Stabilization of Spray-Dried 1,4-α-Glucan Branching Enzyme Using a Food-Grade Inulin–Maltodextrin Matrix
Abstract
Background
Liquid 1,4-α-glucan branching enzyme (GBE) preparations are prone to activity loss during storage, while spray drying may cause enzyme inactivation due to thermal and dehydration stresses.
Objective
This study aimed to develop a food-grade carbohydrate matrix to stabilize GBE during spray drying and storage while preserving its catalytic functionality.
Results
Protective excipients and drying aids were screened, and the optimized treatment (IM2) was defined as the pretreated enzyme solution supplemented with 2.5% (w/v) inulin and 6% (w/v) maltodextrin before spray drying. The IM2 powder achieved an enzyme activity recovery of 93.20%, and its reconstituted solution retained more than 96% of the initial activity after incubation at 65°C for 16 h. After 120 d of storage, the powder maintained good stability, with water activity remaining at 0.17–0.19. Functional analysis showed that spray drying did not impair GBE activity: the native enzyme solution and IM2 reconstituted solution increased the proportion of short chains with a degree of polymerization below 14 (DP < 14) in maltodextrin from 60.46 to 73.97% and 73.88%, respectively. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR) analyses indicated that the inulin–maltodextrin matrix formed a compact amorphous glassy structure with an elevated glass transition temperature (Tg = 72.52°C), which may restrict molecular mobility and stabilize the enzyme.
Conclusion
This food-grade formulation provides a practical strategy for producing shelf-stable GBE powder for industrial food bioprocessing.