关键词: 超声波处理；牛乳；切达奶酪；理化指标

Abstract: This study investigated the effects of ultrasound-treated raw milk on the quality of Cheddar cheese by applying ultrasound treatment at six different combinations of temperature (40, 50 and 60 ℃) and duration (15 and 30 min). Cheese made from pasteurized (63 ℃, 30 min) milk served as a control. The physicochemical properties, texture characteristics, rheological properties, yield, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns, and protein contents of cheese samples were measured. The results demonstrated that compared with the control group, ultrasonic treatment increased the water activity, elevated the pH value, and enhanced the thermal stability and texture properties. Ultrasonic treatment at 50 ℃ for 30 min resulted in the best texture, sensory and rheological properties of Cheddar cheese, while ultrasonic treatment at 40 ℃ for 30 min resulted in the highest cheese yield (12.34%). Cheese yield was not significantly affected by either ultrasonic temperature or time (P > 0.05). Moreover, ultrasonic treatment significantly increased the pH 4.6-soluble nitrogen content (P < 0.05), with the highest value of 1.54% being observed using ultrasonic treatment at 40 ℃ for 30 min. In summary, ultrasonic treatment at 50 ℃ promoted protein crosslinking and homogenization of fat globules to form compact networks, thereby improving cheese quality; however, ultrasonic treatment at 60 ℃ aggravated protein denaturation and consequently resulted in deterioration of cheese texture.

Key words: ultrasonic treatment; raw milk; Cheddar cheese; physicochemical indexes