Microstructural and textural properties of rennet-induced milk protein gel: Effect of guar gum

Micaela Galante,Valeria Boeris,Estela Álvarez,Patricia Risso

doi:10.1080/10942912.2017.1375513

Abstract

ABSTRACTThe knowledge of the effect of polysaccharide addition on the textural properties of milk protein gels is important for foodstuff engineering design. Therefore, the microstructure, texture, and water-holding capacity of rennet-induced milk protein gel with and without the addition of different concentrations of guar gum (GG) were determined. It was found that the presence of GG changed the microstructure of rennet-induced milk gel. The addition of a GG concentration higher than 0.075% w/v led to a discontinuous protein network. Changes in the structure of the gel samples are reflected in the texture perception and their capability of water retention. When a limit GG concentration of 0.15% w/v was exceeded, a very weak gel sample was obtained. The results demonstrated that different milk protein gel microstructures can be created by the addition of different concentrations of GG.

Highlights

Milk protein gel (MPG) formation is a crucial first step in the manufacturing of cheese, yoghurt, and many other dairy products
Large pores and a less interconnected protein network structure were observed in samples containing more than 0.075% w/v of guar gum (GG)
Image analyses, textural and water-holding capacity (WHC) approaches were found to be useful in determining the effect of the presence of GG on MPG characteristics

Summary

Introduction

Milk protein gel (MPG) formation is a crucial first step in the manufacturing of cheese, yoghurt, and many other dairy products. Many polysaccharides are added to different dairy products (cheese, yoghurt, ice cream) because they render a desirable texture due to their stabilizing, thickening, and gelling properties[3] or because they can be used as fat replacers.[4,5] The characteristics of the final products emerge as a consequence of the effect of the polysaccharide on their microstructure. The ability of gels to immobilize water represents another important structural property of coagulated dairy products. The final texture of dairy products as well as their susceptibility to syneresis are closely related to the microstructure, especially the structure of the protein matrix.[7,8]

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