The main factor limiting the preparation of high value-added rice proteins (RPs) is their low solubility. In this experiment, whey protein isolates (WPIs), which are of high nutritional value, were ...compounded with RPs at pH 12, and formed RP-WPI complexes by neutralization to pH 7 (pH-cycle). The formation of the protein complexes was studied by fluorescence and ultraviolet (UV) spectra. The results showed that hydrogen bond, hydrophobic force and electrostatic interaction mediated the merging of the two proteins into particulate spheres. Meanwhile the complexes acquired considerable surface charges resisting aggregation of the protein bodies, and the solubility of RPs was increased to more than 50%. The effectiveness of protein interactions by pH-cycle used in this study indicated that the technique may be a versatile approach to improve the functional properties of food proteins.
•Interactions between RPs and WPIs were investigated.•Soluble protein complexes were innovatively fabricated.•The amino acid compositions between the two proteins were balanced.
•Phenolic contents and cellular antioxidant activity of oat varieties were determined.•Longyan 3 and Beiyan 1 exhibited the highest levels of total avenanthramides (AVs).•Shaotong exhibited the ...highest levels of total phenolic acids.•ORAC values correlated with AVs while CAA values correlated with phenolic acids.•All the oat extracts showed antiproliferative capacities.
The objectives of this research were to determine the phenolic contents, oxygen radical absorbance capacities (ORAC), cellular antioxidant activities (CAA), and antiproliferative capacities of nine oat varieties and four brans in China. Of all varieties, Longyan 3 and Beiyan 1 exhibited the highest total avenanthramides (146.94±7.31 and 120.95±6.66µg/g, respectively) and ORAC values (21.03±0.56 and 21.18±1.45µM Trolox/g, respectively), while Shaotong exhibited the highest total phenolic acids (143.52±9.42µg/g) and CAA values (33.38±1.74µM quercetin/100g). The EC50 of antiproliferative capacities ranged from 167.31±6.42 to 233.42±21.31mg/mL, with the lowest in Beixiao 8 while the highest in Jinyan 8. ORAC values correlated with avenanthramides while CAA values correlated with phenolic acids. Moreover, phenolic contents, antioxidant properties, and antiproliferative capacities of oat brans was higher than that of corresponding whole oats in most cases.
The effect of tea polyphenols (TPLs) on the retrogradation of rice starch (RS) was investigated. TPLs-fortified RS exhibited retarding of retrogradation as assessed by differential scanning ...calorimetry (DSC) and X-ray diffraction (XRD). The analytic samples had a water–RS/TPLs ratio of 2:1. RS/TPLs mixing ratios were 5/0, 5/0.3, 5/0.5, 5/0.7, and 5/1 (w/w) that equated with RS containing 0%, 6%, 10%, 14%, and 20% TPLs (based on RS weight), respectively. In the DSC analysis, the temperature and enthalpy of starch gelatinization obviously decreased as the polyphenols level increased. After storage at 4
°C, retrogradation enthalpy for RS with 10%, 14%, and 20% TPLs did not appear until storage of 20 days. After 10 days of storage at 4
°C, RS gel with 10%, 14%, or 20% TPLs had almost no recrystallization of the retrogradation. The overall results demonstrate that the marked inhibitory effect of TPLs on the retrogradation of RS.
Four particle size distributions of whole-wheat flour (WWF) with mean particle sizes (MZ) of 125-μm, 96-μm, 72-μm, and 43-μm were obtained by superfine grinding. Starch damage and Farinograph water ...absorption were significantly affected by the reduction of particle size, while dough development time, stability, tolerance index and time to breakdown of WWF were little changed. The peak viscosity, trough, and final viscosity of WWF significantly decreased as particle size reduced. Although finer WWFs produced by superfine grinding caused more discoloration of whole-wheat noodle (WWN) after 24 h storage, they still showed brighter noodle appearance (higher L∗) than coarser WWFs. A significant increase in the cooking yield of WWN was noticed from the 125-μm WWF group to the 43-μm group, perhaps due to increasing damaged starch, while the 72-μm group exhibited the smallest cooking loss of WWN. Additionally, the hardness, cohesiveness, and resilience values of texture profile analysis (TPA) of cooked WWN significantly increased from the 125-μm group to the 72-μm group, and scanning electron microscope (SEM) analysis showed that the 72-μm group revealed the largest coverage of starch granules and degree of protein network connectivity among the WWF groups. The results demonstrated that the superfine grinding technique could improve the quality of WWN by significantly reducing the particle size of WWFs.
•Superfine grinding reduced the particle size and increased starch damage of WWF.•Superfine grinding effectively reduced the starch pasting viscosities of WWF.•The color and cooking properties of WWN were improved by superfine grinding.•Texture property and microstructure of WWN were enhanced as WWF at 72-μm.•Excessive starch damage in WWF had adverse effects on the quality of WWN.
Effects of millfeed particle size on the quality of whole-wheat flour (WWF) and raw noodles were investigated. Four ranges of particle size distribution of millfeeds from hard red spring (median ...diameter: 307, 260, 225, and 178 μm) and hard red winter (median diameter: 319, 274, 235, and 185 μm) were obtained by fine grinding. For both wheat classes, the CIE L* values of WWF decreased and a* and b* values increased with the reduction of millfeed particle sizes. WWF with finer millfeeds exhibited higher PPO activity than that with coarser millfeeds. RVA analysis showed that peak viscosity, trough, and final viscosity of WWF significantly decreased as the particle size of millfeeds reduced, while breakdown and setback values revealed no obvious trend. Reducing the particles of millfeeds not only significantly increased the Farinograph stability time of WWF dough, but also improved the whole-wheat noodle (WWN) brightness (L*) at both 0 and 24 h. Texture profile analysis of cooked noodle indicated that hardness, springiness, cohesiveness and resilience values all significantly increased as the particle sizes of millfeeds were decreased. These results suggest that reduction of millfeed particle sizes before reconstituting WWF could provide beneficial effect on the quality improvement of WWN.
•Millfeed particle sizes of two wheat classes were determined after fine grinding.•WWF PPO activity increased and CIE L* decreased as millfeed particle sizes reduced.•Pasting and dough mixing properties of WWF changed with millfeed particle sizes.•Color and texture of WWN were improved by reduction of millfeed particle sizes.•Fine grinding of millfeeds improved the overall quality of WWN.
To elucidate the effects of land-use types and afforestation age on litter decomposition, soil nutrient dynamics, and their relationship with substrate quality and soil environmental conditions, soil ...and litter samples were collected from farmland as well as four afforested land-use types (Robinia pseudoacacia: Rps; Caragana korshinskii: Cko; Pinus tabulaeformis: Pta; and Armeniaca sibirica: Asi), with each land-use type having three succession chronosequences (10, 25, and 40 a) in the Gaoxigou catchment area. These twelve afforested lands were converted from similar farmlands, and litterbag experiments were conducted in each land to determine litter decomposition rate (LDR). In addition, the carbon, nitrogen, and phosphorus contents and stoichiometry in soil and litter, soil properties, and litter biomass were determined. The results showed that soil environmental conditions such as soil water content, bulk density, pH, and temperature improved with afforestation age. Soil nutrient contents were higher in afforested lands and increased with afforestation age. The soil organic carbon (OC), total nitrogen (TN), and total phosphorus (TP) were positively correlated with the litter biomass, soil microbial carbon, and soil water content, but were negatively correlated with the soil bulk density, pH, and temperature. The litter OC, TN, and TP contents were mainly affected by the land-use types without being influenced by afforestation age. LDR is the main litter factor affecting soil nutrients, and is significantly influenced by substrate quality and environmental conditions, especially litter TN and N:P ratio, soil water content, and pH. The annual rates of increase for soil OC and TN during the initial (farmland–10a) and middle (10–25 a) periods were significantly higher than those during the later period (25–40 a) in Rps and Cko, but the Pta forest showed a completely opposite trend, which can be explained by a synchronous change in the LDR driven by the soil water content. In addition, the soil OC, TN, and TP contents were positively correlated with the litter TN, TP, and biomass, but had no correlation with the litter OC. The N:P ratio can be used as an indicator to reveal a tight coupling among soil and litter nutrients. Overall, these results provide evidence that litter decomposition in afforestation systems is linked to soil nutrient dynamics, and is mainly limited by substrate quality and environmental conditions.
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•Litter nutrient contents were affected by land-use type but not affected by afforestation age.•Litter decomposition rate was the first factor that contributed to total variation in soil nutrients.•The substrate quality and soil environmental factors significantly influenced the litter decomposition.•Soil moisture affects litter decomposition leading to different increase rates of soil nutrient.•N:P ratios indicates a tight coupling between soil and litter nutrients.
Deoxynivalenol (DON) is a secondary metabolite produced by Fusarium fungi, which is found in a wide range of agricultural products, especially in wheat, barley, oat and corn. In this study, the ...distribution of DON in the wheat kernel and the effect of exposure time to ozone on DON detoxification were investigated. A high concentration of toxin was found in the outer part of the kernel, and DON was injected from the outside to the inside. The degradation rates of DON were 26.40%, 39.16%, and 53.48% after the samples were exposed to 75 mg/L ozone for 30, 60, and 90 min, respectively. The effect of ozonation on wheat flour quality and nutrition was also evaluated. No significant differences (P > 0.05) were found in protein content, fatty acid value, amino acid content, starch content, carbonyl and carboxyl content, and swelling power of ozone-treated samples. Moreover, the ozone-treated samples exhibited higher tenacity and whiteness, as well as lower extensibility and yellowness. This finding indicated that ozone treatment can simultaneously reduce DON levels and improve flour quality.
In this paper, electron beam irradiated rice protein hydrolysates (ERPHs) were assessed for their ability to prevent hydrogen peroxide-induced oxidative stress in human HepG-2 cells. The related ...mechanism was also studied by analyzing the structural changes. Cytotoxicity experiments showed that rice protein hydrolysates pretreated with electron beam irradiation (EBI) were not toxic to cells if appropriate concentrations were applied. Cell viability markedly increased when the cells were treated with ERPHs before H
O
induction. Furthermore, the ERPHs effectively suppressed H
O
-induced ROS production and lipid peroxidation and increased the protein expression levels of the intracellular antioxidant enzymes SOD, GSH-Px and CAT in H
O
-stressed HepG-2 cells. Consequently, the loss of mitochondrial membrane potential and cell apoptosis was alleviated. Circular dichroism analysis showed that pretreatment of rice protein with EBI significantly changed the secondary structure (the conversion of α-helices to random coils), which is beneficial to the improvement of its antioxidative activity. ERPHs exhibited stronger antioxidative effects than those without irradiation, possibly because of the difference in molecular weight distribution and amino acid composition. These findings indicate an efficient way to produce peptides with better antioxidant activity.
The liquid foodstuffs such as edible oil products remain a problem of excessive aflatoxin B1 (AFB1) content. This paper focused on the preparation of magnetic mesoporous silica (MMS) from rice husk ...ash for the removal of AFB1 in oil system. The MMS preparation process, adsorption conditions, structural characteristics, and adsorption mechanism were investigated. The optimum conditions for MMS preparation were pH 11.0 and 80°C for 24 h. The characterization results showed that magnetic particles were successfully embedded in the MMS and had high responsiveness to a magnetic field, which was advantageous for recyclability. The MMS had ordered uniform channels with a specific surface area of 730.98 m2/g and pore diameter of 2.43 nm. The optimum adsorption conditions were 2 h at 20°C. For AFB1 with an initial concentration of 0.2 μg/mL, the MMS adsorption capacity was 171.98 μg/g and the adsorption rate was 94.59%. The MMS adsorption isotherm fitted the Langmuir model well under the assumption of monolayer AFB1 adsorption with uniformly distributed adsorption sites on the MMS surface. The maximum amount of AFB1 adsorbed according to the Langmuir isotherm was 1118.69 μg/g. A quasi-second-order kinetic model gave a better fit to the process of AFB1 adsorption on MMS. The values of ΔH (-19.17 kJ/mol) and ΔG (-34.09, -34.61, and -35.15 kJ/mol at 283, 293, and 303 K, respectively) were negative, indicating that AFB1 adsorption on MMS was a spontaneous exothermic process. The results indicated that MMS was a promising material for AFB1 removal in oil system, and this study will serve as a guide for practical MMS applications.
Low water solubility strictly limits the application potential of such plant-derived proteins as rice proteins (RPs) and walnut proteins (WPs), albeit their nutritional and health-related properties. ...In this study, by simply dissolving RPs and WPs at pH 12 prior to neutralization, we successfully prepared nanoscale hydrocolloidal composites with shared internal molecular arrangements, boosting the solubility of RPs to over 80% (w/v) while completely solubilizing WPs. Atomic force microscopy and transmission electron microscopy showed that the two polypeptide chains were packed into homogeneous particles with a diameter ranging from 50 to 100 nm. Varying the mass ratio of RPs/WPs enabled the flexible or rigid chain configuration, which was confirmed by static and dynamic light scattering. The results from zeta-potential and surface hydrophobicity demonstrated that the burial of hydrophobic groups and the exposure of charged moieties stipulated the aqueous stability of the protein composites. The apigenin encapsulated in protein composites showed preferable aqueous solubility. Moreover, the improvement of bioaccessibility of apigenin was proved by in vitro simulated digestion experiment. This study provided a new route for utilizing underdeveloped protein resources, especially those with hydrophobic attributes, and potentially expanding the applications of these proteins in the fields of food and related areas.
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