Abstract 074
Development of a method for assessing haze-active protein in beer by dye binding
J. Amer. Soc. Brew. Chem. 59 (4): 172-182, 2001
J.-I. Yang and K.J. Siebert
Fifteen candidate dyes were combined with the haze-active protein gliadin in a search for one that would produce a chromatic shift, and form the basis of an analytical method for haze-active (HA) protein in beer. Two dyes, Alizarin Red S and Nuclear Fast Red, produced shifts in the UV region and two, Bromopyrogallol Red and Plasmocorinth B, produced shifts in the visible range. The responses of these four dyes to proteins with a range of haze-forming activity were compared. Bromopyrogallol Red (BPR) was selected for method development. A statistical experiment design and response surface modeling were used to determine optimum conditions. BPR produced a linear response to gliadin in buffer, but suffered interference in the beer matrix. Pretreatment of beer with a C18 cartridge and centrifugal ultrafiltration removed the interference. Measurements of HA protein via the BPR method and by haze induction with tannic acid were performed on unchillproofed beer samples treated with varying levels of silica gel, bentonite and PVPP. The results showed agreement in the patterns, but some differences in the levels. It appears that the BPR method gives a different perspective on beer haze stability that should not be influenced by the level of endogenous polyphenol.
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