Impact And Control Of Beer Polyphenols
I. Beer Source of polyphenols 1. Malt and barley, wheat, and other accessories
Finished beer Wine About 70% of polyphenols? 80% comes from the malt, malt polyphenol about 0.1% of the dry weight of malt? 0.3%, primarily in wheat bran and aleurone layer, the small amount present in the endosperm, including anthocyanins , protocatechuic acid and so on. Generally lower protein content with the variety, the more thick oatmeal barley, the higher the polyphenol content. Wheat, polyphenols have a strong smell and bitter taste stimuli. Polyphenol content and barley malt varieties, regions, harvest, germination process, and there is a certain relationship between the solubility of malt.
2. Hop Hop in with 4%? Of 10% polyphenols, a class of non-crystalline mixtures, it is almost the only remaining in the bract and flower axis. Hop polyphenols from 20% of the available material and 80% of hydrolysis can be composed of condensed matter. Hop polyphenol content and composition, and variety, origin, storage conditions and other factors. Bitter hops flavor generally low high tannin containing polyphenols. Hops than malt polyphenols polymerization and high polyphenol in beer brewing process are more likely to respond, the final residue in a small amount of beer.
Second, the composition of polyphenols in beer and on beer flavor and quality, role
1. Single phenol and low molecular polyphenols
Mainly phenolic compounds, flower color of the original material, flavonol, catechin compounds. They have a reductive, anti-aging beer one of the main material. As phenolic compounds, mainly with the role of oxygen free radicals. If their content is high, molecules will aggregate into big beer turbidity or sedimentation caused. Among them, flavonoids eliminate free radical effect is a biological active agent, helps cardiovascular and cerebrovascular diseases, adjuvant treatment, but also easy to flavonol cause oxidative polymerization of non-biological turbidity. Such low polyphenol content, beer taste Guadan, beer aging resistance and nutritional effects will be much lower. Therefore, the beer should retain a certain amount of small molecules polyphenols, in order to maintain the beer’s rich and full sense.
2. Tannin By the molecular weight of 500? 3000 phenolic composition combined with protein precipitation and precipitation formation, reducing the wort and beer, the nitrogen content in the polymer is conducive to non-biological stability of beer, but the precipitation ability with the degree of polymerization increase and decrease. Such polyphenols are also oxidation, aggregation tendency.
3. Poly phenol By the molecular weight of more than 3000 poly phenol in the composition of non-tannin compounds, which in itself can aggregate and precipitate. Such is the beer oxidation of polyphenol substrate, could promote aging of beer, the beer will taste sketch maps exist to become rough, bitter, but also deepen the color of beer.
Conclusion, polyphenols in beer brewing role mainly as follows:
(1) scavenging free radicals OH (so as to improve the performance of DPPH).
(2) chelate metal ions (Cu2 +, Fe2 +).
(3) inhibition of lipoxygenase (LOX) role.
(4) the role of protective enzymes in some of the radical damage or interfere with its role in helping to improve the extraction rate.
(5) increase the brewing process, the antioxidant capacity of intermediate products (TBA in wort and beer showed stable or slightly lower).
(6) can improve the performance of wort and beer filtration.
(7) inhibit the degradation of formaldehyde formation, is conducive to beer flavor stability.
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