Effect of pasteurization on coagulation properties of bovine milk and the role of major composition traits and protein fractions

Abstract

Milk coagulation properties (MCP) worsens after heat treatment, however the specific mechanisms responsible have been scarcely explored. In this study, 100 milk samples were available to i) identify the raw milk characteristics responsible for unfavorable changes in MCP after pasteurization and ii) develop infrared prediction models for pasteurized milk MCP using spectra of raw samples. The loss in coagulation ability due to pasteurization was lower when raw milk had optimal MCP, higher acidity, greater protein content and lower β-lactoglobulin content. For the four MCP, the trait measured before pasteurization (raw milk) was the most important variable influencing the corresponding trait after heating. For example, rennet coagulation time (RCT), κ-casein, protein, lactose and pH of raw milk significantly affected pasteurized milk RCT (P < 0.001). For curd firmness, each unit (mm) corresponded to 58.65 g/100 g κ-casein. In general, raw milk β-lactoglobulin unfavorably affected pasteurized milk MCP (e.g., the estimate of curd firming time was 81.39 g/100 g). Results suggested that only the prediction model of RCT (pasteurized milk) achieved an exploitable coefficient of determination in cross-validation (0.66). Our outcomes are relevant for dairy plants manufacturing cheese from pasteurized standardized milk and could support producers’ decision-making.