General Composition of Non-Biological Hazes of Beers and Some Factors in Their Formation. Part I

Abstract

A study has been made of the chemical composition of chill-hazes and oxidationhazes of certain commercial and experimental beers. In addition to amino acid and sugar units, the hazes have been shown unequivocally to contain tannin derived both from malt and from hops. The hazes have been shown to be heterogeneous both by means of chemical fractionation and by ultracentrifugation. Spectrographic exami nation of the ash from certain specimens revealed that the hazes contained concen trations of heavy metals, particularly copper, iron and aluminium, which were high relative to their concentrations in the beers giving rise to them. The study was extended to include some factors which affect the rate of formation of hazes in beers. Heating of hazy beers resulted in solution of the haze already present slowly followed by the precipitation of a further haze with solubility characteristics different from those of the original. The effect of cooling beers which had been heated for a brief period at 70°C. was also studied. It was found that the rate of formation of haze was lower after rapid cooling of the beer than after slow cooling. Finally, the rate of formation of haze was, within limits, independent of the amount which had already separated from solution, suggesting that there is a considerable reserve in the beer of potential haze constituents.General Composition of Hazes 36 mg. per litre of lager beer (average 13-4

A Discussion of Polyphenols in Beer Physical and Flavour Stability

“…Brewers should also keep in mind that, beyond playing significant roles in beer off-flavour formation, trace metals have also been associated with beer colloidal instability in the forms of haze and gushing 14,42,48,65,84 .…”

“…Constituents known to play a role in haze formation include proteins, tannins (polyphenol), carbohydrates, oxygen and metal ions. Several metals have been found in haze: aluminium, barium, calcium, chromium, copper, iron, lead, magnesium, manganese, molybdenum, nickel, phosphorus, silicon, silver, strontium, tin, vanadium and zinc 14 . Metals such as copper, iron and aluminium can exist in the haze at several thousand fold higher concentrations than in the parent beer.…”

Formation mechanism of microvoids and microcracks of poly(vinyl chloride) under an artificial aging environment

“…Many efforts have been done to simulate the dependence of both the macrocosmic and microcosmic structure of PVC molecular chains on aging conditions in the accelerating aging process 4–10. It is convinced that the photo‐dehydrochlorination of PVC is dominated in the initial aging step.…”

“…Many efforts have been done to simulate the dependence of both the macrocosmic and microcosmic structure of PVC molecular chains on aging conditions in the accelerating aging process. [4][5][6][7][8][9][10] It is con-vinced that the photo-dehydrochlorination of PVC is dominated in the initial aging step. Subsequently, double bonds even conjugated polyenes are formed, which will directly lead to the discoloration of polymer.…”

General Composition of Non-Biological Hazes of Beers and Some Factors in Their Formation: Ii. Chromatographic Separation of Hop and Malt Tannins

“…The phenolic acids present give colorations as described in Fart I. 7 Details of the colorations yielded by the polyphenols of hops and malt with each of the reagents cited above are given in Tables II and III shaken overnight in an atmosphere of nitro gen with 70% ethanol (3 litres). The mix ture was filtered, the residual cones were washed with 70% ethanol and the nitrate was evaporated to approximately 1 litre.…”