Mechanical properties of heat-cured whey protein-based edible films compared-with collagen casings under sausage manufacturing conditions

Edible films were produced using whey protein isolate (WPI) (5%, w/v), glycerol (3.3, w/v) and candelilla wax (0.8%, w/v). One set of films was heat cured at 90 degrees C for 12 h and another at 80 degrees C for 24 h. WPI-based films, together with collagen films, were put through a meat-processig scheme typical of Polish sausage manufacture. Meat-processing conditions were stage 1: 57 degrees C/60 min/36% RH; stage 2: 65 degrees C/90 min/60% RH; and stage 3: 77 degrees C/30 min/80% RH. Effects of meat-processing conditions on mechanical properties: tensile strength (TS), elongation (%E), and apparent modulus (AM) were determined. All films remained intact throughout the process. TS, %E, and AM of collagen films did not change during the multistage cooking process. The %E of heat-cured WPI films was similar to that of collagen films and also did not change during the cooking stages. The TS and AM of both heat-cured WPI-based films were initially lower than collagen films and continued to decline during the cooking stages. TS and AM of both films at the end of cooking were lower (P < 0.05) than films that did not go through the multistage cooking process.