The effect of transglutaminase on colloidal stability of milk proteins

Maria Tarapatskyy,Jacek Domagała,Czesław Puchalski,Bogdan Saletnik,Grzegorz Zaguła

doi:10.1007/s11694-019-00153-0

Abstract

Food industry is on constant search for improved, enzymatically modified forms of proteins, which are the most important functional food ingredients, capable of either introducing or modifying texture, appearance, and flavour. One of the key aspects of food design is creating new functional properties and novel food macro- and microstructures in order to provide tailored food characteristics expected by consumers. Milk proteins are among the most thoroughly studied protein complexes occurring in foods and having a wide range of functionalities. The common usage of milk proteins has also contributed to the development of techniques designed to modify and improve functional properties of milk proteins. The aim of this study was to investigate the impact of enzymatic modification induced by microbial transglutaminase (TGM) in milk proteins on the range of cross-linking as well as heat and ethanol stability of these proteins. Milk used in the study was subjected to various technological processes and then incubated with the enzyme added at an amount of 2 Units g−1 protein for 2 h at 40 °C. Modification of milk proteins by transglutaminase leads to their partial cross-linking and formation of high molecular weight polymers in the range of 55–200 kDa. The changes of cross-links between milk proteins occur most dynamically in the first hour of incubation at 40 °C. Enzymatic modification of milk proteins significantly increases the ethanol stability of raw as well as pasteurized milk and UF concentrate. Addition of transglutaminase does not change the heat stability of milk measured as the time of heat coagulation at 140 °C.Graphical abstract

Highlights

Milk proteins are among the most thoroughly studied protein complexes occurring in foods and having a wide range of functionalities
An increase in dry matter contents may be achieved by concentration of ingredients via ultrafiltration. This technique is recommended in the technology of manufacturing fermented milk beverages, cheeses and milk proteins concentrates and it facilitates the process of normalizing dry matter ingredients and their respective proportions [18, 19]
Modification of milk proteins with transglutaminase did not significantly impact their heat stability measured as the time of thermal coagulation

Summary

Introduction

Milk proteins are among the most thoroughly studied protein complexes occurring in foods and having a wide range of functionalities. Suitable fractional composition of milk proteins provides protection for the colloidal system of these proteins, ensuring stability during such technological processes as freezing and heating. Because of their excellent the functional properties, easy availability, as well as low costs of purifying and fractioning, milk proteins have been more and more frequently used as popular functional additives in the form of highly purified commercial preparations based on isolates and concentrates of the specific fractions and their mixtures. The common usage of milk proteins has contributed to the development of techniques designed to modify and improve functional properties of milk proteins. In addition to physical and chemical methods of processing milk proteins there are enzymatic methods enabling changes in their functional properties

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