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The Effect of Beer pH on Colloidal Stability and Stabilization�A Review and Recent Findings

Peer-Reviewed Paper


MBAA TQ doi:10.1094/TQ-47-2-0607-01  |  VIEW ARTICLE

Karl J. Siebert. Food Science and Technology Department, Cornell University, Geneva, NY.

Abstract
pH has a pronounced effect on the amount of haze produced in both model systems and beer from the same amounts of haze-active (HA) proteins and HA polyphenols. The greatest haze intensity is seen slightly above pH 4 and varies slightly with alcohol content. This pH promotes removal of HA material during maturation, resulting in better beer colloidal stability. Fining with HA proteins (gelatin or isinglass) or HA polyphenols (e.g., tannic acid) is similarly affected by pH, with the greatest effectiveness near pH 4.3. Factors that influence beer pH are reviewed for their effects on colloidal stability. Under low adsorbent dose conditions, both silica and PVPP are slightly less effective at the pH at which proteins bind polyphenols most strongly. This appears to be due to competition between a stronger protein�polyphenol interaction and binding of HA material to an adsorbent.

Keywords: adsorbent, fining, haze, polyphenol, protein 

S�ntesis
El pH tiene un gran efecto sobre la cantidad de turbieza formada (tanto en cerveza como en sistemas modelos) aun con id�nticas concentraciones de prote�nas turbieza-activas (TA) y polifenoles TA. La mayor intensidad de turbieza se manifiesta a un pH ligeramente superior a cuatro y var�a un poco seg�n el contenido de alcohol. Este pH promueve la remoci�n de material TA durante la maduraci�n, as� mejorando la estabilidad coloidal de la cerveza. El tratamiento con prote�nas TA (gelatina o �isinglass�) o con polifenoles TA (�cido t�nico) tambi�n es afectado por el pH, siendo m�s eficaz cerca de un pH de 4,3. Se discuten los factores que afectan el pH de la cerveza y como estos pueden afectar la estabilidad coloidal. En condiciones de baja dosificaci�n de adsorbente, tanto s�lica gel como PVPP se muestran menos efectivos a un pH donde las prote�nas se unen m�s fuertemente a los polifenoles. Parece que esto se debe a la competencia entre una interacci�n prote�na-polifenol muy fuerte y la fuerza de la uni�n de un material TA a un adsorbente.

Palabras claves: adsorbentes, polifenoles, prote�nas, tratamiento anti turbieza coloidal, turbieza

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