Influence of processing temperature on plasmin activity and proteolysis in process streams from cold microfiltration of skim milk. (May 2023)

• Record Type: Journal Article
• Authors: France, Thomas C.; Kelly, Alan L.; Crowley, Shane V.; O'Mahony, James A.
• Is Part Of: International dairy journal. Volume 140(2023)
• Publication Date: 2023-05
• Subjects: Dairying -- Periodicals; Industrie laitière -- Périodiques; Electronic journals; 338.1762142
• DOI: 10.1016/j.idairyj.2023.105590
• Languages: English
• ISSNs: 0958-6946

Abstract

Abstract: Plasmin in process streams derived from microfiltration of skim milk can result in casein hydrolysis, potentially affecting the quality and functionality of ingredients produced. To determine whether partitioning of plasmin into permeates was impacted by processing temperature, cold microfiltration of skim milk was investigated at 4, 8 and 12 °C. Permeate generated at 4 °C had the highest plasmin activity (0.0185 AMC units mL −1 ). When plasmin activity was expressed relative to β-casein content, differences in the extent of dissociation of β-casein, at the different processing temperatures, did not influence plasmin activity in the resulting permeate streams. Throughout storage at 37 °C, all retentates exhibited extensive plasmin-mediated hydrolysis of β- and αS2 -casein; αS1 -casein to a lesser extent. Particle size measurements before and after plasmin-mediated hydrolysis of permeates indicated that the proteolysis products of β-casein, γ-caseins, retained the ability to self-associate on heating, with particle size increasing with increasing temperature.