Research on Preparation and Properties of Edible Composite Protein Films

Abstract

Edible films based on whey protein isolate and sodium caseinate were prepared by uniform design method. Glycerol has been incorporated into the edible films as a plasticizer. For all types of films, the influences of components and forming temperature on film properties, such as mechanical properties, water solubility, optical properties, gas and water vapor permeability were investigated. The results suggested that glycerol was the most important factor influencing all the properties of edible composite protein films. However, both increases of sodium caseinate concentration and glycerol content contributed to decrease the barrier properties of gas and water vapor. Among the films studied, group D (prepared with 5% whey protein isolate, 2% sodium caseinate, 50% glycerol at the temperature of 50 °C) showed moderate mechanical properties, optical properties, water solubility and maximum barrier properties of gas and water vapor, with tensile strength=5.85MPa, elongation=101.20%, transparency=91.4%, gas permeability rate=49.92cm3m-2d-10.1MPa-1and water vapor permeability of 0.128×10-11g m-1s-1Pa-1, 0.260×10-11g m-1s-1Pa-1, 0.513×10-11g m-1s-1Pa-1, 1.252×10-11g m-1s-1Pa-1at the RH gradient of 10-40%, 10-50%, 10-60%, 10-70%, respectively.