Improvement of oxidized myofibrillar protein gel properties by black rice extract.

In order to investigate the effects of black rice extract (BE) on the composition of oxidized myofibrillar protein (MP) gel, different concentrations of BE (0, 10, 20, 50 mg g-1) were analyzed experimentally. Results revealed that the addition of small doses of BE significantly inhibited the formation of carbonyl groups in oxidized MP, and improved surface hydrophobicity and gel water holding capacity. Additionally, 10 and 20 mg g-1 BE increased the ordered structure of oxidized MP. Furthermore, dynamic rheometer results showed a significant increase in the storage modulus (G') of oxidized MP with 10 and 20 mg g-1 BE during heating. Scanning Electron Microscopy (SEM) showed that MP formed a denser network structure with addition of 10 and 20 mg g-1 BE. Low-Field Nuclear Magnetic Resonance (LF-NMR) and magnetic resonance imaging (MRI) showed that there is a significant increase in immobile water in MP gel and a decrease in free water within the 20 mg g-1 BE group. In conclusion, 20 mg g-1 supplemented BE significantly improved the structure order and hardness of oxidized MP gel, increased its structure density and water holding capacity, and it provides a theoretical basis for the application of antioxidants in meat products.

Loadings of lycopene in emulsion and sodium alginate-K-carrageenan composite systems: Preparation, characterization, bioaccessibility, and kinetics.

This research aims to prepare capsules emulsion using gallic acid (GA), dextran (DEX), bovine serum albumin (BSA), sodium alginate, and K-carrageenan (K-Car) as the biological delivery system of lycopene. The stability and bioaccessibility of lycopene were further improved through encapsulation of covalent complex of sodium alginate and K-Car. The molecular weight distribution and secondary structure of the conjugates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared spectroscopy (FTIR). The storage stability of the emulsion stabilized by conjugates was measured with Turbiscan stability index (TSI) and fluctuation of the particle size. The TSI value of ternary conjugates was 18.7 (37℃) with particle sizes ranging from 208 to 319 nm. Then, the changes of three-dimensional reticulate structures and physical properties of sodium alginate-K were analyzed by scanning electron microscopy (SEM) and TPA. The thermal stability of the sodium alginate-K-Car composite systems was increased compared with sodium alginate. The bioaccessibility of lycopene was significantly improved under the dual embedding of BSA-DEX-GA conjugate emulsion and sodium alginate-K-Car composite systems.

Proanthocyanidin B2 and transglutaminase synergistically improves gel properties of oxidized myofibrillar proteins.

We investigated the roles of Proanthocyanidin B2 (PCB2) and transglutaminase (TGase) in improving myofibrillar protein (MP) gel properties. TGase and PCB2 increased the surface hydrophobicity (41 %) and water holding capacity (WHC) (16 %) of the MP. Secondary and tertiary structures of MP were respectively analyzed by Fourier transform infrared spectroscopy (FTIR) and fluorescence spectrophotometry. The content of α -helix in MP was found to be increased while its fluorescence intensity decreased upon the addition of PCB2 and TGase. The addition of PCB2 and TGase resulted in formation of a dense MP network structure as revealed by scanning electron microscopy (SEM). Low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) analysis showed that immobilized water levels in the MP gel were markedly increased while the amount of free water was significantly decreased after PCB2 and TGase addition. These findings indicate that a combination of PCB2 and TGase are potential additives for meat products.

Stability and bioaccessibility improvement of capsorubin using bovine serum albumin-dextran-gallic acid and sodium alginate.

This study attempted to prepare ternary conjugate emulsion from bovine serum albumin (BSA), dextran (DEX) and gallic acid (GA) to improve the stability of conjugate emulsion and the bioaccessibility of capsorubin. The release of capsorubin was further delayed by sodium alginate capsules in the intestinal phase. First, protein formed new functional groups and covalent bonds was analyzed by Fourier transform infrared (FTIR) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Next, the stability of the ternary conjugate showed distinct pH correlation and the higher stability near the isoelectric point. Finally, the bioaccessibility of capsorubin embedded in sodium alginate emulsion was higher than that of ternary conjugate emulsion (65% and 34%).