Efeito do processo de pasteurização sobre a qualidade química, aromática e sensorial do leite de cabra do cariri paraibano.

Abstract

Goat milk produced on a small scale is generally subjected to the pasteurization process, followed by cooling, in order to decrease its microbiological load, enzymatic inactivation and increase its useful life, facilitating its distribution in government feeding programs, in Brazil. However, heating pasteurization can also cause changes in the physicochemical and sensory properties of milk. The objective of this research was to evaluate the effect of the pasteurization process on the chemical, aromatic and sensory quality of goat's milk collected in milk processing plants located in Cariri Ocidental Paraibano. In this context, the physical-chemical parameters (proteins, ash, moisture, lipids, lactose and pH) required by the current Brazilian legislation for goat's milk were evaluated; the fatty acid profile was identified; and the sensorial and volatile compounds profile of fresh (raw) and pasteurized goat milk was characterized. All samples of raw and pasteurized goat milk showed values of ash and lactose below that recommended by legislation; and one sample had protein content below the recommended limit. Regarding the fatty acid profile, the saturated and monounsaturated found with the highest percentage of area were the same for raw and pasteurized milk (capric, myristic, palmitic, stearic and oleic); however, polyunsaturated fatty acid differed, with linoleic acid found with higher values in raw milk and eicosapentaenoic acid in pasteurized milk. After the thermal process, the rates of atherogenicity and thrombogenicity decreased; while the ratio of hypocholesterolemic and hypercholesterolemic fatty acids increased, as well as the desirable fatty acid content. The Microextraction method in manual solid phase stood out in comparison to the other methods, in the preliminary study. The Microextraction method in manual solid phase stood out in comparison to the other methods, in the preliminary study. Forty volatile compounds were extracted from raw goat milk, the majority of which were terpenes (9), followed by aromatic compounds (7), aldehydes (6), hydrocarbons (5) and carboxylic acids (5). In pasteurized goat milk, 153 volatile compounds were identified, most of which were composed of hydrocarbons (40), followed by terpenes (36), aldehydes (15), aromatic compounds (12) and furans (12). Eight compounds with an aroma described as "sweet" and five compounds with an aroma described as "caramel" were identified only in pasteurized goat milk. Regarding the sensory attributes obtained by the Flash Profile method, raw goat milk was more influenced by the "corral" odor and the "goat" odor, while pasteurized goat milk was more influenced by the "milk smell" odor, "curd", "fresh cheese" and "sweet". The thermal pasteurization process reduced the humidity and pH value, increasing the results of lipids and lactose in most samples; it provided a decrease in the amount of saturated fatty acids, associated with a considerable increase in polyunsaturated; influenced the volatile profile of goat milk, with the formation of new chemical compounds / classes in pasteurized milk, in addition to modifying the sensory profile of goat milk.