15C-38 |
Autolytic properties of acid lactic cultures isolated from commercial Prato cheese |
I. MORENO1, A. L. S. Lerayer1, A. Vialta, A. G. F. Van Dender1, and M. T. Destro. (1) Centro de Tecnologia de Laticínios, Instituto de Tecnologia de Alimentos, Avenida Brasil, 2880, Campinas, 13073001, Brazil Proteolysis is one of the most important processes that occur during ripening. This process, depending on its intensity, may show a positive or a negative influence on the development of flavors in cheeses. Many factors are involved in proteolysis, including the nutritional needs of acid lactic bacteria, which convert milk proteins using its complex proteolytic system. This system is composed by exopeptidases, enzymes that hydrolyses casein to high molecular weight peptides, and by endopeptidases, which transform these larger peptides to small peptides and aminoacids. The endopeptidases are released in cheese due to a process named autolysis, produced by lytic enzymes named autolysins. Autolysis of acid lactic bacteria has been considered an important process in order to improve ripening, reduce bitter taste of ripened cheeses and to enhance flavors of low fat cheeses. It knows that this autolytic capacity may change among the different strains and has an influence in the quality of processed product. The main objective of this work was to evaluate the autolysis capacity of lactic bacteria isolated from three different trademarks of Prato cheese. Using morphological and biochemical tests, 69 cultures were isolated and characterized as Lactobacillus lactis spp (32), L. lactis subsp. lactis biovar diacetylactis (9), L. lactis subsp cremoris (4), Streptococcus thermophilus (11), and Lactobacilli of the groups Streptobacterium (11) and Thermobacterium (2). The presence of lytic enzymes in these cultures was evaluated using a modified well diffusion assay according TAGG & McGIVEN (1971). It was observed the presence of autolysins in 32 (42%) cultures, which produced inhibition zones between 1 to 7 mm of diameter after incubation of 24 to 72 hours. These results clearly show that endogenous cultures with high autolytic activity could be used in cheesemaking in order to improve its organoleptics characteristics.
Session 15C, Dairy Foods
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