Saccharolysis of laccase delignified <scp><i>Aloe vera</i></scp> leaf rind and fermentation through free and immobilized yeast for ethanol production

Abstract

Abstract Aloe vera gel has found prominent application in food, therapeutic and cosmetics manufacturing that eventually increased the generation of leaf rind as processing waste. This biomass was previously delignified by laccase to have better accessibility of holocellulose and an attempt has been made through this study to optimize enzymatic hydrolysis using crude cellulase (5.25 [U/ml]) produced from Aspergillus sp . A maximum saccharification of 63.00 ± 0.45% was achieved under the optimum conditions (solid‐to‐liquid ratio 1:17 [wt/vol], 53°C and 8.5 hr) with sugar yield of 309 ± 2.1 mg/g. Fermentation of saccharified liquid to ethanol using Saccharomyces cerevisiae (yeast) was performed using three different modes of inoculum application such as free cell suspension; Ca‐alginate immobilized yeast suspension and immobilized yeast loaded in a packed bed reactor (PBR) under uniform process conditions. Immobilized yeast in PBR has resulted in maximum ethanol yield of about 16.50 ± 1.02 g/L with a fermentation efficiency of 76.14%. Practical application In a global scenario of diminishing resources, there is dire need to establish the cradle‐to‐grave approach for each of industrial operations. Especially, with food processing industries and its waste management this became truly inevitable, as these wastes are rich in nutrient and perishable in nature. On the other hand, it could also serve as a potent source for value added products. Thus, the utilization of Aloe vera (AV) leaf rind to produce bioethanol could underpin the AV gel processing industries toward circular bioeconomy as an option of waste to wealth. The methodology followed to develop this technology is a complete green approach where there is no requirement of chemicals and harsh reagents that remain recalcitrant postprocessing. Adoption of this technology could add value to the sustainable goals and reduce the carbon footprint of the food processing industrial operations.