engleski

Influence of bentonite type and water hardness on protein stability and organoleptical characteristics of Malvazija istarska wine

Malvazija istarska bijela ( Vitis vinifera L.) is the most represented grapevine variety in Istrian winegrowing subregion. Wines of Malvazija istarska contain high quantities of proteins for which removal are required high doses of bentonite, reflecting on physical- chemical and organoleptical aspects of wine. In production of Malvazija wines the most used is Ca-bentonite prepared in aqueduct water of high hardness ((Poreč ; 19, 1 °D / 340 mg CaCO3/L). After performed protein stabilisation, it was determined that treated wines are greatly different from non treated wines in respect of organoleptical characteristics. The aim of this paper was to examine how the bentonite type (Na- ; Ca- and Ca/Na) and water hardness (distilled and aqueduct) for bentonite preparation influence on bentonite doses necessary for protein stabilisation, quantity of originated sediment and physical-chemical and organoleptical parameters of Malvazija istarska wine quality from harvest 2009. It was determined that application of distilled water during bentonite wetting requires generally lower doses of bentonite for protein stabilisation: Ca = Na < Ca/Na ; for aqueduct water, bentonite dose is higher: Na < Ca< Ca/Na. Regardless the water hardness, Ca- bentonite generated most sediments (10 – 12 %). The reduction of total acidity, as well as of hue and colour intensity in relation to control/non treated treatment was determined for all treatments. Wines were organoleptically scored by a method of 100 points. All samples on which were applied distilled water were better scored than ones with aqueduct water.

wine ; Malvazija istarska ; bentonite ; water hardness

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