Abstract
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 CaCl2 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 T2 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.
Highlights
The dairy industry is moving towards the Industry 4.0 concept, which aims at digitalization and automation across the entire production chain by increasing connectivity from raw materials to final product [1]
Even though in some Countries, such as Italy, the use of milk powder or reconstituted milk is still forbidden in cheese manufacturing [7], process analytical technology (PAT) implementation in case of reconstituted milk use would be beneficial for local dairy processing industries of many other Countries
The Fourier transform (FT)-NIR spectra collected by the 64-scan procedure showed a characteristic behaviour, already reported by Strani et al [19]
Summary
The dairy industry is moving towards the Industry 4.0 concept, which aims at digitalization and automation across the entire production chain by increasing connectivity from raw materials to final product [1]. Industry 4.0 calls for process analytical technology (PAT), which ensures final product quality through real-time measurements of performance attributes along the whole production process, reducing process cycle time, replacing costly laboratory tests, enhancing efficiency, minimising waste, and enabling continuous learning [2]. The key point of PAT is the use of analysers, i.e., measurement systems and sensors, suitable for implementation in the process line. Even though in some Countries, such as Italy, the use of milk powder or reconstituted milk is still forbidden in cheese manufacturing [7], PAT implementation in case of reconstituted milk use would be beneficial for local dairy processing industries of many other Countries
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