Impact of transglutaminase reaction on the immunoreactive and sensory quality of yoghurt starter

Abstract

Cross-linking reaction with transglutaminase (m-TG) was used to obtain yoghurt produced with YO-MIX™ 511 yoghurt starter (Danisco). The use of two different temperatures (37 and 42°C), the presence of m-TG and the storage time (28 days) of the yoghurt were the factors that influenced the immunoreactive and sensory properties. The ELISA results obtained during the reaction of yoghurt proteins with a specific antibody against individual milk proteins (β-lactoglobulin, α-lactalbumin, α-casein, β-casein and κ-casein) indicated differences on the level of immunoreactivity of individual proteins. The β-lg immunoreactivity of yoghurt produced at 37°C was not detectable in any of the samples whereas during the process conducted at 42°C the presence of this protein at low level was observed (1.00 and 3.33% without and with m-TG, respectively). The lack of κ-casein was detected in the storage yogurt sample prepared during fermentation at 42°C. The samples were subjected to sensory evaluation using quantitative descriptive analysis (QDA). A trained personnel (n = 6) rated the yogurts for smell, taste and texture. The data obtained from QDA (16 attributes and 4 yoghurts) were subjected to a principal component analysis (PCA). The results (QDA and PCA) proved that the addition of the m-TG enzyme had significant impact on the sensory quality of the samples. Four principal components (PC1–PC4) determined 96.05% of the total variance of the samples.