Search

This paper investigates the effect on the physicochemical and functional properties of soybean protein concentrate (SPC) by using Alcalase protease and high-pressure homogenization (HPH) (0, 20, 40, 60, 80, and 100 MPa) for the combined modification. The results showed that the degree of hydrolysis of SPC was 4.1% and the antigen protein was degraded after Alcalase hydrolysis, when the homogenization pressure (HP) was 6 0Mpa, the particle size of the SPC was the smallest, the zate potential absolute value up to 33.45 mV, the secondary structure has the lowest β-sheet content, the highest random coil content, and the highest surface hydrophobicity (H0), the size of protein fragments on the microstructure surface is the smallest, the lowest denaturation temperature (Td) and enthalpy (△H) are 72.59°C and 1.35 J/g, the highest solubility is 80.54%, and the highest water and oil holding capacities are 7.73 g/g and 6.51 g/g, respectively. The best emulsifying activity and emulsifying stability were 43.46 m2/g and 190.35 min, the most even distribution of emulsion droplets. This indicates that the HPH treatment destroys the structure of enzymatic hydrolyzed SPC, changes its physicochemical properties, and improves its functional properties. In this study, SPC was modified by HPH and enzyme combined treatment, in order to improve the functionality and application range of SPC, and provide a theoretical basis for its high-value utilization in the food field.

Native soy protein isolate (N-SPI) has a low denaturation point and low solubility, limiting its industrial application. The influence of different industrial modification methods (heat (H), alkaline (A), glycosylation (G), and oxidation (O)) on the structure of SPI, the properties of the gel, and the gel properties of soy protein isolate (SPI) in myofibril protein (MP) was evaluated. The study found that four industrial modifications did not influence the subunit composition of SPI. However, the four industrial modifications altered SPI’s secondary structure and disulfide bond conformation content. A-SPI exhibits the highest surface hydrophobicity and I850/830 ratio but the lowest thermal stability. G-SPI exhibits the highest disulfide bond content and the best gel properties. Compared with MP gel, the addition of H-SPI, A-SPI, G-SPI, and O-SPI components significantly improved the properties of the gel. Additionally, MP-ASPI gel exhibits the best properties and microstructure. Overall, the four industrial modification effects may impact SPI’s structure and gel properties in different ways. A-SPI could be a potential functionality-enhanced soy protein ingredient in comminuted meat products. The present study results will provide a theoretical basis for the industrialized production of SPI.

The combination of protein and flavonoids can ameliorate the problems of poor solubility and stability of flavonoids in utilization. In this study, soybean protein isolate pretreated by ultrasonication was selected as the embedding wall material, which was combined with luteolin to form a soybean protein isolate-luteolin nanodelivery system. The complexation effect and structural changes of soybean protein isolate (SPI) and ultrasonic pretreatment (100 W, 200 W, 300 W, 400 W and 500 W) of soybean protein isolate with luteolin (LUT) were compared, as well as the changes in digestion characteristics and antioxidant activity in vitro. The results showed that proper ultrasonic pretreatment increased the encapsulation efficacy, loading amount and solubility to 89.72%, 2.51 μg/mg and 90.56%. Appropriate ultrasonic pretreatment could make the particle size and the absolute value of ζ-potential of SPI-LUT nanodelivery system decrease and increase respectively. The FTIR and fluorescence results show that appropriate ultrasonic pretreatment could reduce α-helix, β-sheet and random coil, increase β-turn, and enhance fluorescence quenching. The thermodynamic evaluation results indicate that the ΔG 0, ΔH 0 and ΔS 0, so the interaction of LUT with the protein was spontaneous and mostly governed by hydrophobic interactions. The XRD results show that the LUT was amorphous and completely wrapped by SPI. The DSC results showed that ultrasonic pretreatment could improve the thermal stability of SPI-LUT nanodelivery system to 112.66 ± 1.69 °C. Digestion and antioxidant analysis showed that appropriate ultrasonic pretreatment increased the LUT release rate and DPPH clearance rate of SPI-LUT nanodelivery system to 89.40 % and 55.63 % respectively. This study is a preliminary source for the construction of an SPI nanodelivery system with ultrasound pretreatment and the deep processing and utilization of fat-soluble active substances.

In this study, rice protein was used as raw material to explore the effects of γ-irradiation treatment doses (0, 0.5, 1, 2, 3, 5 kGy) on the physicochemical properties of rice protein (particle size, zeta potential, secondary structure, scanning electron microscope microstructure), surface hydrophobicity (H0), thermal stability), functional properties (solubility, water and oil retention, emulsification) and sensory quality. The results show that when the γ-irradiation dose is 2 kGy, the average particle size of rice protein is the smallest, the absolute value of the potential is the highest 33.58 mV, the content of β-sheets in the secondary structure is at least 31.16 ± 0.16, and the content of random curl is at most 14.56 ± 0.06, the surface of the microstructure is rough and the degree of pore depression is the deepest, the highest H0 is 160.45 ± 2.98, the minimum denaturation temperature (Td) and enthalpy (△H) are 70.49 ± 0.05 °C and 1.30 ± 0.01 J/g, which shows that γ-irradiation treatment can be significant affect the physicochemical properties of rice protein. When the irradiation dose is 2 kGy, the highest solubility of rice protein is 69.18 ± 1.07%, and the highest water and oil holding capacity are 5.89 ± 0.08 g/g and 3.45 ± 0.04 g/g, respectively. The highest emulsification activity and emulsification stability are 45.65 ± 1.26 m2/g and 208.33 ± 4.79 min, which shows that γ-irradiation treatment can improve the functional properties of protein. When the irradiation dose was less than 5 kGy, the sensory quality of rice protein was not significantly affected. The research results provide a theoretical basis for the deep processing and value-added utilization of rice protein by γ-irradiation technology.

The effects of different structural parameters on the sealing performance of self-tightening metal U-shaped seal rings were studied. A two-dimensional axisymmetric model of a self-tightening U-shaped seal ring was established using finite element software. The influence of structural parameters such as side wall thickness, bottom wall thickness and boss radius on the sealing performance of the seal ring was analyzed by the control variable method. The results show that as the thickness of the side wall increases, the stress shows a downward parabolic trend, which is the smallest at 0.55 to 0.65 mm; as the bottom wall thickness increases, the stress first increases steadily, and then decreases slowly after 0.8 to 0.9 mm; When the inclination angle is from 0 to 9 °, the sealing ring can obtain better sealing performance. The results have guiding significance for the design, optimization and application of subsequent seal ring structures.