engleski

Differential affinity of bentonite towards pathogenesis-related proteins depending on the time of addition during fermentation of Malvazija istarska grape must

The grape pathogenesis-related thaumatin-like proteins (TLP) and chitinases are the major soluble proteins in grape juice and are considered responsible for haze formation in white wines. Bentonite is still the most efficient and cost-effective agent for their removal. In this work, the differential affinity of bentonite towards pathogenesis- related proteins was investigated, with respect to the time of addition at various stages of fermentation of Malvazija istarska (Vitis vinifera L.) must in order to possibly reduce the total dosage required. Five treatments were established, with an initial bentonite dose of 100 g/hL added in clear must (MU), at the beginning (BE), in the middle (MD), and at the end of fermentation (EN), while control (CO) received no bentonite. After fermentation, protein-stable wines were obtained by additional bentonite fining. Proteins were determined by reversed-phase high-performance liquid chromatography (HPLC-DAD). Four TLPs and two chitinases were tentatively identified. All the treatments reduced both groups of proteins. MD and especially EN treatments were characterised by the highest affinity of bentonite towards particular TLP proteins, while the time of bentonite addition did not influence the removal of chitinases. MD and EN turned out to be the most effective among the treatments and reduced the required total bentonite amount for 19 and 21 %, respectively. This work has been supported by Croatian Science Foundation under the project UIP-2014- 09-1194.

pathogenesis-related proteins ; bentonite ; fermentation ; Malvazija istarska ; protein stability

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