14A-43 |
Physical-chemical composition and proteolysis indexes of Prato cheese from different origins. |
I. Moreno1, A. G. F. VAN DENDER2, G. Costa3, A. Vialta, A. L. S. Lerayer1, and M. T. Destro5. (1) Instituto de Tecnologia de Alimentos - ITAL, Avenida Brasil, 2880, Campinas - Sao Paulo, 13073-001, Brazil, (2) Centro de Pesquisa e Desenvolvimento de Laticínios - Tecnolat, Instituto de Tecnologia de Alimentos - ITAL, Avenida Brasil, 2880, Campinas - Sao Paulo, 13073-001, Brazil, (3) Tecnolat - ITAL, Instituto de Tecnologia de Alimentos, Campinas, Brazil, (4) Fac. Ciencias Farmaceuticas - USP, Universidade de São Paulo Prato cheese - a semi-scalded and pressed curd cheese obtained from pasteurized milk by enzyme coagulation and ripened for at least 30 days - is the most important Brazilian ripened cheese variety. Prato cheese typically exhibits: semi-hard consistency, elastic curd, smootth and buttery texture, few and small eyeholes, mild flavor, non-acidic odor and slightly sweet taste. The present study is an attempt to determine the ripening profile of Prato cheese manufactured in 4 parts of the country: Santa Catarina (A), Goiás (B), São Paulo (C) and Minas Gerais (D). Samples were evaluated on the basis of variations in chemical composition, physical-chemical parameters and nitrogen fractions thoughout the ripening process. The variations in chemical and physical properties which occurred in the course of the ripening process were mainly caused by variations in the composition of the milk used as raw material and certain differences between the manufacturing processes, such as the salt concentration which might influence chymosin and bacterial peptidase activity accelerating or slowing down the ripening process as a whole. In the early stages of the ripening process, the proteolysis indexes of cheeses B, C e D were about 2 times greater than that of cheese A. The extension index - which measures the conversion of total nitrogen into soluble nitrogen - has a strong impact on the final composition and sensory characteristics and increased with ripening time by 108, 115, 86 and 121% in cheeses A, B, C and D, respectively. On the other hand, the depth indexes exhibited by cheeses C and D were greater than those of cheeses A and B and increased by 159, 160, 67 and 130% in cheeses A, B, C and D, respectively. The level of tyrosine increased by 185, 177, 174 and 60% in cheeses A, B, C and D, respectively. The higher secundary proteolysis exhibited by cheeses C and D at the beginning of ripening may be the result of premature autolysis of Non Starter Lactic Acid Bacteria.
Session 14A, Dairy Foods: General developments in dairy technology I
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