The development of functional edible films is promising for the food industry, and improving the water barrier of edible films has been a research challenge in recent years. In this study, curcumin (Cur) was added to zein (Z) and shellac (S) to prepare an edible composite film with a strong water barrier and antioxidant properties. The addition of curcumin significantly reduced the water vapor permeability (WVP), water solubility (WS), and elongation at break (EB), and it clearly improved the tensile strength (TS), water contact angle (WCA), and optical properties of the composite film. The ZS–Cur films were characterized by SEM, FT-IR, XRD, DSC, and TGA; the results indicated that hydrogen bonds were formed among the curcumin, zein, and shellac, which changed the microstructure and improved the thermal stability of the film. A test of curcumin release behavior showed controlled release of curcumin from the film matrix. ZS–Cur films displayed remarkable pH responsiveness, strong antioxidant properties, and inhibitory effects on E. coli. Therefore, the insoluble active food packaging prepared in this study provides a new strategy for the development of functional edible films and also provides a possibility for the application of edible films to extend the shelf life of fresh food.

To reduce the adverse physical effects on the oral mucosa caused by excessive hardness of betel nut fibres, steam explosion was used to soften betel nuts. The effect of 3 operating parameters (pressure holding time, explosion pressure and initial moisture content) on the morphology, texture and chemical composition of the betel nuts was investigated. The fibre hardness and Shore hardness decreased by 56.17%-89.28% and 7.03%-34.29%, respectively, and the transverse tensile strength and fibre tensile strength also decreased by up to 60.72% and 24.62%, respectively. Moreover, the coefficient of friction and moisture content increased. After steam explosion, the betel nut increased in transverse diameter, became darker and more yellow‒red in colour, and showed a damaged microstructure. The contents of lignin, hemicellulose, free phenol, bound phenol and alkaloids decreased after steam treatment, with total phenols and alkaloids decreasing from 44.07 mg(GAE)/g and 7.84 mg/g to 30.61 mg(GAE)/g and 6.50 mg/g, respectively, after the A-50 s treatment condition. A slight increase in cellulose was observed when steam explosion conditions exceeded 80 s or 0.75 MPa. The steam explosion increased the quantity of phenols, alkaloids and soluble solids released from the betel nut under the same simulated release conditions. The research also showed that the explosion efficiency was positively correlated with the pressure holding time and explosion pressure, while the initial moisture content was reduced the explosion efficiency. Therefore, steam explosion is an effective pretreatment approach to soften betel nut and facilitate healthy development of the betel nut industry.