Effect of Transglutaminase on Textural and Microstructural Properties of Probiotic Yoghurt Produced with Mixture of Cows’ Milk and Soy Drink

Abstract

This study surveyed the effect of the addition of microbial transglutaminase (m-TGs) on textural, microstructural, FTIR spectra and SDS-PAGE electrophotogram parameters of probiotic yoghurts made with mixture of cows’ milk and soy drink during refrigerated storage for 28 days. Mixture was treated with different rates of m-TGs (0, 0.5, 1, 1.5 U/g protein) and incubated with Lactobacillus acidophilus La-5, Bifidobacterium lactis Bb-12, Streptococcus thermophilus probiotic starter cultures. Yoghurts prepared with m-TGs had higher textural parameters than samples without m-TGs. SDS-PAGE patterns, SEM imagines and FTIR spectra demonstrated that milk caseins were well cross-linked by transglutaminase. Scanning electron microscopic studies showed that the microstructure of m-TGs added probiotic yoghurt samples appeared denser than that of control. Results of this study indicated that the textural and microstructural properties of probiotic yoghurt prepared with soy drink could be improved by incorporating m-TGs up to a level of 1.5 U/g protein. © 2020 The authors.