Grassi Silvia, Strani Lorenzo, Alamprese Cristina, Pricca Nicolò, Casiraghi Ernestina, Cabassi Giovanni
Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Via Giovanni Celoria 2, 20133 Milan, Italy.
Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Via Campi 103, 41125 Modena, Italy.
Foods. 2021 Dec 23;11(1):33. doi: 10.3390/foods11010033.
The study proposes a process analytical technology (PAT) approach for the control of milk coagulation through near infrared spectroscopy (NIRS), computing multivariate statistical process control (MSPC) charts, based on principal component analysis (PCA). Reconstituted skimmed milk and commercial pasteurized skimmed milk were mixed at two different ratios (60:40 and 40:60). Each mix ratio was prepared in six replicates and used for coagulation trials, monitored by fundamental rheology, as a reference method, and NIRS by inserting a probe directly in the coagulation vat and collecting spectra at two different acquisition times, i.e., 60 s or 10 s. Furthermore, three failure coagulation trials were performed, deliberately changing temperature or rennet and CaCl concentration. The comparison with fundamental rheology results confirmed the effectiveness of NIRS to monitor milk renneting. The reduced spectral acquisition time (10 s) showed data highly correlated (r > 0.99) to those acquired with longer acquisition time. The developed decision trees, based on PC1 scores and T MSPC charts, confirmed the suitability of the proposed approach for the prediction of coagulation times and for the detection of possible failures. In conclusion, the work provides a robust but simple PAT approach to assist cheesemakers in monitoring the coagulation step in real-time.
该研究提出了一种过程分析技术（PAT）方法，用于通过近红外光谱（NIRS）控制牛奶凝固，基于主成分分析（PCA）计算多元统计过程控制（MSPC）图。将复原脱脂乳和市售巴氏杀菌脱脂乳按两种不同比例（60:40和40:60）混合。每种混合比例制备6份重复样品，并用于凝固试验，通过基础流变学作为参考方法进行监测，以及通过将探头直接插入凝固罐并在两个不同采集时间（即60秒或10秒）采集光谱来进行近红外光谱监测。此外，进行了三次失败的凝固试验，故意改变温度或凝乳酶和氯化钙浓度。与基础流变学结果的比较证实了近红外光谱监测牛奶凝乳的有效性。缩短的光谱采集时间（10秒）显示数据与较长采集时间采集的数据高度相关（r>0.99）。基于主成分1得分和T MSPC图开发的决策树证实了所提出方法适用于预测凝固时间和检测可能的失败情况。总之，这项工作提供了一种强大而简单的PAT方法，以协助奶酪制造商实时监测凝固步骤。
