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

摘要： 采用不同超声温度（40、50、60 ℃）与超声时间（15、30 min）处理原料乳制备切达奶酪，以巴氏杀菌（63 ℃、30 min）处理原料乳制作奶酪为对照，通过测定其基本理化指标、质构特性、流变特性、得率、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳图谱、蛋白质含量，探究超声处理原料乳对切达奶酪品质的影响。结果表明，超声处理原料乳可提高奶酪水分活度、pH值、热稳定性和质构特性。其中，50 ℃超声30 min处理原料乳所制切达奶酪的质构特性、感官特性和流变特性较优，40 ℃超声30 min奶酪得率最高（12.34%），但奶酪得率受超声温度和时间影响不显著（P＞0.05）。超声处理能够显著提升奶酪pH 4.6可溶性氮含量（P＜0.05），40 ℃超声30 min奶酪pH 4.6可溶性氮含量（1.54%）最高。综上，50 ℃超声处理能够通过促进蛋白交联与脂肪球均质化形成致密网络，改善奶酪品质，而高温（60 ℃）超声加剧蛋白变性，导致奶酪质构劣化。

关键词: 超声波处理；牛乳；切达奶酪；理化指标