Principles of lactose crystallization and rheology of milk protein concentrate

Débora Brito Goulart

doi:10.33448/rsd-v10i15.23028

Débora Brito Goulart

Open Access

https://doi.org/10.33448/rsd-v10i15.23028

Copy DOI

Abstract

Milk protein concentrate (MPC) is a commercial designation for dairy ingredients with higher protein and lower lactose content than conventional skim milk powder. Lactose in its amorphous form is found in several spray-dried dairy powders. Amorphous lactose is thermodynamically unstable and can mobilize and crystallize over time under adequate temperature and moisture content. Moisture sorption from the air precedes crystallization, enhancing MPC cohesiveness and caking. This increased humidity results in poor rehydration and dispersibility, lower yield during drying, operation problems, difficulties in handling and storage. Moreover, lactose crystallization in MPC can cause Maillard browning reaction and fat oxidation. To avoid this problem, it is necessary to pre-crystallize lactose as alpha-lactose monohydrate, which is non-hygroscopic, before spray drying. Such a procedure is essential in preventing deterioration of MPC resulting from lactose crystallization or chemical reactions. Additionally, the control of this step is important to obtain specified and reproducible powder, in terms of size and crystallization level. There are various reports on the rheology of milk-based products; however, there is a lack of investigation on concentrated systems. Consequently, the objective of the present work is to review basic concepts of lactose crystallization and rheology of milk protein concentrate.

Highlights

Milk is the secretion of the mammary glands of female mammals, whose natural function is to feed the newborns
From a physicochemical point of view, milk is a homogeneous mixture of various components, some of which are in emulsion, some in suspension, and others in true dissolution
It is important to note that several articles used in this review were published before 2011, they were still included in the study due to their scientific importance, and most of them have more than one hundred citations

Summary

Introduction

Milk is the secretion of the mammary glands of female mammals, whose natural function is to feed the newborns. From a physicochemical point of view, milk is a homogeneous mixture of various components (lactose, glycerides, proteins, salts, vitamins, and enzymes), some of which are in emulsion (fat and substances associated), some in suspension (caseins associated with mineral salts), and others in true dissolution (lactose, water-soluble vitamins, whey proteins, and salts). Milk protein concentrates (MPCs) contain casein and whey proteins in concentrations ranging from 40 to 89%. Lactose levels decrease when the protein concentration of MPC increases. MPCs with a higher protein content provide a clean dairy flavor to food and beverage without adding a significant amount of lactose. MPC provides food with many benefits, including water binding, gelling, foaming, emulsification, and heat stability (Havea, 2006; Li et al, 2018)

Objectives

Methods

Results