Production, characterization, and application of novel fungal pullulanase for fruit juice processing.

The present study aimed to produce, characterize, and apply pullulanase from Aspergillus flavus (BHU-46) for fruit juice processing, assessing its enzymatic properties and impact on juice quality. Pullulanase was produced via solid-state fermentation using wheat bran as the substrate. Purification and characterization included specific activity, molecular weight, pH and temperature optima, and substrate specificity. The enzyme was immobilized in sodium alginate beads and used for clarifying mosambi, apple, and mango juices. Parameters such as yield, clarity, reducing sugar, total soluble solids (TSS), total phenol, and enzymatic browning were evaluated pre-and post-treatment. The purified pullulanase had a specific activity of 652.2 U/mg and a molecular weight of 135 kDa. Optimal pH values were 6.5 and 10, with maximum activity at 50 °C. Pullulanase showed a high affinity for pullulan and starch, indicating Pullulanase type II classification. Immobilized pullulanase improved yield, clarity, reducing sugar, TSS, and total phenol in fruit juices. The highest yield and clarity were observed in mosambi juice. Additionally, the enzyme reduced enzymatic browning, increasing the lightness of the juice. This study provides a significant contribution to the juice processing industry and represents the first report on the application of pullulanase for fruit juice processing.