4 and 0,6 ppm) in the microbiological quality of this fruit. The antimicrobial effect was evaluated in native microflora (molds and yeasts, psychotrophs and aerobic mesophiles), molds (Botrytis cinerea) and bacteria (S. aureus, S. enterica and E. coli). The results show the antimicrobial effectiveness of O3 by decreasing 1,64, 1,15 and 0,64 log units of molds and yeasts, psychrotrophs and mesophilic aerobic, respectively. For the two Gram (-) bacteria (S. enterica and E. coli), blackberry juice with modified pH was used, obtaining reductions of 1.08 (with 0.6 ppm of O3) and 0.54 (with 0,4 ppm of O3) log units. In the case of B. cinerea, the reduction of 0,25 log units was observed on day ten after having applied 0,6 ppm of O3. With respect to S. aureus (Gram + bacteria) no growth was observed, this could have occurred due to the presence of characteristic compounds of blackberries, such as flavonoids, which have antibacterial power.