Influence of sodium hexametaphosphate addition on the functional properties of milk protein concentrate solutions containing transglutaminase cross-linked proteins

peer-reviewedThe functional properties of milk protein concentrate (MPC) powders are often hindered by their poor solubility. Calcium chelating salts have been shown to improve powder solubility, but generally their action contributes to higher viscosity due to disintegration of casein micelles and higher levels of serum-phase calcium. To help mitigate increases in viscosity associated with calcium chelation, transglutaminase (TGase), an enzyme that covalently crosslinks protein, was employed in an effort to stabilise the casein micelle structure. Sodium hexametaphosphate (SHMP) was added to control (C-MPC) and TGase crosslinked MPC (TG-MPC) dispersions at concentrations of 5, 12.5 and 25 mm prior to analysis. TG-MPC dispersions had lower viscosity than C-MPC dispersions across all SHMP concentrations studied. Crosslinking limited micelle dissociation on SHMP addition and led to greater retention of the white colour of the protein dispersions, while the turbidity of C-MPC dispersions decreased with increasing SHMP addition.Wash Fellowship Programm

Water sorption and hydration properties of high protein milk powders are influenced by enzymatic crosslinking and calcium chelation

Calcium chelating agents, such as sodium hexametaphosphate (SHMP), can be added to milk protein (MPC) solutions to aid in rehydration; however, this leads to a concomitant increase in solution viscosity due to micelle swelling/dissociation. Crosslinking casein proteins in MPC using transglutaminase (TGase) can help retain casein micelle structure and maintain low viscosity. This study aimed to determine the water sorption and hydration properties of MPC powders, as influenced by the crosslinking of milk proteins and the addition of SHMP. Crosslinked casein protein (TG-MPC) powders without SHMP addition had improved wettability, water sorption and water diffusion compared to the non-crosslinked control (C-MPC) powder. All powders containing SHMP were found to have increased water sorption compared to control powders without SHMP addition. Powder dissolution data showed that increasing SHMP content increased powder particle size, compared to powders without SHMP addition, indicating increased powder particle swelling due to increased water uptake