Optimization and antioxidant study of protein film prepared from corn germ pulp

Abstract

Objective: This study aimed to prepare a zein film from the gliadin in corn-germ pulp and study its process, performance and antioxidant properties. Methods: The corn-germ pulp was used as raw material, and zein was extracted from corn germ pulp by alkali-soluble acid precipitation. A certain amount of ethanol solution was added, and then an appropriate amount of plasticizer and reducing agent was added by using the ultrasonic assist method. After the membrane solution was in a water-bath at room temperature for 30 minutes, the membrane solution was cast into a zein membrane. The influence of the four factors of glycerol addition, ultrasonic time, ethanol concentration and water bath temperature on the water solubility, water vapor transmission rate, and CO2 transmission rate of the zein film were explored, and the best preparation process was obtained. By coating the film-forming liquid on the surface of the pear slices, the anti-oxidation preservation test was performed, and the blank control of the coating film was used to observe the degree of browning on the surface of the pear slices. Results: Through orthogonal experiments, the optimal membrane preparation process was obtained as follows: glycerin addition of 0.3 g/g gliadin, ultrasound time of 5 min, ethanol concentration of 80%, and water bath temperature of 70 ℃. Under the control of these conditions, the water solubility of the zein membrane was 19.75%, with the WVP of 6.13 g·mm/(m2·d·kPa), and the CO2 permeability was 0.21 g/(m2·h), The preparation of protein film liquid from corn germ pulp could significantly reduce the browning speed of pear slices. Conclusion: It is feasible to prepare protein film from corn germ pulp, and the film liquid can play a good antioxidant effect on the preservation of fruits and vegetables.

Keywords

• corn germ pulp
• zein
• protein film
• antioxidant