Enhancement of glucose recovery from banana stem by 4-cycle enzymatic hydrolysis

Valorisation of banana waste into value-added products has gained an increasing interest since decades ago. To date, there is still limited information on the rational direction of banana stems, which are conventionally dumped and burnt at the field or disposed into water streams, leading to serious environmental pollution. In this work, we present a novel approach to maximise the recovery of glucose from banana stem. Initially, the effect of substrate load (1%, 3%, 5%, 7% and 9%) on the enzymatic hydrolysis by liquozyme and spirizyme was investigated. Following that, 4-cycle enzymatic hydrolysis was performed and the recovery of glucose was determined for every cycle. The results showed that the optimum substrate concentration for the enzymatic hydrolysis of the banana stem was 1% (w/v) which gave the best hydrolysis yield. Evaluation of one to five cycles of enzymatic hydrolysis showed that the highest hydrolysis yield and rate were achieved during the fourth cycle, which was 2.3-fold and 4.4-fold compared to that achieved in the first cycle. Moreover, the glucose concentration recovered in the fourth cycle was 2.4-fold higher than that attained in the first cycle. Our results clearly showed the advantages of conducting multiple cycles of enzymatic hydrolysis of banana stems. In summary, this work presents a novel approach for maximising the glucose recovery from the banana stem where the method may also be applicable for recovering sugar from other agricultural wastes.