Obtención de hidrogel de grado alimenticio de la celulosa presente en la cáscara de arroz

Abstract

The objective of this study was to obtain a food-grade hydrogel from the cellulose present in rice husk through a chemical methylation process. The transformation of the hydrogel was carried out through alkaline delignification using NaOH at different concentrations (0.75%, 1%, and 1.25%) to remove the lignin present in the rice husk and increase the purity and solubility of the cellulose. Through this process, the cellulose was transformed into cellulose esters, which are watersoluble and form a stable gel when neutralized with 20% hydrochloric acid (pH: 7.0). The gel was then lyophilized, yielding a 92.4% recovery rate. Reducing sugar studies were conducted using the 3,5-dinitrosalicylic acid (DNS) method with a digital UV spectrophotometer. Additionally, cellulose quantification was performed using the phenol-sulfuric acid method, lignin content was determined through the Klason methodology, and moisture and ash content were analyzed by the gravimetric method. The results showed an increasing trend with higher NaOH concentrations, where T3 presented the highest value for reducing sugars at 4.56 g/L. Regarding cellulose, a progressive increase was observed depending on the NaOH concentration. Meanwhile, lignin content decreased significantly as higher NaOH concentrations promoted lignin removal. To determine the potential use of rice husk, the highest viscosity of 237 Cps was obtained in the treatment with 0.75% NaOH. The hydrogel obtained through the described process was used to prepare an emulgel (milk fat and CA CMC) and to evaluate the sensory characteristics of chocolate with added emulgel. The sensory attribute with the highest acceptance was the cocoa aroma. Based on the obtained results, the addition of hydrogel in chocolate enhances the characteristic cocoa aroma, and no significant differences were observed in other chocolate characteristics compared to the traditional cocoa chocolate formulation.