Physicochemical characterization of carboxymethyl cellulose from differently sized rice husks and application as cake additive

Abstract

Derivatization of cellulose from rice husk for food application can be a sustainable approach of valorization. Three differently sized rice husks exhibited differences in compositional arrangements. Cellulose extraction gave variable yield (85–94%), purity (92–98%) and crystallinity (43–64%). Different molecular arrangements were reflected upon pyrolytic thermogravimetry. Carboxymethyl celluloses (CMC) were obtained by appropriate derivatization resulting in 0.42, 0.53 and 0.87 degrees of substitution. Long grain P10 rice husk gave the highest cellulose yield and best CMC quality. CMC samples showed substantial reduction in crystallinity (3–8%) and thermostability with enhanced hydrophilicity. When applied as a minor ingredient, CMC improved batter viscosity and cupcake volume. Approximate retention of hardness and chewability over 7 days of storage indicated improved textural integrity of the cakes with CMC behaving as a binder, supporting gas and structure retention. Use of rice husk CMC in different foods as improver and prebiotic ingredient can be explored.