LE PROTEINE DEL LIEVITO: ULTERIORE STRUMENTO PER LA STABILITÀ PROTEICA DEI VINI

During wine production and storage, several defects can appear. These can be due to unwanted microbiological activity or unstable levels of some compounds, resulting from an unbalanced grape chemical composition or inadequate winemaking practices and storage conditions. Several approaches can be adopted to reduce wine instability, in general by several fining agents or additives, and technologies with different performances and impacts on wine quality. The yeast proteins extracts (YPEs) are already approved by OIV for the treatment of musts and wine. The YPEs are constituted of complex and heterogeneous mixtures, and their chemical properties can be extremely variable. Several authors reported interesting electric properties of YPE, that can induce possible specific interaction with haze-related wine proteins and a possible use of YPEs as an alternative and more sustainable fining agent against wine protein instabilities. The best results were obtained at 20-30 g/hL of YPE concentration and 4 hours, which induced a 42 % decrease of initial PR-protein concentration. The Yeast protein extract increased the protein stability of white wines, but it can’t allow their complete stabilization. The addition of YPE could be considered a combined treatment with conventional ones, aimed to decrease the amount of conventional fining agents (e.g bentonite) for a precision enology to respect the aromatic properties of the white wines.