Identification, in silico selection, and mechanism study of novel antioxidant peptides derived from the rice bran protein hydrolysates.

The work aimed to assess the antioxidant ability and obtain a new antioxidant peptide from rice bran protein. Rice bran protein was hydrolyzed by Alcalase, Neutral, Pepsin, Chymotrypsin, and Trypsin, separately. Trypsin hydrolysate (T-RBPH) showed high Fe2+ chelating activity (IC50, 2.271 ± 0.007 mg/mL), DPPH and hydroxyl radical scavenging ability (IC50, 0.191 ± 0.006 and 1.038 ± 0.034 mg/mL). Moreover, T-RBPH could alleviate the H2O2-induced oxidative damage in Caco-2. The T-RBPH was purified and identified by UF, GF, FPLC, and LC-MS/MS. Finally, 9-amino acid peptide-AFDEGPWPK with low molecular weight (1045.48 Da), high antioxidant activity, good safety, and solubility was screened by in silico method and chemical oxidation determination, and its interaction with Keap1 was also demonstrated. The ORAC and DPPH radical scavenging ability of AFDEGPWPK were 44.16 ± 0.79 and 28.38 ± 0.14 µmol TE/mM. Moreover, the Molecular docking and Western blot (WB) results showed that AFDEGPWPK could enter the binding pocket in the Kelch domain and activate Keap1/Nrf2/HO-1 pathway.

Identification and in silico analysis of novel antioxidant peptides in broken rice protein hydrolysate and its cytoprotective effect against H2O2-induced 2BS cell model.

Broken rice is an important by-product during milling process of rice, which is rich in protein. To increase the value of by-products and search for effective antioxidants, the antioxidant peptides from broken rice protein hydrolysate were separated and identified by ultrafiltration, gel filtration chromatography, fast protein liquid chromatography, and LC-MS/MS in this study. These identified peptides were further screened using a combined in silico and in vitro method and their antioxidant mechanism was explored by Western blot and molecular docking analysis. Ninety-eight peptides were obtained after antioxidant activity-oriented isolation and four novel peptides, SGDWSDIGGR, DFGSEILPR, GEPFPSDPKKQLQ, and GEKGGIPIGIGK, with excellent solubility, safety, and antioxidant activity were synthesized. Among these, SGDWSDIGGR showed good antioxidant activities in the extracellular assay (41.57 µmol TE/g and 29.41 % in ORAC and DPPH assay, respectively.), and it possessed a protective effect against H2O2-injured oxidative stress in 2BS cells in a dose-dependent manner. Furthermore, Western blot and molecular docking results showed that SGDWSDIGGR achieves antioxidant ability by occupying the Nrf2-binding site, activating the Keap1-Nrf2 signaling pathway, and upregulating the expression of antioxidant enzymes. This study extends the rice industry chain and provides insights into the selection and mechanisms research of antioxidant peptides.

Effects of Concentration of Soybean Protein Isolate and Maltose and Oil Phase Volume Fraction on Freeze-Thaw Stability of Pickering Emulsion.

There is growing interest in enhancing the freeze-thaw stability of a Pickering emulsion to obtain a better taste in the frozen food field. A Pickering emulsion was prepared using a two-step homogenization method with soybean protein and maltose as raw materials. The outcomes showed that the freeze-thaw stability of the Pickering emulsion increased when prepared with an increase in soybean protein isolate (SPI) and maltose concentration. After three freeze-thaw treatments at 35 mg/mL, the Turbiscan Stability Index (TSI) value of the emulsion was the lowest. At this concentration, the surface hydrophobicity (H0) of the composite particles was 33.6 and the interfacial tension was 44.34 mN/m. Furthermore, the rheological nature of the emulsions proved that the apparent viscosity and viscoelasticity of Pickering emulsions grew with a growing oil phase volume fraction and concentration. The maximum value was reached in the case of the oil phase volume fraction of 50% at a concentration of 35 mg/mL, the apparent viscosity was 18 Pa·s, the storage modulus of the emulsion was 575 Pa, and the loss modulus was 152 Pa. This research is significant for the production of freeze-thaw resistant products, and improvement of protein-stabilized emulsion products with high freeze-thaw stability.

HS-GC-IMS and PCA to Characterize the Volatile Flavor Compounds in Three Sweet Cherry Cultivars and Their Wines in China.

The aim of this research was to characterize differences and sources of volatile flavor compounds by using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and principal component analysis (PCA). Three sweet cherry fruits from different cultivars (cv. Tie, Van, and Lap) and their wines that were produced by the same yeast were detected. The results showed that 27 flavor compounds were identified in cherry fruits, including 10 alcohols, 7 esters, 7 aldehydes, 2 ketones, and 1 organic acid. Twenty-three flavor compounds were identified in cherry wines, including nine esters, eight alcohols, three aldehydes, two organic acids, and one ketone. In cherry fruits, aldehydes, several alcohols, and one ketone were the most prevalent in cv. Tie, and the majority of esters and alcohols in cv. Van. After fermentation, ethanol, butanol, butanal, ethyl propionate, propionaldehyde, 3-hydroxy-2-butanone, and acetic acid increased, whereas 1-hexanol, 3-methyl-3-buten-1-ol, 1-penten-3-ol, ethyl acetate, methyl acetate, (E)-2-hexenal and hexanal decreased. Few differences were detected in the type and content of volatile compounds in cherry wines from cv. Tieton (WT) and cv. Van (WV). Almost all aldehydes are derived from cherry fruits, which cannot be produced during wine-making, and other volatile compounds are almost all produced by saccharomyces cerevisiae. The volatile compounds of cherry wines were determined by row materials and fermentation cultures. Flavor fingerprints were established by HS-GC-IMS and PCA, which provided a theoretical foundation for the evaluation and improvement of flavor quality in cherry wine-making.

Species diversity of fishes in the Dingqu River Basin, tributary of the upper Yangtze River, China.

BACKGROUND: The Dingqu River Basin, a major tributary of the upper Yangtze River, is located at southeast edge of the Qinghai-Tibet Plateau of China. The fishes of this plateau constitute a major faunal component of this basin, particularly Schizothoracinae (Cypriniformes: Cyprinidae) and Triplophysa (Cypriniformes: Nemacheilidae). Hydropower development is an impact that affects natural habitats and biological resources of the upper Yangtze River and this has led to a decrease in biodiversity. This study investigated the species diversity of fishes of the Dingqu River Basin and accumulated basic data for conservation of biodiversity and assessment of ecological health of the upper Yangtze River. NEW INFORMATION: The upper streams of the Jinshajiang River harbours numerous endemic fish species in China. Most of them belong to the Qianghai-Tibet Plateau fish fauna. However, while the fish species of the Jinshajiang River have been well studied, there is still a gap in the research on fish species diversity of the Dingqu River Basin tributary. This study provides information for 18 native fish species belonging to two orders, four families, three subfamilies and eight genera, and is the first complete record of fishes in the Dingqu River Basin, a primary tributary of the Yangtze River. Supplemental information of species diversity in the Jinshajiang River is also provided. The study includes two datasets, which present taxonomic, distribution, habitat condition, endemism and threat information for each species collected from the Dingqu River Basin and historical literature, respectively. In particular, these fish species all have limited distribution within the south-eastern Qinghai-Tibet Plateau areas of China and could determine the importance of habitat protection for the upper Yangtze River.

Characterization of magnetic soluble starch-functionalized carbon nanotubes and its application for the adsorption of the dyes.

Soluble starch-functionalized multiwall carbon nanotube composites (MWCNT-starch) were prepared to improve the hydrophilicity and biocompatibility of MWCNTs. Characterization of the MWCNT-starch by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), showed that the starch component (about 14.3 wt%) was covalently grafted onto the surface of MWCNT. MWCNT-starch-iron oxide composites, intended for use as adsorbents for the removal of dyes from aqueous solutions, were prepared by synthesizing iron oxide nanoparticles at the surface of MWCNT-starch. Starch acts as a template for growth of iron oxide nanoparticles which are uniformly dispersed on the surface of the MWCNT-starch. MWCNT-starch-iron oxide exhibits superparamagnetic properties with a saturation magnetization (23.15 emu/g) and better adsorption for anionic methyl orange (MO) and cationic methylene blue (MB) dyes than MWCNT-iron oxide.

Preparation and characterization of glycerol plasticized-pea starch/ZnO-carboxymethylcellulose sodium nanocomposites.

Among natural polymers, starch is one of the most promising biodegradable materials because it is a renewable bioresource that is universally available and of low cost. However, the properties of starch-based materials are not satisfactory. One approach is the use of nano-filler as reinforcement for starch-based materials. In this paper, a nanocomposite is prepared using ZnO nanoparticles stabilized by carboxymethylcellulose sodium (CMC) as the filler in glycerol plasticized-pea starch (GPS) matrix by the casting process. According to the characterization of ZnO-CMC particles with Fourier transform infrared (FTIR), Ultraviolet-visible (UV-vis), X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), ZnO (about 60 wt%) is encapsulated with CMC (about 40 wt%) in ZnO-CMC particles with the size of about 30-40 nm. A low loading of ZnO-CMC particles can obviously improve the pasting viscosity, storage modulus, the glass transition temperature and UV absorbance of GPS/ZnO-CMC nanocomposites. When the ZnO-CMC contents vary from 0 to 5 wt%, the tensile yield strength increase from 3.94 MPa to 9.81 MPa, while the elongation at break reduce from 42.2% to 25.8%. The water vapor permeability decrease from 4.76 x 10(-10) to 1.65 x 10(-10) g m(-1) s(-1) Pa(-1).