Evaluation and comparison of functional properties of whey protein isolate-inulin mixtures and conjugates

Proteins are sensitive to environmental stresses, which limits their nutritional applications. Millard reaction leads to increases the functional and biological properties of proteins.Whey protein isolate has a wide range of applications in the food industry, but is sensitive to to the certain environmental conditions and its functional properties are reduced. Inulin is a water-soluble polysaccharide widely used in the food and pharmaceutical industries.The aim of the present study was to prepare and compare the mixture and conjugate of whey protein isolate-inulin, different weight ratios of protein-polysaccharide (1:1, 1:2 and 2:1) and investigate their functional properties.

Glycation via Maillard reaction (MR) done at 60 ◦C and a relative humidity of 79%, during 24 h. In this regard, polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared spectroscopy (FT-IR) was performed to confirm the Millard reaction, and also evaluated DPPH free radical scavenging activity, (DSC), emulsifying activity index and emulsion stability index as well as viscosity.

The results of SDS-PAGE patterns and FT-IR validated the occurrence of the Maillard reaction between whey protein isolate and inulin. Also, the results indicated that the whey protein isolate and inulin conjugates have better functional properties than natural proteins and mixture of the whey protein isolate and inulin. Whey protein isolate - inulin conjugates at ratio of 2:1 showed higher emulsifying activity index, emulsion stability index and antioxidant activity, whereas the emulsions formed by conjugated whey protein isolate - inulin at ratio of 1:2 showed the highest viscosity.

Whey protein isolate glycation via Maillard reaction improve the thermal stability, antioxidant activity and emulsion stability of samples. The Maillard reaction is an effective process of improving the functional properties of proteins, so It causes the widespread use of whey protein isolate in food industry. The Maillard reaction conjugates of whey protein isolate and inulin have been used in food products such as mayonnaise and salads dressing, dairy products and diet products.

Whey protein isolate glycation via Maillard reaction improve the thermal stability, antioxidant activity and emulsion stability of samples. The Maillard reaction is an effective process of improving the functional properties of proteins, so It causes the widespread use of whey protein isolate in food industry. The Maillard reaction conjugates of whey protein isolate and inulin have been used in food products such as mayonnaise and salads dressing, dairy products and diet products.