Highly effective Candida rugosa lipase immobilization on renewable carriers: Integrated drying and immobilization process to improve enzyme performance

Abstract

The overall stability of Candida rugosa lipase (CRL) was improved via immobilization onto low-cost eco-friendly carriers (agroindustrial wastes) followed by using spouted bed dryer or spray dryer. Lipase covalently immobilized on glutaraldehyde-activated rice husk proved the greatest performance, retaining 94.1% of the initial activity, followed by sugarcane bagasse (90.3%) and green coconut fiber (89.3%). On the other hand, the enzyme activity retention of CRL-lipase bioencapsulated in magnetic chitosan treated with glutaraldehyde or sodium tripolyphosphate ranged from 73.6% to 84.6%. The dried product moisture content, and water activities ranged from 4.1% and 6.5% and from 0.2 to 0.35, respectively. After storage for six months at 5 °C, the immobilized enzyme systems retained at least 70.0% of its initial activity (vs 18.3% retained activity for the free lipase). After ten reuse cycles, enzyme immobilized onto lignocellulosic carriers retained on average 72.7% of its initial activity. The thermostability of all immobilized derivatives was significantly improved and lipase immobilized onto rice husk showed a stabilization factor of 20.44 at 80 °C. The kinetic data showed that the CRL-lipase suffered alterations in catalytic behavior after the immobilization/drying, mainly a slight decrease in affinity to the substrate (↑KM). Among all the assessed immobilized lipase for aroma synthesis the rice husk immobilized lipase displayed the best result towards the production of isoamyl caprylate (62.40 g.L−1). In conclusion, this report reinforces the urgent need for the economic development of eco-sustainable immobilized biocatalysts to boost the use of enzymatic technology on industrial scale, and the feasibility of the association of immobilization and drying processes to improve the enzyme-quality features.