Combined Use of Trisodium Citrate and Transglutaminase to Enhance the Stiffness and Water-Holding Capacity of Acidified Yak Milk Gels

Lin Yang

doi:10.1155/2018/1875892

Abstract

In this research, the synergistic effect of trisodium citrate (TSC) and microbial transglutaminase (TGase) treatment on the textural properties of acidified yak skim milk gels was investigated. TSC was added to yak skim milk to concentrations of 0, 20, and 40 mmol/L, followed by adjusting the pH to 6.7. The samples were incubated with TGase for the cross-linking reaction, after which the samples were acidified with 1.4% (w/v) gluconodelta-lactone (GDL) at 42°C for 4 h to form gels. The stiffness and water holding capacity (WHC) of gels exhibited higher values at 20 or 40 mmol/L than without TSC. The final storage modulus (G′) of yak milk gels was positively related to the concentration of TSC prior to TGase treatment. Cryoscanning electron microscopy observations showed that the gel networks were more rigid with higher TSC concentrations. Overall, TSC dissociated particles in yak milk into smaller ones. The newly formed particles in yak skim milk could form acid-induced gels with greater stiffness and higher WHC in the presence of TGase.

Highlights

Yak (Bos grunniens) milk is produced in the China QinghaiTibet Plateau area at an altitude of 3000 m [1]
With the aim to improve the textural properties of yak yogurt, we investigated the effect of trisodium citrate (TSC) prior TGase treatment on the properties of acid-induced gel prepared from heated yak skim milk
It is well established that calcium-chelating agents can disrupt the micellar framework by removing calcium from the micelles, leading to the dissociation of casein micelles. erefore, it was expected that the citrate ions would dissociate the particles in yak skim milk into smaller particles

Summary

Introduction

Yak (Bos grunniens) milk is produced in the China QinghaiTibet Plateau area at an altitude of 3000 m [1]. E sti ness and WHC of yogurt gels are determined by their gel network structures, whose primary building blocks are caseins and whey proteins. Whey proteins can be denatured and interacted with caseins after heated (higher than 70°C), which could further improve the textural properties of acid-induced milk gels [11, 12]. Is might alter the gel formation of TGase-treated caseins [18] In this case, the cross-link bonds among milk proteins before or during acidification would be altered. With the aim to improve the textural properties of yak yogurt, we investigated the effect of TSC prior TGase treatment on the properties of acid-induced gel prepared from heated yak skim milk. Our finding will be beneficial to improve the textural properties of yak yogurt

Materials and Methods

Results and Discussion

Conclusion