Evaluation of phytosterol esters as a highly effective quality, structural, and functional improver in set-type yogurt production

The production process of set-type yogurt fortified with phytosterol esters was systematically optimized in this paper. Subsequently, the relevant quality characteristics, microstructure, and antioxidant activity of the phytosterol ester set-type yogurt were also evaluated. The results showed that the phytosterol ester set-type yogurt had a maximal sensory score of 88.07 under the optimized conditions (0.4% phytosterol ester, 5.7% white sugar, and 0.38% gelatin). Compared with the control yogurt, the obtained phytosterol ester set-type yogurt exhibited significantly higher sensory quality, lower pH value, and greater titratable acidity. Moreover, the phytosterol ester set-type yogurt achieved enhanced water holding capacity and textural properties. The rheological results suggested that the phytosterol ester set-type yogurt displayed shear-thinning behavior, along with improved apparent viscosity and thixotropic properties. Additionally, the microstructure analysis demonstrated that the phytosterol ester set-type yogurt showed a denser network structure than the control yogurt, indicating a uniform distribution of phytosterol esters within the set-type yogurt. Furthermore, the phytosterol ester set-type yogurt displayed stronger antioxidant activities than the control yogurt due to its higher 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt free radical scavenging rates. Finally, molecular docking analysis revealed pi-alkyl and alkyl interactions between phytosterol esters and casein. These interactions facilitated the formation of a more compact protein gel structure, thereby improving the consistency and stability of set-type yogurt. These findings revealed that phytosterol esters were highly effective quality, structural, and functional improvers in set-type yogurt.