Study Of Emulsifying Properties Of Soy β-Conglycinin Fibrils Formed At PH 2.0

The application of self-assembly fibrils in food industry has recently attracted increasing interest. Many publications have pointed out that these fibrillar could be used as compound emulsifying thickener. However there were few knowledge about the emulsifying properties of fibrils and influence factors. The emulsifying properties of 7S-fibrils and native 7S was comparative studied in this thesis. The effect of protein concentration(c), self-assembly reaction time, ionic strength or oil fraction(?) on the emulsifying properties of 7S-fibrils were also investigated. The main results are as follows:1. The emulsifying properties of 7S-fibrils at various protein concentration were investigated. The results showed that the emulsifying ability of 7S-fibrils was significantly higher than that of native 7S in c≥2% case, which was attributed to the more conformational flexible linear fibrillar structure of 7S-fibrils favoring its adsorption to the oil-water interface.On c ≥ 4.0% occasion, the emulsions stabilized by 7S-fibrils exhibited lower coalescence index(CI) and creaming index(CI%) compared to native 7S. The observations are generally consistent with those observed for conventional Pickering emulsions, suggesting that7S-fibrils could be applied as a new kind of effective Pickering-like stabilizer.2. The emulsifying properties of 7S-fibrils and the rheological characteristics(e.g.apparent viscosity and storage modulus) of emulsions stabilized by 7S-fibrils which were heated for different time were investigated. The results showed that under heating at 85℃ for2~6 h(pH 2.0), length of 50~200 nm 7S-fibrils were formed. The Surface hydrophobicity(H0)of 7S-fibrils was significantly higher than that of native 7S, while there was no significant difference on the aspect of ζ-potential. The emulsifying properties and the rheological properties of emulsions stabilized by 7S-fibrils were improved along with the increase of reaction time. On 6 h occasion(H-6) showed a certain strength as gel-like emulsions. The rheological properties and microstructure have good consistency with emulsion properties.3. The emulsifying properties of 7S-fibrils at various ionic strength and oil fraction were investigated. The results showed that the stability and rheological properties of emulsions stabilized by 7S-fibrils were improved along with the increase of ionic strength(0~200 mM),on 200 mM occasion, the emulsion showed a certain strength as gel-like. The observationswere attributed to that hydrophobic interaction between 7S-fibrils leaded to the formation of network structure while the enhancement of electrostatic screening. The rheological properties were improved along with the increase of oil fraction(0.1~0.7). As a consequence, oil droplets acted as a kind of active filler on this occasion.In general, it was confirmed that the emulsifying properties of 7S-fibrils were influenced by various factors( e.g protein concentration, the level of self-assembly, ionic strength and/or oil fraction). Gel-like emulsion could be prepared by controlling conditions mentioned above.The results have a certain reference value to explore the application of self-assembly fibrils.