Identification and Some Properties of Antioxidant produced by the Yeast

Abstract

To be able to produce a new antioxidant from yeast, 2250 yeast strains of this microorganism, both wild and commercial strains, were screened. Of the strains tested, AN231 gave the highest amount of antioxidant which we identified as Pichia ohmeri based on morphological and physiological features. The strain was grown in a medium made up of 2% glucose, 1% yeast extract and 1% polypeptone and incubated with shaking at 30 °C for 5 days. The culture was harvested by centrifugation and the supernatant was obtained. The supernatant was subjected to ultrafiltration and extracted with ethyl acetate. The extract was fractionated and purified using 2-dimensional TLC. A single spot corresponding to a single substance was detected using FeCl3. The substance possessed high antioxidant activity and had phenolic compounds as functional groups. It was produced at a rate of 56 mg per l of culture broth. Comparison with known commercial antioxidants revealed that the activity was less than or equal to those of synthetic antioxidants, i.e. BHA and BHT, where as higher than those of α-tocopherol and ascorbic acid. The activity of the purified antioxidant was not lost even after 11 days at 40°C.