Repositori URV

Identifier: TDX:338

Handle: https://hdl.handle.net/20.500.11797/TDX338

Authors:
Salazar González, Fernando Noé

Abstract:
Heat-unstable soluble proteins in grapes, grape juices and wines may become insoluble and precipitate causing the formation of undesirable hazes or deposits in white wines after bottling and during storage. Proteins are commonly prevented from forming hazes with bentonite, though this technique does have drawbacks: for example, the sensory properties of the wine are affected adversely because flavour compounds are removed and wine volume is lost as lees because of the swell and settling of the bentonite. In addition, the handling and disposal of spent bentonite continues to be a concern, because it involves high labour input and the associated costs, occupational health and safety issues, and the wine industry's environmental responsibilities and legislative requirements. It is estimated that the cost of bentonite fining to the wine industry worldwide is in the order of US$300-500 m per annum. Alternative fining technologies to bentonite, which are economically viable and maintain wine quality, are currently being sought. However, no successful techniques have been developed to date: all the attempts so far have either affected the quality of the wine or not been economically viable under standard winemaking conditions. Therefore, research on the implementation of new practices that have a less negative impact on the environment and are economically viable is particularly challenging.For this reason the aim of this thesis was to study the industrial viability of an alternative technology to bentonite fining which enables unstable proteins to be removed from white wines using zirconia as the adsorbent material. We also attempted to develop a continuous process, which stabilizes wine protein without having any negative effects on the physicochemical and sensory properties