The effect of protein oxidation on the formation of advanced glycation end products after chicken myofibrillar protein glycation

Investigation that protein oxidation to the formation of advanced glycation end products(AGEs)after chicken myofibrillar protein glycation is limited.Models of protein oxidation induced by different concentrations of hydroxyl radicals(·OH)were developed after the chicken myofibrillar protein mild glycation(MPG).Results exhibited that levels of AGEs and surface hydrophobicity(H_(0))steadily increased with the a ddition of h ydrogen peroxide(H_(2)O_(2))concentration.However,levels of s ulfhydryl group,free amino group,and particle size gradually decreased with the H_(2)O_(2)concentration.The protein carbonyl value increased in H_(2)O_(2)concentration until 10 mmol/L.Pearson's correlation indicated that MPG structure modification(unfolding and degradation)induced by protein oxidation were significantly positively correlated with AGEs concentration(P<0.05).Finally,a mechanism was proposed to hypothesize t he effect of protein oxidation on the formation of AGEs under MPG conditions.

Evaluation of the Role of Mixed Amino Acids in Nitrate Uptake and Assimilation in Leafy Radish by Using ^(15)N-Labeled Nitrate

In this paper, the role of mixed amino acids in nitrate uptake and assimilation was evaluated in leafy radish by using ^15N labeled nitrate. The mixtures of alanine, β-alanine, aspartic acid, asparagines, glutamic acid, glutamine, and glycine were sprayed to plant leaf two or four times. The activity of the enzymes related to the process of NO3- reduction （nitrate reductase, nitrite reductase and glutamine synthetase） was affected differently depending on the application rate of mixed amino acids. Applying mixed amino acids increased the fresh weight, dry weight, and N yield. The NO3 content was reduced to 24-38%, but no significant differences were observed in amino acids and proteins. In addition, the nitrogen derived from fertilizer and the ^15N-NO3-recovery rate increased to 2-8% and 15-47%, respectively. These results strongly suggest that the positive effect of mixed amino acids on nitrate uptake and assimilation might be attributed to the regulation on NO3- uptake and assimilation, but not to the preference for amino acids as sources of reduced nitrogen.

Advances in Biodegradation of Aflatoxins

Aflatoxins are secondary metabolites of fungi such as Aspergillus flavus and Aspergillus parasiticus. They are one of the contaminants most common in food and feed, with high toxicity and carcinogenicity. Aflatoxins usually enter animal body together with feed and then enter human body by food chain, thereby seriously threatening human health. In recent years, the degradation of aflatoxins has become a hot research topic. This study overviewed the characteristics and detoxification ways of aflatoxins, specifically for the advances in biodegradation and degradation products of aflatoxins.

Effects of fi lleting methods on composition, gelling properties and aroma profi le of grass carp surimi

Traditionally,fi sh carcass is headed and gutted to prepare a skin-on fi llet in surimi production.In this study,tail and/or belly of grass carp carcass were further cut off in the fi lleting step.Yield,composition,gelling properties and aroma profile of surimi as affected by filleting methods were investigated by SDS-PAGE,ELISA,SEM,magnetic resonance imaging(MRI)and electron nose.Cutting tail off increased surimi yield by 14.0%,whereas cutting belly off decreased it by 11.2%.Cutting tail or belly off signifi cantly decreased fat content,but did not change protein content,ash content,cathepsin(B,H and L)contents,nor protein patterns.Both breaking force and whiteness of surimi gel signifi cantly increased after cutting tail off.Cutting belly off slightly increased whiteness of surimi gel.The microstructure of all the surimi gels was compact and uniform,with fractal dimensions(Df)ranging from 2.81 to 2.85.As for the macrostructure,cutting tail off apparently improved the integrity of surimi gel while cutting belly off did not.Aroma profi les of the surimi prepared under different fi lleting methods could be clearly distinguished by linear discriminant analysis(LDA).Our results indicate that cutting tail off contribute positively to surimi production.

Preparation of Rice Seedling-raising Substrate with Spent Mushroom Substrate of Pleurotus eryngii

This study aimed to explore the effect of fermented spent mushroom substrate(SMS) of Pleurotus eryngii as a basic material on rice seedling-raising substrate. The physical and chemical indices of the SMS indicated that the fermented SMS was fully composted and was very suitable for preparing rice seedling-raising substrate. The fermented SMS effectively regulated the bulk density, total porosity, aeration porosity and water-holding porosity of rice seedling-raising substrate. With the increased addition amount of fermented SMS, the bulk density of rice seedling-raising substrate was decreased, but the total porosity, aeration porosity and water-holding porosity were increased. Compared with those in the substrates of 100% soil and 100% SMS,the height, chlorophyll content, 100-shoot dry weight, 100-root dry weight, root activity, nitrogen content, phosphorus content and potassium content of rice seedlings in the substrate composed of spent mushroom substrate of P. eryngii and soil were higher.The quality of rice seedlings in the substrate composed of 20% soil and 80% SMS was best, followed by that in the substrate composed of 30% soil and 70% SMS.

Effect of Vacuum Packaging on Storage Quality of Peanut

The purpose of the study is to investigate the effect of vacuum packaging on storage quality of peanut. The acid value,peroxide value,relative conductivity,mildew rate and germination rate of peanut were examined in both vacuum-packed bags and control packaging bags.The results showed that the acid value,peroxide value,relative conductivity and mildew rate of peanut were maintained at a lower level and germination rate was maintained at a higher level in vacuum-packed bags than in control packaging bags. The storage quality of peanut in vacuum-packed bags was better than in control packaging bags. The order of different vacuum degree of vacuum-packed bags from good to bad according to storage quality of peanut was- 0. 06 MPa >- 0. 09 MPa >- 0. 03 MPa,and- 0. 06 MPa was the most beneficial vacuum degree for the peanut storage.

Simulation of the Flow Conditions in Different Types of Bar Structures of Disc Refiner

Disc refiner is a critical equipment in the pulping and papermaking industry, pulp is refined in the refining zone, and different bar structures of refining disc constitute the different refining zones. With the use of the 3D modeling software SOLIDWORKS, five different refining discs that are commonly used in low consistency pulping, were built. The five refining discs were simulated and analyzed using the Computational Fluid Dynamics(CFD)software. The distribution of pulp velocity and surface shear stress, which is displayed between the bar and groove structures, can indirectly show the stress conditions on the refining discs. This paper provides a theoretical basis for research on the bar and groove failure of the refining discs.

Design Method of Curved-bar Refining Plates for Disc Refiner

Straight-and curved-bar refining plates are two important types of plates commonly used in disc refiners in the papermaking industry.Theoretically,the curved-bar refining plate has a relatively uniform bar interaction angle,which indicates uniform refining effects.The bar angle of the curved bar was proposed and two typical curved-bar plates,the three-stage radial curved-bar plate and isometric curved-bar plate,were designed in this paper.The arc equations of the curved-bar center line and curved-bar edges were established and finally,the specific edge load(SEL)of the curved-bar plate was derived.The determination of bar parameters was discussed,which provides a theoretical basis for the design of curved-bar plates.

Variations of DON Content in Grain during Wheat Tempering at Different Temperatures

[Objective] The aim of this study was to observe variations of DON content in grain of two wheat cultivars during tempering at different temperatures, and explore the possible causes of the variations. [Method] Two naturally Fusarium-infested wheat samples Youmai 3 and Yangmai 14 were selected as experimental materials. Tempering was carried out at different temperature(15, 25 and 35 ℃) for 48 h. During tempering, wheat grain samples were collected every 8 h. DON contents in tempered grain were measured by HPLC coupled with UV detector. [Result] For Youmai 3, DON contents were in the ranges of 3.94-12.49, 4.26-6.11 and 3.41-7.91 μg/g during tempering at 15, 25 and 35 ℃, respectively. The highest DON contents were observed at the 32ndhour at 15 ℃, the 8thhour at 25 ℃ and the 32ndhour at 35 ℃, respectively. After tempering for 48 h, DON contents in grain were increased by 175.1%, 27.5% and 7.2%, respectively. For Yangmai 14, DON contents were in the ranges of 0.55-1.56, 0.39-0.77 and 0.57-3.17 μg/g during tempering at 15, 25 and 35 ℃, respectively. The highest DON contents were observed at the 24thhour at 15 ℃, the 40thhour at 25 ℃ and the 48thhour at 35 ℃, respectively. After tempering for 48 h, DON contents in grain were increased by 94.5% at 15 ℃ and 456.1% at 35 ℃, respectively, whereas it was decreased by 35.0% at 25 ℃. From the point of view of reducing DON level, 15 ℃ was not reasonable for the tempering of both wheat cultivars, and tempering at 35 ℃ for 16 h and tempering at 25 ℃ for 24 h appeared to be desirable for Youmai 3 and Yangmai 14, respectively. [Conclusion] The results suggested controlling the tempering temperature and time would be helpful to reduce DON level in grain.

Optimization of Chelation Process for Complex Microelement Iron Supplement Derived from Pig Blood by Response Surface Methodology

[Objectives]This study aimed to optimize the chelation process for complex microelement iron supplement derived from pig blood by response surface methodology.[Methods]On the basis of single-factor test,p H value,concentration of polypeptide solution and volume ratio of polypeptide solution to FeCl_2 solution were selected as influencing factors with Fe(II)chelation rate as the indicator for Box-Behnken central composite experimental design with three factors and three levels.The effects of three factors on the response value were analyzed by response surface methodology.[Results]The optimized chelation process for complex microelement iron supplement derived from pig blood by response surface methodology was as follows:pH 5.40,polypeptide solution concentration 2.27%,volume ratio of polypeptide solution to FeCl_2 solution 2.16∶1.Under this condition,the predictive Fe(II)chelation rate of iron supplement was 79.37%,while the actual value was 79.41%.[Conclusions]The optimized process may provide new thoughts for the development and utilization of complex microelement iron supplement derived from pig blood.

Ultrafiltration of Shiitake Polyphenol with Ultrasound Enhancement

Ultrafiltration(UF) experiments were subjected to the concentration of Shiitake polyphenol(SP) with ultrasound(US) enhancement, by which the effects of the main parameters such as ultrasonic power, transmembrane pressure, temperature and axial flow-rate on the membrane fluxes were analyzed, and then the SP of the ultrafiltrate after follow-up resin adsorption by HPLC was investigated. The results indicated that US could significantly enhance the membrane fluxes. The optimal conditions obtained was as follows: 0.60 W/cm2 US power, axial flow-rate of 80 L/h,operation temperature 30 ℃, transmembrane pressure 0.10 MPa. US increased the absorption capacity of the absorbent resin during the following stage. The HPLC analysis also showed that catechins were purified to some extent as the ultrafiltrate was treated by US and macroporous resin, indicating the technology of US enhancement coupled with UF showed the potential for concentration and purification of SP by absorbent resins.

Effects of Phosphate Fertilizer on Yield and Quality of Eleocharis dulcis

The effects of different application levels and species of phosphatic fertilizer on Eleocharis dulcis were studied. The results showed that the growth stage of Eleocharis dulcis was not significantly influenced by different levels of phosphatic fertilizer application, with phosphorus level in 195-375 kg/hm^2. With increasing of the phosphorus level, starch and total soluble sugar accumulated, but the yield was not improved significantly. The analysis on the economic benefits showed that the best phosphorus level was 195 kg/hm^2. The growth stage and yield of Eleocharis dulcis were not considerably influenced by different proportions of calcium-magnesia phosphate fertilizer and ammonium dihydrogen phosphate. With increasing of ammonium dihydrogen phosphate, big-fruit rate of Eleocharis dulcis kept growing, but the accumulations of starch and total soluble sugar were decreasing.

3D printed lactic acid bacteria hydrogel:cell release kinetics and stability

In this study,a new type of 3 D printed living biological hydrogel was developed by integrating lactic acid bacteria(LAB)into biocompatible and non-toxic polymer materials.Interestingly,the living materials loaded with LAB can be freeze-dried and reused for more than 100 times.The bio-hydrogel can be used to co-culture different LAB and keep its fermentation performance stable in long-term use.The release kinetics model and response surface method were used to simulate and optimize the bacteria release mode in the bio-hydrogel.The results show that the release of bacteria from hydrogel is regulated by the coupling of Fickian diffusion and polymer swelling.The stability of LAB hydrogel was evaluated by reuse experiments.The images of confocal microscopy and scanning electron microscope showed that the bacteria with high cell viability were distributed in the hydrogel and intact structure of the living hydrogel was maintained after 100 times of reuse as yoghurt starter.In conclusion,the 3 D printed LAB bio-hydrogel developed in this study has the advantage of reuse and sustainability,which is expected to open up a new way for the preparation of food culture starter.

Positioning-control Based on Trapezoidal Velocity Curve for High-precision Basis Weight Control Valve

Traditionally, basis weight control valve is driven by a constant frequency pulse signal. Therefore, it is difficult for the valve to match the control precision of basis weight. Dynamic simulation research using Matlab/Simulink indicates that there is much more overshoot and fluctuating during the valve-positioning process. In order to improve the valve-positioning precision, the control method of trapezoidal velocity curve was studied. The simulation result showed that the positioning steady-state error was less than 0.0056%, whereas the peak error was less than 0.016% by using trapezoidal velocity curve at 10 positioning steps. A valve-positioning precision experimental device for the stepper motor of basis weight control valve was developed. The experiment results showed that the error ratio of 1/10000 positioning steps was 4% by using trapezoidal velocity curve. Furthermore, the error ratio of 10/10000 positioning steps was 0.5%. It proved that the valve-positioning precision of trapezoidal velocity curve was much higher than that of the constant frequency pulse signal control strategy. The new control method of trapezoidal velocity curve can satisfy the precision requirement of 10000 steps.

Crystallization Kinetics and Morphology of Poly(vinylidene fluoride)/Poly(ethylene adipate) Blends

The miscibility, isothermal crystallization kinetics and morphology of the poly（vinylidene fluoride）（PVDF）/poly（ethylene adipate）（PEA） blends have been studied by differential scanning calorimetry（DSC）, optical microscopy（OM） and scanning electron microscopy（SEM）. A depression of the equilibrium melting point of PVDF was observed. From the melting point data of PVDF, a negative but quite small value of the interaction parameter ？PVDF-PEA is derived using the Flory-Huggins equation, implying that PVDF shows miscibility with PEA to some extent. Nonisothermal and isothermal crystallization kinetics suggest that the crystallization rate of PVDF decreases with increasing the amount of PEA, and a contrary trend was found when PEA crystallizes with the increase of the amount of PVDF. It was further disclosed that the blend ratio and crystallization temperature affect the texture of PVDF spherulites greatly, which determines the subsequent crystallization of PEA. At high temperatures, e.g. 150 ℃, the band spacing of PVDF spherulites increases with the addition of PEA content and the spherulitic structure becomes more open. In this case, spherulitic crystallization of PEA is not observed for all blend compositions. At low temperatures, e.g. 130 ℃, for the PEA-rich blends, the interpenetrated structures are eventually formed by the penetration of the spherulites of PEA growing within the pre-existing PVDF spherulites.

Crystallization of Poly(ethylene adipate) within γ-Phase Poly(vinylidene fluoride) Matrix

The effects of PEA on the ）γ-phase PVDF crystal structure and the crystallization of PEA within the pre-existing γ-phase PVDF spherulites have been investigated by optical microscopy （OM）, infrared spectroscopy （IR） and scanning electron microscopy （SEM）. The results demonstrate that the γ-phase PVDF spherulites consist of the lamellae exhibiting a highly curved scroll-like morphology and develop preferentially in PEA-rich blend. With increasing PEA concentration, the scroll diameter increases and the scrolls are better separated from each other. PEA crystallizes first in the interspherulitic region and transcrystalline layer develops. Subsequently, the transcrystalline layer of PEA continues to grow within theγ-phase PVDF spherulites, e.g., in the region between the scrolls, until impinging on other PEA transcrystalline layers or spherulites. The crystallization kinetics results indicate that the growth rate of PEA crystals in the intraspherulitic region of γ-phase PVDF shows a positive correlation with content of PEA, but a negative one with the crystallization temperature of γ-phase PVDF.

Techniques for postmortem tenderisation in meat processing:effectiveness,application and possible mechanisms

Developing efficient and promising tenderising techniques for postmortem meat is a heavily researched topic among meat scientists as consumers are willing to pay more for guaranteed tender meat.However,emerging tenderising techniques are not broadly used in the meat industry and,to some degree,are controversial due to lack of theoretical support.Thus,understanding the mechanisms involved in postmortem tenderisation is essential.This article first provides an overview of the relationship of ageing tenderisation and calpain system,as well as proteomics applied to identify protein biomarkers characterizing tenderness.In general,the ageing tenderisation is mediated by multiple biochemical activities,and it can exhibit better palatability and commercial benefit by combining other interventions.The calpain system plays a key role in ageing tenderisation functions by rupturing myofibrils and regulating proteolysis,glycolysis,apoptosis and metabolic modification.Additionally,tenderising techniques from different aspects including exogenous enzymes,chemistry,physics and the combined methods are discussed in depth.Particularly,innovation of home cooking could be recommended to prepare relatively tender meat due to its convenience and ease of operation by consumers.Furthermore,the combined interventions provide better performance in controlled tenderness.Finally,future trends in developing new tenderising techniques,and applied consideration in the meat processing industry are proposed in order to improve meat quality with higher economical value.

A Highly Efficient and Recyclable Solid Acid Catalyst for Synthesis of Spiro-oxindole Dihydroquinazolinones Under Ultrasound Irradiation

A simple,efficient and green procedure for the synthesis of spiro-oxindole dihyfroquinazolinones was developed by multi-component condensation of isatoic anhydride,aniline and isatin in the presence of a novel solid acid catalyst under ultrasound irradiation.The present environmentally benign protocol offers several advantages, such as shorter reaction time,a wide range of fimctional group tolerance,the use of an inexpensive heterogeneous catalyst,and a high yield of products via a simple experimental and work-up procedure.The mesoporous solid acid catalyst was directly prepared from phytic acid by microwave-sulfonation method without template.The phytic acid based solid acid was fully characterized by means of Fourier transform infrared spectroscopy(FTIR),Raman spectroscopy,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and transmission electron imcroscopy(TEM).The catalyst can be recovered and reused for at least five runs without significant impact on the product yields.

Low-temperature combined with high-humidity thawing improves the water-holding capacity and biochemical properties of Portunus trituberculatus protein

This study compared the effects of conventional thawing methods(water immersion thawing(WIT,(25±1)℃),natural air thawing(AT,(25±1)℃,relative humidity(RH(65±2)per cent),refrigerator thawing(RT,4℃,RH(80±2)per cent)and low-temperature(LT)combined with high-humidity thawing LT,-1℃to 1℃(LT-1-1),2-4℃(LT2-4),5-7℃(LT5-7)and 8-10℃(LT8-10),RH>95 per cent)on the water-holding capacity,lipid oxidation and biochemical properties of Portunus trituberculatus(P.trituberculatus)myofibrillar protein.The results showed that WIT and AT significantly decreased the water-holding capacity while dramatically increasing lipid oxidation,protein oxidation and degeneration,resulting in serious P.trituberculatus quality deterioration.High humidity was beneficial for P.trituberculatus\.ha\A/\ng.The thawing time of P.trituberculatus under the conditions of LT2-4 was only 39.39 per cent of that of conventional air thawing at 4℃(RT),and the LT2-4 samples not only maintained better water-holding capacity but also had an obviously reduced degree of lipid oxidation,protein oxidation and denaturation.Thawed samples LT2-4 and LT5-7 provided better maintenance of P.trituberculatus quality than the LT-1-1 and LT8-10 samples.The best quality was exhibited after thawing at 2-4℃.The levels of thiobarbituric acid reacting substances,carbonyl content and surface hydrophobicity observably decreased in these samples,while the total sulfhydryl contents dramatically increased compared to those of conventionally thawed samples,indicating lower lipid oxidation and protein oxidation.Moreover,the Ca2+-ATPase activity of the sample thawed at 2-4℃(2.06 μmol Pi/mg prot/h)was markedly higher than that of samples subjected to WIT and AT.The product qualities observed after thawing at-1℃to 1℃,5-7℃and 8-10℃under LT were comparable to that observed by RT.Considering its thawing efficiency and product quality,LT is a suitable method for the thawing of P.trituberculatus,and the ideal thawing conditions were LT at 2-4℃.