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.

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.

Initial Screening of 10 Plant Essential Oils in Vitro Antibacterial Activity Against Blueberry Pathogens

In order to develop natural antistaling agent for blueberries preservation,the antibacterial activities of 10 kinds of plant essential oils were analyzed by oxford-cup test and tube dilution method,and their inhibitory abilities to two kinds of representative Gram bacteria which are Escherichia coli and Staphylococcus aureus,and three kinds of harmful fungi in blueberries,involving Alternaria alternata,Penicillium digitatum and Botrytis cinerea,were tested.The results showed that 7 kinds of essential oils can inhibit the three fungi,among which cinnamon oil,clove oil,anise oil and thyme oil have strong fungi static efficacy.Cinnamon oil and thyme oil can effectively inhibit the Gram-positive bacterium(Staphylococcus aureus);cinnamon oil and masson pine oil are strongly inhibitory to Gram-negative bacterium(E.coli).Cinnamon oil has broad-spectrum ability to inhibit fungi,Gram-negative and positive bacteria,with a minimum inhibitory concentration(MIC)ranging from 0.0391 to 0.1560 L/mL.With strong inhibition effects on fungi,cinnamon oil can be used as a compound base oil and mixed with other essential oils to retain the freshness of blueberries,thus achieving better antibacterial and anti-corrosion effects.

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.

Characterization of Specific Spoilage Bacteria and Volatile Flavor Compounds of Flavored Crayfish

It is a common issue in the processing industry of crayfish that flavored crayfish stored at room temperature is perishable.In order to establish an effective putrid prediction mechanism,high-throughput sequencing and solid phase microextraction gas chromatography-mass spectrometry(SPME-GCMS)were used to analyse the microbial community structure and volatile flavor compounds of normal and putrid crayfish.The results showed that Aeromonas(57%),Macrococcus(7.7%),Vibrio sp.(6.6%),Acinetobacter(5%),Citrobacter(4.9%)and Enterobacter(1.49%)were the main bacterial genus in the refrigerated fresh crayfish(HNA).And Staphylococcus(17.04%),Aeromonas(4.46%),Xanthomonas(4.16%),Streptococcus(4.62%)and Enterococcus(2.77%)were the main bacterial genus in the marinated and refrigerated crayfish(HND).With the spoilage of samples(HNE and HNC),the diversity of bacteria decreased,and the specific spoilage bacteria grew rapidly,mainly Enterococcus,Bacillus,Lactobacillus,Leuconostoc,Weissella.Meanwhile,the volatile compounds in non-spoilage sample(HNA and HND)were mainly alkane compounds,aldehydes compound and esters compounds;and the volatile compounds in spoilage samples were mainly alcohols,acids,benzene compounds,terpenoids,N-containing compounds,S-containing compounds and ethers.This indicated that the contents and types of volatile compounds changed with the sample spoilage and deterioration.Correlation analysis results showed that Enterococcus,Lactobacillus and Bacillus were significantly positively correlated with alcohols,acids,benzene,terpenoids,N-containing compounds,S-containing compounds and ether compounds,while Aeromonas,Megasphaera,Acinetobacter,Citrobacter and Vibrio were significantly positively correlated with alkane compounds and esters compounds,and Leuconostoc were significantly positively correlated with alcohol compounds.These results can provide a theoretical guidance for the storage of cooked flavor crayfish at room temperature.

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.

Purification of Starch from Cadmium-Contaminated Rice and Development of Functional Recombinant Rice

In order to provide a new utilization method for cadmium-contaminated rice,a preliminary study of the removal of rice starch cadmium by water,calcium hydroxide,sodium hydroxide and citric acid was conducted,the damage degree of starch was compared by SEM,and then the recombinant rice was obtained by a twin-screw extruder using the starch which met the safety standard.The physical and chemical properties of recombinant rice were analyzed by acid hydrolysis and texture analyzer.The results showed that citric acid was a good rice cadmium removal agent.The quality of recombinant rice prepared from cadmium-removed rice starch was improved;the acid resistance was increased.Heavy metal contaminated rice can be a staple food with better quality and higher value through processing.

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.

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.

Storage Characteristics of Five Kiwifruit Varieties in Hunan Province

Five kiwifruit varieties(Hongyang, Donghong, Jinyan, Cuiyu, Miliang1)in Hunan were picked and stored at room temperature. Sensory indicators(softening rate, decay rate, and firmness), nutritional quality(soluble solid content, titratable acid, and VC), tissue cell aging indexes(malondialdehyde, membrane permeability),and activity of polyphenol oxidase(PPO) and peroxidase(POD) during storage were analyzed. Results showed that firmness of Hongyang, Miliang1, and Cuiyu decreased rapidly, particularly Hongyang. The firmness of Donghong and Jinyan decreased slowly, but the decrease of Jinyan was slower than that of Donghong. Softening rate and decay rate were significantly different among the varieties. To be specific, the softening rate and decay rate of Jinyan were lower than those of Hongyang. Soluble solid content rose at early stage and then declined. Soluble solid content was high in Hongyang after storage for 12 d and high in Donghong and Jinyan after storage for 15 d. Content of titratable acid dropped slowly. Maximum VC content of Donghong,Jinyan, and Cuiyu was higher than that of Hongyang and Miliang 1. The inflection point of relative conductivity increase increase of Jinyan appeared later than that of Hangyang. The MAD content of Jinyan and Donghong kept at a low level. Storage characteristics of different kiwifruit varieties were significant. Storage time was in the order of Hongyang < Miliang 1 < Cuiyu < Donghong < Jinyan. In summary,Hongyang, Cuiyu, and Miliang1 should not be stored for a long time, while longterm storage is favorable for Jinyan and Donghong.

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.

Effects of Chemical Osmotic Pretreatment on Drying Characteristics and Quality of Blueberry under Hot Air Drying

In order to study the effects of chemical osmotic pretreatment on the characteristics and quality of blueberry under hot air drying,fresh blueberries were pretreated with 2.5 g/100 mL K2CO3+0.6 g/100 mL olive oil,and 5.0 g/100 mL K2CO3+0.6 g/100 mL olive oil at(45±0.5)℃,respectively.The changes of water content,rehydration,hardness,microstructure,color difference,active ingredient anthocyanin,total phenol and DPPH radical scavenging capacity of dried blueberries in different treatment groups under hot air drying were compared and analyzed.The results showed that the dehydration rates of blueberries vary greatly according to the type of pretreatments when the samples were dried to the same water content with hot air.Specifically,the dehydration rate of dried blueberries pretreated by 5.0%K2CO3 solution was the highest,followed by 2.5%K2CO3 osmotic pretreatment and lastly the control group;the corresponding dehydration time was 10,14 and 20h,respectively.The physical qualities of dried blueberries,involving the browning degree,color difference,rehydration and microstructure,were significantly different between the chemical osmotic pretreatment group and the control group(P<0.05).The chemical osmotic pretreatment of K2CO3 solution increased the dehydration rate of the samples,shortened the drying time and maintained the quality of blueberries dried with hot air.There was no significant difference between the physical quality of dried blueberries pretreated by 2.5%and 5.0%K2CO3 solution(P>0.05),whereas there was significant difference in drying time and nutrient quality which is characterized by total phenols,anthocyanins,DPPH radical scavenging rate,soluble total sugar(P<0.05).Conclusion:5.0%K2CO3 osmotic pretreatment combining with hot air drying can improve the dehydration rate,shorten the drying time and maintain the physical and nutritional quality.

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 32^nd hour at 15 ℃, the 8^th hour at 25 ℃ and the 32^rd hour 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 ob- served at the 24^th hour at 15 ℃, the 40^th hour at 25 ℃ and the 48^th hour 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 rea- sonable 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 Yang- mai 14, respectively. [Conclusion] The results suggested controlling the tempering temperature and time would be helpful to reduce DON level in grain.

Effects of Wet Superfine Grinding on Polyphenols and Antioxidant Activities of Whole Fruit Pulp of Navel Orange

The navel orange were cleaned and pulverized by a wet superfine grinding and a broken wall cooking machine,then the navel orange whole fruit pulp were obtained by wet superfine grinding once,wet superfine grinding twice,and broken wall cooking machine processing.The particle size distribution,free polyphenols,bound polyphenols and antioxidant activity of whole fruit pulp prepared by the three kinds of pulverization methods were discussed.The results showed that the particle size distribution of the whole fruit pulp by wet superfine grinding was more concentrated compared with the broken-wall cooking machine processing,and the total phenols dissolution rate of the navel orange whole pulp was increased by 6.9%,and the total flavonoid dissolution rate was increased by 13.5%.The results also suggested that wet superfine grinding twice could improve 1,1-diphenyl-2-picrylhydrazyl(DPPH)free radical scavenging activity of polyphenols in the whole fruit pulp,wet superfine grinding once and wet superfine grinding twice also could obviously enhance the reducing power and iron reduction ability of polyphenols in the whole fruit pulp.In conclusion,wet superfine grinding could increase both the polyphenol content and antioxidant activity of navel orange whole fruit pulp,it can be used as a pretreatment processing method for preparing navel orange whole fruit pulp.

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 Shi- itake 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 in- dicated that US could significantly enhance the membrane fluxes. The optimal con- ditions obtained was as follows： 0.60 W/cm2 US power, axial flow-rate of 80 L/h, operation temperature 30 ~C, 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 en- hancement coupled with UF showed the potential for concentration and purification of SP by absorbent resins.

Protective Effect of Immaturue Bitter Orange(Citrus aurantium L.)Flavonoids Extracts on PC12 Cell Injury Induced by 6-Hydroxydopamine

To study the neuro protective effect of flavonoids extracts from immature bitter orange(Citrus aurantium L.),the PC12 cells treated with 6-hydroxydopamine(6-OHDA)were used as the Parkinson’s disease(PD)model.To determine the optimal dose of 6-OHDA for constructing a PD model,PC12 cells were incubated with different concentrations of 6-OHDA for 24 h.After 24 h incubation,PC12 cells of drug groups were added 6-OHDA and different concentrations of flavonoids extracts were measured cell viability by CCK8 for selecting effective concentration of flavonoids extracts;the ROS level was determined using flow cytometry;the levels of MDA,CAT,SOD and GSH-Px were assayed by Colorimetric kit for oxidative stress investigation.Compared with the model group,PC12 cell viability was significantly enhanced(P<0.05),the levels of ROS and MDA were reduced significantly(P<0.05),and the activities of SOD,CAT and GSH-Px were significantly enhanced(P<0.05)in drug groups.In conclusion,immature bitter orange flavonoids extracts could protect PC12 cells against 6-OHDA-induced oxidative stress.

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.