Enhancing cassava beer quality: Extrusion-induced modification of cassava starch structure boosts fermentable sugar content in wort

Abstract

The high starch content and cost-effectiveness of cassava make it an attractive adjunct in beer brewing, with the fine structure of starch playing a crucial role in determining the composition of fermentable sugars (FS) and overall beer quality. This study investigated the effect of extrusion-induced changes in the starch structure of cassava flour on the FS profile of the wort and, consequently, on the quality attributes of cassava beer. The findings revealed that the shear stress during extrusion significantly reduced the molecular weight to 1.20 × 105g/mol and the branching degree of amylopectin. Simultaneously, there was an increase in the concentrations of short- and intermediate- chain amylose by 5.61% and 42.72%, respectively. These structural changes enhanced the enzymatic hydrolysis of extruded cassava flour (ECF), resulting in a higher total fermentable sugars content (22.00g/100 mL) in the ECF wort, predominantly composed of maltose and glucose. Furthermore, the altered FS profile led to an increased production of higher alcohols and esters in extruded cassava beer (ECB), particularly noted for the elevation of 2-phenylethyl alcohol levels, which imparted a distinctive rose aroma to the ECB. Consequently, the sensory profile of ECB showed significant improvement. This study offers critical insight into optimizing cassava beer quality and broadens the potential applications of cassava flour in the brewing industry.