Polyvinylpolypyrrolidone, PVPP

Wine and beer industry Polyphenols can alter color and flavor of products such as wines. There are many aggressive ways of removing polyphenolic compounds, such as using polyvinylpolypyrrolidone (PVPP) or sulfur dioxide. However, polyphenol removal should be selective to avoid the undesirable alteration of the wine s organoleptic characteristics. For this reason, one option is to use laccases that polymerize the polyphenolic compounds during the wine-making process and then to remove these polymers by clarification (Morozova and others 2007). Several papers have reported that laccase is able to remove undesirable polyphenols and produce stable wines with a good flavor. 

McMurrough, I., Madigan, D., and Kelly, R. J. (1997). Evaluation of rapid colloidal stabilization with polyvinylpolypyrrolidone (PVPP). J. Am. Soc. Brew. Chem. 52, 38-43. 

The designation polyvinylpolypyrrolidone (PVPP) is still used in the literature, although it is certainly not correct. This is confirmed by a comparison of the infrared spectra for crospovidone and povidone, which reveals no recognizable difference (see Section 3.3.1.1). 

The polymerization of vinylpyrrolidone prodnces water-solnble polyvinylpyrrolidone (PVP). However, if polymerization occurs in the presence of an alkali, the pyrrolidone cycle is broken, pro-dncing insolnble polyvinylpolypyrrolidone (PVPP) (Fignre 10.14). 

Fig. 10.14. Polymerization of vinylpyrrolidone into (a) polyvinylpyrrolidone (PVP) and (b) polyvinylpolypyrrolidone (PVPP)...

Toth, G. B. and Pavia, H. (2001). Removal of dissolved brown algal phlorotannins using insoluble polyvinylpolypyrrolidone (PVPP). /. Chem. Ecol. TCI, 1899-1910. 

Protein-polyphenols interaction has been probed by various analytical methods that include high performance liquid chromatography (HPLC) [4,8], sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) [9], binding assay [2,10-11], nephelometry [12-15], and nuclear magnetic resonance (NMR) spectrometry [1,3,16,17], but with protein models that were often far from giving a realistic representation of salivary proteins bovine serum albumin (BSA) [18,19], gelatin [20,21], casein [1,22], polyvinylpolypyrrolidone (PVPP) [23,24], bradykinin [25,26], or diverse synthetic proteins [27,28]. 

Other alternatives to counteract haze include the adsorbants silica hydrogels, bentonite and polyvinylpolypyrrolidone (PVPP), the precipitant, tannic acid, and the proteolytic enzyme, papain. These additives, unfortunately, may leave residues in the beer and each may then be associated with problems in the finished product, for example, papain and bentonite may lessen foam stability and some hydrogels have been implicated in the formation of solid materials in the beer (Nelson and Young, 1986 Bamforth, 1988). Suggested physical alternatives are centrifugation, refrigeration and filtration (Hashimoto, 1981 Mathews, 1990). 

To preserve beer colloidal stability, brewers usually remove haze-active materials [34]. To get rid of haze-active proteins, precipitation with tannic acid, hydrolysis with papain and adsorption to bentonite [35] or silica gel [36, 37] are very effective, but unfortunately in some cases, such procedures also remove foam proteins. To remove haze-active polyphenols, the most usual way is adsorption to polyvinylpolypyrrolidone-PVPP. Because of the structural analogy between these compounds and proline [38], pyrrolidone rings bind polymerized flavanoids through hydrogen and ionic bonds. 

The acidic EtOAc fraction (343 mg) was dissolved in about 250 ml of 0.1 M phosphate buffer, pH 8.0. Polyvinylpolypyrrolidone (PVPP) was added to the solution and the mixture was stirred for 30 min. The PVPP concentration was about 50 mg/ml of the buffer. The PVPP was removed... 

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