Using a novel supercritical fluid extrusion (SCFX) process to texturise whey protein concentrate (tWPC), researchers from Cornell University’s Institute of Food Science report that the new ingredient could improve the stability of an emulsion and boost the rheological properties of cold, gel-like emulsions.
“The results of this study confirmed our hypothesis that reactive SCFX rendered WPC into an ingredient with excellent gelling and emulsifying properties,” wrote Khanitta Manoi and Syed Rizvi in the journal Food Hydrocolloids.
“This may open up a new avenue for utilization of tWPC in food emulsions, especially in food formulations containing heat-sensitive ingredients.”
Whey proteins from cow's milk are used as emulsifiers in a broad range of food products including ice creams, beverages, salad dressing and sports supplements, and are classified as either concentrates (protein content between 25 and 80 per cent) or isolates (more than 90 per cent protein).
“To the best of our knowledge, cold, gel-like emulsions prepared with tWPC, the derivatized WP powder, at ambient temperature have not yet been reported,” wrote the researchers. “This approach could be beneficial for controlling the texture of emulsion-filled gel products and their derivatives.”
Manoi and Rizvi employed the supercritical fluid extrusion process to texturise the whey protein concentrate (WPC) and produce an ingredient with cold-setting gel characteristics.
Oil-in-water emulsions were prepared using the new tWPC, and compared to emulsions compared to emulsions prepared with a commercial whey protein concentrate.
The cold, gel-like emulsions were prepared at 25 degrees Celsius and the results “revealed that the tWPC showed excellent emulsifying properties compared to the commercial WPC in slowing down emulsion breaking mechanisms such as creaming and coalescence”, wrote the Cornell researchers.
Indeed, they add that homogenous, very stable, and finely dispersed fat droplets were produced. Impressive thermal stability up to 85 degrees Celsius was also observed.
Increasing the oil fraction allowed the researchers to produce emulsions with higher viscosity.
“This study demonstrates that tWPC exhibited excellent emulsifying properties,” wrote Manoi and Rizvi. “It may be suggested that there are two possible stabilization mechanisms in the emulsion prepared with tWPC. First mechanism serves for emulsifying capability and the second mechanism serves for the stability effect, preventing creaming.
“These mechanisms, alone or synergistically, were responsible for the higher surface activity and emulsion stability of tWPC compared to that of commercial WPC80.”
Source: Food Hydrocolloids Published online ahead of print, doi: 10.1016/j.foodhyd.2009.02.011“Emulsification mechanisms and characterizations of cold, gel-like emulsions produced from texturized whey protein concentrate”Authors: K. Manoi, S.S.H. Rizvi