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Barley and Malt Starch in Brewing: A General Review

MBAA TQ vol. 40, no. 2, 2003, pp. 89-97  |  VIEW ARTICLE

Peer-Reviewed Paper

Dr. Charles W. Bamforth. University of California, Department of Food Science & Technology, Davis, CA 95616-8598. Based on a paper presented at the 115th Convention of the Master Brewers Association of the Americas, Austin, TX, October, 2002.

Abstract
The degradability of barley starch in malting and brewing can be addressed (and has been reviewed) within a two-part model that comprises the exposure of the substrate in a form accessible by enzymes, followed by the enzyme hydrolysis itself. Recent research on the accessibility of starch has included interference by the presence of protein (including friabilin) and lipid. However, it is also worth revisiting older studies that highlighted treatments such as heating that, while inducing gelatinization, can also lead to physical changes in the starch, rendering it less digestible. Recent studies have highlighted the limitations to wort fermentability that previously were supposed to be due to the thermal instability of limit dextrinase but are actually due to a shortage of enzyme in a free and active form. Release of this enzyme is facilitated, among other things, by reduced pH and reducing conditions.
Keywords: amylases, gelatinization, granules, heat, limit dextrinase, lipid, protein, starch, structure

 

Síntesis
La degradabilidad del almidón de cebada en los procesos cerveceros y de malteo puede ser visto como un modelo de dos etapas: la exposición del substrato en una forma accesible a las enzimas, seguido por la hidrólisis enzimática propiamente dicho. Investigaciones recientes con respecto a la accesibilidad del almidón han incluido el tema de la interferencia causada por la presencia de proteína (incluyendo la friabilina) y lípidos. Vale la pena revisar estudios antiguos que investigaron tratamientos tales como el calentamiento, que si bien induce la gelatinización, también ocasiona cambios físicos en la estructura del almidón que lo hace menos digerible. Estudios recientes han demostrado que las limitaciones a la fermentabilidad del mosto, que antes se suponía debida a la inestabilidad térmica de dextrinasa límite, en realidad se debe a una falta de suficiente enzima en una forma libre y activa. La liberación de esta enzima es facilitada por, entre otras cosas, un pH reducido y condiciones reductoras.
Palabras claves: amilasas, gelatinización, granulas, calor, dextrinasa límite, lípidos, proteína, almidón, estructura molecular

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