Influence of the heat treatment of sugarcane juice on the fermentative process and chemical composition of cane spirit

Abstract

The introduction of different strains of microorganism in the fermentations destined for the production of cane spirit, due to successive broth feeds, may contribute to the development of different classes of microorganism, compromising the metabolic activity of the yeasts and hence the direction of the fermentative process. Thus the present study aimed to evaluate the influence of the heat treatment of the sugarcane juice on the technological and microbiological characteristics of the substrate and their effects on the direction of the fermentative process and the chemical quality of the cane spirit. The juice was treated at 90 °C for 5 minutes and the concentrations of lactic bacteria, total yeasts and non-Saccharomyces yeasts then quantified. Five fermentative cycles were carried out using heat treated and untreated sugarcane juice musts. The process was monitored via cell viability and bud production and determination of the budding index, and the total and non-Saccharomyces yeast populations quantified in the recycled yeast. At the end of the fermentations, the pH, total titratable acidity, alcohol content by volume and total residual reducing sugars of the wines were determined, these being distilled in a copper still for quantification of the chemical composition of the cane spirit. The heat treatment allowed for inactivation of the microorganisms in the juice without compromising their physicochemical characteristics. The cell viability was reduced when the fermentations were carried out with untreated juice, although the physicochemical characteristics of the wines were not affected. The distillates from fermentations carried out with untreated juice showed higher levels of volatile acidity and esters at the end of the 5th cycle. The concentrations of higher alcohols and furfural were elevated for both treatments in the 1st and 5th cycles, respectively.

Keywords:
Heat inactivation; Alcoholic fermentation; Yeasts; Microorganisms, Cell viability; Secondary compounds