Alginate immobilized Saccharomyces cerevisiae cell alternative during alcoholic fermentation

The effects of immobilization on yeast metabolism during alcoholic fermentation were studied by means of 31P nuclear magnetic resonance (NMR) spectroscopy. 31P-NMRnalysis of perchloric aextracts of cells harvested at half fermentation showed that he percentage of phosphomonoesters (PME)with respect to totale phosphorus was 1.8% for supended yeast and 30.8% for immobilized ones, and that polyphosphate contents were 56.7% and 22.6%respectively. the ATP/ADP ration was higher for immobilized yeast. 31P-NMR spectra of phospholipids extracted from yeasts at the end of fermentation showed marked differences among the different classes. Phospholipid composition scels to be simpler, as indicated by the low number of peaks. more-over some phospholipid species, well reprensented in suspended yeasts, were not found in immobilized yeast extract, where other types are predominant. The total fatty acid content of yeasts, determined by gas liquid chromatography analysis at the end of fermentation, was 50% higher in immobilized yeasts. Such a difference is mainly due to a larger amount of C8-C14 fatty acids, and of palmitic, stearic and oleic acids. The ration between saturated fatty acids and unsaturated ones was significantly higher for immbolized yeasts.