用单螺杆拉伸机制作纤丝干酪，采用主成分分析法分析拉伸温度对纤丝干酪主要理化性质的影响规律。研究表明，未经拉伸的凝块和70 ℃拉伸的纤丝干酪的共同特征是可榨乳清含量高，结合水、束缚水和自由水流动性强，束缚水和自由水组分比例高，L*和a*值高，同时结合水组分比例低、硬度、胶黏性、咀嚼性和回复性低；90 ℃拉伸的纤丝干酪样品与其他拉伸温度干酪样品相比可榨乳清含量较低，结合水、束缚水和自由水流动性弱，束缚水和自由水组分比例小，L*和a*值低，同时结合水组分比例高、硬度、胶黏性、咀嚼性和回复性高。拉伸温度对纤丝干酪弹性、b*和C影响不显著(p＞0.05)。运用主成分分析建立了拉伸温度与纤丝干酪理化指标的主成分综合评估模型。结合主成分评分，拉伸温度为80 ℃且螺杆转数为45 r/min时，纤丝干酪能获得较佳的理化性质。

String cheeses were prepared using a single-screw extruder, and principal component analysis (PCA) was used to investigate the influence of the stretching temperature on their physicochemical properties. The results showed that both cheese curd and string cheese stretched at 70 ℃ had a high expressible serum content; strong mobility in bound, occluded, and free waters; a high proportion of occluded and free water components; high L* and a* values; a low proportion of bound water component; and low hardness, gumminess, chewiness, and resilience. Compared with the cheeses prepared at other stretching temperatures, string cheese prepared at a stretching temperature of 90 ℃ had a lower expressible serum content; weaker mobility in bound, occluded, and free waters; lower proportions of occluded and free water components; lower L* and a* values; higher proportion of bound water component; and higher hardness, gumminess, chewiness, and resilience. The elasticity, b*, and c values of string cheese were not significantly influenced by the stretching temperature (p > 0.05). The comprehensive assessment model of the stretching temperature and physicochemical properties of string cheese was established based on the PCA. The principal component score indicated that good physicochemical properties of string cheese could be obtained at 80 ℃ with a screw speed of 45 r/min.

“十一五”国家科技支撑计划项目（2006BAD04A06）