Citrus limetta peels: a promising substrate for the production of multienzyme preparation from a yeast consortium

Citrus limetta peels (CLP), a waste material generated by juice industries, has scarcely been reported for the production of yeast enzymes. The study was conducted to obtain a multienzyme preparation from a yeast consortium under solid-state fermentation of CLP. The substrate, CLP, was pretreated using either acid or alkali, and factors affecting production of multienzyme were studied by generating two separate Plackett-Burman designs. Since, alkali-pretreated CLP yielded higher titers; therefore, significant factors affecting multienzyme preparation using this substrate were optimized by employing Box-Behnken design. The analysis revealed that under optimized conditions, i.e., cultivation of yeast strains for 72 h to alkali-pretreated CLP moistened with mineral salt medium having pH 5 yielded more than 10 IU mL(-1) of cellulase, xylanase, and amylase. The multienzyme was studied for its application to saccharify fruit and non-fruit wastes and for orange juice clarification. The data showed that the enzyme preparation could release 3.03 mg L-1 h(-1) of reducing sugars from various crude substrates and was able to reduce turbidity of orange juice by 11% with substantial decrease in viscosity and acidity. Hence, CLP appeared as a promising substrate to produce multienzyme preparation from yeast consortium.