Abstract
The secondary structure of a protein has been identified to be a crucial indicator that governs its water solubility. Tilapia protein isolate (TPI), soybean protein isolate (SPI), and tilapia-soybean protein co-precipitates (TSPC3:1, TSPC2:1, TSPC1:1, TSPC1:2, and TSPC1:3) were prepared by mixing tilapia meat and soybean meal at different mass ratios. The results demonstrated that the water solubility of TSPCs was significantly greater than that of TPI (p <0.05). The changes in ultraviolet–visible and near-ultraviolet circular dichroism spectra indicated that the local structure of TSPCs was different from that of TPI and SPI. Fourier transform infrared Spectroscopy revealed the co-existence of TPI and SPI structures in TSPCs. The secondary structures of TSPCs were predominantly α-helix and β-sheet. TSPC1:1 was unique compared to the other TSPCs. In addition, there was a good correlation between the water solubility and secondary structure of TSPCs, in which the correlation coefficients of α-helix and β-sheet were −0.964 (p <0.01) and 0.743, respectively. TSPCs displayed lower α-helix contents and higher β-sheet contents compared to TPI, which resulted in a significant increase in their water solubility. Our findings could provide insight into the structure–function relationship of food proteins, thus creating more opportunities to develop innovative applications for mixed proteins.
Highlights
Tilapia is a widely-cultured freshwater fish species in Africa and Asia.This species has attracted a considerable amount of attention due to its low fat levels, high protein contents, being rich in unsaturated fatty acids, and being suitable for children and the elderly [1]
The pH-solubility profiles of the tilapia-soybean protein co-precipitates (TSPCs) are U-shaped, which is similar to a previous study on water solubility, in a wide pH range of tilapia protein concentrate [7] and commercial soy proteins [11]
−1 which an absorption peak was observed at cm was observed at 936 cm. These results prove that the tilapia protein and soybean protein structures soybeanin protein structures co‐existed in
Summary
Tilapia (oreochromis niloticus) is a widely-cultured freshwater fish species in Africa and Asia This species has attracted a considerable amount of attention due to its low fat levels, high protein contents, being rich in unsaturated fatty acids, and being suitable for children and the elderly [1]. Even though the excellent nutritional properties of tilapia proteins are well-recognized, they remain unable to meet the various needs of food systems because of limitations regarding their water solubility and related functional properties [6,7].
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