Resumen de Analytical Characterization of the Hydrolysis of Barley Malt Macromolecules During Enzymatic Degradation Over Time Using AF4/MALS/RI

Heinrich Rübsam, Thomas Becker, Martina Gastl

• The changes on the molecular weight distribution (MWD) and particle size distribution (PSD) during hydrolysis of barley malt in isothermal mashing procedures were determined using asymmetrical flow field flow fractionation coupled to multiangle laser light scattering and refractive index (AF4/MALS/RI). Mash/trials were focused on amylolytic starch degradation. Therefore, temperatures (65, 70, and 75 °C) were selected according to α‐ and β‐amylases range of activity. Samples were produced by triplicate, tracking amylolytic processes over time periods from 10 to 90 min in each mash/trial. AF4/MALS/RI analysis demonstrated significant differences on the values of the MWD and PSD according to the temperature/time profile used. At mashing times over 30 min at a temperature of 65 °C, when α‐ and β‐amylase are both active, the decrease over time of the MWD and PSD was significantly higher (P< 0.005) than at 70 °C when mainly α‐amylase is active. At 75 °C, also the activity of α‐amylase decreased and the MWD and PSD were significantly lower (P< 0.005) than at 70 or 65 °C at any time of the procedure. The MWD and PSD of beer components influence beer palate fullness, thus AF4/ MALS/RI would be a powerful tool for breweries to adapt their technological processes to obtain beers with particular sensorial attributes. AF4/MALS/RI enabled the study of the changes of the MWD and the PSD due to the hydrolysis of barley malt during mashing processes. These parameters are associated to beer sensorial attributes, such as palate fullness and can be modified according to mashing temperature. Therefore, application of AF4/ MALS/RI would be a powerful approach helping to improve technological processes in breweries and to obtain different types of beers with particular sensorial attributes.