Valorisation of Citrus limetta peel for Aspergillus terreus FP6 mediated pectinase fermentation and application in grape juice clarification

Objectives: The present investigation highlights the process parameters influencing the pectinase fermentation by a newly isolated Aspergillus terreus using valorised agro-wastes and determination of the efficacy of the pectinase in grape juice clarification. Methods: The fungal pectinase was produced under submerged fermentation with the optimisation of carbon and nitrogen sources, initial pH of the medium, inoculum load, incubation time and effect of agitation. The pectinase was later used for the clarification of grape juice and improvement of its total phenolic content. Results and Conclusions: Medium supplemented with sweet lime peel and yeast extract (1 % w/v), at initial pH 6.0, when incubated for 72 h under agitated conditions favoured the highest pectinase production by the fungal culture. Following the pectinase action for 1 and 3 h, the grape juice clarification percentages and total phenolic content were 34.21 %, 69.54 %, 3004, and 3484 mg GAE/L, respectively. The results highlight the valorisation of sweet lime peel for the industrial production of fungal pectinase. The study pronounces the cost-effective pectinase fermentation due to the fungi’s non-fastidious nutritional requirement and ubiquitous nature. The increase in the grape juice clarification and total phenolic content following the A. terreus FP6 pectinase treatment was significantly superior to similar commercial enzyme formulations. The result advocates the candidature of the enzyme in the beverage industry, where it can help mediate a greener approach for fruit juice clarification.