Extrusion Process to Improve the Availability of Fermentable Sugars in Sorghum Wort

Abstract

A common challenge in producing gluten-free beer from sorghum is the inefficient conversion of sorghum starch into fermentable sugars. This issue can be attributed to the high proportion of resistant starch and natural inhibitors that hinder starch digestibility in sorghum grains. To address this, an extrusion process was proposed to improve gelatinization and hydrolysis of sorghum starch. Two experimental designs were conducted, one with extrusion and one without, to assess the impact of utilizing two exogenous enzymes during mashing: papain and α-amylase. The results showed that the extrusion process significantly improved sorghum starch gelatinization and increased the concentration of fermentable sugars by an average of four times compared to trials without extrusion. By incorporating the extrusion process and utilizing 3% α-amylase and 0.1% papain, a highquality wort with the desired concentration of fermentable sugars for yeast fermentation was obtained. This improvement was supported through the analysis of scanning electron microscopy (SEM) images and energy dispersive x-ray spectroscopy (EDS) by revealing changes in the structure and composition of gelatinized and hydrolyzed sorghum grains with and without extrusion.