Effect of protein-glutaminase on the texture, rheology, microstructure and sensory properties of skimmed set-type yoghurt

• Published in: Food chemistry 2023-12, Vol.429, p.136831-136831, Article 136831
• Main Authors: Wu, Jiajing, Dai, Tian, Lin, Rongyu, Niu, Jinjin, Li, Zhen, Chang, Zhongyi, Jia, Caifeng, Zou, Chunjing, Jiang, Deming, Jin, Mingfei, Huang, Jing, Gao, Hongliang
• Format: Article
• Language: English
• Subjects: Protein-glutaminase; Rheology; Sensory evaluation; Skimmed set-type yoghurt; Texture
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2023.136831

[Display omitted] •Protein-glutaminase (PG) deamidation dissociated caseins into smaller sub-micelles.•Deamidated caseins filled protein cavities of yoghurt, showing a denser microstructure.•PG increased the solubility and decreased the average size of proteins in skim milk base.•PG improved the smoothness and creaminess of skimmed yoghurt.•0.06 U·mL−1 PG-treated set-type yoghurt had the most attractive sensory acceptability. The effects of enzymatic deamidation by protein-glutaminase (PG) on the texture, rheology, microstructure, and sensory properties of skimmed set-type yoghurt were studied. The proportion of small-particle size milk protein micelles (10–50 nm) increased significantly from 0 to 99.39% after PG deamidation. Cryo-SEM results revealed that PG-treated yoghurt had a denser and less open 3D structure. PG was effective at inhibiting post-acidification during storage at 4 ℃. The water holding capacity of PG-treated yoghurt (0.12 U·mL−1) increased by more than 15%. The fluidity and viscosity of yoghurt were significantly improved with increasing PG dose. Sensory evaluation revealed that PG (0.06 U·mL−1) significantly improved the smoothness and creaminess of skimmed set-type yoghurt, which corresponded to the pastiness in texture. In summary, PG can effectively address the problems of post-acidification, gel fracture, and flavors change in skimmed set-type yoghurt, providing new applications for PG in the food industry.