Atividade de alfa-amilase como indicadora da eficiência da pasteurização de ovos e sua qualidade microbiológica

Abstract

In order to evaluate the whole egg pasteurization efficiency, it was used 30 batches of raw eggs that were subjected to heat treatment in two different binomials of temperature and time. After removal of a raw egg sample of each batch, they were divided into two parts, one part beingintended for pasteurization at 60 ° C for 3.5 minutes and the other at 68 ° C for 2.5 minutes. The treatments were arranged in a randomized block design using 30 samples of raw eggs, 30 samples of pasteurized eggs at 60 ° C and 30 samples of pasteurized eggs at 68ºC. To verify thatthe pasteurization process was conducted in recommended temperatures and times, it was evaluated the thermosensitivity of alpha-amylase enzyme by indirect quantification starch hydrolysis, and to evaluate the microbiological quality of these eggs, it was made counts ofaerobic mesophilic microorganisms, total and thermotolerant coliforms, Staphylococcus spp. and research for Salmonella spp .. The results of the research for the activity of alpha-amylase enzyme in raw eggs demonstrated that this activity was high because the most part of starchadded was hydrolyzed. In pasteurized eggs at 60 ° C for 3.5 minutes, it was observed variations in the percentage of hydrolyzed starch, and it demonstrated that there were variations in the pasteurization temperature, which allowed the partial or total inactivation of enzyme. In the samples of pasteurized whole egg to 68 ° C for 2.5 minutes no hydrolysis of starch was noted, and it could be explained by the inactivation of this enzyme that occurs in the binomial above 64.4 ° C for 2.5 minutes. The results of microbiological analyzes had significant decrease (p<0.0001) in the counts of aerobic mesophilic micro-organisms and total and thermotolerant coliforms in pasteurized eggs at two recommended temperatures and times, while the raw eggsshowed high contamination (p<0.0001). There were differences in the counts of Staphylococcus spp. across all treatments (p<0.0001) and higher counts (above 2.0 x 105 CFU / mL) were observed in the raw eggs. Salmonella spp. was present in 23 (76.6%) samples of raw eggs, however, in the heat-treated eggs, this micro-organism was found in only one (1.6%) sample, which according to the evaluation of the enzyme alpha-amylase activity, was subjected to a temperature lower than 60 ° C. It was concluded that the study of the enzyme alpha-amylase activity is effective for the evaluation of thermal processing in whole eggs, and that the two binomial temperature and time employed in the pasteurization of whole eggs are effective for obtaining high quality pasteurized eggs