An automatic fermentation nutrition system compared to a traditional one: fermentation performances and composition of white wines

The Avaferm® automatic yeast nutrition system was tested in comparison to manual nutrition management during the fermentation of white wines. To evaluate the two approaches, a factorial experimental design with interaction was established consisting of the two ways of nutrition (Avaferm® and Control) and two white grape varieties (Catarratto and Chardonnay). The experiments were conducted on an industrial scale, ensuring the practical relevance of the findings. The parameters that underwent evaluation encompassed a wide range of aspects, including the fermentation kinetics of sugars, the use of α-amino nitrogen and ammonium, as well as the technological and aromatic volatile composition of the wines. To study the sugar consumption kinetics during fermentation, a new use of the 5-parameter logistic regression was applied to fit these compounds. The automatic nutrition showed a substantial similarity in the fermentative kinetics and in all cases, we have reached adequate sugar depletion (almost no residual fermentable sugars). Moreover, with regards to the composition of the wines, the two methods were found to be similar, although with a slightly higher concentration of residual YAN in the control nitrogen management. The wines obtained with Avaferm® showed a greater concentration in 3-oxo-α-ionol and a slightly lesser concentration in butanoic hexanoic, octanoic and decanoic acids as well as ethyl hexanoate, ethyl octanoate and ethyl decanoate. The variety factor as expected showed several differences, which can be explained by the chemical composition of the different grape musts.