Heating sequence-dependent non-covalent interactions between soy protein isolate and oat β-glucan under hot acid treatment: Structural regulation and techno-functional properties

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The inherent properties of proteins and polysaccharides, combined with environmental conditions, jointly determine the nature of their interactions and the characteristics of the complexes formed. This study adopted soy protein isolate (SPI) and oat β-glucan (OG) as model substrates to explore the influence of heating sequence on the properties of biopolymer complexes. Experimental results indicated that SPI-OG complexes formed under different heating sequences exhibited distinct structural and techno-functional properties. Compared with the treatment of mixing-after-heating (HM), the SPI-OG complexes prepared at a mass ratio of 5:4, pH 3.0, and 90 °C under the treatment of heating-after-mixing (MH) had a relatively smaller average diameter with 109 nm, and the complexes formed under the MH mode demonstrated superior solubility, emulsifying activity, and foaming properties. This might be because heating the pre-mixed protein-polysaccharide system would cause SPI to unfold, thereby creating more binding sites for OG molecules to embed into the protein matrix. Therefore, this study may provide a theoretical basis for the development of protein-polysaccharide-based products and offer novel functional raw materials for the food industry.