Liquid virgin whey protein concentrate optimizes product texture.

Whey proteins are important to the ingredients industry due to an incessant demand for products of a specific texture and nutritive value. The compositional variability and fractional protein denaturation in commercial whey protein products give rise to varied levels of aggregation when using the proteins in heat and shear applications. Such usage usually results in the development of an uncontrolled structure and impedes the attainment of the desired texture.

Harvested before the cheesemaking process and concentrated using membrane technology alone, liquid virgin whey protein concentrate (LVWPC) offers unique physicochemical properties not observed in commercial products. Researchers at Cornell University examined LVWPC's behavior, how its microstructure forms and texture develops under heat and shear applications. Then they compared this information with that of commercial products. Their research suggests that LVWPC is ideally suited for imparting finely tuned texture in foods, compared with existing commercial WP products.

The investigators determined thermal properties by using differential scanning calorimetry. Textural changes during heat and shear applications were quantified by making rheological measurements. The development of structure was elucidated using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM).

While the peak of denaturation was similar to that of commercial products, LVWPC's onset and enthalpy of denaturation were higher, indicating it has a higher thermal stability. The apparent viscosity at pH 6.1 of 8% LVWPC at 70 C and a shear rate of 245 s-1 were constant for a period of time before increasing at a steady rate of 0.18 mPa-s per minute to 27 mPa-s. On the other hand, those of commercial products increased rapidly at 0.25 mPa-s per minute from the start of the test.

SEM images showed that the sheared and heat-treated LVWPC formed a continuous structure, giving a smooth texture. The commercial products yielded a fractured or flaky texture that was caused by extensive aggregation that led to phase separation. CLSM results indicated that a well-controlled structure development of LVWPC evolved when the material was heated.

Further information. Syed Rizvi, Department of Food Science, Cornell University, 116 Stocking Hall, Ithaca, NY 14853; phone: 607-255-7913; fax: 607-254-4868; email: ssr3@cornell.edu.

Liquid virgin whey protein concentrate is a novel ingredient rich in native whey proteins.