Optimizing skim milk yogurt properties: Combined impact of transglutaminase and protein-glutaminase

The lack of fat in yogurt can lead to alterations in taste and whey separation, reducing consumer acceptance. In this study, the feasibility of enhancing the quality of skim milk yogurt through a combination of transglutaminase (TG) and protein-glutaminase (PG) was investigated. The combination of TG and PG resulted in simultaneous cross-linking and deamidation of CN micelles, with PG deamidation taking priority over TG cross-linking, leading to higher solubility and lower turbidity of milk proteins compared with TG alone. When 0.06 U/mL TG and 0.03 U/mL PG were added, firmness and viscosity indexes significantly increased by 38.26% and 78.59%, respectively, as compared with the control. Microscopic images revealed increased cross-linking with CN and filling of cavities by smaller submicelles in the combination of TG and PG treatment. Furthermore, the combination of TG and PG resolved issues of rough taste and whey separation, leading to improved overall liking. This study highlights the benefits of using both enzymes in dairy production and has important implications for future research.