Improving wort filtration using extruded cassava flour: insights from macromolecular analysis

Abstract

Why was the work done: The high starch content of cassava flour makes it a potential adjunct for beer production, but its poor filtration performance limits its utilisation. How was the work done: This study investigated how the inclusion of extruded cassava flour (30%) affected the filtration of malt wort by analysis of the content and molecular weight distribution of macromolecules - starch, β-glucan, arabinoxylans, and protein - in both wort and fine particles from spent grain. What are the main findings: Extrusion enhanced the hydrolysis of starch, β-glucan, and protein, leading to a lower soluble starch and β-glucan content, higher total nitrogen levels, and reduced high molecular weight fractions in extruded cassava flour (ECF) wort. These changes also reduced the viscosity of the ECF wort compared to native cassava flour (NCF) wort. Additionally, more low and medium molecular weight polysaccharides were found in fine particles from wort from the ECF mash separated from spent grain. Accordingly, these polysaccharides were less likely to aggregate with gel-protein, thereby improving filtration speed. Scanning electron microscopy and particle size analysis supported these findings, showing that fine particles in wort from the ECF wort had a looser, more porous structure and a smaller particle size. Why is the work important: This study provides practical insight into how extrusion can improve the filtration efficiency of cassava flour used as an adjunct, broadening its potential use in the production of beer.