Development of Films, Based on Oxidized Ipomea Batatas Starch, with Protein Encapsulation

Dialdehyde starches (DAS) have been used as biomaterials due to their biocompatibility and biodegradability; nonetheless, sweet potato (Ipomea batatas L.) starch has not been researched. Films based on sweet potato DAS, mixed with native starch (NS), poly-vinyl alcohol (PVA) and glycerin have been developed with protein encapsulation, using central composite design (CCD) and response surface methodology (RSM). Input variables were oxidation degree, NS concentration and polymeric mixture volume, while output variables were film's thickness, equilibrium swelling and BSA (Bovine serum albumin) release. DAS was obtained through hydrogen peroxide (H₂O₂) oxidation, and the oxidation degree is referred to as H₂O₂ concentration. Films presented rough surfaces, and formulations containing 10% H₂O₂ DAS presented micropores. Water uptake was greater with higher DAS content. Film thickness depended on the volume of the polymeric suspension and influenced swelling capacity. According to RSM, the optimal formulation was DAS with 5% H₂O₂ and 35% NS. These results demonstrate that oxidized sweet potato starch has potential for protein encapsulation and delivery.