Effect of Protein Hydrolysate on the Instrumental Texture Profile of Gelatin Gels

The texture of gels containing 2 to 8% of gelatin and 1 to 10% of alcalase protein hydrolysate obtained from poultry meat was examined using the instrumental texture profile analysis (TPA) method in compression and penetration mode. Response surface analysis modelled the effects of the two components of the gels on textural properties. In both tests the addition of hydrolysate decreased hardness and chewiness, and the effect was more pronounced for higher gelatin concentrations. The senses of changes in cohesiveness and springiness as measured in both tests employed here were not in agreement with each other owing to different consequences produced on the sample. In the case of compression, both parameters decreased with increased hydrolysate addition, whereas for penetration an increase in cohesiveness was observed as well as small changes in springiness. Hydrolysate produced a statistically significant negative linear and positive quadratic effect with regard to the majority of the studied texture parameters. This component interacted significantly with gelatin with regard to hardness, chewiness, and fracturability which led to a decrease in the first two and an increase in the last texture parameter. The weakening effect of the protein hydrolysate upon texture may be of great importance for the quality of gelatin gels.