Influence of Agitation on Milk Lipolysis and Release of Membrane-Bound Xanthine Oxidase

Abstract

Low speed agitation of buffalo and cow milk at different temperatures caused an increase of lipolysis with temperature of agitation up to 15°C, a decrease to 25°C, and an increase at higher temperatures. Although lipase activity in buffalo milk was lower than in cow milk, the increase in lipolysis from agitation was higher in buffalo milk. Studies on milk systems in which washed fat globules and skim milks from cow and buffalo milks were interchanged showed that buffalo fat globules were more susceptible to lipolysis than cow globules. Agitation of buffalo and cow milk resulted in greater release of membrane-bound xanthine oxidase into skim milk agitated at 15° than at 10° or 25°C. Hence, agitation conditions that resulted in higher lipolysis coincided with greater release of membrane-bound xanthine oxidase. Milk fat globule membrane rupture from agitation plays an important role in the susceptibility of fat to lipase.