Mixture design applied to study the interaction between a commercial hydrocolloids-based egg replacer and monoglyceride gel for partial egg substitution in muffin formulation.

This study investigated the partial substitution of eggs in a muffin formulation. A mixture design approach was used to optimize a new formula, based on three variables (X1: egg, X2: water and commercial egg replacer (CER), and X3: monoglyceride gel). The physico-chemical and techno-functional characterization of the CER showed that protein and carbohydrate contents are equal to 23.71 and 65.25%, respectively. Three optima were obtained for F (firmness), H (height), and FH (both firmness and height). The percentage of egg substitution attained 53% for F and H and 41% for FH. The physico-chemical characterization of the final muffins showed that optima had a higher level of proteins and carbohydrates reaching around 12 and 50%, respectively compared to the control muffin (10 and 47%, respectively). Optima had a darker color with more entrapped air and less dense structure observed in scanning electron microscopy. According to FTIR and fluorescence spectroscopy, CER and monoglyceride gel limited the movement of oxidizing agents and decreased molecular mobility which protects tryptophan and vitamin A from degradation. Monitoring the firmness and height of muffins during storage showed that the optima maintained a better firmness (2.3 N) and a higher height than the control products. For the sensory evaluation, the descriptors of the optima had the highest score compared to the control muffin which indicated the suitability of the optimized formulation.