FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY

Authors

JOLANTA KRZYCZKOWSKA, IZABELA STOLARZEWICZ, DOMINIKA BELLOK, MAŁGORZATA BELLOK, EWA BIAŁECKA-FLORJAŃCZYK

Title

Effect of medium modification on bio-catalytic properties of yeasts

Abstract

Yeasts constitute a rich source of enzymes used in biotechnological processes in food industry. The activity of enzymes consists in catalyzing chemical reactions not only in live organisms, but, also, outside those live organisms, thus, yeasts can also fulfil an important role in chemical syntheses. From the point of view of food products processing, the reactions of esterification and hydrolysis of esters are particularly essential. The objective of this paper was to determine the impact of medium composition on the catalytic activity of three kinds of yeasts: Pichia jadiniiRhodotorula glutinis, and Saccharomyce cerevisiae exemplified by a model reaction of hydrolysis of phenyl laurate. The yeasts studied were cultured under the typical conditions (YDP medium) and on media enriched by various sources of nitrogen and carbon. The Pichia jadinii yeasts proved to be most efficient in the hydrolysis of esters with a medium containing olive oil (about 50 % of the conversion of phenyl laurate after 10 h compared to 8 % of conversion using a standard YPD medium). As for Rhodotorula glutinis, the ester studied hydrolyzed most efficiently while being culture with the participation of urea (more than 50 % after the 5 h compared with 8 % with the YPD medium applied). In the case of Saccharomyce cerevisiae, cultured in the presence of olive oil, a level of 50% of the conversion was reached as late as after 40 h. Therefore, it can be concluded that proper modifications of medium allow for the stimulation of lypolytic activity of individual kinds of yeasts.

Keywords

lipase, Rhodotorula glutinis, Pichia jadinii, Saccharomyces cerevisiae, microbiological medium

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