Takifugu rubripes has a delicious taste. To date, a series of umami peptides have been separated and identified from T. rubripes, but their formation mechanism is not yet clear. Cathepsin L degrades myofibrillar protein and troponin during muscle degradation and thus plays an important role in the flavor formation. This study aimed to elucidate the possible mechanism of flavor peptide formation. We obtained a 1 336 bp sequence of cathepsin L gene from the NCBI database, and extracted RNA from the muscle of T. rubripes, and then reverse-transcribed it into cDNA. PET-28a (+) as the expression vector and E. coli BL21 as engineering bacteria was used to clone and express the cathepsin L gene. Recombinant cathepsin L was obtained with a molecular mass of 36 kD, and the E. coli expression system was also successfully validated. This study can provide useful information for further studies on enzymatic characteristics and of cathepsin L and its role in taste formation in T. rubripes.

The exopolysaccharide of Grifola frondosa possesses anti-tumor, anti-HIV, and anti-oxidant effects. In order to investigate the genetic basis for polysaccharide synthesis by G. frondosa, the transcriptome of G. frondosa was sequenced by high-throughput sequencing technology. A total of 74 575 910 reads and 10.4 G data were generated, which formed 18 077 Unigenes after de novo splicing. A total of 11 651 Unigenes were annotated in the Nr database. Among them, G. frondosa transcriptome had the most similar sequence (18.74%) to M. tumefaciens. A total of 8 332 Unigenes were annotated in the GO database, which were divided into 3 major categories: molecular composition, molecular function and biological processes, including 59 branches. Compared with the KEGG database, 5 200 Unigenes were annotated which belonged to 376 metabolic pathways. A total of 1 155 simple sequence repeat (SSR) loci were found in 18 077 Unigenes, among which the highest repeat was single nucleotide whereas the repetition of hexanucleotide was the least, and the frequency of A/T was the highest. In this study, 115 unigenes which have been annotated in the database of KEGG were related to the biosynthesis of polysaccharide by G. frondosa. These annotated Unigenes and the information about them can lay the foundation for further studies on polysaccharide metabolism pathways and related functional genes in G. frondosa.

The aims of this study were to optimize the culture conditions of Monilinia fructicola for the production of cell wall degrading enzymes (CWDE) and to clarify the role of the culture supernatant obtained as crude CWDE in the pathogenesis of brown rot caused by Monilinia fructicola in postharvest plums. The optimization of the culture conditions was carried out using one-factor-at-a-time and orthogonal array design methods. Besides, the pathogenesis was investigated by wounding and inoculating plum fruits with the crude CWDE and observing the incidence of brown rot. The results showed that the optimal culture conditions were as follows: culture time, 6 d; pH, 6.0; 3.5% sucrose as carbon source; and 2.5% KNO3 as nitrogen source. The crude enzymes produced by M. fructicola could cause brown rot of plum fruits. In addition, the activities of polygalacturonase (PG), pectin methylgalacturonase (PMG) in the fruits inoculated with the crude enzymes were enhanced, thereby leading to the conversion of insoluble protopectin to soluble pectin and cellulose reduced cellulose content and consequently accelerating the softening and rotting process.

The present study aimed to purify and characterize a novel bacteriocin produced by Lactobacillus panis C-M2. The bacteriocin was purified through sequential ethyl acetate extraction, cation exchange chromatography and semi-preparative high-performance liquid chromatography (RP-HPLC). Finally, the specific activity reached 5 044.96 AU/mg and the purification fold was 79.8, but the recovery was only 0.35%. The bacteriocin had a molecular mass of 863.52 D and its N-terminal sequence was MVKKTSAV as determined by LC-MS/MS, showing low similarity with other class II bacteriocins reported earlier. It showed a good stability to heat and pH and retained 82.1% of the original antibacterial activity even after exposure to 121 ℃ for 15 min and retained 85.6% of the original activity at pH 6. The bacteriocin could be totally inactivated after treatment with protease, but it was not sensitive to lipase or amylase. These results indicate the potential of the bacteriocin for application in food preservation.

This study aimed to fully demonstrate the microbial diversity in dairy products from Xinjiang, China and to compare the microbial community composition of raw and fermented milk from different animal species. The composition and structure of bacterial communities in bovine milk, camel milk, mare’s milk, caprine milk, fermented cow milk, fermented camel milk and koumiss from Kizilsu Kirghiz and Tacheng regions of Xinjiang were analyzed based on high-throughput sequencing of the V4-V5 region of the 16S rDNA. A total of 539 557 effective sequences and 379 OTUs were obtained. The results showed that the Shannon-Wiener diversity index for raw milk was higher than that for fermented milk. The microbiota of raw and fermented milk were significantly different. Two bacterial phyla, Firmicutes and Proteobacteria, dominated the microbiota of all seven dairy products, and Proteobacteria dominated the microbiota of raw milk, while Firmicutes was the predominant phylum in fermented milk. At the genus level, Pseudomonas was dominant in cow milk, Escherichia-Shigella was the major bacterial population in camel milk, Leuconostoc was the most abundant bacteria in mare’s milk, Lactococcus was the dominant bacteria in goat milk samples, and Lactobacillus dominated the microbiota of yogurt, camel yogurt and koumiss. The microbiota in raw and fermented milk from different animals were significantly different, and the abundances of environmental bacterial and pathogenic bacteria (or conditional pathogenic bacteria) in raw milk were highest. The results of this study would provide preliminary data of the microbial diversity in dairy products to assess their effect on the health of Xinjiang minorities.

Codon optimization, construction of recombinant baculovirus system (Bac-to-Bac), screening of optimal expression conditions and Ni-chelating affinity chromatography were used to develop an efficient strategy for the expression and purification of β2 adrenergic receptor（β2AR）gene in Sf9 cells. The modified β2AR gene was artificially synthesized and cloned to the transfer vector pFastBac1 to construct the recombinant baculovirus expression plasmid pFastBac1-β2AR′. Then Sf9 cells were transfected with the recombinant plasmid. The expression conditions were optimized. The expression product was purified by Ni-NTA-affinity chromatography and its ligand binding affinity was determined by enzyme-linked immunosorbent assay (ELISA). The results showed that the optimal expression conditions were as follows: multiplicity of infection (MOI) of the infected cells, 5; and expression time, 48 h. In the Western blot analysis, a single band with an apparent molecular mass of 47 kD appeared as expected. After purification, the recombinant protein was more than 90% pure. The ligand binding assay indicated that it could specifically bind to all three horseradish peroxidase (HRP)-β-agonists: clenbuterol, salbutamol, ractopamine, and the OD values obtained from ELISA were 0.983, 0.947 and 0.912, respectively. In this paper, the efficient expression of β2AR in Sf9 cells was accomplished. Furthermore, the purified receptor protein remained better binding affinity to β-agonists, laying a foundation for developing a rapid multi-residue assay for the determination of β-agonists with β2AR.

Meat flavorings were prepared by thermal reactions of enzymatic hydrolysates of black pig and common white pig (large white) meat proteins with oxidized lard. The volatile compounds of the two meat flavorings were analyzed by solvent assistant flavor distillation (SAFE) combined with gas chromatography and mass spectrometry (GC-MS). Based on retention indices and mass spectra, a total of 123 volatile compounds, including sulfur-containing compounds, nitrogen-containing heterocycles, oxygen-containing heterocycles, aldehydes, ketones, alcohols, acids, esters and hydrocarbons, were identified. In comparison, the white pig meat-derived flavoring had a greater percentage (relative to the total peak area) of alkyl furanes, aliphatic aldehydes and acids while the black pig meat-derived flavoring had a greater percentage of sulfur-containing compounds, nitrogen-containing heterocycles, and esters. However, their relative contents of ketones and alcohols were similar. Furthermore, by gas chromatography-olfactometry (GC-O), a total of 31 odor-active compounds were identified through comparison of their retention indices and odor characteristics with those of authentic standards. Among them, 28 compounds were common to two meat flavorings, and in particular dimethyltrisulfide, furfuryl mercaptan, 3-ethyl-2,5-dimethylpyrazine, 3-(methylthio)propanal, 2-ethylthiophene, (E,E)-2,4-decadienal, (E)-2-decenal, (E)-2-nonenal, 1-octen-3-ol and 3-hydroxy-2-butanone had high flavor dilution (FD) factors. However, the number of compounds with high FD values was greater in the black pig meat-derived flavoring than in the white pig meat-derived flavoring. Additionally, the spider-web plots for the potent odor-active compounds revealed that the black pig meat-derived flavoring had higher scores for meaty and fatty odors than the black pig meat-derived flavoring, which could explain why the black pig meat-derived flavoring had stronger meaty aroma than the black pig meat-derived flavoring.

Purpose: The effects of cryogenic treatment on volatile compounds and monomeric phenols in Cabernet Sauvignon grape skins and musts were investigated to ascertain the optimum temperature for wine quality improvement. Methods: Cabernet Sauvignon grapes were treated at temperatures of 16 (control), 4, –8, –20 and –32 ℃, respectively. Then the aroma compounds and monomeric phenols were qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). Results: Thirty-four aroma compounds were detected simultaneously in both grape skins and musts. The contents of esters, organic acid and alcohols were significantly increased in musts but were reduced in grape skins after exposure to –8, –20 and –32 ℃. Treatment at 4 ℃ led to increased contents of aroma compounds in grape skins rather than in musts. A total of 18 monophenols were detected. After cold and freezing treatments, monophenol contents were decreased in grape skins and increased in musts, but the effect was not significantly correlated with temperature. Conclusions: Cryogenic treatments increased the contents of esters, organic acids, alcohols and monomeric phenols in grape must, but had in the opposite effects on skins.

Headspace solid phase micro extraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was employed to detect the contents of taste-related amino acids, fatty acids, betaine and aroma components in the hepatopancreas, ovary, muscle of wild, “Keyong No. 1” and aquaculture populations of Portunus trituberculatus. For the evaluation of flavor and nutritional differences, statistical analysis of the obtained data was made by one-way analysis of variance (ANOVA). The results indicated that taste active values (TAV) of glutamate were greater than 1 in all tissues suggesting it to be the major contributor to the umami taste of all tissues, followed by glycine and alanine, both of which were the main contributors to sweetness. “Keyong No. 1” was superior to wild and cultured populations with respect to the amino acid-derived flavor, and glutamic acid, arginine, and alanine could be considered as the characteristic amino acids in the female hepatopancreas of “Keyong No. 1” and the muscle of male “Keyong No. 1” craba, respectively. The flavor of the populations in terms of betaine was decreased in the following order: wild > “Keyong No. 1” > aquacultural. A total of 33 fatty acids were detected in all the populations, while the contents of C18:2t(n-6) and C22:6(n-3) in the ovaries of aquacultural population were significantly lower (P < 0.05) than those in wild and “Keyong No. 1” populations, respectively. The contents of C15:1 and C17:1 in the male hepatopancreas and the contents of C18:3(n-6), C20:3(n-6), C21:0, C22:2, C23:0, and C24:0 in the muscles of wild and “Keyong No. 1” male populations were significantly higher than those of farmed population, respectively. Consequently, it was proved that the wild and “Keyong No. 1” populations were superior to the aquacultural population with respect to the flavor contributed by polyunsaturated fatty acids. A total of 88 volatile flavor compounds were identified in the ovary of the three populations including alkanes, aldehydes, alcohols, esters, ketones and phenols. Among these compounds, 13 were common to all these populations with no significant differences being observed for their relative contents overall. The difference in the contents of branched alkanes and toluene in the three populations may be the main cause of the flavor differences, which needs to be confirmed in further study.

The effect of aliphatic aldehydes on Maillard reaction and meaty flavor formation was investigated in cysteine-xylose model systems. The Maillard reaction in the absence and presence of hexanal, (E)-2-heptenal, or (E,E)-2,4-decadienal, was carried out at 90 ℃, pH 5.5 for 5 h. Changes in the concentrations of xylose, cysteine, initial reaction intermediates (2-threityl-4-carboxythiazolidine and Amadori rearrangement product of cysteine (Cys-Amadori)) with reaction time were determined by high performance liquid chromatography with evaporate light scattering detection (HPLC-ELSD). Also, changes in the pH and absorbance values at 294 and 420 nm of the reaction mixtures were monitored. Volatile flavor compounds in the 3 h reaction mixtures were compartaively analyzed by solid phase microextraction coupled with gas chromatography and mass spectrometry (SPME-GC-MS). As indicated by decreased concentrations of Cys-Amadori and 2-threityl-4-carboxythiazolidine in the presence of aliphatic aldehydes, all the three aldehydes showed inhibitory effects on the initial stage of the Maillard reaction, among which (E)-2-heptenal was the stongest inhibitor, followed by (E,E)-2,4-decadienal and hexanal. Additionally, hexanal also showed inhibitory effect on the intermediate and final stages of the Maillard reaction, as indicated by decreased absorbance at 294 and 420 nm. However, (E)-2-heptenal and (E,E)-2,4-decadienal accelerated both the intermediate and final stages, as indicated by increased absorbance values at 294 and 420 nm, with the latter being more effective than the former. On the other hand, the reaction systems in the presence of (E)-2-heptenal and (E,E)-2,4-decadienal produced a relatively greater amount of total volatile sulfur-containing compounds than the blank model system, and additionally produced some new alkyl chain sulfur-containing compounds and furane derivatives such as 2-hexylthiophene and 2-propylfuran as detected by GC-MS analysis, due to participation of the aldehydes in cysteine-xylose reaction and reaction of the aldehydes themselves in the buffered cysteine-xylose solution.

It is important for winemakers to understand the chemical constituents of oak heartwood used for barrels as different grain types and toasting regimes influence wine flavor. Changes induced by different heating regimes in low-molecular-weight (LMW) phenolics and volatile compounds of oak heartwood of different grain types were evaluated. The results showed that a higher temperature during the toasting process changed the chemical compositions of the heartwood and increased the amounts of several key soluble and volatile compounds as a result of various heat-induced reactions. Moreover, independent of toasting, the fine-grained oak samples had higher concentrations of volatile compounds, e.g., cis/trans-oak-lactone, cis/trans-isoeugenol, furanic aldehydes, syringol, and LMW phenolics, particularly sinapaldehyde, coniferaldehyde, vanillin, and syringaldehyde, while the medium- and coarse-grained oak samples showed higher levels of total phenol, tannins, ellagic acid and gallic acid. Principal component analysis (PCA) showed that the moderately and heavily toasted samples of medium- and fine-grained oak displayed higher positive correlations with the level of volatile compounds, while the untoasted and lightly toasted heartwood of coarse-grained oak were positively correlated with total tannin and ferulic acid contents.

The proximate composition, monosaccharide composition, fatty acid and amino acid compositions, and mineral contents of the fruiting bodies of Boletus griseus were detected and the protein composition of the mushroom was evaluated by successive extraction. Besides, the nutritional value of proteins of the mushroom was also assessed systematically. Results showed that the crude protein content in the mushroom was 28.22% and the glucose content was 258.04 mg/g. A total of 17 fatty acids were detected, with linoleic acid, oleic acid and palmitic acid accounting for 35.91%, 28.46% and 24.50% of the total fatty acids, respectively. A total of 29 free amino acids were detected, among which, Tyr and Ala showed the highest contents. Sweet amino acids and umami amino acids accounted for 23.37% and 12.69% of the total free amino acids, respectively. The amino acid score (AAS), essential amino acid index (EAAI), biological value (BV), nutritional index (NI) and score of ratio coefficient of amino acid (SRCAA) of essential amino acids in the protein hydrolysate of Boletus griseus, which accounted for 38% of the total amino acids, were 71.88, 69.93, 64.52, 19.73 and 50.05, respectively. B. griseus contained high levels of Mg, Fe, Zn, and Cu. Meanwhile, the toxic element Cd was also at a relatively high level. Furthermore, albumin was the most prominent protein in the mushroom, accounting for 65.62% of the crude protein, but the content of Cd in albumin accounted for 38.79% of total Cd. The molecular masses (mw) of albumin and globulin in Boletus griseus were identified by SDS-PAGE to be around 40 kD. Differential scanning calorimetry (DSC) results showed the thermal denaturation temperatures of the two proteins were 125.04 and 75.04 ℃, respectively. In conclusion, the results indicated that B. griseus showed high nutritional quality, but its consumption could pose considerable health risk due to the high content of Cd.

The volatile flavor components of sweet and sour spareribs flavoring were extracted by solid phase microextraction (SPME) and then were determined by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). The results showed that a total of 55 volatile compounds were identified in the flavoring, including 11 hydrocarbon (16.45%), 3 ethers (13.41%), 10 alcohols (12.38%), 5 nitrogen-containing compounds or heterocyclic compounds (12.03%), 4 ketone (5.45%), 3 esters (3.82%), 8 aldehydes (3.54%), 6?acids (3.46%), and 5 phenols (1.74%). A total of 12 key aroma compounds were identified by GC-O, including β-pinene, acetic acid, furfural, 2,3,5,6-tetramethylpyrazine, benzaldehyde, linalool, 3-methyl-butanoic acid, trans-2-decenal, (E,E)-2,4-decadien-1-al, 4-hydroxy-2,5-dimethyl-3(2H) furanone, anisaldehyde, and eugenol.

Textural analysis, electronic nose and solid phase microextraction combined with gas chromatography-mass spectrometry (SPME-GC-MS) were used to analyze the texture and flavor properties of biscuits incorporated with surimi and potato flour. Based on sensory evaluation and texture properties, the optimal formulation was composed of low-gluten wheat flour added with 30% potato flour, 20% potato starch, 40% surimi, and 40% palm oil. Then the flavor compounds of biscuits incorporated with surimi, potato flour, or both and common biscuits were analyzed by electronic nose and SPME-GC-MS. The results indicated that the main flavor substances of the four biscuits were heterocyclic compounds, hydrocarbons and aldehydes, with the Maillard reaction products methylpyrazine and 2,5-dimethylpyrazine being the predominant constituents. The number and amounts of aldehydes detected in biscuits incorporated with surimi were significantly increased as compared to three other samples. Our findings provided the scientific basis for the research of flavor characteristics of biscuits and provided a useful reference for the exploitation and utilization of potato and surimi.

The aim of this study was to explore the effect of adding superfine powder of grape seed residue from oil extraction into cookies on aroma components and sensory quality. The aroma constituents of common grape seed powder, ultrafine powder of grape seeds (UPGS) and cookies with and without UPGS were detected by gas chromatography-mass spectrometry (GC-MS). Partial least squares discriminant analysis (PLS-DA) was used to study the effect of UPGS on the aroma components of cookies. The results showed that the species of aroma substances were not changed markedly, but the aroma content was increased remarkably after ultrafine pulverization of grape seed meal. Upon the addition of 5% UPGS, the baking aroma of cookies was relatively rich. The flavor of cookies with 10% UPGS was composed of a complex mixture of bitter apricot kernel, banana, fruity grassy, bread and nut aromas. The results of 9-point hedonic sensory evaluation showed that the addition of UPGS could cause perceived sensory changes of cookies. Upon the addition of 5% UPGS, the aroma score was the highest. In conclusion, UPGS addition could cause a positive impact on the aroma of cookies, and a proportion of less than 10% could be accepted by consumers.

A method using high performance liquid chromatography with diode array detection and fluorescence detection (HPLC-DAD-FLD) was developed to simultaneously analyze 12 compounds of polymethoxyflavones (PMFs), coumarins and furocoumarins in citrus juice samples. Baseline separation of twelve compounds was achieved within 30 min using gradient elution with a ternary mobile phase composed of 0.01% phosphoric acid, methanol and acetonitrile. Qualitative identification of the components in citrus juices was confirmed by comparing their UV and fluorescence (FL) spectra and retention times with those of the reference standards. Quantitative analysis of the juice components was operated at a UV wavelength of 320 nm (OD320 nm) and a fluorescence emission of 450 nm. The calibration curves showed good linearity. The limit of quantitation (LOQ) with FLD was at as low as μg/L level so that FLD could be an important complementary tool to UV detection. The recovery tests showed a good accuracy for both UV (95.2%–104.8%) and FL (94.5%–103.5%) examination. In general, this method is accurate and reliable for qualitative and quantitative analysis of citrus juice components, especially the ones having fluorescence emission like PMFs and coumarins.

This study aimed to evaluate the changes in nutritional quality during the processing of giant salamander soup. At five different lengths of cooking times (30, 60, 90, 120, and 150 min), the nutritional indexes including soluble solids content, soluble protein content, crude fat content, inosine monophosphate content, fatty acid and amino acid composition were analyzed. The results showed that the contents of soluble solids and soluble protein in giant salamander soup increased significantly from 30 to 60 min, tended to be stable during the following 60 min, and then significantly increased again from 120 min onward; inosine monophosphate content was increased during the whole cooking period of 150 min. A total of 16 fatty acid were detected from giant salamander soup, the predominant ones being palmitic, palmitoleate, oleic acid, linoleate acid, cis-5,8,11,14-eicosatetraenoic and nervonate; the ratio of saturated fatty acids to polyunsaturated fatty acids (SFA/PUFA) decreased at first and then increased, and desired contents of crude fat and fatty acids were obtained at 60 min, together with the lowest SFA/PUFA ratio (1.37). The contents of total amino acids, essential amino acids and umami amino acids and the ratio of essential to non-essential amino acids first increased with cooking time until reaching a peak at 60 min (239.529 mg/100 g total amino acid content, 0.858 EAA/NEAA ratio), and then decreased. In conclusion, giant salamander soup cooked for 60 min under atmospheric pressure condition had a better nutritional quality as indicated by the highest amino acid content, the best SFA/PUFA ratio and a desired fat content.

Objective: To fingerprint dark tea from Anhua, Hunan using high performance liquid chromatography (HPLC) and to quantitatively determine its major water-soluble constituents for the purpose of providing theoretical evidence for the identification of Anhua black tea. Methods: A total of 22 dark tea samples from Anhua, Hunan and 4 dark tea samples from other provinces (Liupu tea from Guangxi, Tusi tea from Sichuan, brick tea from Hubei and Pu’er tea from Yunnan) were fingerprinted by HPLC. The chromatographic conditions were as follows: gradient elution using 0.17% acetic acid aqueous solution as mobile phase A and acetonitrile as mobile phase B; column temperature, 30 ℃; flow rate, 1.0 mL/min; and detection wavelength, 280 nm. Similarity evaluation and principal component analysis were performed to ascertain the peaks common to these tea samples. Results: A total of 19 peaks were common to all Anhua dark tea samples with similarities ranging from 0.783 to 0.958 while the similarities between Anhua dark tea and other dark tea samples were quite low (lower than 0.3). Furthermore, the contents of gallic acid and epigallocatechin gallate in Anhua dark tea were remarkably higher than in any other dark tea, but caffeine in Liupu tea and gallocatechin in Pu’er Tea were significantly more abundant in Anhua dark tea. In addition, fuzhuanin A could be detected only in Anhua dark tea and hence regarded as an effective indicator for the identification of Anhua dark tea. Conclusion: The established HPLC fingerprinting method can be used to identify and evaluate Anhua dark tea based on fuzhuanin A content.

This work reports the effect of heat processing treatments on the characteristic flavor components of Chlamys nobilis adductor muscle as determined using high performance liquid chromatography (HPLC) and headspace solid phase micro extraction coupled to GC-MS (HS-SPME-GC-MS), in comparison with fresh and vacuum freeze dried samples. The results showed that the contents of crude protein and crude fat in scallops were little affected by various processing treatments. Compared with fresh C. nobilis adductor muscle, the contents of AMP, betain and Cl- and Na+ were increased significantly (P < 0.05) and the contents of free amino acids, K+, nucleotides and related compounds (except AMP), succinic acid and PO43- were decreased significantly (P < 0.05) after heat processing treatments. However, vacuum freeze drying caused less significant changes. A total of 63, 34 and 64 volatile compounds were identified from heat processed, fresh and vacuum freeze-dried scallops, respectively. The major volatile compounds in three scallops were alcohols, acids and hydrocarbons, and aldehyde, which accounted for 26.20%, 30.84%, 29.38%, and 16.78% of the total volatile compounds, respectively. The major odors of heat processing treatments scallops were confirmed as fishy, honey like, fruity, fatty and greasy, trimethyl amine, 1-octen-3-ol, (2Z)-2-penten-1-ol, 1-penten-3-ol, 1-pentanol, nonanal, undecanal, hexanal, heptaldehyde, benzaldehyde, octanal, decanal and 3-octanone were found to be involved in the formation of characteristic flavor components.

The objective of the present study was to optimize the preparation of liposomes incorporating the angiotensin converting enzyme (ACE) inhibitory peptide Arg-Leu-Ser-Phe-Asn-Pro (RLSFNP) using combination of one-factor-at-a-time method and response surface methodology. The response variable was the entrapement efficiency. The optimum preparation conditions were determined as follows: soy lecithin, 120.0 mg; cholesterol, 24.6 mg; RLSFNP, 15.3 mg; ether, 15 mL; PBS buffer (pH 7.4), 5.8 mL; and ultrasonication time, 5.2 min. Under these conditions, the average diameter, potential and entrapement efficiency of liposomes were 168 nm, –31.2 mV and (67.5 ± 0.8) %, respectively. The liposomes could sustainably release RLSFNP.

This study aimed to obtain the optimum conditions for the extraction of free amino acids from the flesh of Canarium album fruits by the combined use of one-factor-at-a-time method, Plackett-Burman design, steepest ascent design and response surface methodology. The results showed that the effects of factors on the extraction yield of free amino acids were in the descending order of solid-to-liquid ratio > number of extraction cycles > ultrasonication time > ultrasonic power > ethanol concentration > temperature, and the optimum levels of these variables were determined to be 20 min, 1:41 (g/mL), 3, 50 ℃, 270 W and 60%, respectively. Under these conditions, the predicted extraction yield of free amino acids was 77.84 mg/g while the actual value was 79.88 mg/g. The relative error was 2.62%, indicating that the optimized extraction method was reliable.

Seabuckthorn pomace is rich in phenolic acid and is a byproduct produced during the processing of seabuckthorn pulp. However, the astringency and bitterness of seabuckthorn pomace hinder its utilization in the feed industry. The preparation of microcrystalline cellulose from seabuckthorn pomace is a potential solution to this problem. Therefore, in this study, the crude cellulose extracted from seabuckthorn pomace was hydrolyzed with commercial cellulase S10041 to obtain microcrystalline cellulose. Eight processing parameters were investigated, namely solid-to-solvent ratio, enzyme dosage, hydrolysis time, temperature, buffer pH, centrifugal rotational speed, drying temperature, and comminution degree of cellulose. The significant factors were selected and optimized using one-factor-at-a-time method, Plackett-Burman design, steepest ascent path design and Box-Behnken design combined with response surface methodology. The prepared microcrystalline cellulose was structurally elucidated. The results showed that the degree of polymerization of seabuckthorn microcrystalline cellulose was 355 ± 1.02 under the optimal follows: ratio of buffer solution to cellulose, 49:1 (mL/g); enzyme dosage, 68 U/mL; hydrolysis time, 1.3 h; and centrifugal rotational speed, 3 640 r/min, which was close to that of cotton microcrystalline cellulose. The analysis of variance showed that the four selected factors had independent influences on the degree of polymerization but their interactions had no significant effect on the response (P = 0.10). The scanning electron micrograph revealed that the surface structure of seabuckthorn microcrystalline cellulose was more porous as compared to cotton microcrystalline cellulose. The infrared spectra of two microcrystalline celluloses revealed that similar functional groups existed.

In this study, phytosterol (PS) was included with hydroxypropyl-β-cyclodextrin (HP-β-CD) to improve its solubility and thereby broaden the range of its application in the food industry. The inclusion complex was tested by differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction. The inclusion process was optimized using response surface methodology. The optimum conditions obtained were as follows: molar ratio between PS and HP-β-CD, 4.27:1; temperature, 47 ℃; and inclusion time, 11.93 h, yielding an inclusion rate of 96.57%. However, to improve operating convenience, these parameters were modified as 4.30:1, 47 ℃, and 12 h, respectively. Triplicate experiments carried out under these conditions gave an average inclusion rate of up to 97.25%. At 37 ℃, the water solubility of HP-β-CD/PS clathrate reached an average of 8.31 mg/mL, which was 307.90 times of its original solubility (0.027 mg/mL).

Umami peptide was prepared by microwave-assisted sequential enzymatic hydrolysis of perilla seed meal protein with alcalase followed by flavorzyme. Optimization of the hydrolysis conditions was performed using an orthogonal array design. Sephadex G-15 gel permeation chromatography, reversed phase-high performance liquid chromatography (RP-HPLC) and electronic tongue were applied to characterize the changes in peptide composition and umami taste during the hydrolysis process. The results showed that the optimum conditions for alcalase hydrolysis were as follows: microwave power, 400 W; enzyme dosage, 1 600 U/g; pH, 10.0; temperature, 60 ℃; and hydrolysis time, 35 min, and the optimum conditions for flavorzyme hydrolysis were as follows: enzyme dosage, 1 600 U/g; pH, 6.5; temperature, 65 ℃; and hydrolysis time, 40 min. A degree of hydrolysis of 44.86% was obtained under the optimized conditions. Compared with single enzymatic hydrolysis, the microwave-assisted stepwise enzymatic hydrolysis was quicker and more efficient and showed improved taste.

The aim of the present study was to establish the optimum onboard cooking process for jumbo squid (Dosidicus gigas) by using an independently designed onboard cooking device. The thermal denaturation temperature for squid protein was determined by using a differential scanning calorimeter (DSC). Box-Behnken design coupled with response surface methodology (RSM) was used to optimize the cooking parameters employing cooking loss and soluble protein content as response values. The longitudinal and transverse cross-sectional microstructure of cooked and raw squid muscle tissue was analyzed by scanning electron microscopy (SEM) and texture properties were measured. The changes in squid protein composition were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In addition, the total volatile basic nitrogen (TVB-N) content was determined to analyze the freshness of squid. The results showed that the fitting degrees of the two regression models developed were excellent and there was a good agreement between the actual experimental and the model-predicted values with small relative errors. The optimum cooking temperature, cooking time, and material-to-water ratio were determined to be 85 ℃, 11 min, and 1:2 (kg/L), respectively. The cooking loss was (25.53 ± 0.25)% and soluble protein content was (15.38 ± 0.16) mg/g under these optimized conditions. The transverse cross-sectional microstructure of squid muscle was less damaged by the cooking process, while the space among muscle bundles in the longitudinal cross-section was increased. SDS-PAGE showed that the small protein bands of cooked squid, such as squid tropomyosin, were diminished and even disappeared whereas the other ones were not changed significantly. The texture characteristics of squid were not significantly affected by cooking and the TVB-N value of onboard processed squid was (28.12 ± 0.34) mg/100 g.

This study aimed to improve the extraction yield and evaluate the immune modulatory activity of polysaccharides of Lepista sordida mycelia. Optimization of the extraction conditions was carried out using one-factor-at-a-time and orthogonal array design methods. The immune modulatory effect of the polysaccharides extracted was evaluated by measuring cell survival, TNF-α and IL-6 secretion, the percentage of neutral red phagocytosis and the expression levels of Toll-like receptor (TLR) TLR2 and TLR4 when mouse Ana-1 macrophages were exposed to different concentrations of the polysaccharides. The optimal extraction conditions were determined as follows: extraction temperature, 65 ℃; extraction time, 2.5 h; solvent-to-solid ratio, 40:1 (mL/g), leading to an extraction yield of 15.88%. In the concentration range of 0.05–1.6 mg/mL, the polysaccharides could promote the proliferation of macrophages, TLR2 and TLR4 expression, the phagocytosis of neutral red and TNF-α and IL-6 production; the most effective concentration was 1.6 mg/mL. These data illustrated that the polysaccharides possessed good immune modulatory activity.

The subcritical water extraction of walnut meal protein was optimized by response surface methodology. The variables optimized were extraction time, solid-to-solvent ratio, extraction temperature and pH. The response was the extraction yield of protein. One-factor-at-a-time method was used to determine the appropriate levels of independent variables for further optimization by response surface methodology. The results showed that the optimal conditions were as follows: pH, 9.0; solid-to-solvent ratio, 1:25 (g/mL); and temperature, 133 ℃. Under these conditions, the extraction yield was up to 75.01%. The results of amino acid analysis indicated that the walnut protein contained almost all kinds of amino acids with glutamic acid, arginine, and aspartate being the predominant amino acids, accounting for 59.7% of the total amino acids. Essential amino acids accounted for 20.03%. Sub critical water extraction could be considered as convenient and efficient method for the extraction of walnut protein.

A simple analytical method was established using dispersive solid phase extraction combined with liquid chromatography-positive mode electrospray ionization-tandem mass spectrometric (LC-MS/MS) for the determination of six pesticide residues in ginger, sweet potato, potato, and litchi, including carbendazim, imidacloprid, aldicarb, triadimefon, acetochlor and difenoconazole. The analytes were extracted with acetonitrile and cleaned up using primary secondary amine (PSA) and octadecyl silane (C18). Qualitative analysis of six analytes was carried out under the positive scanning model after the chromatographic separation on a reversed phase C18 column with gradient elution using a mobile phase composed of methanol and 0.1% formic acid aqueous solution. A good linearity was observed for the six pesticides in the range of 10–500 μg/L with a coefficient of determination (r) of greater than 0.995. The recoveries of the pesticides in four classical minor crops were in the range of 87.9%–110.3% at three spiked concentration levels, and the precision, as indicated by relative standard deviations (RSDs, n=5), was not more than 14.6%. The method is simple, rapid and sensitive, and can meet the requirements for the determination of pesticide residues in minor crops.

A novel molecularly imprinted polymer was developed by a one-step polymerization using dicyandiamide as template, methacrylic acid as functional monomer, ethylene glycol dimethylacrylate as cross-linker, and azobisisobutyronitrile as initiator. The physicochemical properties of the prepared material were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and ultraviolet spectroscopy. A molecularly imprinted solid phase extraction coupled with high performance liquid chromatography method was developed using this material to detect dicyandiamide in real milk powder samples. The linear range of this method was from 0.01 to 2.00 mg/L, with a correlation coefficient (R2) equal to 0.999 4, which had a good linear relationship. The limit of detection (LOD) was 0.57 × 10-2 mg/L (RSN = 3). The recovery was ranged from 102.5% to 104%, and the relative standard deviation was between 0.21% and 0.86%.

A high performance liquid chromatography (HPLC) method was established for detecting two antioxidants (Irganox1076 and Irgafos168) in graphene/low density polyethylene (LDPE) composite food packaging films. The effect of time, temperature and the presence of graphene and graphene nanoplatelets on the migration of the antioxidants from LDPE films to isooctane as a fatty food simulant was studied. The interactions of the two antioxidants with isooctane during migration were discussed. The experimental results showed that the migration rates of the antioxidants increased until reaching equilibrium with increasing time or temperature. The antioxidants synergistically affected the migration of each other. The presence of graphene and graphene nanoplatelets hindered the migration of the antioxidants due to their agglomeration and adsorption capacity.

The aims of the study were to quantitatively monitor viable but non-culturable (VBNC) cells of Vibrio parahaemolyticus induced by different conditions and to analyze their respiratory activity. Fluorescence quantitative PCR (qPCR) coupled with propidium monoazide (PMA-qPCR) was used to quantify viable cells of V. parahaemolyticus. A new method combining confocal laser-scanning microscopy (CLSM) and flow cytometry with 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) reduction was applied to detect the respiratory activity of VBNC cells. Results showed that PMA-qPCR with culture-based method allowed successful monitoring of the number of VBNC cells of V. parahaemolyticus and then the density of VBNC cells could be calculated. Seven of the tested conditions could entirely induce cells into VBNC state within 60 day. The minimum and maximum density of VBNC cells were 5.75 × 102 and 1.70 × 105 CFU/mL, respectively. In the respiration test, 5-cyano-2,3-ditolyl tetrazolium chloride/ 4’,6-diamidino-2-phenylindole (CTC/DAPI) staining allowed to clearly distinguish viable cells from dead cells under CLSM by fluorescent formazan. Flow cytometry enabled rapid discrimination between respiratory active and non-active cells based on fluorescence intensity. In summary, this study provided new methods for the detection of V. parahaemolyticus in VBNC state and for better understanding of their metabolism.

A rapid method to detect mutton adulterated with duck by electronic nose combined with gas chromatgraphy-mass spectrometry (GC-MS) was proposed and validated by applying it on adulterated samples of Ningxia small-tailed han sheep meat with different amounts of cooked meat added. The electronic nose responses to the volatile components of meat samples were used to establish qalitative and quantitative models through Fisher linear discriminant analysis (FLDA) and linear regression analysis. Meanwhile, solid phase microextraction coupled with GC-MS was used to detect the volatile compounds. The results showed that different proportions of adulteration could be distinguished by FLDA with an accuracy rate of 98.2%. The correlation coefficient from linear regression analysis was as high as 0.965. A total of 26 volatile compounds were detected by GC-MS, including 3-cyclohepten-1-one and 3-methyl butyraldehyde, which played a significant role in the discrimination of different adulterated samples. The partial least squares regression models established based on the electronic nose and GC-MS data exhibited a determination coefficient of greater than 0.950. There was a high correlation between the response values of sensors S1, S3, S5, S6, S8 and S9 and the GC-MS data.

The feasibility of using Fourier transform infrared (FTIR) spectroscopy and chemometrics as a rapid and non-invasive technique to determine the geographical origin and protein content of Sudanese Acacia gums was investigated. Seventy-two samples of Acacia gums were collected from six different regions (12 samples from each region). Linear discriminant analysis (LDA) was used to discriminate the geographical origin of Acacia gums, and backward interval partial least squares (Bi-PLS) was applied to build a prediction model for the protein content of Acacia gums. The results showed that the recognition rates of LDA for calibration set (48 samples) and prediction set (24 samples) were both 100% when the first 6 principal components were used. In addition, Bi-PLS yielded a good prediction model (RP = 0.937 3 and RMSEP = 0.173%) for protein content by using the optimal combination of 4 out of 20 spectral intervals. Hence, FTIR spectroscopy coupled with chemometrics can be considered as a valid approach for the determination of the geographical origin and protein content of Acacia gums.

A method was developed for the simultaneous determination of 7 pesticide and metabolite residues in vegetables by employing quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction coupled with liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS). Samples were extracted with acetonitrile, and then the extract was purified by dispersive solid phase extraction (SPE) using graphite carbon black (GCB) and C18 sorbent. The analytes were monitored by liquid chromatography-tandem triple quadrupole mass spectrometry in the dynamic multiple reaction monitoring (DMRM) mode, and quantification was carried out by the external standard method with matrix-match standard solution. The recoveries at spiked levels of 10 and 20 μg/kg were in the range from 71.9% to 117.8% and the precision, expressed as relative standard deviation (RSD, n=3), ranged from 0.8% to 9.6% under the selected conditions. The limits of quantification (LOQs) were in the range of 0.2–10 μg/kg. The method proved to be simple, fast, sensitive and useful for the analysis of the 7 pesticides and their metabolite residues in vegetables.

Aim: This study aimed to develop an enzyme-linked immunosorbent assay (ELISA) method for detecting the residues of furazolidone (FZD) in animal food. Method: The indirect competitive ELISA method based on single chain fragment antibody was established. Result: The optimal antigen mass concentration was 2 μg/mL, and the optimal antibody dilution ratio was 1:500, and the optimal reaction time of primary antibody, the optimal reaction time of secondary antibody and the optimal reaction time of TMB were 60 min, 45 min, and 20 min, respectively. The good linearity was seen in the range of 10-100 ng/mL of FZD, with the IC50 value being 13.01 ng/mL, and the lowest detection limit (LOD) being 1.28 ng/mL, and the recovery rates being 73.38%-84.52%. Conclusion: Compared with the monoclonal antibody against FZD, the detection kit based on single chain fragment antibody displayed wider detection range, higher sensitivity, better specificity and detection stability.

A method for the simultaneous identification and quantification of thirteen perfluoroalkyl carboxylic acids (PFCAs), six fluorotelomer saturated carboxylic acids (FTCAs) and three fluorotelomer unsaturated carboxylic acids (FTUCAs) in bivalve shellfish tissues was developed using ultra fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS). Samples were extracted with acetonitrile-water (90:10, V/V), and the extract was cleaned up by solid-phase extraction (SPE) using Oasis WAX SPE coupled in-line to ENVI-Carb. Then, the separation was performed on a Kinetex XB-C18 column (2.1 mm × 100 mm, 2.6 μm) with gradient elution using a mixture of 95% methanol solution containing 5 mmol/L ammonium acetate and 5% methanol solution containing 5 mmol/L ammonium acetate as the mobile phase. Mass spectrometry was carried out under the multiple reaction monitoring (MRM) mode with negative electrospray ionization and the internal standard method was employed for quantification. The calibration curves for 22 analytes were linear well with correlation coefficient over 0.995. The limits of quantification ranged from 0.03 to 1.67 ng/g. The average spiked recoveries for 22 analytes were between 63.05% and 127.18%, with relative standard deviations (RSDs) from 4.70% to 17.1%. This method was successfully applied for the simultaneous determination of 13 PFCAs and 9 potential precursors in bivalve shellfish tissue samples.

A method was developed to simultaneously analyze the contents of five bactericides including 2-methyl-4-isothiazoline-3-one (MI), 5-chloro-2-methyl-3(2H)-isothiazolone (CMI), 1,2-benzisothiazolin-3-one (BIT), pentachlorophenol (PCP) and bronopol, in food contact paper and wood products using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Samples were extracted ultrasonically with methanol. The analytes were separated on an Eclipse Plus column C18 (4.6 mm × 100 mm, 3.5 μm) with methanol-water as the mobile phase. The multiple reaction monitoring (MRM) mode was applied to qualitatively analyze the five bactericides with a positive or negative electrospray ionization source according to their retention times and characteristic structures. The external standard method was used for quantitative analysis. The results showed that the linear ranges of the five bactericides were from 1 to 100 μg/L, and the limit of detection (LOD) of the method (RSN = 3) was in the range from 2.7 to 47 μg/kg. The mean recoveries for paper and wood samples at spiked concentration levels of 8 to 500 μg/kg ranged from 82.88% to 106.31%, and the precision relative standard deviations (n = 5) were 0.5%–8.1%. The method was applicable to analyze the contents of the five bactericides in food contact paper and wood products and therefore ensure food safety.

Objective: To establish a matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) method to detect Campylobacter jejuni and Listeria monocytogenes in environmental samples from a chicken farm and samples from commercial live chickens using VITEK MS. Methods: The suspicious colonies of both bacteria were separated from the samples, and then suspended in matrix solutions consisting of mixtures of different proportions of ethanol, acetonitrile and water before identification by MALDI-TOF-MS. The effect of matrix solution composition on the bacterial detection was evaluated by examining the differences in characteristic peak value and relative abundance. Results: Significantly different matrix solutions were needed for the detection of Campylobacter jejuni and Listeria monocytogenes; the former did not require cracking by formic acid and was sensitive to trifluoroacetic acid (TFA), but the latter were just the opposite. A 30% water content in matrix solution (V/V) could avoid the lack of characteristic peak and enhance the detection rate. Conclusion: Control of the water content in matrix solution, TFA concentration and matrix concentration can enhance the number and relative abundance of characteristic peaks, and detection rate. The optimized matrix solution enables the rapid identification of foodborne pathogens, which was able to improve the timeliness of disease prevention and food-borne risk monitoring.

BALB/c mice were immunized with Cronobacter sakazakii type strain ATCC 29004. Seven strains (1E9, 2A7, 2D10, 3E5, 5B10, 6E3, and 12A2) of hybridoma cell lines that secreted monoclonal antibodies were prepared by two cycles of cell fusion using hybridoma technique. The titers of 2A7, 2D10, 3E5 and 12A2 reached 1:256 000, the titer of 6E3 was 1:128 000, the titer of 5B10 was 1:64 000 and the titer of 1E9 was 1:32 000. The results of subtype identification showed that the subtype of 1E9 was IgG1, the subtype of 6E3 was IgG2b, and the subtypes of the other antibodies 2A7, 2D10, 3E5, 5B10 and 12A2 were all IgG2a. 2A7 could specifically bind to 3 strains of Cronobacter sakazakii (ATCC 29004, ATCC 29544, and ATCC 12868), and 1E9 could specifically bind to two of them (ATCC 29004 and ATCC 12868). The results of cross-reaction with 11 other similar pathogens showed that 7 antibodies had good specificity. The sensitivity of indirect competitive enzyme linked immunosorbent assay (ELISA) using 2A7 reached 106 CFU/mL for the detection of Cronobacter sakazakii.

A method was developed for the determination of dithianon residues in apple and soil by using high performance liquid chromatography (HPLC). The residues in samples were extracted with acetonitrile, cleaned up by a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method, separated on an Agilent Eclipse XDB-C18 column, and then analyzed by HPLC with variable-wavelength detection (VWD) at a wavelength of 250 nm. The analyte was quantified by the matrix-matched external standard method. Under the optimal conditions, the calibration curve showed good linearity in the range of 0.02–5.00 mg/L for dithianon. The average recoveries of dithianon were in the range of 74%–92%, with relative standard deviations (RSDs) of 1.02%–6.20%. The limit of detection (LOD, RSN > 3) of dithianon was 0.005 ng, and the limit of quantitation (LOQ) was 0.02 mg/kg. The half-life of dithianon was 3.8–12.6 and 1.0–8.3 days in apple and soil, respectively. At harvest, apple samples were found to contain dithianon levels below the maximum residue limit (MRL) in China (5 mg/kg). The harvest interval was recommended to be 14 days after the last application.

Objective: To establish a rapid, specific and sensitive polymerase chain reaction (PCR) method for the detection of fish-derived ingredients. Methods: A set of primers was used to selectively amplify a short DNA fragment of the fish mitochondrial 12S rRNA gene. The specificity was evaluated by analyzing 24 kinds of fish as well as meat, poultry and shrimp, commonly added in fish products. The sensitivity was evaluated by amplifying DNA extracted from grass carp mixed with meat from other animal species. Results: The method established could specifically detect fish-derived ingredients with a sensitivity of 0.5%. Conclusion: This PCR method is a rapid, sensitive and specific method for preliminary screening of fish-derived ingredients in foods, and is of important significance to safeguard the interests of consumers and standardize the market order.

In this research, a method for the quality control of 30 batches of quinoa from many different areas of the world was established by ultra-performance liquid chromatography (UPLC). UPLC fingerprints were established after evaluation of figures of merit. The similarity was analyzed by similarity evaluation software. The relationship between geographical origin and quality was analyzed by cluster analysis, principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA) and other chemometric methods. The results showed that there were 12 peaks common to 30 batches of quinoa, and the similarity among samples was greater than 0.7. Using the chemometric methods, the quinoa samples were classified into four categories according to their geographical orgins. The PCA and pattern recognition analysis indicated that the quality difference was mainly related to three compounds. Therefore, UPLC fingerprinting and chemical pattern recognition can provide detailed references for the quality control of quinoa.

In order to obtain the best hyperspectral characteristic wavelength for wolfberry grading, a feature wavelength selection method for hyperspectral image analysis based on information entropy was presented. Under different wavelengths, firstly, the self-information of each sample image was calculated, and the mean self-information of hyperspectral images of each class of wolfberry was calculated; secondly, the mutual information between two arbitrary sample classes was calculated to obtain the mean mutual information between the corresponding hyperspectral images. Furthermore, the ratio of the mean mutual information to the sum of the mean self-information which corresponded to each sample class under a certain wavelength was calculated and defined as A. Finally,?it was found that A value could be taken as a quantitative index to select the optimal hyperspectral image wavelength for wolfberry grading. The analytical results showed that the optimal wavelength was 950 nm. Then the texture features of all wolfberry samples under the selected wavelength were extracted, and Fisher discriminant analysis (FDA) was employed to classify six classes of wolfberries for the purpose of verification. The results of this study showed that wavelength selection of hyperspectral image analysis based on information entropy is highly feasible for wolfberry grading.

An analytical method was developed to determine three fumonisins in corn and wheat flour samples using on-line solid phase extraction combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS). Samples were extracted with an acetonitrile-water mixture (50:50, V/V) and purified with an on-line solid phase extraction column (WAX column). The fumonisins were separated on an XBridge C18 colum by using 0.1% formic acid solution mixed with acetonitrile as the mobile phase. Multiple reaction monitoring was used to acquire mass spectrometric data under positive electrospray ionization mode. The internal standard method was adopted for quantification. The results showed that good linearity was obtained in the range of 0.05–50 ng/mL for fumonisin B1, fumonisin B2 and fumonisin B3, and the correlation coefficients were all greater than 0.999 0. The limits of detection (LOD) and quantitation (LOQ) for these analytes were 0.08 and 0.2 μg/kg, respectively. Recoveries of the method were in the range of 93.9%–117.8% at spiked levels between 0.2 and 50 μg/kg, and precision (expressed as relative standard deviation) ranged from 1.8% to 9.4%. The developed method could be used for the accurate quantitative measurement of fumonisins in corn and wheat flour samples.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine three pesticide residues including carbendazim, diethofencarb and prochloraz in four different processed products of Agaricus bisporus. Meanwhile, the key process and parameters for reducing pesticide residues were analyzed. The results showed that the percentage removal of three pesticide residues by different processing methods were in the following decreasing order: canning > salting > quick freezing > freeze drying, and the residual levels of pesticides in these processed products were in the ranges of 3.4%–11.7%, 11.5%–22.3%, 61.5%–86.1% and 150.4%–152.3% respectively. Washing and heating were the key steps for reducing 3 pesticide residues in canned products. Soaking in Na2CO3 solution for 25 minutes was the most effective among these processing treatments, resulting in 37.2% removal of carbendazim. The percentage removal of three pesticides were increased by increasing precooking time, which were 22.0%, 15.9%, and 17.1%, respectively after precooking for 14 minutes.

A microsphere-based fluorescence immunochromatographic assay was established for the detection of tetrodotoxin. A binding site protection procedure was developed for antibody labeling with fluorescent microspheres, which prevented damage to the antibody binding site and consequently enhanced the fluorescence signal. The whole process of binding and separation was efficiently completed on an affinity spin column. The sensitivity of the antibody-microsphere conjugate was nine times higher than that prepared by direct labeling. The immunochromatographic assay exhibited a linear range from 2 to 200 ng/mL for the detection of tetrodotoxin (y = ?0.15lnx + 0.95, R2 = 0.98) with an IC50 of 18.4 ng/mL. The limit of detection (LOD) for tetrodotoxin was 10 μg/kg in puffer with an average relative standard deviation (RSD) of less than 25% (n = 6). The assay method could be applied on heat-processed products without the need for large-scale equipment. The whole analysis process took only 15 min for each sample.

This study aimed to establish a new rapid and simple method for the quantitative determination of riboflavin in biological samples, namely molecular fluorescence differential standard addition method. The results showed that the riboflavin content in yolks determined by the method was 402 μg/100 g with relative standard deviation (RSD) of less than or equal to 1.5% (n = 6). The recoveries of the analyte from spiked samples ranged between 92.0% and 104%. The limit of detection (LOD) of the method was 5.76 × 10-3 μg/mL and the limit of quantitation (LOQ) was 1.92 × 10-2 μg/mL. This method was tested under the same conditions without background interference and without the need to prepare a working curve and to remove impurities by column chromatography. It was rapid, accurate, simple, practical and suitable for the determination of vitamin B2 in egg yolks.

In this study, electro-membrane extraction was used as a highly efficient sample pre-treatment method for the UV-VIS spectrophotometric determination of arsenic (As) in food samples. The influences of experimental parameters were investigated and optimized as follows: organic solvent, 1-octanol containing 2.5% (V/V) disononyl phthalate; applied voltage, 70 V; extraction time, 15 min; pH of acceptor, 13, and stirring rate, 700 r/min. The limit of detection (LOD) of this method was 1.5 μg/L. Average recovery rates for different matrices spiked with As were 96%–104%. The precision, expressed as relative standard deviation (RSD), was 0.1%–3.6%. The method presented in this study exhibited a good selectivity, low cost and simplicity and was applicable to total As in food samples.

A rapid method was established for screening 51 antibiotic residues in bean sprouts using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) after a rapid and high throughput pretreatment. Samples were extracted with acetonitrile and the extract was cleaned up by quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction. The target compounds were separated on BEH C18 UPLC column with gradient elution, monitored using positive electrospray ionization in the multiple-reaction monitoring (MRM) mode and quantitated by the external standard method. The results showed that the limits of quantity (LOQs) for 51 antibiotics were between 0.5 and 5 μg/kg. Average recoveries at 3 different spiked levels were 62.93%-118.69%, and the precision values expressed as relative standard deviations (RSDs) were 0.29%-9.72%. This method proved to be a rapid, high throughput, multi-component screening method for antibiotic residues in bean sprouts.