Occurrence of spore-forming bacterial in brazilian dairy desserts

Abstract

Dairy desserts are commercially sold refrigerated products that are widely consumed due to their nutritional characteristics, practicality, and sensory appeal. Their deterioration is related to changes in texture, odor, and the production of off-flavors caused by spore-forming bacteria and other contaminating bacteria that produce heat-stable spoilage enzymes. This study aimed to determine the presence of spore-forming bacteria in three types of dairy desserts, which were subjected to thermal shock to induce the germination of bacterial spores. The ability of vegetative cells to grow under different conditions, as well as the synthesis of proteolytic enzymes and their multiplication rates, were evaluated. The results indicated a higher occurrence of mesophilic aerobic bacteria with higher proteolytic and lipolytic activity, and a higher growth rate. Twenty isolates showed statistically significant differences (P<0.05), exhibiting superior capacity for synthesis of enzymes and growth rate. These isolates were genetically identified as B. subtilis, B. cereus, B. thuringiensis, B. tequilensis and B. parabrevis. These results reinforce the necessity for control measures against spore-forming aerobic mesophilic or thermoduric bacteria to ensure quality. Therefore, production losses, reduced shelf life, damage to brand reputation, and sales losses continue to be challenge for the Brazilian dairy industry.