Influence of microwave radiation on lipase and xanthine oxidase activity in milk. [Hungarian]Original Title Mikrohullamu sugarzas hatasa a fogyasztoi tejben levo lipaz es xantin-oxidaz enzimek mukodesere.

摘要

In the research skimmed milk samples of 3.6% fat content were heated up by microwave and on hot plate, respectively. After treatment the change of lipase and xanthine oxidase (XO) activities were examined by HPLC and spectrophotometry. It was established that microwave radiation has not influenced the lipase activity, but the XO activity has been significantly increased due to the effect of electromagnetic radiation. This activated XO and its products can be found in dispersed phase of milk. In living organisms where the stomach pH is higher than 2 the XO will not be denaturated and the enzyme can get into the bloodstream producing hydrogen peroxide and uric acid. Consequently, these chemicals may increase the risk of the development of arteriosclerosis and coronary artery diseases. On the other hand it is not clear how does the changed enzyme activities influence the membrane permeability of milk fat globule.