The Influence of Composition and Manufacturing Approach on the Physical and Rehydration Properties of Milk Protein Concentrate Powders

Abstract

This study investigated the physical and rehydration properties of milk protein concentrate (MPC) powders with five different protein contents (i.e., 38.9, 53.7, 63.6, 74.1, and 84.7%, w/w) prepared by recombining the ultrafiltration (UF) retentate and UF permeate of skim milk. Powder density and flowability increased, while the powder particle size decreased with decreasing powder protein content. The amount of non-wetting MPC powder decreased with decreasing protein content, demonstrating greater wettability for lower protein powders. At protein contents >65% (w/w), the dispersibility and solubility of the powders decreased significantly, likely due to the greater hydrophobic interactions between casein proteins and a lower concentration of lactose. Therefore, as the protein content of the MPC powders was decreased, their rehydration properties improved. The results obtained in this study provide novel insights into the relationship between the composition of recombined UF retentate and UF permeate streams on the subsequent powder particle size, density, and rehydration properties, and demonstrate that such powders possess similar properties to those prepared using conventional direct membrane filtration.

A novel approach for dynamic in-situ surface characterisation of milk protein concentrate hydration and reconstitution using an environmental scanning electron microscope

“…In MPC70 and MPC80, the particle movement and initial swelling due to water entry was much less noticeable than in the other MPCs. This is confirmed by other work looking at the same (Maidannyk et al, 2020) or similar (McSweeney et al, 2020) MPC powders, where the authors reported that MPC40-60 have a higher rate of water diffusion and wettability than higher protein powders. Moisture sorption is facilitated by hydrophilic lactose that acts as a channel for moisture transfer within the CM and as a spatial separator, disrupting the direct interaction of the hydrophobic ends of adjacent casein molecules (Baldwin, 2010;.…”

“…There is also evidence that milk fat can melt forming viscous liquid bridges (Peleg, 1977), however, this is unlikely to have occurred in our study (Foster, Bronlund & Paterson, 2005) because of the low temperature (5 o C) used in our experiments. MPC powder caking was confirmed (in the same powders as used in this study) by Maidannyk et al (2020), by an increase in particle size as found in MPC40 and MPC50 kept at RH >76 % at 21 ± 2°C. The same was observed in skim milk powder (SMP) but occurred at RH >54% (Murrieta-Pazos et al, 2011).…”

“…In recent work on the same MPC powder samples as were used in this study, moisture sorption isotherms of the MPC powders showed that only MPC40 and MPC50 displayed clear lactose crystallisation above RH of 54.5% and 85% (respectively) at the T° of 21 ± 2°C (Maidannyk et al, 2020). The experiments performed in this study have been carried out at a constant 5°C, so lactose crystallisation would be expected to occur at higher RH values (Lloyd et al, 1996;Thomas et al, 2004).…”

“…With RH increase, the T o at which the lactose changes state from glass to crystalline (glass transition temperature, T g) decreases (Fitzpatrick et al, 2007). The adsorbed water of amorphous lactose is released during the process of crystallisation (Carpin et al, 2016) The fact that the samples showed deflation after the transitional phase, is due to the collapse of the amorphous structure and, therefore, the protein/lactose/fat matrix, that leads to the supercooled liquid state (Carpin et al, 2016;Maidannyk et al, 2020;Murrieta-Pazos et al, 2011). Subsequently, lactose crystallisation may take place (Carpin et al, 2016).…”

Effect of pH on the physicochemical characteristics and the surface chemical composition of camel and bovine whey protein’s powders

“…This fact indicated that the variation of whey composition (depending on the pH and the species) before drying was the main determining factor for the size distribution. Actually, it was demonstrated that a significant decrease in the particle size distribution of milk powder could be observed as a result of the decrease of the protein content and the increase of the ash quantity (McSweeney, Maidannyk, Montgomery, O'Mahony, & McCarthy, 2020). This fact may explain the variation in the size distribution between acidic or sweet camel and bovine whey powders.…”