SOME FACTORS AFFECTING LIPASE ACTIVITY IN GOAT MILK

The influence of different temperatures (20 degrees C, 37 degrees C and 50 degrees C), pasteurization (71 degrees C for 15 s), boiling (100 degrees C), agitation for 5 and 10 min, pH changes (milk on acidic and alkaline side of pH), certain chemicals (copper sulphate, silver nitrate, lead nitrate and sodium chloride) on the lipase activity in local goat and cow milks was investigated. There were no significant (P > 0.01) differences in gross chemical composition between local goat and cow milks. Lipase activity in goat milk (2.76 mu eq/ml) was non-significantly lower than in cow milk (3.78 mu eq/ml) at 37 degrees C. Lipase activity in cold milk (5 degrees C) was nonsignificantly (P > 0.01) lower in goat milk (2.50 mu eq/ml) compared to cow milk (3.22 mu eq/ml). Effect of different temperatures (20 degrees C and 50 degrees C) on lipase activity was non-significantly (P > 0.01) lower in goat milk (2.63 mu eq/ml at 20 degrees C and 2.46 mu eq/ml at 50 degrees C) than in cow milk (3.65 mu eq/ml and 3.43 mu eq/ml, respectively). Pasteurization and boiling milk caused a nonsignificant (P > 0.01) decrease in lipase activity in goat (0.47 mu eq/ml and 0.10 mu eq/ml) and cow (0.53 mu eq/ml and 0.12 mu eq/ml) as compared to fresh goat (2.76 mu eq/ml) and cow (3.78 mu eq/ml) milks examined at 37 degrees C. Agitation showed non-significantly lower lipase activity in goat milk (6.52 mu eq/ml) at 5 min and at 10 min (7.23 mu eq/ml) than in cow milk at 5 min (7.17 mu eq/ml) and 10 min (8.04 mu eq/ml). Effects of added chemicals were more pronounced in cow milk than goat milk, but copper sulphate had more inhibition effect on lipase activity than lead, silver and sodium. Lipase activity in goat milk (4.13 mu eq/ml) on the alkaline side of pH was non-significantly higher than in cow milk (3.96 mu eq/ml), while it was non-significantly lower in Seat milk (2.01 mu eq/ml) and cow milk (2.64 mu eq/ml) on the acidic side of pH. It can be concluded that lipase activity can be enhanced by agitation and alkaline side of pH or reduced by heating, pasteurizing, boiling, cooling, addition of certain chemical and the acidic side of pH.