engleski

The effect of alternative bentonite fining on selected aspects of Malvazija istarska (Vitis vinifera L.) wine quality and protein stability

Standard white wine fining with bentonite, still the most efficient fining agent in achieving protein stability, often reduces wine quantity and quality. To evaluate the effectiveness of alternative approaches and possible positive effect of tannins that can react with proteins, bentonite was added to Malvazija istarska must during fermentation and tannins were also applied. After fermentation with bentonite, with tannins, or both, heating tests were performed for evaluation of protein stability. Wine quality was also evaluted by GC-MS measurements of volatile aroma compounds extracted by SPE, by HPLC-DAD measurements of phenolic compounds and by 100-point OIV method and quantitative descriptive sensory analysis. Bentonite treatments in fermentation showed better efficacy in relation to control treatment (standard wine fining after fermentation). Required dose of bentonite was reduced up to 21%, the wines preserved higher concentrations of major fermentation acids and esters, and higher concentrations of hidroxycinnamoyltartaric acids. Sensory attributes were also positively affected. Use of tannins showed positive impact on bentonite efficacy related to protein stabilization. In combination with bentonite, tannins had positive impact on preservation of aromas and hidroxycinnamoyltartaric acids, as well as good sensory quality. Despite higher intensity of sensory descriptors like astringency and bitterness, overall effect was considered positive. This work has been supported in part by Croatian Science Foundation under the project UIP-2014-09-1194.

bentonite ; tannin ; wine stability ; aroma ; phenols

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