O Instituto de Investigação e Tecnologia da Agronomia e Meio Ambiente (IITAA) desenvolve trabalho de investigação com o objetivo de perseguir estudos em diversas áreas, como a caracterização / previsão do clima insular e os efeitos das mudanças globais em comunidades do oceano para os to... Ler mais »
Seventy-seven strains of lactic acid bacteria (LAB) isolated from a traditional Azorean cheese (Pico cheese, PDO) were evaluated for their enzymatic activities and diacetyl production. The enzymatic profile of LAB isolates were assayed using commercial API-zym galleries (bioMerieux, France) in order to select strains as potential starter cultures based on superior enzyme profiles, especially peptidases and esterases, for accelerated maturation and flavour development of fermented products.
Diacetyl, a flavour compound generated as an end product of citrate metabolism by certain LAB, was determined by the Voges-Proskauer test. Enzymatic activities were assessed by the API Zym kit.
The enzymatic activity of the strains showed that peptidase activity was often present in the isolates under study. Alkaline phosphatase activity was not frequent, but the activity of other phosphatases was very common. Most of the 77 LAB isolates had esterase (C4 and C8) activity, but only one isolate displayed lipase (C14) activity. None of the isolates showed α-mannosidase or α-fucosidase activity.
Diacetyl production was found to be isolate-dependent. Most of the LAB isolates showed medium level (36,4%) of diacetyl generation, 31,2% showed low level and just 16,9% high level. Some of the isolates did not produce diacetyl (15,5%).
Due to their high proteolytic, lipolytic activities and diacetyl production some of the studied LAB isolates are promising as starter/adjunct cultures for dairy products.
Quarta, 06 Julho, 2011