Characterization of high-milk-protein powders upon rehydration under various salt concentrations

Abstract

Rehydration of native micellar casein and native whey isolate protein powders was followed in different ionic environments. Solutions of NaCl and CaCl2 in the concentration range of 0 to 12% (wt%) were used as rehydration media. The rehydration profiles obtained were interpreted in terms of wetting, swelling, and dispersion stages by using a turbidity method. Two behaviors were observed depending on the salt concentration. For native micellar casein powder, a significant change was observed between 3 and 6% NaCl and between 0.75 and 1.5% CaCl2. The first behavior (low salt concentration) presents a typical rehydration profile: quick wetting, swelling, and long dispersion stage. The dispersion stage of the second behavior (high salt concentration) was significantly shortened, indicating a strong modification of the protein backbone. The rehydration of whey protein powder was less influenced by salts. At low salt concentrations, a typical profile for whey powders was observed: wetting with lump formation and no swelling followed by a quick dispersion. At high CaCl2 concentrations, no turbidity stabilization was observed, indicating a possible protein unfolding and denaturation. Additionally, the changes in secondary structures of the 2 proteins upon salt increase were followed by Fourier transform infrared spectroscopy and confirmed the different profiles observed.

Rehydration characteristics of milk protein concentrate powders

“…Values are presented as mean ± standard deviation of data from three independent trials. (Udabage et al, 2012) or other high-ionic strength media such as NaCl solutions (Schuck et al, 2002;Gaiani et al, 2007;Hussain et al, 2011). It is clear from the conductivity profiles for the MPC suspensions during rehydration (Fig.…”

Multiscale Characterization of Casein Micelles Under NaCl Range Conditions

“…Caseins also have an ample capacity for cations binding. [13][14][15][16] Addition of NaCl generally increases hydration, voluminosity, screening of charges of caseins and calcium ion activity in the milk serum whereas it decreases pH and the amount of supernatant casein, 17,18 improves rehydration of casein micellar powder, 19 imparts changes in casein micellar structure and micellar mineral composition. [20][21][22] In earlier investigations, various but limited techniques have been employed to study the effect of NaCl on the structural properties of casein micelles or milk systems including transmission electron microscopy (TEM) [23][24][25] , scanning electron microscopy (SEM) 26 and dynamic light scattering (DLS).…”

From high milk protein powders to the rehydrated dispersions in variable ionic environments: A review

“…Another solution is to enrich the concentrate with suitable soluble proteins or carbohydrates before spray drying (Schuck et al, 1994(Schuck et al, , 1998. In recent years, several studies are made to improve the rehydration properties of NMC powders with or without salt addition (Gaiani et al, 2005;Hussain et al, 2011b;Schuck et al, 2002). Indeed, by improving its rehydration properties, this powder would be able to serve as an attractive material for dairy and food industry.…”

“…can notably amend the behavior, water transfer properties and overall performance of proteins (Hussain et al, 2011a,b;Schuck et al, 2007). Due to lack of basic data on the dynamics of hydration in connection with salt environment and inadequately controlled Table 2 Rehydration times obtained for casein and whey proteins powders in different media in comparison with the same powders rehydrated in water (adopted from Hussain et al, 2011b). …”

“…It is well-known that microenvironments such as pH and/or salt can significantly alter the behavior and overall performance of proteins. Whey proteins also have an ample capacity for cations binding (Hussain et al, 2011b). Globular proteins present compact and ordered conformations because of the presence of disulphide bridges which give them well defined secondary and tertiary structure.…”