The effect of various food parameters on the activity and stability of catalase from Aspergillus niger and catalase from bovine liver

Abstract

The effects of a number of food relevant parameters on catalase activity and stability were studied. The direct responses of different combinations of the parameters ethanol, pH and ionic strength on bovine liver catalase and Aspergillus niger catalase activity were investigated in a full factorial 2 4 statistically designed experiment. Statistically significant effects ( p = 0.001) on both types of catalases were exerted by ethanol (2% ≈ 420 m m), decreased pH (4.5), and high ionic strength ( I = 2). Further, it was found that A. niger catalase was comparatively more robust to low pH than bovine liver catalase, but that bovine liver catalase activity was significantly more tolerant to ethanol (2%) than catalase from A. niger. The stability of bovine liver catalase and A. niger catalase activity to 32 different combinations of the parameters pH, ethanol, ascorbic acid, enzyme concentration, enzyme type, protein concentration, storage temperature and atmosphere in headspace were monitored during 12 days. As expected, the responses to the different treatments varied significantly with time. It was found that ascorbic acid (500ppm ≈ b2.85m m), low pH (pH 4.5), and increased storage temperature (25 °C) each exerted significantly destabilising effects on catalase activity ( p < 0.05), while addition of ethanol (2%) resulted in a statistically significant stabilising effect ( p = 0.001) that increased during the test period. During storage, ethanol was also found to exert significantly positive two factor interactions with ascorbic acid and temperature, respectively, signifying that addition of ethanol (2%) protected both types of catalases against inhibition by ascorbic acid (500 ppm) and against destabilisation by increased temperature (25 °C) during storage.