engleski

Bentonite in fermentation of Malvazija istarska must reduces the dose required and limits the hydrolysis of hydroxycinnamoyltartaric acids

Bentonite is still the most efficient and cost- effective agent in achieving the protein stability of white wines. However, its excessive use may have a negative effect on the properties of final wine, so the reduction of its dose is of great interest for producers. In this work, the effectiveness of bentonite addition at various stages of fermentation of Malvazija istarska (Vitis vinifera L.) must with respect to standard wine fining was evaluated. Doses of 100 g/hL were added in clear must (MU), at the beginning (B), in the middle (MI), and at the end of fermentation (E), while control received no bentonite. In the produced wines, protein stability was evaluated, and additional doses required were determined. The additional doses were applied and protein-stable wines were obtained. Phenolic compounds were determined by HPLC-DAD analysis after fermentation and in protein- stable wines. Bentonite added during fermentation significantly reduced the total amount required in relation to control. The most effective were the treatments MI and E, which reduced its amount for 19 % and 21 %, respectively, as determined by the heating with tannins test. All wines fermented with bentonite contained significantly higher amounts of the major hydroxycinnamoyltartaric acids, such as trans-caftaric, trans-coutaric, and trans-fertaric acid, in relation to control. The control wine had higher amounts of free caffeic, p-coumaric and ferulic acid. It was concluded that bentonite added during fermentation, besides reducing its total amount, probably limits the activity of enzymes responsible for the hydrolysis of hydroxycinnamoyltartaric acids. This work has been supported in part by Croatian Science Foundation under the project UIP-2014-09-1194.

bentonite, fermentation, Malvazija istarska, protein stability, phenols

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