Steering the formation of cellobiose and oligosaccharides during enzymatic hydrolysis of asparagus fibre
Joanne W. Siccama, Rianne Oudejans, Lu Zhang, Mirjam A. Kabel, Maarten A.I. Schutyser
Abstract
The enzymatic conversion of cellulosic-rich waste streams of white asparagus into cellobiose and cello-oligosaccharides (COS) is proposed for producing a natural carrier agent. The enzyme cocktail ‘Celluclast’ was used to steer towards maximum conversion and minimum formation of monosaccharides to obtain an enzymatic hydrolysate with a high glass transition temperature (Tg). Different enzyme loadings and hydrolysis times were tested in combination with a sodium hydroxide pre-treatment of the asparagus fibre. A loading of 700 nkat/g substrate and 7 h of hydrolysis time resulted in the best yield/purity combination, namely a conversion of 36 g/100 g cellulose with 81% celllobiose/COS. The same hydrolysis conditions were tested in a larger bench-scale experiment (conversion of 45 g/100 g cellulose) and the soluble hydrolysates were concentrated and spray-dried. The high Tg (108 °C) of the spray-dried hydrolysates of asparagus fibre proves its potential usage as a carrier agent for spray drying.