Characteristics of porous starch from cocoyam (Xanthosoma sagittifolium) by enzymatic hydrolysis with thermostable α-amylase, glucoamylase, and their combination

Cocoyam is an underutilized, low-amylose tuber and has significant potential for conversion into porous starch (PS). This study aimed to evaluate the physicochemical and functional properties of cocoyam porous starch produced using thermostable α-amylase (AM), glucoamylase (GA), and their combination (AM:GA). Cocoyam starch was hydrolyzed with AM (50, 100, 150 U/g), GA (25, 50, 75 U/g), and AM:GA (50:25, 100:50, 150:75 U/g) at 60 °C for 8 h, followed by drying at 40 °C for 48 h. The results showed that PS produced with GA at 75 U/g exhibited the highest swelling power and water absorption capacity. The combination treatment (AM:GA 150:75) resulted in the highest solubility, while PS treated with AM at 150 U/g had the highest oil absorption capacity. Scanning electron microscopy (SEM) revealed that AM and AM:GA treatments produced larger pores, whereas GA treatment formed smaller pores. FTIR and XRD results indicated increased short-range order and maintained A-type crystallinity following hydrolysis. As the first systematic investigation of enzymatic pore formation in cocoyam starch, this study demonstrates that enzyme type and concentration uniquely influence pore architecture and functional performance in low-amylose starch. These findings suggest that cocoyam porous starch has potential as an encapsulation agent in food and pharmaceutical applications.