Potencial probiótico de Kluyveromyces lactis e Torulaspora delbrueckii como culturas iniciadoras na produção de queijo

Abstract

Cheese is one of the most consumed dairy products in the world, being a highly nutritious, tasty food and constituted by a rich microbial diversity that characterizes it in several types. In this context, yeasts have stood out due to their interaction and prevalence in dairy products that contribute to the maturation and fermentation processes. The yeasts have interesting characteristics that make them potential probiotic candidates and cheese can be a good carrier for these microorganisms. The present work aimed to produce cheeses using the two yeasts Kluyveromyces lactis and Torulaspora delbrueckii, previously isolated from Canastra cheese using two treatments, inserting them into the surface and mass of the cheese, evaluating their influence on the physical-chemical and sensory characteristics that contribute to the organoleptic aspects of the final product. The cheeses produced were evaluated for their intrinsic and extrinsic aspects through microbiological, textural, sensory analysis, production of extracellular enzymes. In vivo and in vitro tests were carried out to validate whether the potential yeasts under study are safe to be ingested. The isolates were subjected to the preservation method by freeze-drying, evaluated for storage conditions at room temperature, and in the 4°C for 120 days. Subsequently simulated the passage through the gastrointestinal tract, to be used as a probiotic supplement or starter culture in the food industry. Yeasts remained viable throughout the cheese maturation process, with populations of 108 CFU / g and 107 CFU / g, respectively. When inoculated into the dough, the textural parameters showed less hardness and chewability, emphasizing that these factors interfere with the acceptance of the product by the consumer, thus having better sensory acceptability. The results obtained showed that K. lactis B10 and T. delbrueckii B14 are interesting yeasts in the context of probiotics due to the absence of hemolytic activity, gelatinase, DNAse, and mucin degradation being considered a safety prerequisite for the selection of a probiotic strain. Under in vivo conditions, they showed high survival in the gastrointestinal tract. Furthermore, the yeast K. lactis B10, when administered to mice, resulted in greater survival after challenge with Salmonella enterica subsp enterica serovar Typhimurium. Yeasts did not show proteolytic activity and only lipolytic activity that improves the taste of dairy products resulting in a greater sensory appreciation. The lyophilized isolates remained stable throughout the process by being conditioned only at a temperature of 4 ° C. The plate counts showed that the viability of the 4 ° C temperature was 105 UFC / ml at the end of the process, while at room temperature at 60 days the population was 104 UFC / ml. Lyophilized yeasts when submitted to chemically simulated conditions of the gastrointestinal tract remained viable. These results demonstrate that the preservation method used was adequate, maintaining the chemical, physical and microbiological properties, providing the consumer market with a probiotic supplement.