Evaluation of different co-inoculation time of non-Saccharomyces/Saccharomyces yeasts in order to obtain reducing ethanol wines

MESTRE M.V.; MATURANO Y.P.; COMBINA M.; MERCADO L. A.; TORO M.E.; VAZQUEZ F.

Bento Gonzalves

Congreso; 39º Congresso Mundial de la Viña y el Vino; 2016

Organizacion Internacional de la Vid y el Vino (OIV)

Decreasing ethanol content in wines has become one of the main objectives of winemaking in different areas of the world. Numerous viticultural and engineering strategies have been proposed to achieve this purpose. Use of selected wine yeasts can be considered one of the most effective and simple tools. In order to obtain wines with reducing ethanol levels and positive oenological properties, 114 non-Saccharomyces native yeast were studied. Based on oxidative metabolism, fermentative performance and oenological traits, Hanseniaspora uvarum BHu9, Starmerella bacillaris BSb55 and Candida membranifasciens BCm71 were selected to co-inoculate with a Saccharomyces cerevisiae selected native yeast. The aim of the present study was to evaluate the effect of co-inoculation times of no-Saccharomyces/ Saccharomyces yeasts on the reduction the ethanol levels in wines. Microfermentations (grape must at 24°Bx) were carried out at 24±1°C under static conditions. Treatments assayed were: pure fermentations of non- Saccharomyces yeasts BHu9, BSb55 and BCm71 and S. cerevisiae yeast BSc203; -co-fermentations: A- BHu9/BSc203; B- BSb55/BSc203 and C- BCm71/BSc203. These co-inoculations were carried out under mixed conditions (simultaneous inoculation):T1, and sequential conditions: non-Saccharomyces yeast inoculated at initial time and S. cerevisiae yeast at 48 h: T2, 96 h: T3 and 144 h: T4. Fermentations were monitored during 21 days by weight loss of fermentation systems (as CO2 production). Samples were taken at Day 2, 4 and 6 for T2, T3 and T4, respectively. Also, Days 14 and 21. Ethanol, pH, volatile acidity, total acidity, density, glycerol, residual sugars, glucose, fructose, sucrose, lactic, malic, citric and tartaric acid were analyzed by F-TIR spectrophotometer. According to the results of vinifications, specifically the values of conversion efficiency of sugars into ethanol (consumed sugar (g/L) / ethanol produced (% v/v)), and considering those combinations that showed inefficient production of ethanol, some trends were established. When non-Saccharomyces yeasts remained pure more time, lower fermentative efficiencies were registered. This happened in co-cultures of BHu9 and BSb55 with BSc203 (AT1: 16.7, AT2: 17.38, AT3: 18.68 and AT4: 18.99). Conversely, the conversion efficiency was reduced in co-inocula of BCm71/BSc203, when both yeasts interact more time (CT1: 19.36; CT2: 18.40; CT3: 18.18; CT4: 16.67). All vinifications produced metabolites concentrations within acceptable ranges according to the current legislations. Conclusion: non-Saccharomyces and Saccharomyces yeasts time interaction during fermentations showed effect on ethanol production and this effect would be dependent on the co-inoculated species.