Características microbiológicas, físico-químicas e índice de caseinomacropeptídeo em leite de cabra refrigerado por até sete dias e fraudado com soro de queijo

Abstract

The consumption of goat milk in Brazil is expanding, as a way to supply the demand of the growth of the allergic population to the bovine milk and the consumption of gourmet products. Minas Gerais, is the main producer of goat dairy derivatives for commercial purposes. Goats present lower daily productivity when compared to cows, a factor which favors that the raw milk is kept under refrigeration for long periods until the collection by the processing industry becomes economically viable. Most goat milk producers market it in pasteurized form and in the form of special cheeses, like this, it is questioned the occurrence of the practice of adding whey of goat cheese to raw milk, in order to increase the sale of fluid milk for direct consumption. This addition of serum may compromise the nutritional quality and microbiological safety of the final product. The objective was to verify the possibility of the application of the caseinomacropeptide index, derived from the breakage of casein during the cheesemaking process, as a detection method for fraud of addition of serum in goat milk, for this, two experiments were carried out in parallel. The first consisted of to evaluate the changes in the physical and microbiological quality of ten samples of raw goat milk on days 0, 2, 4 and 7 of storage at a mean temperature of 4 ° C, collected from five properties in the Metropolitan Region and the Zona da Mata Mineira and the influence of storage on the caseinomacropeptide index. In the second experiment carried out with the same ten samples, the objective was to carry out chromatographic analyzes on raw goat's milk added with 0, 2, 5, 10 and 20% of goat cheese serum in order to quantify the caseinomacropeptide index and to evaluate its application in goat milk. For both experiments the samples were evaluated for their microbiological and physicochemical quality. The stored samples presented high counts (105, 106 and 107 UFC/ mL) of proteolytic, lipolytic and mesophilic aerobic psychrotrophic microorganisms, with peak growth after the fourth day of storage. However, the physicochemical parameters were within the limits recommended by the legislation. Was observed during storage, an increase (p <0.05) in the caseinomacropeptide index, a factor associated with the growth of proteolytic psychrotrophs. In the fraudulent samples with known concentrations of serum, it was observed that the routine physical-chemical and microbiological analyzes carried out in the routine of the dairy industry, it was not possible to detect the fraud, since, although there was an expressive reduction of protein and fat content, most of the samples still met the limits recommended by the current legislation. However, there was an increase (p <0.05) in caseinomacropeptide values for milk added by serum, using the high efficiency liquid chromatography technique. Therefore, the study suggests the feasibility of the use of the caseinomacropeptide index as a method to detect fraud by addition of cheese serum in goat milk. News studies are needed to determine the borderline values of the index studied.