Response Surface Optimization of Jackfruit Seed Starch Hydrolysis Using Bacillus licheniformis Alpha-Amylase for the Preparation of Maltose-Rich Starch Hydrolysate

Jackfruit seeds, a by-product of the jackfruit processing industry, comprise a substantial proportion of starch. As a result, jackfruit seeds are emerging as a viable source of fermentable sugars for fermentation processes. In this study, α-amylase from Bacillus licheniformis TKU004 was employed to hydrolyze gelatinized jackfruit seed starch slurry, and the hydrolysis conditions were systematically optimized using the Box–Behnken design (BBD) coupled with response surface methodology (RSM). Three independent variables, including incubation temperature (40–60 °C), enzyme-to-substrate ([E]/[S]) ratio (5–10 U/g), and reaction time (2–6 h), were evaluated, with dextrose equivalent (DE, %) as the response. The optimal hydrolysis parameters were determined to be 47 °C, an [E]/[S] ratio of 10 U/g, and a reaction time of 5.1 h, yielding a predicted DE of 31.72%. Experimental validation confirmed a DE of 32.85 ± 1.12%, in close agreement with the model prediction. HPLC (high-performance liquid chromatography) analysis of the hydrolysate revealed a composition of 14.20% glucose, 56.51% maltose, and 29.29% maltooligosaccharides, indicating that this process is well-suited for producing high-maltose syrup. In short, this study demonstrates the feasibility of valorizing jackfruit seed waste into value-added carbohydrate products through enzymatic hydrolysis with B. licheniformis α-amylase.