Résumé:
Abstract: Background and Objective: Improvements in the shelf life of yogurt can be brought about by addition of gelatin not only increase its nutrient content but also improve its properties. The objective of this study was to extract the gelatin from bovine bone, characterize and understand their functional properties and to study the effect of its incorporation on the quality of yogurt. Materials and Methods: Gelatin was extracted from bovine bones after their characteristics and functional properties were analyzed in comparison with commercial gelatin (CG). The effects of bovine gelatin (BG) addition on properties of yogurt added with bovine gelatin (YABG) were studied. Results: The yield of BG was 6.32±0.20% and the pH of BG was 9.63±0.01. It was observed that BG and CG had higher solubility at low pH with a maximum value observed at pH 4. A significant effect (p<0.01) of ionic strength was observed. Increasing the NaCl concentration to more than 2% resulted in a significant decrease of the solubility. BG showed higher foaming expansion (FE) and higher foaming stability (FS) than CG. Increasing the concentration of BG and CG decreased the emulsifying activity index (EAI) but increased the stability index (ESI). Significant effects of BG rate on acidity and pH of YABG were observed. Viscosity of YABG was increased significantly (p<0.01) with increasing the BG rate. YABG added with 1.5% of BG recorded the highest viscosity. In addition, there was a significant effect of BG addition on Streptococcus thermophilus counts. According to sensory properties, addition of BG had significant effect on adhesiveness, cohesiveness and taste of the YABG. Sensory results indicated a preference for YABG with 1.5% of BG. There was no significant effect of BG on the odour and aftertaste of YABG. Conclusion: The bovine bone could serve as raw material for the extraction of gelatin with desired functional. The addition of 1.5% of this gelatin had a considerable effect on the physiochemical properties and the texture of YABG.
