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PVPP treatment of wine production


Polyvinylpolypyrolidone (PVPP) is a synthetic, high-molecular-weight fining agent composed of cross-linked monomers of polyvinylpyrolidone (PVP). PVPP is a "proteinlike" fining agent with affinity for low-molecular-weight phenolics. The mechanism of action is hydrogen bond formation between carbonyl groups on the polyamide (PVPP) and the phenolic hydrogens. As a selective phenol absorbent, PVPP is available in several particle sizes. Unlike the soluble protein fining agents that remove larger polyphenols by conforming with the molecule, insoluble PVPP contacts relatively few reactive groups. Therefore, PVPP finds its major application in binding with and removing smaller phenolics such as catechins and anthocyanins, which conform to the PVPP molecule. These compounds are precursors to browning in white wines, and browning and bitterness in red.

 

PVPP may be effective in "toning down" bitterness or the potential for this problem in wines. PVPP is most beneficial immediately post-fermentation, but is occasionally added to juice and removed by settling before fermentation. PVPP treatment of Traminer must reduces the formation of 4-vinylguaiacol, an important character impact compound for the variety. It may be a benefit in prefermentation fining of juice from moldy grapes and for removing excess color for blush wine production. PVPP removes more tannin and anthocyanin than gelatin. This represents a potential problem in use of this agent in red wine fining. In addition, PVPP is used in removal of browning or pinking precursors in young white wines. Recommended use levels are from 12 to 72 g/hL (1-6 lb/1,000 gal). PVPP has the ability to strip wine complexity. It is therefore desirable to fine juice or young wines before the development of aged bouquet.

 


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