Effects of homogenization on the molecular flexibility and emulsifying properties of soy protein isolate

Abstract

The sensitivity of soy protein isolate (SPI) to trypsin was characterized by its flexibility. The effects of different homogenization conditions on soy protein isolate flexibility and emulsifying properties were investigated. Set the homogenization pressure was 120 MPa (megapascal) and the homogenous number of times is 0-4 times, the flexibility increases with the increase of the homogenization times (0-3 times), the change trend of flexibility is not obvious (3-4 times). When the homogenization times was 0-3 times, the emulsifying activity increases, and the emulsifying activity was the strongest at 3 times, after homogenization 3 times, the change trend of emulsifying activity is not obvious, the trend of emulsification stability and emulsification activity were similar. The surface hydrophobicity increases with the increase of homogenization times, while the turbidity decreases. The other structural indicators such as Ultraviolet scanning and endogenous tryptophan fluorescence spectroscopy suggest that the structure of SPI becomes more stretch as the flexibility increases.

Effect of High Pressure Treatment on Interfacial Properties, Structure and Oxidative Stability of Soy Protein Isolate-Stabilized Emulsions

“…The pres-ence of β-sheet, β-turn and random coil structures is beneficial to increase the flexibility of SPI. Therefore, the effect of HPH makes the spatial structure of soybean protein molecules more stretched, which is consistent with the structure of ultraviolet scanning spectroscopy and endogenous fluorescence spectroscopy put forward by Xu 16 .…”

“…In this study, the result might attribute to the changes of structure and flexibility. Undergo the HPH process, flexibility of SPI was enhanced, SPI spatial structure was unfolded, and the hydrophobic group originally contained inside of the molecule was exposed, which enhanced the lipophilicity of the protein, thereby improving the efficiency of SPI adsorbed to the oil-water interface, the macroscopic performance is an improvement in protein emulsifying ability 16 . Similar results were also observed for peanut protein 29 , lupin protein 30 , whey protein 31 and hazelnut meal proteins 32 .…”

“…Wang et al 15 found that protein structure was more stretched, subunit appeared dissociation and reunion after HPH, thereby the solubility and emulsifying properties of globulin were remarkably improved. Xu et al 16 pointed that there was a positive correlation between the flexibility of SPI and emulsifying properties under the condition of HPH, HPH could improve the emulsifying properties of SPI. A result got by Hebishy et al 17 showed that the HPH together with sodium caseinate has the ability to produce emulsions which are physically stable against coalescence and creaming with reduced particle size.…”

Evaluating the viscoelastic properties of soy protein isolate by creep–recovery behavior

“…The preparation method of the soy protein was slightly modified (Bi et al, ; Xu et al, ). In brief, first, the defatted soy meal was dispersed in distilled water (1:10, w/v) and the pH was adjusted to 8 with 2 N of NaOH.…”

“…Soy protein isolate (SPI) with a protein content higher than 90% contains nearly 20 essential amino acids, representing an important natural plant‐derived protein (Akin & Ozcan, ; Ying et al, ). Currently, the production of edible SPI is mainly made of low‐temperature defatted soybean meal by alkali‐soluble acid precipitation (Bi, Li, Wang, & Adhikari, ; Xu et al, ). According to the remarkable physical functional properties of SPI, such as emulsifying, gelling, and hydrating (Brito‐Oliveira, Bispo, Moraes, Campanella, & Pinho, ; Yang et al, ), the application of SPI is relatively mature in meat products; however, the application in cereals has great potential for improvement and research (Lee et al, ; Srikanlaya, Therdthai, Ritthiruangdej, & Zhou, ).…”