Tribomineral treatment of whey proteins
Tribomineral activation treatment of whey proteins affects the appearance of a greater amount of protein particles and, consequently, causes an increase of the number of protein active groups available for interactions with polyanion polysaccharides (CMC and DIKO). The result is lower water binding capacity of hydrocolloids and decreasing viscosity of the model systems. The above observations confirm the fact that all model systems prepared with tribomineral treated WPC and carragenan, guar gum, amid pectin, pectin classic or inulin addition have a distinctly higher viscosity than the same systems prepared with untreated WPC. This may be explained by non-existence of interactions between proteins and these hydrocolloids as well as by the specific molecular structure of whey proteins. After tribomineral treatment, as it has been stated above, a greater number of protein fragments and peptides occurred. The outer side of protein fragments (particles), consists mostly of hydrophobic side chains of aminoacides making them more efficient in binding with water molecules and resulting in a significant increase of model systems viscosity.
The process of tribomineral micronisation causes the change of granulometric composition of powdered whey protein concentrates. Their particle size decreases dramatically and specific area increases significantly. These changes are greater as the rotor speed increases. Rheological properties of the examined model systems are adequately described according to the Ostwald de Waele (power-law) model. The systems without hydrocolloid addition were Newtonian, while those with hydrocolloids addition exhibited mostly pseudoplastic properties (non-Newtonian). All model systems prepared with WPC-80 showed a significantly higher viscosity than model systems prepared with WPC-60. Model systems prepared with tribomineral treated whey proteins had greater viscosity except for the model systems prepared with CMC as well as hydrocolloid DIKO addition, as the result of the interaction between whey proteins and carboxymethylcellulose. This behavior is more expressive when the rotor speed of TMA equipment is higher. From the results obtained it follows that the procedure of tribomineral micronisation could be used to improve some of the whey protein functional properties such as viscosity of protein dispersions, better interactions between proteins and hydrocolloids (except hydrocolloids based on cellulose), better gelling and foaming ability. This can lead to the production of various whey protein based food products (infant foods, athletes foods, dairy desserts, ice cream, etc.) of better organoleptic and nutritional quality as well as structural stability.
