Significance of polyphenolic compounds for protein precipitation during wort boiling.

Škach, Josef; Mikyška, Alexandr

doi:10.18832/kp1990016

Cited by 1 publication

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“…Differences in the "natural" haze stability of beers were removed by PVPP treatment and all stabilized beers had a good shelf life prediction of more than 12 months. However these results cannot be generalized, as results from previous experiments at RIBM 46 , found that extension of the stabilizing effect also depended on the particular quality of the raw materials.…”

Section: )79087 %2( (-7'977-32 E^i Wxefmpmx]mentioning

confidence: 69%

The Role of Malt and Hop Polyphenols in Beer Quality, Flavour and Haze Stability

Mikyška

Hrabák

Hašková

et al. 2002

Journal of the Institute of Brewing

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Pilot-scale brewing trials of a 12°P pale lager beer were conducted to look at the effect of a modified dose of hop and malt polyphenols on haze, flavour quality, and stability. Results confirmed that malt polyphenols, and particularly hop polyphenols, in the course of wort boiling, improved reducing activity values and the carbonyl content in fresh and stored beers. Hop polyphenols significantly increased reducing activity and decreased the formation of carbonyls (TBA value) in fresh and stored beer. Reduced content of malt polyphenols, combined with the use of hop CO 2 extract, caused an increase in the TBA value in beer. PVPP stabilized beers tended to be lower in reducing activity. Both malt and hop polyphenols affected the intensity of "harsh taste" in fresh beers and a significant influence from PVPP stabilization of beer was not observed. The staling degree of forcedaged beers depended on the polyphenol content in the brewhouse. Both hop and malt polyphenols had a positive impact on flavour stability. PVPP treatment of beer had a positive effect on the flavour stability of heat-aged beers. Polyphenols, especially hop polyphenols, slowed down flavour deterioration during the nine month storage period, but the primary effect was seen during the first four months of storage. Storage trials did not show any unambiguous effects for PVPP stabilization on beer flavour stability. Results confirmed the negative impact of malt and hop polyphenols on haze stability, and PVPP stabilization minimized differences in shelf life prediction values between beers prepared with the modified dose of polyphenols.

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Section: )79087 %2( (-7'977-32 E^i Wxefmpmx]mentioning

confidence: 69%