Título em Inglês Production of fuel ethanol: effects of free nitrogen on the fermentation of very high gravity sugar cane juice

Abstract

The objective of this project is to verify the influence of nitrogenous supplementation on fermentative parameters of very high gravity sugar cane juice. The nitrogen plays an essential role on yeast physiology and in very high gravity fermentations allows higher productivity and yield. It also protects yeast cells against osmotic and ethanolic stress. Will be fermented with a supplementation of 16mM of urea high concentration sugar cane juices at 25, 30 e 35º brix, as well as supplemented with 24 mM of diammonium phosphate, will be fermented at 30ºC by yeasts Saccharomyces cerevisiae (strains of PE-2 and CAT-1) for 6 fermentative cycles. The wines will be analysed for the concentrations of assimilable nitrogen, ethanol and residual sugars. The yeasts will be analysed for cell viability. It is expected that the supplementation of the juice with 16mM of urea and 24 mM of diammonium phosphate, allow complete and faster fermentations, reaching higher ethanol concentrations. It is also expected that the yeasts maintain their viability during the fermentative recycles.