Polyphenol removal

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. 

The resistence to oxidation was related to the high content of polyphenols removal of polyphenols greatly reduced oxidative stability [39]. The subsequent studies were devoted to identifying the compoimds which more contribute to oil stability and the mechanism of protection. Hydroxytyrosol and caffeic acid were better protection factors than BHT tyrosol and other monohydroxy phenols gave little contribution to oil stability [43] oil shelf-life was positively correlated to hydroxytyrosol / tyrosol ratio [44]. 

Figure 8 illustrates one of the processing schemes used for separating various components in a hydrocarbon-containing plant. Acetone extraction removes the polyphenols, glycerides, and sterols, and benzene extraction removes the hydrocarbons. If the biomass species in question contain low concentrations of the nonhydrocarbon components, exclusive of the carbohydrate and protein fractions, direct extraction of the hydrocarbons with benzene or a similar solvent might be preferred. 

The crospovidones are easily compressed when anhydrous but readily regain their form upon exposure to moisture. This is an ideal situation for use in pharmaceutical tablet disintegration and they have found commercial appHcation in this technology. PVP strongly interacts with polyphenols, the crospovidones can readily remove them from beer, preventing subsequent interaction with beer proteins and the resulting formation of haze. The resin can be recovered and regenerated with dilute caustic. 

Sample pre-treatment. Novel procedures of electrochemical sample treatment have been proposed to decrease the signal interference with native cholinesterase inhibitors present in fruits and vegetables. Polyphenolic compounds were removed by electrolysis with soluble A1 anode followed by the oxidation of thionic pesticides with electrogenerated chlorine. The procedure proposed makes it possible to decrease the background current and the matrix effect by 80-90%. Thus, the detection limits of about 5 ppb of Pai athion-Methyl and Chloropyrifos-Methyl were obtained in spiked grape juice without any additional sepai ation or pre-concentration stages. 

When appreciable amounts of pectin, proteins, lipids, unwanted polyphenols, or other compounds are suspected to be present in anthocyanin-containing extracts, some of them can be precipitated or the anthocyanins may be crystalhzed and separated from the others. Pectin and proteins can be removed by organic solvents such as methanol and acetone in order to reduce their solubility, then precipitated and separated by centrifugation. Gelatin was used to remove proanthocyanidin due to its high molecular weight. Anthocyanins were reported to be precipitated early by lead acetate to achieve isolation from other materials. ... 

Instant tea produced as described above will dissolve completely in hot water but not in cold water, as the caffeine-polyphenol complexes are insoluble under those conditions. Since virtually all instant tea manufacture in the U.S. is for iced tea preparation, process modification is required. This initial extract may be cooled to 5 to 10°C and the cold water insoluble material or cream be allowed to precipitate. Under these conditions, 20 to 35% of the extract solids may be separated by centrifugation. The supernatant solids will reconstitute in cold water after concentration and drying.105 It is also possible to process the cream to make a portion of it compatible with the product and thereby retain the caffeine and some polyphenolic components that are present in this fraction.106 Commercial use of the enzyme Tannase, which removes gallic acid from gallated tea polyphenols107 and reduces cream formation108 can be used to reduce cream losses and manufacture instant teas retaining more of the natural polyphenol content. 

A similar problem occurs with beer stabilization. A serious problem in the brewing industry is the tendency of some beers to develop hazes during long-term storage due to protein precipitation that is usually stimulated by small quantities of naturally occurring proanthocyanidin polyphenols. In the same way as observed for wine, the excess polyphenols are traditionally removed by treatment with insoluble PVPP, with the same resulting problems. To resolve the problems, several authors have proposed the use of laccase, which forms polyphenol complexes that may be removed by filtration or other separation means. 

Sajo M Mar, Nunez-Delicado E, Garcia-CarmonaF, Sanchez-Ferrer A. Partial purification of a bannana polyphenol oxidase using Triton X-l 14 and PEG 800G for removal of polyphenols. J Agric Food Chem 1998 46 4924-4930. 

Removing Interfering Polyphenols. The most troublesome problem encountered was high polyphenol content. If not removed, this dark-colored wood extractive decreased resolution during chromatographic separations, quickly render expensive chromatographic media (e.g., HPLC columns) nearly useless, and often precipitated enzymes during subsequent purification steps (14,15), We found it best to remove the bulk of this material prior to the first concentration step. 

Chemical analysis of haze materials isolated from a beverage must be interpreted with caution because composition is often not well-related to cause. For example, beer hazes typically contain a high proportion of carbohydrate, with a modest amount of protein, and little polyphenol (Belleau and Dadic, 1981 Siebert et al., 1981). In order to prevent or delay haze formation, however, it is not necessary or helpful to remove carbohydrate. Reducing the amount of either protein or polyphenol typically has that effect. As a result, it appears that the large amount of carbohydrate found in the haze was coagulated with or adhered in some way to the protein-polyphenol haze backbone. 

Even higher proline contents have been reported in salivary PRPs these can contain 40-45 mol% proline and also have a substantial amount of glutamine. This protein binds ingested polyphenols, which precipitates the PRPs and removes the lubrication these normally provide. The result is the sensation of astringency (Green, 1993 Haslam and Lilley, 1988). 

Adsorbents that remove proteins or polyphenols are used to treat a number of beverages to delay the onset of haze formation. Protein adsorbents include bentonite and silica. Bentonite removes protein nonspecifically (see Fig. 2.19) and so is unsuitable for stabilizing beverages where foam is desirable (beer and champagne). Silica, on the other hand, has remarkable specificity for HA proteins while virtually sparing foam-active proteins in beer (Siebert and Lynn, 1997b) (see Fig. 2.20). Silica removes approximately 80% of the HA protein from unstabilized beer, while leaving foam-active protein nearly untouched at commercial treatment levels. 

This was shown to occur because silica binds to the same features in polypeptides that polyphenols do (peptidically linked proline Siebert and Lynn, 1997b) (see the concept in Fig. 2.21). In contrast, in unstabilized apple juice, silica removes only on the order of 20% of the HA protein... 

PVPP is commonly used to remove undesirable brown or pink pigments from wine (Jackson, 1994). However, because much of the color of red wine is due to polyphenolic compounds, treatment with PVPP or other polyamides can diminish the red color and so must be carefully controlled. Additions of gelatin or egg white (egg albumin has about... 

Khan, A. A., Husain, Q. (2007). Decolorization and removal of textile and non-textile dyes from polluted waste-water and dyeing effluent by using potato (Solanum tuberosum) soluble and immobilized polyphenol oxidase. 

Milk thistle (Silybum marianum) is an annual to biennial plant of the Aster-aceae family. It is native principally to southern Europe and northern Africa. The crude drug consists of the ripe fruits from which the pappus has been removed. Milk thistle fruits contain 15% to 30% proteins. The main active compounds constitute only about 2% to 3% of the dried fruits. The active principle is a mixture of flavolignans called silymarin. Silymarin, a polyphenolic extract isolated from the seeds of milk thistle, is composed mainly of silybin (50 70%), with small amounts of other silybin structural isomers, namely isosilybin, silydianin, and silychristin (Fig. 11) (123-125). The highest concentration of silymarin is found in the ripe fruits (126). Silibinin is the main compound, also considered to be the most active one in several paradigms (127). 

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