Xiguang Qi

In vitro and in vivo antioxidant activity of polyphenols extracted from black highland barley.

The objective of this study was to determine the antioxidant capacity of polyphenols extracted from black highland barley (BHLPE) in vitro and in vivo. BHLPE was found to have strong superoxide radical, hydroxyl radical and 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity, ferric reducing antioxidant power and moderate metal ion-chelating activity. Compared with a high fat diet (HFD) group, mice that were administered 600mg BHLPE/kg body weight showed significant decreases in total cholesterol, low-density lipoprotein cholesterol and the atherosclerosis index, in addition to markedly increased high-density lipoprotein cholesterol levels. Furthermore, the antioxidant defense system and antioxidant gene expression were significantly improved in vivo in mice that were administered BHLPE compared with mice in the HFD group. These results suggest that BHLPE has significant potential as a natural antioxidant to promote health and to reduce the risk of disease.

Extraction of Carrot (Daucus carota) Antifreeze Proteins and Evaluation of Their Effects on Frozen White Salted Noodles

Homogenate and vacuum infiltration-centrifugation were adopted and compared in carrot antifreeze proteins (CaAFPs) extraction, and effects of CaAFPs on thermophysical properties, texture properties, cooking properties, and microstructure of frozen white salted noodles were studied. Results showed that the vacuum infiltration-centrifugation was more targeted than homogenate in CaAFPs extraction, while its protein extraction rate was much lower than homogenate. Differential scanning calorimeter measurement showed that CaAFPs could not only lower the initial point of freezing (Tf) and the end point of freezing (Tm′) of water but also decrease the freezable water content. It also confirmed that CaAFPs were enriched in apoplast extract. The addition of CaAFPs could lower the enthalpy of melting of frozen noodles. V-CaAFPs could lower Tm′ of frozen noodles but the Tm′ of H-noodles was slightly increased. Freezable water content of frozen noodles was decreased by the addition of CaAFPs and Tg″ of them was increased. Texture profile analysis showed that texture properties of white salted noodles were significantly influenced (p < 0.05) by the addition of CaAFPs. Cooking properties of frozen white salted noodles were also significantly enhanced (p < 0.05) by increasing cooking absorption and reducing dry material loss. NMR measurement showed that the addition of CaAFPs could shift water from mobile state to less mobile state. Microstructure of noodles suggested that the addition of CaAFPs could protect the gluten network from the damage caused by freezing and temperature fluctuation, which resulted in an integrated gluten network in white salted noodles.

Targeted separation of antibacterial peptide from protein hydrolysate of anchovy cooking wastewater by equilibrium dialysis.

Anchovy (Engraulis japonicus) cooking wastewater (ACWW) is a by-product resulted from the production of boiled-dried anchovies in the seafood processing industry. In this study, the protein hydrolysate of ACWW (ACWWPH) was found to have antimicrobial activity after enzymatic hydrolysis with Protamex. For the targeted screening of antibacterial peptides, liposomes constructed from Staphylococcus aureus membrane lipids were used in an equilibrium dialysis system. The hydrolysate was further purified by liposome equilibrium dialysis combined with high performance liquid chromatography. The purified antimicrobial peptide (ACWWP1) was determined to be GLSRLFTALK, with a molecular weight of 1104.6622Da. The peptide exhibited no haemolytic activity up to a concentration of 512μg/ml. It displayed a dose-dependent bactericidal effect in reconstituted milk. The change in cell surface hydrophobicity and membrane-permeable action of the purified ACWWP1 may have contributed to the antibacterial effect. This study suggests that liposome equilibrium dialysis can be used for the targeted screening of antimicrobial peptides.

Isolation And Identification Of An Antioxidant Peptide Prepared From Fermented Peanut Meal Using Bacillus Subtilis Fermentation

In order to recover and utilize peanut protein resource, peanut meal was fermented using Bacillus subtilis to prepare antioxidant peptides in this study. The antioxidant activities of the peanut peptides were evaluated via six in vitro tests, namely, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) scavenging activity, inhibition of linoleic acid autoxidation, reducing power, and metal chelating capacity. The peanut peptides showed 63.28% of scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radical, 70.67% of scavenging effect on 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and 39.32% of superoxide anion radical scavenging activity at 1.0 mg/ml, and 62.69% of inhibition on linoleic acid autooxidation at 0.8 mg/ml. Besides, the peanut peptides exhibited 32.8% of reducing power and 60.44% of Fe2+-chelating capacity at 2 mg/ml. Then the peanut peptides were desalted with macroporous resin; the fraction eluted with 75% ethanol showed the highest scavenging activity on 1,1-diphenyl-2-picrylhydrazyl radical. This fraction was subject to further purification using gel filtration chromatography and reverse phase-high performance liquid chromatography. At last, a peptide was gained, and it was identified to be Tyr-Pro with matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. The results indicated that it is feasible to prepare natural antioxidants from peanut meal using B. subtilis fermentation.

The anti-diabetic activity of oat β-d-glucan in streptozotocin–nicotinamide induced diabetic mice

This study was initiated to investigate the mechanism by which oat β-d-glucan (OBG) can control blood sugar levels and improve hepatogenic glycometabolism in streptozotocin-nicotinamide induced mice. After administration of different concentrations and molecular weights of β-d-glucan by oral gavage for 28 days, the body weight, fasting blood glucose, serum insulin, hepatic glycogen, glucose kinase and glucose-6-phosphatase activity of the diabetic mice were measured. In comparison with a negative control group (saline), β-d-glucan, especially medium or high doses of high-molecular-weight β-d-glucan, had a strong hypoglycaemic effect in streptozotocin-nicotinamide-induced mice. The mechanism of this effect may be associated with the high viscosity of the solution, an increase in insulin secretion, a decline in insulin resistance, and especially an improvement in hepatogenic glycometabolism. Moreover, β-d-glucan also markedly repaired and improved the integrity of pancreatic islet β-cell and tissue structures.

Effect of whole wheat flour on the quality of traditional Chinese Sachima.

The effects of whole wheat flour (WWF) on the properties of the dough and the final quality of Sachima were investigated. Refined wheat flour (RWF) in the recipe for Sachima dry mix was replaced with WWF at different levels. The farinograph characteristics of the Sachima dough were significantly weakened by adding WWF, except for the water absorption ability. The dough extensibility was also weakened by adding WWF, while the values of resistance to a certain extension increased. WWF enhanced the fried crust hardness and breaking force and darkened the surface colour with lower L(∗) and higher a(∗) values. The puffing quality was negatively affected by WWF with a decreased specific volume. The structural oil content in fried Sachima sticks was reduced by 34.86% compared with the control. In conclusion, WWF can be used in Sachima to partially substitute RWF to produce a lower oil content Sachima.

Interaction between Vaccinium bracteatum Thunb. leaf pigment and rice proteins.

In this study, we investigated the interaction of Vaccinium bracteatum Thunb. leaf (VBTL) pigment and rice proteins. In the presence of rice protein, VBTL pigment antioxidant activity and free polyphenol content decreased by 67.19% and 68.11%, respectively, and L(∗) of the protein-pigment complex decreased significantly over time. L(∗) values of albumin, globulin and glutelin during 60-min pigment exposure decreased by 55.00, 57.14, and 54.30%, respectively, indicating that these proteins had bound to the pigment. A significant difference in protein surface hydrophobicity was observed between rice proteins and pigment-protein complexes, indicating that hydrophobic interaction is a major binding mechanism between VBTL pigment and rice proteins. A significant difference in secondary structures between proteins and protein-pigment complexes was also uncovered, indicating that hydrogen bonding may be another mode of interaction between VBTL pigment and rice proteins. Our results indicate that VBTL pigment can stain rice proteins with hydrophobic and hydrogen interactions.

Extraction, purification and identification of antifreeze proteins from cold acclimated malting barley (Hordeum vulgare L.).

Antifreeze proteins from cold-acclimated malting barley were extracted by infiltration-centrifugation. The infiltration time was optimised, and its extraction effect was evaluated. The effect of cold acclimation on the accumulation of barley antifreeze proteins (BaAFPs) was assessed by comparing the thermal hysteresis activities (THA) of proteins extracted from both cold acclimated and non-cold acclimated barley grain. Ultra-filtration, ammonium precipitation and column chromatography were used successively to purify the BaAFPs, and MALDI-TOF-MS/MS was used for protein identification. The results showed that infiltration-centrifugation was more targeted than the traditional method, and 10h was the optimal infiltration time. THA was observed only after cold acclimation implied that AFPs only began to accumulate after cold acclimation. After purification, BaAFP-I was obtained at an electrophoresis level and its THA was 1.04°C (18.0 mg ml(-1)). The mass fingerprinting and sequencing results indicated the homology of the BaAFP-I to alpha-amylase inhibitor BDAI-1 (Hordeum vulgare).

The effect of oat β‐glucan on in vitro glucose diffusion and glucose transport in rat small intestine

BACKGROUND Many previous studies have reported the role of oat β-glucan (OBG) in the reduction of postprandial glucose, and hypothesised that OBG may form a protective layer along the intestinal wall, acting as a viscous barrier to decrease glucose transportation. This study examined whether the molecular weight (MW) and concentration of OBG affected the diffusion of glucose in vitro. The effect of OBG on glucose transportation in vitro and sodium-potassium adenosine triphosphatase (Na(+)/K(+)-ATPase) activity in the everted small intestines of normal rats was also examined. RESULTS In vitro, higher MWs and concentrations of OBG increased the inhibitory effects on glucose diffusion and glucose adsorption. The transport of glucose by glucose transporters and Na(+)/K(+)-ATPase activity in the small intestinal mucosa of rats were significantly lower following the addition of OBG than those in the absence of OBG at the same time-points throughout glucose transportation (P < 0.05). In the OBG-treated group, the Na(+)/K(+)-ATPase activity decreased with increasing OBG MW. However, as the concentration of OBG in the solution increased, the Na(+)/K(+)-ATPase activity in the small intestine increased due to stronger gastrointestinal motility. We also found that higher MWs of OBG had a greater inhibitory effect on intestinal disaccharidase activities in vitro. CONCLUSION Oat β-glucan is able to adsorb glucose molecules, inhibit glucose transport, decrease the concentration of available glucose and suppress disaccharidase activities in the small intestine.

Effects of extrusion conditions on the extrusion responses and the quality of brown rice pasta

This research investigated the effects of extrusion temperature and screw speed on the extrusion system parameters and the qualities of brown rice pasta. The die pressure and motor torque value reached a maximum at 90°C but decreased when the screw speed increased from 80 to 120rpm. The extrusion temperature and screw speed also significantly affected the cooking quality and textural properties of brown rice pasta. The pasta produced at an extrusion temperature of 120°C and screw speed of 120rpm had the best quality with a cooking loss, hardness and adhesiveness of 6.7%, 2387.2g and -7.0g⋅s, respectively, similar to those of pasta made from gluten-free flour. The results indicated that brown rice can be used to produce gluten-free pasta with improved nutrition.