Micellar changes induced by high pressure. influence in the proteolytic activity and organoleptic properties of milk.

We investigated the effects of high-pressure treat-of 25 to 60 degrees C, on micelle structure, proteolytic activity, and sensory properties of milk. Pressure treatments at 25 degrees C considerably reduced micelle size, while pressurization at higher temperatures progressively increased micelle dimensions. Pressure-induced denaturation of beta-lactoglobulin (beta-LG) amounted 76% at 25 degrees C and was almost 100% in milks treated at 40 to 60 degrees C. alpha -Lactalbumin (alpha-LA) was resistant to pressure at temperatures up to 40 degrees C, but its denaturation reached 56% at 60 degrees C. Plasmin resisted pressurization at room temperature; however, pressure treatments at higher temperatures increased plasmin inactivation, which reached 86.5% at 60 degrees C. Pressurization at temperatures from 40 to 60 degrees C reduced the proteolytic activity and improved the organoleptical properties of milk, compared with the same treatments at 25 degrees C, which suggested that these combined treatments could be used to produce milk of good sensory properties with an increased shelf life. These results are discussed in the light of the changes found in micellar structure.