Proteolytic activity during storage of UHT milk

UHT milk samples from two different industrial plants have been analyzed fo r plasmin/plasminogen enzymatic system, pH, protein, casein, non protein ni trogen and proteosopeprone throughout 3 months, i.e. the shelf-life period for UHT milk. Some of the samples have been stored at 4 degrees C, while the others have been stored at room temperature. The research clearly indicated that plasmi n was nearly completely inactivated by the UHT process, while plasminogen s howed a good heat stability. To a plasminogen derived activity it: can be a scribed the proteolysis of casein, which significantly decreased mainly dur ing the First two months of storage. The casein breakdown has been confirme d by the increased level of proreosopeptone Fraction. No effect of storage temperature on proteolysis phenomenon has been observed.