Human beings are up against serious health hazards when ingesting toxins-contaminated shellfish.It is badly required to i-dentify shellfish contaminated by toxins.Near-infrared spectroscopy and a class-specific residual constraint nonnegative representation clas-sification(CRNRC)were applied to recognize toxins-contaminated mussels rapidly.The changes in the tissue of mussels contaminated with diarrhea shellfish toxins(DST)could be reflected in the near-infrared spectral curves.The CRNRC model was used to classify healthy and DST-contaminated mussel samples with the preprocessed near-infrared spectra of mussels as input.Class-specific residual terms and collab-orative representation were introduced into the CRNRC model to relate the coding with classification.The coding vectors of collaborative representation were shown for CRNRC.The optimal parameters affecting the performance of the CRNRC model were determined through ex-periments.The experimental results showed that CRNRC model was superior to collaborative representation classification,and non-negative representation classification(NRC)for the evaluation indexes of average accuracy,F-measure,and 1-specificity.The study indicated that NIRS combined with the CRNRC could distinguish DST-contaminated mussel samples,which had the advantages of intelligence,non-de-struction accuracy,and without chemical reagents.The detection method of CRNRC with NIRS would be extended to detect other seafood products,for example,testing the level of nuclear contamination in seafood products,which could ensure human beings ingest healthy seafood products.
In this study, we investigated the protective effect of selenium (Se)-enriched peptide isolated from Cardamine violifolia (SPE) against ethanol-induced liver injury. Cell proliferation assays show that different concentrations of SPE protect human embryonic liver L-02 cells against ethanol-induced injury in a dose-dependent manner. Treatment with 12 μmol/L Se increases the cell survival rate (82.44%) and reduces the release of alanine aminotransferase, aspartate transaminase, lactate dehydrogenase, and apoptosis rate. SPE treatment with 12 μmol/L Se effectively reduces the concentration of intracellular reactive oxygen species and increases the contents of intracellular superoxide dismutase (51.64 U/mg), catalase (4.41 U/mg), glutathione peroxidase (1205.28 nmol/g), and glutathione (66.67 μmol/g), thereby inhibiting the effect of ethanol-induced oxidative damage. The results of the transcriptomic analysis show that the glutathione metabolism and apoptotic pathway play significant roles in the protection of L-02 hepatocytes by SPE. Real-time qPCR analysis shows that SPE increases the mRNA expression of GPX1 and NGFR. The results of this study highlight the protective effects of SPE against ethanol-induced liver injury.
In this research, Barley was used as the main material to investigate the quality characteristics of disparate sizes of barley flour after superfine grinding. The results showed that moisture content, starch content, solubility, brightness value and whiteness value all increased remarkably with the decline of the particle size of the whole powders (P<0.05). However, the swelling power, peak viscosity, oil absorption, setback value, and the water holding capacity declined obviously with the declined of the size of the barley powder(P<0.05). The results of scanning electron microscopy showed that the particle size declined, the powders shape changed from round or ellipse to irregular shape, and the surface changed from smooth to rough. Meanwhile, compared with the barley powders from regular grinding technology, the quality of the barley powders from superfine grinding was significantly improved, which expanded the application scope of the barley powders in food processing. In conclusion, the quality characteristics of barley flour with different particle sizes were different after superfine grinding, and the barley flour with the size less than 54 μm had the best quality characteristics.
To investigate the suitable forced air pre-cooling conditions for broccoli and the effect of forced air pre-cooling on the stor-age quality of broccoli,this study used alpine broccoli as the research material and chose to precool the broccoli with different air speeds and different wind temperatures.Results showed that the use of a high air speed of 7.4 m/s and a low air temperature of 0 ℃ precooling could reduce the precooling time and save electricity.It also reduced cell membrane damage,increased the activity of superoxide dis-mutase,ascorbate peroxidase,and peroxidase,improved the ability of broccoli to decompose reactive oxygen species,and maintained the quality of broccoli during storage.This study provides a feasible precooling treatment for the preservation of alpine broccoli,which can provide a theoretical basis for the logistical preservation of alpine vegetables in the industry and a research basis for exploring the biological mechanism of the effect of forced air pre-cooling on the storage quality of broccoli.
Fermentation is a crucial technique for enhancing the nutritional value of food materials.This study investigated the impact of Lactobacillus plantarum fermentation on the contents of Moringa oleifera leaves,including proteins,flavonoids,polyphenols,and poly-saccharides,as well as its antioxidant activity.Non-target metabolomics technology was utilized to analyze the changes in metabolites of M.oleifera leaves before and after fermentation.The findings indicated that after ten days of fermentation,the protein content of M.oleif-era leaves increased by 16.12％,flavonoid content by 2.1％,polyphenol content by 16.35％,and polysaccharide content by 42％.However,there was no significant change in the antioxidant activity.Furthermore,the study identified a total of 96 differential metabolites post-fermentation,including 52 up-regulated and 44 down-regulated metabolites.Metabolic pathway analysis revealed five key metabolic pathways,primarily associated with amino acid metabolism and biosynthesis of flavonoids,alkaloids,and other substances.These findings demonstrated that L.plantarum fermentation has a positive impact on the formation of nutrients and the enhancement of biological activity of M.oleifera leaves.Consequently,the results provide a theoretical foundation for identifying metabolites of fermented M.oleifera leaves by Lactobacillus and offer a theoretical reference for developing functional foods from M.oleifera leaves.
To provide basic data for the synthesis regulation and study of the formation mechanism of anthocyanin,this paper investi-gated the changes in the components and relative content of anthocyanin in different growth stages of the wild Lycium ruthenicum Murr.The components and relative content of anthocyanin in stems,leaves,flowers,and fruits of the leaf-spreading stage,flowering stage,and fruit-ing stage were studied by the ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry and high-resolution mass spectrometry.Results showed that 19 anthocyanin components were found in stems,leaves,flowers,and fruits.The main compo-nent of anthocyanin in the stems,leaves,flowers,green fruits,and purple fruits was delphinidin-3-O-(p-coumaroyl)-glucoside,and pe-tunidin-3-O-rutinoside(trans-p-coumaroyl)-5-O-glucoside in the black fruits.The components of anthocyanin in stems and leaves re-mained unchanged during the 3 growth stages,while the components of anthocyanin in fruits increased from 8 to 13 with the maturity of fruits.The stems,leaves,flowers,and fruits of L.ruthenicum Murr.were rich in anthocyanin.There were mainly 5 anthocyanin compo-nents with relatively high content in these tissues and the proportions of these five main components varied among tissues.The total antho-cyanin content in the stems remained unchanged at different stages,and it increased at the second stage and then decreased at the last stage in the leaves,while it increased significantly in fruit with the maturity of the fruits.This study showed that there were tissue-specific and temporal differences in the accumulation of anthocyanin components in the L.ruthenicum Murr.at different growth stages.The stems,leaves,and flowers of the L.ruthenicum Murr.are also rich in anthocyanin and have potential application value.
In order to investigate the usage of endophytic fungus Diaporthe orixae sp.nov.from the Orixa japonica on the biosynthesis of silver nanoparticles and their catalytic activity,the endophytic fungus D.orixae was used in this study,the silver nanoparticles were synthesized by the hypha lysate,the synthesis conditions were optimized,the synthesized silver nanoparticles were characterized,and the catalytic activity of the synthesized silver nanoparticles was further investigated.The optimum conditions for the synthesis of silver nanop-articles in the hypha lysate of strain D.orixae were as follows:reaction time 12 h,strain biomass 5 g,AgNO3 concentration 2.0 mmol/L,pH 8,and 55 ℃.Scanning electron microscope results showed that the synthesized silver nanoparticles were spherical and had good dis-persion;the X-ray diffraction pattern showed that the synthesized nano-silver crystal structure was face-centered cubic structure;the strain D.orixae was identified by Fourior transform infrared analysis self-carrying hydroxyl,carbonyl,amide bond,and other functional groups may contribute to the formation and stabilization of silver nanoparticles.In addition,the silver nanoparticles synthesized in this experiment have good catalytic activity for 4-nitrophenol,methyl orange and methylene blue.Endophytic fungus D.orixae the hypha lysate can be used for green synthesis of silver nanoparticles,and the synthesized silver nanoparticles have potential research value in green catalytic degradation of 4-nitrophenol and organic dyes.
This paper used hydrophilic emulsifier Tween 80 and oleophilic emulsifiers monoglyceride(MAG)in different mass ratios to prepare the whipped cream,the total mass fraction of the compound emulsifier was fixed to 0.3％,and the synergistic effect of Tween 80 and MAG on product quality was studied through studied the change of emulsion interfacial film properties and fat crystallization proper-ties.Results showed that the protein concentration of the liquid phase and apparent viscosity of emulsion decreased,the heat resistance of the crystalline increased,the β'crystal was obvious,the overrun of products increased,and the leakage rate of foam whey decreased when the mass ratio of Tween 80 to MAG increased from 1∶1 to 1∶4.When the mass ratio of Tween 80 and MAG was 1∶5 and 1∶6,the β'crys-tal content of crystalline fat in emulsion decreased,the crystal size decreased significantly,the overrun of product decreased,and the leakage rate of foam whey increased.Therefore,the mass ratio of Tween 80 to MAG of 1∶4 met the requirements of industrial production of high-quality whipped cream.At this ratio,the stirring time of the product was only(277.3±2.5)s,the overrun was(158.9± 1.23)％,the leakage rate of foam whey was only(1.55±0.47)％,and the emulsion had good stability.
Creatininase,an important tool enzyme for in vitro detection reagents,is currently produced mainly by microbiological methods,which suffer from low yield and poor activity,limiting its practical application.Herein,recombinant Escherichia coli BL21(DE3)/pET28a-CA was constructed by whole gene synthesis and heterologous expression,obtaining high-performance creatininase.The optimal medium composition was determined by single-factor test and response surface design analysis,and the fermentation conditions were systematically optimized,resulting in improved creatininase expression.The medium optimization results showed that the optimal me-dium consisted of glucose 10.33 g/L,yeast extract 21.80 g/L,phosphate 137.63 mmol/L,tryptone 15.60 g/L.After optimization of the fermentation process in 5 L fermenters,the enzyme activity and specific enzyme activity of creatinine was greatly improved and reached 470.24 U/mL and 367.38 U/mg,respectively,under the conditions of 4％inoculum,25 ℃ induction temperature,18 h induction time,0.2 mmol/L IPTG and 30％dissolved oxygen value.This study provides a theoretical basis and technical support for the production and industrial application of creatininase.
With the continuous development of China's wine industry,the problem of homogenization among regions is becoming more and more serious.Marselan is a promising variety that has been performing well in various regions in China in recent years.In order to analyze the characteristics and differences between the commercial wines of Marselan in Ningxia and Hebei and to reveal the different quality in different regions,we analyzed the physicochemical indexes,organic acid,anthocyanin,other phenolics and antioxidant capacity of 27 commercial Marselan wines from Ningxia and Hebei regions,combining with orthogonal partial least squares-discriminant analysis(OPLS-DA)and correlation analysis.The results showed that there was no significant difference in the total acid content of the two re-gions.Other physicochemical indexes were significantly different.Succinic acid was the monomeric organic acid with the greatest differ-ences between the two regions.The content of cyanidin 3-O-glucoside(0.001 1 g/L)was higher in Hebei,and malavidin 3-O-glucoside of Ningxia was higher than Hebei by 0.033 g/L.The OPLS-DA model based on the monomeric phenol content was the best in differentia-tion,where eleven monomeric phenols play a key role in the establishment of this model.The results of antioxidant capacity and correla-tion analysis showed that the antioxidant capacity of samples from Hebei region was significantly higher than that of Ningxia.Total and monomeric phenolics contributes significantly to this,especially(-)-epicatechin gallate and 2,5-dihydroxybenzoic acid.
Aquatic products play an import role in our life.Spoilage of aquatic products causes huge economic losses and seriously af-fects quality safety of aquatic products.Solving spoilage issue of aquatic products becomes urgent.More and more researches indicate that spoilage of aquatic products has close relation with quorum-sensing(QS)of spoilage bacterial.Therefore,we try to elucidate the classifi-cation of QS system,overviews QS phenomena of spoilage bacterial existing in common aquatic products,and states the relationship be-tween QS of spoilage bacterial and spoilage of aquatic products from perspectives of spoilage indicators and formation of biofilm.The role of quorum-sensing inhibitor(QSI)in inhibiting the spoilage of aquatic products,and the feasibility and future development trend on how to control the spoilage of aquatic products by regulating the QS of spoilage bacterial are also discussed,aiming to provide better under-standing of the microbial QS system and developing new intervention strategies to prevent seafood spoilage.
The metabolites from wax gourd pith were separated and identified by ultra-high performance liquid chromatography-tandem mass spectrometry-based extensive metabolomics technology and the information about the composition and abundance of metabolites in wax gourd pith was analyzed and described.By measuring the total flavonoids,total phenols,and antioxidant capacity of four parts of wax gourd skin,pulp,pith,and seed,it was found that the total flavone content of wax gourd pith was second only to that of wax gourd pulp,while the wax gourd pith had the highest total phenol content and the strongest antioxidant capacity.Therefore,the wax gourd pith was se-lected as the research object to analyze its chemical composition.Results showed that a total of 825 metabolites were isolated and identi-fied from the pith of wax gourd,including 451(59.01％)primary metabolites and 374(40.99％)secondary metabolites,including ami-no acids and their derivatives(114,21.41％),lipids(123,13.28％),organic acids(74,10.82％),sugars and alcohols(58,6.68％),nucleotides and their derivatives(62,5.62％),vitamins(20,1.22％),phenolic acids(161,21.10％),alkaloids(57,7.84％),flavonoids(92,7.36％),lignans and coumarins(51,3.63％),and terpenes(13,1.06％).The flesh of wax gourd was rich in various metabolites with high abundance and also had significant nutritional function,active effect and efficacy.The metabolites with relative content ≥0.5％had an important contribution to the nutrition and activity of wax gourd by-products.The results of this study provide a theoretical basis for the deep processing and utilization of wax gourd pulp by-products and improve the added value and economic benefits of the wax gourd industry.
β-Galactosidase is a widely used food additive,primarily used to degrade lactose in dairy products and alleviate symptoms of lactose intolerance.In this study,we optimized the fermentation conditions of Kluyveromyces marxianus,a strain preserved in our labo-ratory.Under the conditions of 20 g/L galactose,20 g/L corn steep powder,40 ℃,initial pH 6.5,and 150 r/min,the crude enzyme displayed an enzyme activity of 26.3 U/mL,indicating that the strain had the potential to efficiently produce β-galactosidase using cheap carbon and nitrogen sources.Further purification via DEAE anion exchange chromatography resulted in a purified enzyme with a specific activity of 124.09 U/mg.The purified enzyme exhibited an optimal temperature of 40 ℃,an optimal pH of 6,a Michaelis constant of 5.28 mmol/L,and a catalytic constant of 4.74 s-1.Additionally,the enzyme was found to be promoted by Mg2+and exhibited excellent thermal stability between 20-40 ℃,retaining 95.6％activity at 40 ℃ for 30 min.As K.marxianus,which belongs to the same edible strain as Kluyveromyces lactis,its β-galactosidase has better thermal stability than common K.lactis,and has potential industrial applica-tion potential.
To reveal the differences of potential functional between goat milk and sheep milk exosomes.The exosomes from goat milk and sheep milk were extracted and identified,then a high-throughput sequencing based on Illumina platform was conducted to analysis the non-coding small RNA(sRNA)and the expression profile of micro-RNA(miRNA)was annotated.161 known and 5 novel miRNAs se-quences were identified in goat milk exosomes.80 known and 7 novel miRNAs sequences were identified in sheep milk exosomes.Among which,miR-148a,miR-26a and let-7b were highly expressed both in two milk samples.miR-151 was detected only in goat milk exosomes sample.Pathway enrichment showed that the molecular function of miRNA target genes in goat milk exosomes may be involved in binding and catalytic activities.While the miRNAs target genes in sheep milk exosomes had a function of enteromycin binding and a certain pro-motion effect on host growth or development.The results suggest that the miRNAs from goat milk and sheep milk exosomes may have some common and unique target gene and may play functions in alleviating infection and inflammation of pathogens and inhibiting proliferation and migration of cancer cells.The above miRNAs sequencing and analysis studies provided references for the follow-up study of goat and sheep milk exosomes function.
Based on high-throughput sequencing technology,the effects of adding different biochar on microbial community structure and microbial network during artificial pit mud culture,as well as the correlation between internal microbial and physicochemical factors,were analyzed.The results showed that the diversity of microbial community and the relative abundance of dominant bacteria(Clostridium_sensu_stricto_12,etc.)are higher in the artificial pit mud added with distiller's grains biochar generated from slow pyrolysis in muffle fur-nace.It does not affect the stability of microbial network.The microbial population of pit mud was centered on functional microorganisms such as Caproiciproducens.And it had a strong correlation with functional microorganisms such as Clostridium,which is beneficial to the enrichment of Clostridium_sensu_stricto_12 in artificial pit mud.It also inhibited the growth of Lactobacillus,thus promoting the transfor-mation of artificial pit mud to high quality pit mud.In this paper,the microbial communities after the addition of different biochar to artifi-cial pit mud were analyzed,which provided a certain microbiological theoretical basis for revealing the addition of biochar to accelerate the transformation of artificial pit mud to high quality old pit mud.
Using ultrasonic homogenization as a technical means,the glycosylation reaction product(WPI-Lac)of whey protein iso-late(whey protein isolate,WPI)and lactose(D-lactose,Lac)was the water phase,and camellia oil was the oil phase,the camellia oil nanoemulsion stabilized by the glycosylation reaction product was prepared by ultrasonic homogenization.The pH,oil phase mass fraction,ultrasonic power,and ultrasonic time were optimized,and the effects of temperature and pH on emulsion stability were studied,including storage stability and oxidation stability.Results showed that the homogeneous nano-emulsion with a particle size of(206.2±1.572)nm and polydispersity index of(0.136±0.109)could be prepared under the conditions of pH 7.0,oil fraction of 10％,ultrasonic power of 450 W,and ultrasonic time of 10 min.During the 15-day storage period,the peroxide value and the concentration of secondary oxidation products of ultrasonic whey protein isolate glycosylated(UWPIL)-camellia oil nanoemulsion were significantly lower than those of ultrason-ic whey protein isolate(UWPI)-stabilized camellia oil nanoemulsion,and maintained at low levels,based on ultrasonic homogenization treatment.Lactose-modified whey protein isolate was used as an emulsifier,which made the encapsulated emulsion more stable and effec-tively slowed down the oxidation of camellia oil.
To explore the variation rule for composition characteristics of raw material in various Maillard reaction systems,high tem-perature sesame meal protein hydrolysate(HTSPH)as a raw material,xylose,xylose and Cys were added respectively,after being reac-ted at 120 ℃ for 2 h,two kinds of Maillard reaction products were produced.The differences in volatile components,peptides,and amino acids between the raw material and products were detected using GC-MS,LC-MS,and LC,the variation in their apparent characteristics and antioxidant activity was also analyzed.Results showed that physicochemical properties of the two Maillard reaction products were re-markably different.The product derived from HTSPH and xylose had high browning intensity and strong roasted almond flavor,whose vol-atile components were mainly aldehyde,ketone,and heterocycle compounds;whereas,the product originated from HTSPH,xylose and Cys showed strong boiled meat flavor,whose volatile components contained abundant sulfur-containing substances.383 peptides were de-stroyed and 386 peptides were produced throughout the reaction.Physicochemical differences in the peptides of raw material and products included hydrophobicity,hydrophilicity,and amphipathicity.The concentration of free amino acid decreased due to the reaction,and the addition of Cys drastically affected the composition of free amino acids in the two products.Both Maillard reaction products improved sig-nificantly in terms of their antioxidant activities when compared to HTSPH,but the antioxidant capacities of products lagged below Cys.The above results provide the data basis and theoretical reference for investigating the law for the participation of peptide and amino acid in the Maillard reaction,also offer a method reference for the utilization of high-temperature sesame meal.
Probiotics have many health benefits.However,probiotics are easily affected by environmental factors during processing,storage,and human digestion,leading to a reduced vitality and bioavailability to intestine to exert probiotic functions.Dietary fiber has great potential as microcapsule wall materials due to its good biocompatibility,gelation,and film-forming properties as well as a wide range of sources.Dietary fiber microencapsulation technology can provide protection for probiotics,improve their survival rate,stability and achieve controlled release in the intestine.This paper reviews the sources and characteristics of dietary fiber and the preparation meth-ods of microencapsulated probiotics,as well as the application of dietary fiber microcapsules in improving the stability,controlling the re-lease and functional properties of probiotics.Furthermore,we also prospect the development trend of dietary fiber microcapsules as deliv-ery systems.
The biogenic amines(BAs)produced by some microorganisms during the fermentation of traditional Sichuan pickles are toxic to human beings.In order to study the main kinds of BA-producing microorganisms and their BA-producing characteristics,natural fermentation and brine fermentation of cowpea pickle were used as experimental materials,samples were taken at different fermentation pe-riods,and the amino acids broth medium was used as the selective medium to screen BA-producing strains,HPLC was used to quantita-tively analyze its BA-producing capacity,and the high BA-producing strains were selected to explore their BA-producing capacity under different environments(pH,salinity,temperature).The results showed that 26 strains of amines-producing bacteria were screened and identified as 8 genera by 16S rRNA gene sequencing,including Enterobacter sp.,Klebsiella sp.,Leclercia sp.,Pseudocitrobacter sp.,Lelliottia sp.,Pantoea sp.,Weissella sp.and Lactiplantibacillus sp.Among them,Enterobacteriaceae strains had strong BA-producing capacity,with the highest total BAs production of 7 400.13 mg/L,and the main types of BA were putrescine and cadaverine.The effect of temperature on the ability of BA-producing was relatively small,but the effect of pH and salinity on the ability of BA-producing was ob-vious.When pH was as low as 3.5 and salinity was as high as 80 g/L,the BA-producing capacity of the strains was strongly inhibited.The results provided some theoretical reference for controlling the growth of BA-producing microorganisms and reducing the accumulation of BAs in pickles.
In this study,the effect of hot air drying and vacuum freeze-drying on the drying characteristics and quality of'Meihong'and'Fuji'apple slices was investigated.Water status,texture characteristics,nutritional quality,and sensory evaluation of'Meihong'apple slices during drying were evaluated.Results showed that both the hot-air drying and vacuum freeze-drying were reduced-speed dr-ying,and the drying rate of hot-air drying was faster.As to the water status,it could be seen that free water disappeared primarily in the early drying stage.The water binding ability of'Meihong'apple slices was weaker than that of'Fuji'apple.The brightness(L*)value of'Meihong'apple slices reduced after hot-air drying and increased after vacuum freeze-drying.When the moisture content was higher than 40％,the total color difference(△E)of apple slices significantly increased(P＜0.05).The content of dry-based total phenols and flavonoids in'Meihong'apple slices significantly decreased after hot-air drying(P＜0.05),while vacuum freeze-drying had no signifi-cant changes(P＞0.05).Hot-air drying led to compact structure,higher hardness,and obvious surface shrinkage.Vacuum freeze-dr-ying slices showed a uniform appearance,porous structure,and higher rehydration.In conclusion,vacuum freeze-drying is suitable for the drying of high-flavonoid red-fleshed apple slices.
