On the basis of the experimental evidence gathered in the course of this investigation, it is concluded that the alkaline steeping of barley leads to better colloidal (physical, non‐biological) stability of the beer without significantly affecting its flavour or any of its standard characteristics. Since the alkaline steeping invariably lowers the tanninogen contents of malt (both anthocyanogens and catechins decrease), whereas its other principal analyses do not change in any predictable manner, it should follow that the tanninogen decrease is mainly responsible for better stability of the beer. It is also apparent that no malt characteristics, except tanninogen and protein contents, have a definite effect on the colloidal stability of the beer. A relationship between the tanninogen and protein contents of malt has also been established.
The preparations obtained from the acidic and caustic desorbates of Nylon-66 beer adsorbates have been submitted to different hydrolytic procedures and the phenolics thus obtained examined by means of uni-and two-dimensional chromatography with the aid of appropriate reference compounds. A number of polyphenols and phenolic as well as cinnamic acids has been identified. The presence of trons-ocoumaric acid has not been previously reported in beer.
Phenolic concentrates, derived from Nylon-66 beer adsorbate, have been submitted to strong oxidative conditions involving refluxing in butanol and air.The changes in chemical composition of the concentrates were followed by various methods, including simultaneous determination of anthocyanogens and catechins (tanninogens). Flavour effects of the fresh concentrates, as well as of their oxidized mixtures, were examined in 5% aqueous ethanol and in beer. The influence of concentrates on the beer flavour was comparable with that of the fresh poiyphenols, while the oxidized mixtures resembled in that respect the oxidized poiyphenols. It was thereby proved that these concentrates retained their basic phenolic character in spite of the contaminants present, both before and after oxidation. Furthermore, the role of polyphenols in beer flavour was thus shown for the actual phenolic combina tions occurring in beer.
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