The influence of unconventional ultrasonic pasteurization on the characteristics of curds obtained from goat milk with the low cholesterol content

This study aimed to evaluate the influence of different power-time ultrasound regimes of pasteurization on the physical, chemical, organoleptic properties, and lipid quality indices of goat curds characterized by a low cholesterol level. Cholesterol was eliminated by a percentage of 92.1 % by treating the raw goat milk with beta-cyclodextrin in the proportion of 0.6 %. Afterward, the goat milk was subjected to the following ultrasound regimes: 320 W for 1 (PA1), 3 (PA3), and 6 min (PA6) and 881 W for 1 (PP1), 3 (PP3), and 6 min (PP6) and then used for the curds production. Due to the ultrasound treatment, the milk suffered a concentration phenomenon, the most accentuated being registered for the PP6 sample. Considering the sensory properties, the most appreciated curd was the one obtained by the PP6 regime which recorded the highest scores for color and taste. Regarding the microbiological aspects, the ability of ultrasounds to inactivate microorganisms is observed and the most accentuated phenomenon is reported in the PP6 case. Thus, in comparison with the control sample, the total number of germs is reduced by a proportion of 91.85 %, the β-glucuronidase-positive Escherichia coli decreased by 93.15 %, while the coagulase-positive staphylococci were completely inactivated for the PP6 curd. The curds obtained for the PA6 and PP6 regimes registered the highest dry matter values as a cause of an accentuated syneresis process. The acidity values were higher for the curds obtained for PA1, PA3, and PA6 regimens due to more pronounced lactose hydrolysis and lower in the cases of PP3 and PP6 regimens compared to the control cheese. Twenty-five saturated, monounsaturated, and polyunsaturated fatty acids were identified in the curd samples and a rise in the unsaturated fatty acids proportion as the intensity of the applied ultrasound regime increased was observed. Also, AI, TI, and H/H lipid quality indices recorded better values as the power and time of the ultrasound action increased.