On the Activation of Alcoholic Fermentation in Wine Making

¹ Instituto di Industrie Agrarie University of Perugia Perugia, Italy

There have been examined singly in experiments on fermentation of grape juice and on secondary fermentation of sweet wines several substances considered as activators of alcoholic fermentation.

The effectiveness of the various products has been evaluated by the acceleration of fermentation speed (conventionally expressed by the medium quantity of carbon dioxide evolved from the yeast inoculation to the stationary phase of the fermentation) by the composition of the wine obtained and by the performances of sugar transformation.

The only products which give an effective contribution to the speed of fermenration are nitrogenous substances, particularly in ammonium, amide and amino forms; also very effective are the complex products such as yeast extract, fermentation lees and Roviferm (special commercial preparation).

Phosphates, trace elements, vitamins, coenzymes, nucleic acid derivatives and intermediate products of fermentation have a small degree of effectiveness, when the yeast finds these products in sufficient quantity in the medium or is sufficiently autotrophic not to require them.

Some mineral elements show a negative effect and the phosphates cause an instability in the clearness of white wines.

The action of nitrogenous substances has been examined in detail. With different doses it has been observed that, although they are the most effective substances, increasing the yeast production, beyond certain limits they decrease the fermentative performance. The fermentative velocity is in logarithmic relation to the concentration of such stimulants, beyond the limit values for the best fermentative performance. In fact, it is evident that the enrichment in nitrogen of the medium increases the fermentation, both through the production of yeast and through the increase of the fermentative activity conferred to the yeast itself from its greater nitrogen content.

Between the supplement of nitrogen to the must and nitrogen content of yeast there is a relationship which seems to be direct for simple nitrogenous substances, and of logarithmic type for those which are complex, while between the nitrogen in the yeast and the speed of fermentation there is a roughly direct relationship.

This article has been cited by other articles:

				C. Varela, F. Pizarro, and E. Agosin Biomass Content Governs Fermentation Rate in Nitrogen-Deficient Wine Musts Appl. Envir. Microbiol., June 1, 2004; 70(6): 3392 - 3400. [Abstract] [Full Text] [PDF]