The Influence of Brewing Adjuncts and Silica Structural Properties on Selective Protein Adsorption from Lager Beers

By Ian McKeown, G. Earl, G. Stewart and K. Leiper Crosfield Ltd., Warrington, England * ICBD, Heriot-Watt University, Edinburgh, Scotland. This poster was originally presented at the MBAA 112th Anniversary Convention, Keystone, Colorado, 1999.

Abstract
Silica has long been used to stabilize beer. Brewing raw materials affect the protein content of beer which in turn influences protein uptake by porous silica. This study shows how adjunct type, and both surface accessibility and hydroxyl activity of silica control this process. Selective adsorption of different protein fractions is a func- tion of silica pore size distribution and beer type. The effect of hydroxyl activity is dependent on the silica structure. While for one silica, protein uptake was enhanced in both all-malt and adjunct beers, for another silica improved adsorptivity was only observed in adjunct beer. The findings show that pore size distribution, as well as surface chemistry are important features of the silica. For optimum performance silica stabilizers should be tailored to customer needs based on beer type.
Keywords: Selective Protein Adsorption, Xerogel Characteristics, malt/Adjunct Impact on Beer Protein, Malt/Adjunct Impact on, bBeer Stabilization, Foam Stability of Xerogel Beers  

Sintesis
La sllice ha sido usada para la estabilizacibn de la cerveza desde hate mucho tiempo. El proceso de la elaboracicin de la materia prima afecta el contenido de proteinas de la cerveza que a su vez influye la toma de proteinas por la &lice porosa. Este estudio muestra coma el tipo de adjunto y tanto la accesibilidad de la superficie coma la actividad hidroxil de la sflice controlan este proceso. La absorcion selectiva de fracciones de proteina diferentes es una funcirin de la distribucicin del tamafio del poro de la sflice y del tipo de cerveza. El efecto de la actividad hidroxil depende de la estructura de la silice. Mientras que en un tipo de silice la toma de proteinas se aumento tanto en la cerveza de pura malta coma en cervezas adjuntas, en otro tipo de silice la mejora de absorci6n solo se observrj en cerveza adjunta. Los descubrimientos mostraron que la distribucion del tamafio del poro, asi coma la quimica de la superficie, son carac- teristicas importantes de la sflice. Para un rendimlento optimo los estabilizadores de sxlice deben ser adaptados a las necesidades del cliente basadas en el tipo de cerveza.