Acid induced gelation behavior of oil-in-water emulsions stabilized by soy proteins and whey proteins mixtures, effect of interfacial composition.
In spite of the extensive knowledge of soy protein or whey protein at oil-water interface and their individual application in processed foods, very little is known about their behavior in a mixed protein emulsion system and no work is available on the rheological properties of soy and whey protein mixed emulsion gel. This current study attempts to study the acid induced gelation behaviour of soy and whey protein emulsion gel by investigating the protein composition at the interfacial layer, changes occurring at the interface with order of protein addition and the effect of interfacial composition on the rheological properties of mixed protein emulsion gel system. The effects of heating after homogenization were also studied. Acid induced gelation of the mixed system led to improved gel structure with heated soy protein emulsion with whey added in the aqueous phase. For unheated emulsion, whey protein emulsion with soy added in the continuous phase generated gel with higher stiffness. It was determined that heating and order of protein addition affected gel network. In addition, it was observed that soy and whey mixed protein emulsion gels generated stiffer gels than soy emulsion or whey emulsion in isolation. This study demonstrated that by modifying order of protein addition and with heating, it is possible to generate different gel structures. This may be of importance to application of mixed protein in food products to obtain desirable gel structures and also serve as platform fostering research to better understand and predict gelation behavior of mixed protein to obtain food products of optimal gel structure and high nutrition density.