MILCHWISSENSCHAFT-MILK SCIENCE INTERNATIONAL, vol.58, pp.593-595, 2003 (SCI-Expanded)
The effect of ultrasound treatment, a cold preservation method, on the activity of lactoperoxidase (LPO) and alkaline phosphatase (AP) enzymes, which have a significant function in milk technology, was studied. The experiment was performed using different amplitude (power) levels (0, 20, 40, 60 and 80%), exposure times (30, 60, 90 and 120 s) and temperatures (20 and 40 degrees C). The extent of inactivation of LPO and AP enzymes depended on level of amplitude, temperature and exposure time. It was found that high amplitude ultrasound (80%) was very effective for LPO and AP enzyme inactivation. Longer exposure times stimulated the ultrasound inactivation effect. In addition, temperature had a synergist effect on enzyme inactivation. The highest enzyme inactivation was obtained in the amplitude level of 80% (LPO: 6.875; AP: 3.813) at 40 degrees C, the lowest in the amplitude level of 20% (LPO: 17.875; AP: 6.750) at 20 degrees C.