Abstract The effect of physicochemical factors and use of skim milk powder on milk rennet-coagulation was investigated combining near infrared (NIR) spectroscopic monitoring and Multivariate Curve Resolution - Alternating Least Squares (MCR-ALS). Coagulum formation has been studied by reference approaches (Formagraph and fundamental rheology) and with NIR spectroscopy on unaltered reconstituted milk samples, pasteurized samples, samples with calcium chloride addition and samples of reconstituted milk mixed with fresh milk. The MCR-ALS models successfully described the process evolution, explaining more than 99.9% of variance. The MCR-ALS profiles revealed to be significantly directly correlated with Formagraph and rheological data (p 0.05) of the CaCl2 concentration level added and the heat treatment applied. The MCR-ALS models calculated for the coagulation trials of pasteurized skimmed milk mixed with reconstituted milk samples highlighted shorter coagulation times with the increasing of reconstituted milk amount (from 4.3-6.6 min to 2–5 min). Profiles extracted from MCR-ALS models developed for a wide range of coagulation conditions proved to be suitable non-destructive, non-invasive and on-line tools to evaluate the rennet-induced coagulation of reconstituted milks.

中文翻译：

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物理化学因素和奶粉使用对凝乳酶凝固的影响：近红外光谱和化学计量学的过程理解

摘要 结合近红外（NIR）光谱监测和多元曲线分辨率-交替最小二乘法（MCR-ALS）研究了理化因素和脱脂奶粉的使用对凝乳酶凝固的影响。已通过参考方法（Formagraph 和基本流变学）和 NIR 光谱对未改变的复原乳样品、巴氏杀菌样品、添加氯化钙的样品以及与新鲜牛奶混合的复原乳样品研究了凝结物的形成。MCR-ALS 模型成功地描述了过程演变，解释了超过 99.9% 的差异。MCR-ALS 曲线显示与 Formagraph 和流变学数据 (p = 0.05) 添加的 CaCl2 浓度水平和应用的热处理显着直接相关。为巴氏杀菌脱脂奶与复原乳样品混合的凝固试验计算的 MCR-ALS 模型强调，随着复原乳量的增加（从 4.3-6.6 分钟到 2-5 分钟），凝固时间更短。从针对各种凝固条件开发的 MCR-ALS 模型中提取的配置文件被证明是合适的非破坏性、非侵入性和在线工具，用于评估凝乳酶诱导的复原乳凝固。