Application of whey protein films

The efficiency of whey protein films packaging was evaluated. The packaging system consisted of whey protein films closing the top extremity of synthetic plastic container. Slices of apple were packed and stored at room temperature (25 degrees C) and at 10 degrees C. Modified atmosphere packaging (N2 gas flushing) was studied to verify the oxygen permeability of the films. Whey protein films (6.5% of protein, 3.0% of glycerol, and pH 7.0) were obtained by thermal denaturation, emulsification (0.5% (w/w) with stearic acid), and enzymatic modification (10U/g protein of transglutaminase, ACTIVA-TG). Mechanical properties (tensile strength and elongation at break), water vapor permeability, and coloropacity properties of different films were evaluated. The film integrity was observed during the packaging and storage processing associated to the good mechanical properties. The water vapor permeability was evaluated by weight loss, moisture content, and texture profile of apple slices. The results showed that the whey protein films presented a moderated moisture barrier if compared with systems with no covering. The browning of the apple slices was investigated associated to the polyphenoloxidase action in presence of oxygen.