To prepare high-purity shikonin from Arnebia euchroma grown in Xinjiang autonomous region, subcritical water extraction and macroporous resin adsorption for purification were conducted. Effects of two extraction modes, namely dynamic circulation and static equilibrium, on shikonin yield were examined. Shikonin adsorption/desorption experiments were carried out using different polar macroporous resins and organic solvents. HPLC-ELSD was used to analyze the purity of the product obtained. Results showed that a maximum shikonin yield of 0.216% was achieved through 8 min extraction in the mode of dynamic circulation under the following conditions: extraction pressure 10 MPa, extraction temperature 120 ℃ and flow rate 1.39 cm3/s; in contrast, the 16 min static equilibrium extraction gave a maximum shikonin yield of 0.198%. Among 5 macroporous resins tested, DA-201 resin exhibited the best adsorption performance and an adsorption rate of 89.7% was obtained after 24 h constant temperature shaking adsorption. Among 4 organic solvents tested, acetone was the best one for shikonin desorption and desorbed 93.2% of shikonin at a fast velocity. The purity of shikonin was increased from 27.31% to 85.07% after optimized purification using DA-201 resin and acetone. The above results demonstrate that subcritical water extraction followed by macroporous resin adsorption provides an effective approach to preparing high-purity shikonin from Arnebia euchroma.

In the present study, corn starch was etherified with N-(2, 3-epoxy propyl) trimethyl ammonium chloride (GTA) under the catalysis of sodium hydroxide and high-substituted cationic starches were obtained. To achieve an optimal compromise between high degree of substitution (DS) and high reaction efficiency, orthogonal array design was used to investigate reaction temperature and time, water content in reaction system and addition amount of sodium hydroxide affecting highsubstituted cationic starch preparation. Meanwhile, products with different DS obtained were structurally characterized by infrared, polarization and X-ray spectroscopies. Results showed that the contribution of the above parameters to the DS of corn starch followed the decreasing order: reaction time ＞ reaction temperature ＞ water content in reaction system ＞ addition amount of sodium hydroxide. The reaction for 4 h at 80 ℃ in a reaction system consisting of 10 g of starch, 1.5 g of GTA and 0.2 g of sodium hydroxide and having 24% water content resulted in a DS of 0.105. As DS increased, the transparency and solubility of catonic corn starch exhibited an increase. Infrared, polarization and X-ray spectroscopic analyses demonstrated some changes in the structure of corn starch due to substitution.

Cetyltrim ethylammonium bromide was used as phase-transfer catalyst to synthesize soybean sucrose polyester from ethyl-esterfied soybean oil and sucrose by two-step method. Response surface analysis based on Box-Behnken experimental design was used to investigate the optimal values of reaction temperature, catalyst amount, ethyl-esterfied soybean oil/sucrose molar ratio and reaction time affecting soybean sucrose polyester yield. Results showed that under the following optimized conditions: reaction temperature 135.6 ℃, catalyst amount 4.1%, ethyl-esterfied soybean oil/sucrose molar ratio 13.5:1 and reaction time 5.5 h, the soybean sucrose polyester yield and the esterfication degree were up to 90.72% and 7.1, respectively.

An enzyme-linked immunoabsorbence (ELISA) test kit was developed for enrofloxacin (ENR) detection. ENR-MBSA and ENR-OVA antigens were prepared by EDC-NHS method. BALB/C mice were immunized with ENR-M-BSA for monoclonal antibody generation. A specific monoclonal antibody was screened using methylcellulose-based semi-solid medium and analyzed using indirect competition ELISA. The molar coupling ratios of ENR-conjugated BSA and ENR-conjugated OVA were calculated to be 15:1 and 7.2:1, respectively. The specific monoclonal antibody 3E9 was obtained and the titer of purified 3E9 antibody reached 107 according to ELISA detection, and belonged to the family of IgG1 according to the detection using an antibody typing kit. The ELISA detection of ENR using the antibody exhibited a sensitivity of 1 ng/mL, a linear range of 1 to 100 ng/mL and a half inhibitory concentration (IC50) of 10 ng/mL. The cross-reactivity between the ELISA detection kit developed and four analogues was less than 1%. These results indicate that the monoclonal antibody has a promising potential in the development of ELISA test kits for ENR detection.

The non-expansive extrusion process of instant oat noodles from a blend of oat and wheat flours using a double-screw extruder was investigated. Differential scanning calorimetry and Brabender farinograph were used to examine effects of mass ratio of oat to wheat flours, amount of water added to their blend, and extruder screw speed and barrel temperatures at areas Ⅱ and Ⅲ on rehydration time and gelatinization degree of instant noodles. Results showed that the optimum processing conditions were as follows: mass ratio of oat to wheat flours 40%, amount of water added to their blend 40%, extruder screw speed 210 r/min, and extruder barrel temperature 90－95 ℃ (Ⅱ) and 110－115 ℃ (Ⅲ). The gelatinization degree and rehydration time of instant oat noodles processed under the optimum conditions were 94.6% and 8 min, respectively.

To screen an optimal adsorbent for purification of flavonoids from bamboo leaves, 7 macroporous resins were compared for difference in adsorption and desorption performance. AB-8 resin was chosen due to the merits of large adsorption capacity, easy desorption and high resolution. Besides, the optimal adsorption/desorption process for purification of bamboo leaf flavonoids using AB-8 resin was investigated. Results showed that the optimal pH and flow rate of sample solution were 5.0 and 1 mL/min, respectively and the optimal desorption was achieved by using 4 BV of 60% aqueous ethanol at a flow rate of 1.5 mL/min. Under such conditions, the purity of bamboo leaf flavonoids obtained was up to 54.16%.

Water was used to extract total flavonoids from sweet orange residue left after squeezing juice under ultrasonic assistance instead of organic solvents. On the basis of single factor experiments, quadratic rotational combination design combined with response surface analysis was used to optimize total flavonoids yield as a function of ultrasonic power and treatment time, temperature and material/water ratio. Results showed that the developed mathematical model for total flavonoids yield exhibited tremendous significance and excellent goodness of fit and a significant effect on total flavonoids yield was observed in linear and quadratic terms. The interactions among the above parameters had a significant effect on total flavonoids yield. Material/water ratio had the most significant effect, temperature took second place and ultrasonic power and treatment time had a little effect. The optimal values of these parameters were determined as follows: ultrasonic treatment time 41 min, ultrasonic power 1410 W, temperature 57 ℃ and material/water ratio 1:16. The total flavonoids yield obtained under such conditions was 1.061%.

One-factor-at-a-time method and quadratic orthogonal rotational combination design combined with response surface analysis were used to optimize temperature, ammonia concentration, fumigation time and moisture content in maize affecting degradation efficiency of ammonia fumigation towards aflatoxin B1 (AFB1) in maize. Results showed that the optimal values of the above parameters were determined as follows: temperature 37 ℃, moisture content in maize 20%, ammonia concentration 7.05% and fumigation time 96 h. Under such conditions, the predicted value of degradation ratio of AFB1 in maize was up to 90.4% and its experimental value was 92%.

Ethanol aqueous solution was used to extract total flavonoids from Artemisia lavandulaefolia under ultrasonic assistance. To optimize extraction yield of total flavonoids, 30 experiments resulting from a five-variable and four-level central composite design were first carried out; subsequently, experimental data obtained were subjected to multiple variable regression fitting to establish a mathematical model for extraction yield of total flavonoids as a response to 5 variables and a significance test was performed for the model; and finally response surface analysis was conducted for investigating the interaction effects of 5 variables on extraction yield of total flavonoids. Results showed that the developed model could describe the relationship between extraction yield of total flavonoids and 5 variables such as ultrasonic treatment time, extraction temperature, ethanol concentration in aqueous solution and solid/liquid ratio very well. The optimal values of the variables were as follows: ultrasonic treatment time 36.7 min, extraction temperature 74.99 ℃, ethanol concentration in aqueous solution 71.78%, and solid/liquid ratio 1:65.68 (g/mL). Under such conditions, the predicted value of extraction yield of total flavonoids was 2.8%, which was very consistent with the experimental value with a relative error of 1.1%.

To make full utilization of Ginkgo biloba leaf resource, enhance its added value and provide experimental reference for exploration of natural food colorants, critical parameters affecting extraction of yellow pigments from Ginkgo biloba leaves including extraction solvent kind, liquid/material ratio and extraction time and temperature were investigated by orthogonal array design and the light, temperature and pH stability of the product obtained were evaluated. Results indicated that the pigments dissolved in petroleum ether exhibited a maximum absorption at 445 nm wavelength. Four-time extraction for 30 min each time using a mixture of ethyl acetate and petroleum ether (70:30, V/V) as extraction solvent at 40 ℃ and a liquid/material ratio of 25:1 (mL/g) gave an optimal yield of yellow pigments of up to 3.0% and the color value of the products obtained was 20.49. The pigments had poor light stability and consequently should be stored in the dark. After 1 h exposure to a temperature below 60 ℃, a low degradation ratio was observed in the pigments, whereas 1 h exposure to 70 ℃ led to a high degradation ratio. The pigments were stable in acidic and alkine media.

The purpose of the present study was to achieve an optimal ultrasonic-assisted extraction of Coix lacryma-jobi seed ester. On the basis of single factor experiments, a three-variable, three-level central composite design leading to 17 experiments combined with response surface analysis was employed to optimize key technological parameters (namely, ultrasonic treatment time, extraction temperature and material/liquid ratio) affecting Coix lacryma-jobi seed ester yield. In the optimization, a mathematical regression model describing Coix lacryma-jobi seed ester yield as a function of the parameters was created. Results indicated that the optimal values of the parameters were as follows: ultrasonic treatment time 50 min, ultrasonic power 300 W, extraction temperature 50 ℃ and material/liquid ratio 1:10 (g/mL). Under such conditions, an optimal Coix lacryma-jobi seed ester yield of 5.798% was obtained.

In this study, soybean hull was first subjected to sequential pretreatment with an aqueous sodium hydroxide solution followed by an aqueous ammonium oxalate solution for the removal of protein and pectin and then hydrolyzed with xylanase to prepare xylooligosacccharides. To maximize total sugar content in soybean hull hydrolysate, this study emphatically focused on optimizing hydrolysis process of soybean hull. Effects of hydrolysis parameters including hydrolysis temperature and time, pH, ratio of solid to liquid and xylanase amount on total sugar content in soybean hull hydrolysate were analyzed by single factor and orthogonal array design methods. Results indicated that the optimal values of these parameters were as follows: hydrolysis for 2 h at 40 ℃, pH 5.3, a ratio of solid to liquid of 1:15 and an enzyme amount of 0.3%. The total sugar content in soybean hull hydrolysate obtained under such conditions was 5.74 mg/mL. Ion chromatographic detection revealed that the predominant monosaccharide in soybean hull hydrolysate was xylose with a relative content of 54.99%.

Macroporous resin adsorption was used to obtain high-purity oleuropein from Syringa pubescens Turcz., an effective antihepatic fibrosis component. Six common macroporous absorption resins were compared for differences in adsorption and desorption performance. D-101 resin was found to be the best choice for oleuropein purification. To achieve an optimal oleuropein purification, the adsorption and desorption characteristics of D-101 resin were investigated. Results showed that the purity of purified crude Syringa pubescens Turcz. oleuropein using D-101 resin under optimized adsorption-desorption conditions was more than 30%. Forty percent aqueous ethanol solution was a fast and effective solvent for oleuropein desorption. D-101 resin exhibited good reusability. This method is easy and convenient in operation and has promising potential for industrial application.

Acetone acidified with hydrochloric acid was used as extraction solvent to extract heme from porcine red blood cells separated from whole porcine blood anticoagulated with sodium citrate by centrifugation. Single factor method and central composite design combined with response surface analysis were employed to optimize parameters such as extraction time, hydrochloric acid/acetone ratio (V/V) and acidified acetone/porcine red blood cells ratio (V/V) affecting heme extraction. Results showed that the optimal extraction for 42 min using a mixture of hydrochloric acid and acetone (3:100) at an acidified acetone/ porcine red blood cells ratio of 5.66:1 gave an actual value of heme yield of 0.225 g/100 mL of whole blood, which was very close to the predicted value of 0.230 g/100 mL of whole blood.

To propose an optimal purification process of total flavonoids in 70% ethanol extract from citrus peel, the static and dynamic adsorption-desorption performance of D-101 macroporous adsorption resin towards total flavonoids from citrus peel was investigated. Major process parameters including pH of sample solution (ethanol extract of citrus peel), sample solution volume/D-101 resin weight ratio (mL/g), standing time and kind and amount (desorption solvent volume/ D-101 resin weight ratio, mL/g) of desorption solvent affecting either adsorption ratio or desorption ratio of total flavonoids were evaluated and their optimal values were determined to be pH 4.43, 15:1, 90 min, 95% ethanol and 25:1, respectively. The method proved to be simple and feasible for purification of crude total flavonoids extracted from citrus peel.

In the present study, naringinase, an enzyme that hydrolyzes naringin responsible for bitter taste, was used to debitter Citrus grandis (L.) Osbeck cv. Guanximiyou (Guanxi pomelo) juice. To maximize the removal rate of naringin from Guanxi pomelo juice, major hydrolysis parameters including enzyme dosage, reaction temperature and time and pH were investigated by single factor and orthogonal array design methods. Naringin in Guanxi pomelo juice was analyzed by reversed phase high performance liquid chromatographic method. Results indicated that a maximum removal rate of naringin of more than 97% was achieved by using 7.4 U/mL of naringinase to treat Guanxi pomelo juice for 100 min at 60 ℃ and pH 3.6.

Response surface methodology based on a central composite design involving 15 experiments of 3 variables at 3 levels was used to optimize nomilin yield at different levels of key supercritical carbon dioxide extraction parameters such as extraction pressure and temperature and entrainer (95% ethanol) dosage. Results showed that the optimal levels of these parameters for achieving a maximum nomilin yield of (6.27 ± 0.06) mg/g were as follows: extraction pressure 25 MPa, 51 ℃ and entainer dosage 1.5 mL/g.

To develop a new packaging material for fresh-keeping of salted egg products, polyvinyl alcohol (PVA) was chemically cross-linked with stearic acid. Effects of major cross-linking reaction conditions on film-forming properties of the resulting coating material were examined. Results showed that the film formed from the PVA/stearic acid compound coating material obtained using glutaraldehyde added at 0.4% level (calculated on the basis of the volume of water used to dissolve PVA) as cross-linking agent exhibited a water vapor transmission rate (WVTR) of 22.3 g/(m2·24 h), with an approximate 2.5-fold enhancement of water barrier performance when compared with the film formed without the addition of glutaraldehyde. Longer cross-linking time and lower film-forming temperature resulted in significantly higher water barrier and water resistance performance (P＜0.05). There was a significant increase in antibacterial effect of the film formed from the PVA/stearic acid compound coating material obtained using a higher concentration of glutaraldehyde (P＜0.05). The optimal formula of crosslinking system consisting of a mixture of 5% aqueous PVA solution and 5% ethanol solution of stearic acid (10:4, V/V) was first left to react at pH 6.2 for 45 min under the catalysis of glutaraldehyde added at 0.4% level and subsequently dried at 55 ℃ for 6 h, and a PVA/stearic acid compound film with an optimal compromise among high water resistance performance, excellent antimicrobial effect and low WVTR was obtained.

Three natural preservatives like Nisin, lysozyme and lactoferrin were tested for minimum inhibitory concentration (MIC) against common food-contaminating bacterial species using the agar diffusion method and for inhibitory zone diameter against Staphyloccocus aureus. To minimize total number of bacteria in chilled pork, the preservatives were complexed and the optimal formulation and the optimal pH were investigated using response surface methodology based on a central composite design involving 31 experiments at 5 levels. Results showed that the optimal complex preservative formula consisted of 0.2773% of Nisin, 0.46% of lysozyme and 0.604% of lactoferrin and the optimal pH was 5.16. Significant interaction effects between pH and either Nisin, lysozyme or lactoferrin and between lysozyme and either Nisin or lactoferrin on total number of bacteria in chilled pork were observed (P＜0.01), whereas the interaction effect between Nisin and lactoferrin was not significant (P＞0.05). These factors affected total number of bacteria in chilled pork in the decreasing order: Nisin＞lysozyme＞pH＞lactoferrin.

Lactoferrin–chromium complexes were prepared by complexation of lactoferrin with chromium trichloride. The optimal complexation conditions between either ferric lactoferrin or apo-lactoferrin and Cr3+ were studied. The complexes formed were structurally characterized by infrared spectroscopy and analyzed for the contents of Fe3+ and Cr3+ by flame atomic absorption spectroscopy. Results showed that a maximum chromium saturation point of more than 90% was achieved through the complexation reaction between ferric lactoferrin and Cr3+ for more than 2 h at 50－60 ℃ and pH 6.5－7.5 and the complexation reaction between apo-lactoferrin and Cr3+ for more than 2 h at 50－65 ℃ and pH 6.0－7.5 gave a maximum chromium saturation point of close to 100%. Therefore, apo-lactoferrin is more suitable for preparation of lactoferrin-chromium complex.

Pulse pressure technique was employed to accelerate the salting process and promote the edible quality of salted eggs. Effects of pulse pressure amplitude, high pressure holding time/atmospheric pressure holding time ratio and their interaction on weight gain rate (WGR) and salt contents of egg white (EWSC) and egg yolk (EYSC) were studied by single factor and orthogonal array design methods. Results showed that the optimum mass transfer rate during 48 h of salting with saturated salt solution was obtained under the following conditions: pulse pressure amplitude 135 kPa and high pressure holding time/ atmospheric pressure holding time ratio 7.5 min/15 min. To obtain salted eggs of optimal quality, pulse pressure amplitude was adjusted to be 120 kPa and high pressure holding time/ atmospheric pressure holding time ratio was kept unchanged.

The basic chemical composition of Camellia oleifera seed meal and the isoelectric point of Camellia oleifera seed meal protein were determined. According to the determination results, a method based on alkaline extraction followed by acid precipitation was proposed for extraction of protein from Camellia oleifera seed meal. Single factor and orthogonal array design methods were employed to examine the effects of alkaline extraction parameters including material particle size, material/liquid ratio, pH and extraction time and temperature on protein yield. Results indicated that the extraction for 80 min at pH 10 and a material/liquid ratio of 1:25 gave a maximum protein yield of 57.8% from material powder with particle sizes below 80 mesh.

The optimal ethanol extraction of black sticky rice pigment was determined by examining the effects of extraction temperature and time, ethanol concentration, pH and material/liquid ratio on black sticky rice pigment yield (represented by the absorbance at 525 nm wavelength) by single factor and orthogonal array design methods. Results showed that the optimal values of the above parameters were as follows: extracting temperature 65 ℃, ethanol concentration 75%, material/liquid ratio 1:110 and pH 1 for an extraction duration of 3 h.

The conventional processing procedure of water boiled salted dusk was modified by supplementing either cooling at 4 ℃ for 12 h or roasting 45 ℃ for 30 min following brine salting. Headspace solid phase microextraction combined with gas chromatography–mass spectrometry was used to analyze the volatile flavor composition of water boiled salted dusk products obtained using three different processing procedures. Results showed that a total of 93 compounds were identified in all three products, including hydrocarbons (24), ketones (13), alcohols (15), aldehydes (24), acids (5), esters (1), furans (3), sulfurcontaining compounds (3), nitrogen-containing compounds (3) and heterocyclic compounds (2). Roasting resulted in a significant increase in the respective relative contents of hydrocarbons, alcohols, acids, aldehydes, esters, furans and sulfur-containing compounds of water boiled salted dusk and made a great contribution to product flavor. Cooling resulted in a significant increase in the respective relative contents of hydrocarbons, aldehydes, acids, sulfur-containing compounds and heterocyclic compounds and helped enhance product color.

A YJYⅡ-type cold press machine was modified and used for extraction of wheat germ oil from full-fat wheat. Pressure chamber temperature was controlled by taking measures such as cooling water injecting into the axis direction, etc. Response surface methodology based on a four-variable, five-level quadratic rotation-orthogonal combination design was employed to investigate the pairwise interaction effects of water content of the material, pressure chamber temperature and extraction pressure on vitamin E content of wheat germ oil. Results showed that the optimal values of the above parameters were determined as follows: water content of the material 7%, pressure chamber temperature 75 ℃ and extraction pressure 3.6 MPa. The product obtained under such conditions contained 268.7 mg of vitamin E /100 g and 925 mg of phospholipids of /100 g, with an extraction yield of 32%.

Freshly harvested old tea leaves were pretreated for the removals of lipid and water-soluble substances such as polyphenols, sugars and amino acids before sequential hydrolysis with amylase followed by papain for production of waterinsoluble dietary fiber (IDF). To maximize IDF yield, papain hydrolysis parameters such as enzyme dosage, pH, hydrolysis temperature and time and material/liquid ratio were investigated by single factor and orthogonal array design methods. Results showed that the effects of the parameters on IDF yield decreased in the following order: pH＞hydrolysis time＞enzyme dosage ＞hydrolysis temperature＞material/liquid ratio. A maximum IDF yield of up to 94.12% was obtained through the extraction for 2 h at 65 ℃, pH 4.0 and a material/liquid ratio of 1:10 using an enzyme dosage of 0.004 g/g. The IDF obtained was good in water holding capacity, swelling capacity, water binding capacity, oil holding capacity, cation exchange capacity and cholesterol and sodium cholate adsorption capacity, thereby providing an excellent IDF resource.

The aim of this study was to investigate three main parameters (inclusion time, temperature and number) affecting ulrea inclusion of gamma linolenic acid (GLA) from evening primrose oil by single factor and orthogonal array design methods. Single factor experiments were carried out to examine the effects of the parameters on the crystal morphology of urea inclusion compounds observed using naked eyes and microscopy and GLA purity. Gas chromatography was used to determine GLA purity. A 4-factor, 3-level orthogonal array design involving 9 experiments was employed to examine the effects of the parameters on GLA yield and purity. Results showed that under the conditions of longer inclusion time and lower inclusion temperature, more urea inclusion compounds were obtained and the crystal shape was longer in length and thicker in diameter. Urea inclusion compounds obtained by either twice, three- or four-time inclusion exhibited longer length and thicker diameter in crystal shape than those obtained by once inclusion. The optimal values of inclusion time, temperature and number for improved crystal morphology of urea inclusion compounds were 36 h, －15 ℃ and 4, respectively. When they were modified to be 60 h, －15 ℃ and 3, respectively, a maximum GLA purity of up to 78.996% was obtained. All these parameters exhibited a significant effect on the formation of urea inclusion compounds. Thus, observations on changing trends in the crystal morphology and amount of urea inclusion compounds provides a feasible guidance for the optimization of urea inclusion of GLA from plant seed oil.

Roasting followed by supercritical fluid CO2 extraction (SFE) was used to produce aromatic soybean oil (ASO). According to the overall odor evaluation, the optimal temperature and time for roasted soybeans with aromatic flavor were 170 ℃ and 30 min, respectively. With increasing particle size of roasted soybean powder, ASO yield increased and the optimal particle size range was 40 － 60 mesh. Orthogonal array design experiments showed that ASO yield first increased and then decreased with increasing extraction temperature and the optimal extraction temperature was 50 ℃; extraction pressure exhibited the same effect on ASO yield as extraction temperature and its optimal value was 25 MPa; ASO yield progressively ascended to the climax appearing at 2.5 h with increasing extraction time. Induction period (IP) and protection factor (PF) were used to evaluate the oxidative stability of ASO. The IP values of ASO and a commercial brand of soybean oil were determined to be 8.93 and 9.47, respectively, which were lower than those of other plant oils determined to be more than 16. The respective additions of BHT and PG at 0.04% level to ASO resulted in an increase of IP value from 8.93 to 12.08 and 18.55 and an increase of PF to 1.353 and 2.077, respectively, thereby indicating much better antioxidant effect of PG on ASO than BHT. ASO added with 0.01% of citric acid exhibited a PF value of up to 2.25, and thus citric acid was a stronger antioxidant for ASO than PG. A PF value of up to 4.14 was observed when 0.01% of citric acid and 0.04% of PG were added to ASO together.

Microwave assistance was used to extract Pu er tea pigments with water as extraction solvent. On the basis of single factor experiments, in which the respective effects of technological parameters including material/liquid ratio, microwave power, and extraction time and number on Pu’er tea pigment yield were examined, quadratic orthogonal rotation combination design combined with response surface methodology was employed to optimize 3 crucial ones of the above parameters such as material/liquid ratio, microwave power and extraction time. Computer generated response surfaces, canonical analysis and contour plot interpretation revealed that extraction time had an extremely significant effect on Pu er tea pigment yield (P＜0.01), microwave significantly affect Pu er tea pigment yield (P＜0.05), whereas no significant effect on Pu er tea pigment yield was observed from material/liquid ratio. The extraction for 9.48 min with 640 W microwave assistance at a material/liquid ratio of 1:58.79 resulted in a maximum Pu er tea pigment yield. The experimental value was up to 97.5% of the predicted value.

A flame atomic absorption spectrophotometric (FAAS) method based on microwave digestion was proposed for the determination of 11 trace metal elements (Ca, K, Mn, Zn, Mg, Fe, Cu, Na, Cr, Ni and Sr) in the fruits of Rosa multiflora Thunb grown in Xinjiang autonomous region. Temperature programmed rise was used for the microwave digestion of samples. The optimal digestion solvent was nitric acid. The proposed method exhibited good accuracy and precision. Spike recoveries of 11 trace metal elements in a real sample were within the range of 96.50%－104.50%, with relative standard deviations (RSDs) of no more than 3.21%. Actual determinations demonstrate that the fruits of Rosa multiflora Thunb grown in Xinjiang autonomous region are rich in Ca, Mg, K, Na, Mn and Fe beneficial for health and contain small amounts of Cr and Ni.

A rapid and sensitive approach to performing competitive immunoassay for chloramphenicol in animal-derived food using capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection was presented. The assay exhibited a linear range of 0.008－5μg/L and a limit of detection of 0.0016μg/L. The sensitivity of this assay was almost 20 times higher than that of the solid-phase ELISA assay and the time consumption was shortened. In the real sample analysis, a detectable level of 0.035μg/kg was obtained.

Totally 150 Pu er tea samples from 5 main producing areas (including 6 representative brands with 5 replicates each brand comprising 3 raw Pu er tea and 3 ripe Pu er tea each area) in Yunnan province were tested for the contents of As and Hg by the atomic fluorescence spectrometric (AFS) methods recommended by the Chinese national standards GB/T 5009.11 －2003 and GB/T 5009.17－2003. Results showed that the content ranges of As and Hg in the Pu er tea samples were 0.026－0.37 mg/kg md and 0.0014－0.020 mg/kg md, respectively. No Hg was detected in 85.9% of the total number of samples. The determination results demonstrate that these samples are all in accordance with the quality standard requirements of the Chinese Ministry of Agriculture for Pu er tea. There were differences in the contents of As and Hg among Pu er tea samples from 5 main producing areas in Yunnan province. Differences in the contents of As and Hg were observed between raw Pu er tea and ripe Pu er tea, whereas they both exhibited good quality safety. In conclusion, the quality safety status of all these samples is good in terms of the contents of As and Hg.

Objective: To develop a rapid reversed-phase high performance liquid chromatographic (RP-HPLC) method for measuring retinyl esters in infant formula milk powder. Methods: Samples were directly extracted with a mixture of dichloromethane and methanol (2.5:1, V/V). The chromatographic separation was performed at 30 ℃ in the isocratic elution mode using a mobile phase composed of a mixture of methanol and chloroform (80:20, V/V). Results: Retinyl acetate and retinyl palmitate presented average spike recoveries of 6 replicates at 2 levels of 100.1% and 102.8%, with relative standard deviations of 1.18% and 0.96%, respectively. The detection limits for retinyl acetate and retinyl palmitate were 3.1 ng and 4.3 ng, respectively. Conclusion: The method demonstrates simplicity and high precision, recovery and sensitivity, and thus has promising potential for practical applications.

A high-throughput and rapid multiplex PCR-denaturing high performance liquid chromatographic (MPCRDHPLC) method was presented for the detection of Listeria monocytogenes, Listeria ivanovii and Listeria innocua in food. Respective primers specific to target genes of Listeria monocytogenes, Listeria ivanovii and Listeria innocua were designed and synthesized, followed by multiplex PCR amplification and DHPLC analysis. Along with repeatability experiments, specificity experiments were performed using 94 reference strains. The MPCR-DHPLC method resulted in a simultaneous detection of specific positive absorption of Listeria monocytogenes, Listeria ivanovii and Listeria innocua rather than other relative species or reference strains of non-relative species and exhibited good specificity and repeatability and other advantages such as rapidity, accuracy and high throughput, thereby providing a novel technique for the detection of microorganisms in food.

A method using capillary gas chromatography was presented for the determination of allyl isothiocyanate (AITC) residue in agro-products fumigated with it. Samples were extracted with dichloromethane. A capillary gas chromatography system equipped with flame ionization detector (FID) was used. Mean recoveries of AITC in a sample spiked at the levels of 1, 5 and 25 mg/kg ranged between 70.6% and 92.3%, with relative standard deviations (RSDs) within the range of 3.6%－9.3%. The presented method exhibited a limit of determination of 0.1 mg/kg. The degradation of AITC in fumigated agro-products including rice seeds, wheat seeds, commercial rice, Chinese date and Jew's-ear, as a result of enzymolysis, hydrolysis or photolysis, complied with first-order kinetic equations, with half-life periods ranging from 28 to 75 d. After 112 d storage, the AITC residues in fumigated rice seeds, wheat seeds, rice, Chinese date and Jew s-ear were 11.8, 150.7, 2.8, 77.5, 3.3 mg/kg and 8.2 mg/kg at the treatment level of 25 mg/L and 5.6, 189.2, 3.6, 26.9, 1.2 mg/kg and 10.2 mg/kg at the treatment level of 100 mg/L. Therefore, the dosage of 20% dichloromethane solution of AITC should be set at the level of 25 mg/L. After 2 d sealed AITC fumigation, at least 14 d air exposure of agro-products is required for the degradation of most AITC residue.

Chloramphenicol is a broad-spectrum antibiotic and its use is prohibited in many countries in the world due to its toxicity and side effects. The detection of chloramphenicol residue in food products has become a critical technical barrier. F1300, a fluorescence indicator, makes it easy to quantify the activity of F0F1-ATPase. Based on this, a complex of chloramphenicol antibody-biotin-streptavidin-biotin- β subunit antibody was constructed and connected to β subunits of F0F1-ATPase in the chromatophore. The concentration of chloramphenicol was measured according to the relative fluoresent value of F0F1-ATPase biosensor tagged by F1300. The detection limit of this method was 1 × 10-11 mg/mL. Only 35 min was needed for the whole detection process. Therefore, this method, thanks to its rapidity, simplicity and high sensitivity, will has a promising application to chloramphenicol detection.

To understand the differences in the contents of trace elements of apples from different geographical origins, 20 trace elements in 9 Fuji apple samples from 3 growth regions were analyzed by inductively coupled plasma mass spectrometry (ICPMS). Results showed that Fuji apples from Changping, Qixia and Baishui regions ranked first, second and third in Mo content, respectively. Qixia apples exhibited a much lower Rb content but much higher Mn, Co and Zn contents than Changping and Baishui apples. The Cu content of Changping apples was lower than that of Qixia and Baishui apples, but much higher B and Ti contents were observed in Changping apples. Baishui apples contained higher Ga and Ba contents than Changping and Qixia apples. These data demonstrate the significant differences in the contents of trace elements of apples from different geographical origins.

An analytic method using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for the determination of 4 perfluoroalkane sulfonates in food contact materials. Samples were extracted using methanol with ultrasonic assistance. The chromatographic separation was achieved on a C18 column using a mixture of methanol and a 5 mmol/L ammonium acetate aqueous solution as elution solvent for gradient elution. A 13C-labelled PFOS standard was used for the quantification of perfluoroalkane sulfonates. The developed method displayed a limit of detection of 0.5μg/kg and a linear range of 0.5－10μg/kg. Mean recoveries (6 replicates) for 4 perfluoroalkane sulfonates in a negative sample spiked at the levels of 1.0, 2.0μg/kg and 3.0μg/kg ranged from 91.1% to 112.8 %. This method proved to be an accurate and rapid method and was successfully used to detect 16 commercial food contact materials.

Headspace solid phase micro-extraction (HS-SPME) followed by gas chromatography/mass spectrometry was used to analyze the volatile composition of lards from pig fat oil and suet. Totally 46 and 27 volatile compounds were identified in lards from pig fat oil and suet, respectively. The volatile composition of lard from suet mainly consisted of n-hexadecanoic acid, oleic acid, hexanal, nonanal, octanal, 2,4-decadienal,(E,E)-, 2-octenal,(E)-, 2-nonenal,(E)-, furan,2-pentyl-, and 2-heptenal,(E)-, and the predominant volatile compounds in lard from pig fat oil were nonanal, 2-heptenal,(E)-, 2-pentadecanone, octanal, 2,4- nonadienal,(E,E)-, hexanal, 2,4-decadienal, 2-octenal,(E)- and 1-octanol.

Sixteen trace elements in Neptunea cumingi cultivated in clean water for 2 days or uncultivated were analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES) and based on this, the edibleness of the two samples of Neptunea cumingi was evaluated. After cultivation in clean water, some trace elements were discharged out of the body together with the waste, whereas some heavy metal elements remained in the body. Neptunea cumingi was rich in Ca, K, Na and Mg with contents of hundreds of milligrams/kilo and other trace elements having physiological functions, such as Fe, Zn, Mn, Ge, Cr and Ni. The contents of Fe and Zn were up to more than 30 mg/kg and 20 mg/kg. The contents of Mg and Cu were higher than the WHO recommended dietary reference values (RDAs). Heavy metal elements like As and Hg were the major pollutants present in Neptunea cumingi.

Headspace-solid phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was employed to analyze the volatile components in three Tai-tsai cultivars including Jingyan Taicai , Nanjing Xiaoye Taicai and Huaye Taicai grown in Spring or Autumn. Totally 11 kinds of volatile compounds such as alcohols, aldehydes, nitriles, ketones, esters, etc were identified. The predominant flavor compounds in Tai-tsai were (E)-2- butenedioic acid diethyl ester, 1-butene, 4-isothiocyanato-, 2,4-hexadien-1-ol, 3-hexen-1-ol, 2,4-hexadienal,(E,E)-, 2-hexenal, 3-pentenenitrile, benzenepropanenitrile and benzene, (2-isothiocyanatoethyl)-. Cultivar and growing season both may make a great contribution to the difference in volatile composition of Tai-tsai.

A ratio spectra derivative spectrophotometric method was developed for the simultaneous determination of pcoumaric acid and ferulic acid. p-coumaric acid and ferulic acid dissolved in either ethanol, water or an ethanol aqueous solution with pH adjusted to be 2.0 exhibited stable maximum absorption at 308 nm and 320 nm, respectively. Spike recoveries for both acids were within the range of 93.40%－103.34%. In the determination of p-coumaric acid and ferulic acid by this method in phenolic acids extracted from sugar cane residue, the presence of other substances having an obvious spectral absorption at wavelengths close to 308 nm led to a large error of p-coumaric acid determination but accuracy determination results of ferulic acid were obtained. This method provides an approach to the effective determination of p-coumaric acid and ferulic acid, between whose spectra, there is a large overlap.

Head-space solid-phase microextraction (HS-SPME) was used for the gas chromatography-olfactometric identification of volatile flavor compounds in Cantonese-style sausage. Four types of extraction fibers were compared for the difference in the sum of kinds of aldehydes and ketones, alcohols, esters and heterocyclic compounds and hydrocarbons in extract from one commercial brand of Cantonese-style sausage. The largest sum of kinds of the above compounds was detected in the sausage extract obtained using the DVB/CAR/PDMS (50/30μm) fiber and the fiber was consequently chosen to conduct the following investigations. Besides, the optimal extraction temperature and time were explored. Totally 13 volatile compounds including 4 aldehydes, 8 esters and 1 ketone greatly contributing to the characteristic flavor of Cantonese-style sausage were identified in the above commercial brand of Cantonese-style sausage and other two representative brands.

A solid phase extraction and high-performance liquid chromatographic (SPE-HPLC) method was developed for the determination of betaine in the fruits of Lycium barbarum L.. The cleanup of sample extracts was achieved on Waters Oasis MCX cartridge. A mixture of acetonitrile and water was used as the mobile phase for the chromatographic separation on Atlantis HILIC column in the gradient elution mode. The detection wavelength was set at 195 nm. The method exhibited a limit of detection of 0.0066 mg/mL and a linear range of 0.2－5.0 mg/mL. Average recoveries of three replicates for betaine in a real sample spiked at the levels of 0.05, 0.1 mg/mL and 0.2 mg/mL ranged between 88.3% and 104%. A simple, rapid and accurate determination of betaine in the fruits of Lycium barbarum L. was successfully achieved using the method.

A gas chromatograph-mass spectrometric (GC-MS) method was proposed for the determination of bromopropylate residue in chicken meat and liver and pork live. The method was based on the sequential procedure consisting of homogenization for extraction with a mixture composed of cyclohexane and acetic ester (1:1), condensation, constant volume dilution, cleanup by gel permeation chromatography (GPC), GC-MS detection and quantification by the external standard method. The detection limit of the method was 5μg/kg. Spike recoveries for bromopropylate at the levels of 5, 10 μg/kg and 50μg/kg and relative standard deviations were 69.4%－104.6% and 9.3 %－11.9% in chicken meat, 74.4%－104.5% and 8.3%－10.8% in chicken liver and 74.6%－103.8% and 9.6%－11.1% in pork liver.

This study aimed to present a high-performance liquid chromatographic (HPLC) method for the determination of 12 antioxidants in foods. Samples were dissolved in n-hexane saturated with acetonitrile and extracted with the lower phase (containing ascorbyl palmitate) resulting from n-hexane saturated with acetonitrile. A C18 column and a mobile phase consisting of methanol, acetonitrile, acetic acid and water were used for the chromatographic separation in the gradient elution mode. The detection wavelength of UV detector was set at 280 nm. Results showed that the thorough separation of 12 antioxidants was achieved within 36 min. The method exhibited limits of quantification (LOQ) ranging from 0.2 to 1.0 mg/kg and a linear range of 0.2 to 200 mg/L (r = 0.9981－0.9999). Mean spike recoveries at 3 levels of 7 replicates for 12 antioxidants in 3 representative samples with complicated matrix such as palm oil, cake and instant noodles were within the range of 81.13%－107.57%, with a relative standard derivation range of 0.26%－4.52%. The method demonstrates the advantages of simplicity, reliability and low LOQ, and is consequently most suitable for large-batch analysis of antioxidants in foods.

Genomic comparisons were carried out on Escherichia coli virulence genes and genome-specific sequences, which were located in the genomes of Escherichia coli serotype O157:H7 strains released in the GenBank. One pair of primers specific for ECs3032 genes was exploited for the amplification to give a 292 bp PCR product. Conventional qualitative PCR and real-time quantitative PCR assays showed higher specificity of the primers. The assays were used for detecting Escherichia coli O157:H7 in ground beef initially inoculated at the dosages of 2, 20, or 200 CFU/mL after 2, 11, 16 h and 20 h of enrichment at 37 ℃ in modified EC broth. Escherichia coli O157:H7 was detected in all samples inoculated. The whole detection procedure was finished within 24 hours with a sensitivity of 2.0 CFU/mg beef sample using the PCR assay established in this study. Thus, an effective method is provided for the rapid PCR detection of Escherichia coli in foods.

Steam distillation extraction followed by GC-MS combined with quantification by peak area normalization method was used to analyze volatile compounds in the fruitbodies of Tricholoma matsutake Sing.. Meanwhile, the relationship between volatile compounds and characteristic aroma of the fruitbodies of Tricholoma matsutake Sing. was explored. Results showed that 46 compounds were identified, accounting for 91.76% of the total volatile compounds from the fruitbodies of Tricholoma matsutake Sing. among which the predominant compounds were hexanoic acid (11.04%), bornyl acetate (11.28%) and methyl cinnamylate (27.37%). Bornyl acetate and methyl cinnamylate were mainly responsible for the characteristic aroma of the fruitbodies of Tricholoma matsutake Sing..

A high-performance liquid chromatographic (HPLC) method was developed for the determination of acid orange 7 in foods. Samples were extracted with n-hexane saturated acetonitrile, and the extract was then extracted twice with acetonitrile saturated n-hexane for the removal of oily pigments and other impurities. The resulting lower phase was subjected to HPLC analysis using Agilent ZORBAX SB-C18 column set at 40 ℃ followed by detection with a diode array detector (DAD) detector at 484 nm. Binary linear gradients were achieved using mobile phase A: acetonitrile and mobile phase B: 0.3% acetic acid aqueous solution at a flow rate of 1.0 mL/min. The calibration curve for determination of acid orange 7 by the method exhibited good linearity over the concentration from 0.01 to 1.0 mg/L with a correlation coefficient of 0.9997 and the limit of detection (LOD) of the method was 0.05 mg/kg. Mean recoveries of 6 replicates for acid orange 7 in 6 different matrix samples spiked at the levels of 0.05, 0.1 mg/kg and 0.2 mg/kg ranged between 74.9% and 100%, with a relative standard deviation (RSD) range of 1.41% to 8.64%. The method proved good in intra-laboratory accuracy and precision.

Simultaneous distillation-extraction followed by GC-MS combined with computer-assisted library search was used for the analysis of volatile compounds in Agastache rugosa. Results showed that the yield of volatile oil from Agastache rugosa was 0.37%. Totally 79 compounds were identified, among which chavicol methylether (47.60%), D-limonene (5.91%), caryophyllene (6.59%), eugenol methyl ether (1.87%) andβ-muurolene (1.42%) were prominent compounds.

A method for the simultaneous determination of 5 sugars such as fructose, glucose, sucrose, maltose and lactose in foods is described, in which high performance liquid chromatography (HPLC) and evaporative light scattering detection (ELSD) are used. A waters-NH2(4.6 mm × 250 mm, 5 μm) column kept at 30 ℃ and eluted with 75% acetonitrile aqueous solution at a flow rate of 1.0 mL/min was used for the chromatographic separation. The detector drift tube was kept at 45 ℃ and the nitrogen pressure was set at 25 psi. A good separation among the analytes and other components was achieved within 20 min (R ＞ 1.5). The response of the detector to analyte concentration over the range from 50 to 2000μg/mL displayed good linearity. Precision RSDs of 6 replicates for the determination of the sugars were less than 3.8% and mean recoveries for the sugars in 4 real samples spiked at the levels of 100, 200 μg/mL and 500μg/mL were more than 80.3%.

A high-performance liquid chromatographic (HPLC) method was developed for the simultaneous determination of 4 antioxidants, 2 sweeteners and 7 preservatives in cakes. Mobile phase A: 1.54 g/L ammonium acetate aqueous solution acidified with acetic acid to pH 5.5 and mobile phase B: acetonitrile were used for the gradient elution. A complete separation among the analytes was achieved. The method exhibited good linearity. Mean recoveries of 5 replicates for the analytes in a real cake sample spiked at the levels of 0.150 and 0.050 g/kg were within the range of 87%－103%, with a relative standard deviation (RSD) range of 2.1%－7.2%. This method, thanks to the merits of low limit of detection, high precision and accuracy and rapidity, will have a promising application to analyzing real samples.

A pre-column derivatization RP-HPLC method with detection with a photodiode array detector (DAD) or a fluorescecse detector (FLD) was developed for the determination of N-acetylneuraminic acid in edible birds’ nest (EBN). Samples were dissolved in 0.5 mol/L sodium bisulfate aqueous solution and kept for 30 min in 80 ℃ water bath. After cooling the derivatization was carried out using O-phenylenediamine · 2HCl as derivative. The chromatographic separation was achieved on a C18 column using a mobile phase composed of 1.0% tetrahydrofuran aqueous solution (containing phosphoric acid and 1- butylamine at the levels of 0.5% and 0.15%, respectively) and acetonitrile (95:5, V/V) at a flow rate of 1.0 mL/min in the isocratic elution mode. The DAD wavelength was set at 230 nm and the FLD Ex and Em wavelengths at 230 and 425 nm, respectively. The relationship between HPLC peak area and N-acetylneuraminic acid concentration over the range of 0.1－750 μg/mL exhibited good linearity (r ＞ 0.9990). A complete separation of N-acetylneuraminic acid was observed within 20 min. Mean recoveries of 6 replicates for N-acetylneuraminicacid in a real sample spiked at 3 levels ranged from 85.03% to 97.14%. The limit of detection (LOD) of the method was 0.2μg /mL with a DAD and 0.005μg /mL with a FLD. Clearly, the LOD with a FLD was two orders of magnitude lower than that with a DAD. Meanwhile, less miscellaneous small peaks were observed in the FLD detection. However, a DAD presented higher detection sensitivity than a FLD at the same concentrations over the LOD resulting from DAD detection. The method demonstrates the advantages of high sensitivity, good repeatability and rapidity, and is consequently most suitable for the determination of N-acetylneuraminic acid in some samples like EBN.

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method was proposed for the determination of imazethapyr in soybeans and its reliability was evaluated by determining various figures of merit such as sensitivity, accuracy and precision. Samples were extracted using a mixture of methanol and 0.1 mol/L sodium carbonate aqueous solution with ultrasonic assistance and centrifugated. The supernatant was then harvested, acidified and extracted twice using methylene chloride. The methylene chloride phase was finally separated using a separatory funnel and cleaned up on a strong cation exchange solid-phase extraction column and the resulting eluate was evaporated to dryness and redissolved in methanol prior to injection into the HPLC system equipped with a UV detector. The method revealed a limit of detection of 0.00837 mg/kg. Mean recoveries of 3 replicates for imazethapyr in 4 varieties of soybeans spiked at 3 levels were within the range of 70.6%－106.7%, with a RSD range of 1.56%－12.8%. This method proved to meet the Chinese national standard requirements for the determination of pesticide residue in foods.

A sensitive and rapid HPLC-MS/MS method was developed for the determination of 10 Beta-adrenergic agonists residues in pork. Samples were subjected to extraction with acidified acetontrile, followed by solid phase extraction clean-up before HPLC-MS/MS analysis. The developed standard curves of 10 Beta-adrenergic agonists all displayed good linearity over the concentration range of 0.5－100μg/kg. Mean recovery rates of 6 replicates for Beta-adrenergic agonist in a negative pork sample spiked at three levels were between 72% and 87%. The limit of detection of the method ranged from 0.1 to 1μg/kg. This method proved to be of simplicity, high sensitivity and good selectivity and provided satisfying determination results. Therefore, its application deserves to be popularized among various food testing laboratories.

The present study aimed to analyze and compare the evolution of aromatic compounds in grape wines fermented with and without the addition of Ginkgo biloba leaf extract during aging. The aromatic compounds in grape wines were extracted by the solvent extraction method, analyze by GC-MS and identified by the computer search technique. Totally 32 compounds were separated, among which 29 were identified, mainly including aldehydes, alcohols, esters, and furans. There was an obvious difference in aromatic compounds between both freshly fermented grape wines. However, the difference became unobvious after 1 year of aging and both aged grape wines exhibited similar kind and amount of aromatic compounds.

A high performance liquid chromatography-tandem mass spectrometric (HPLC-MS/MS) method was developed for the determination of chloramphenicol, thiamphenicol and florfenicol in animal muscles. Samples were spiked with deuterated chloramphenicol-d5 (d5-CAP) as internal standard and extracted with alkaline ethyl acetate. The resulting extract was then treated with n-hexane for the removal of lipids and injected directly into the HPLC-MS/MS system without the requirement of solidphase extraction clean-up. The electrospray ionization (ESI) mass spectrometry was run in negative ion multiple reaction monitoring mode. Instrumental parameters for MS analysis were optimized to maximize the detection sensitivity. The method exhibited the same limit of detection of up to 0.01μg/kg for the analytes. The internal standard method gave determination results closer to the actual values than the external method and the correlation coefficients of the linear regression equations developed for the determination of the analytes were all more than 0.9990. Mean recoveries of 5 replicates for chloramphenicol, thiamphenicol and florfenicol at the spike levels of 0.02－1μg/kg were within the ranges of 92.8%－97.0%, 93.5%－96.6% and 91.2%－ 95.9%, respectively.

A head space solid-phase microextraction (HS-SPME) combined with gas chromatography mass spectrometric (GCMS) method was proposed for the quanlitative and quantitative analysis of C6 aldehydes and alcohols responsible for the aroma of grapes. In additions, three different varieties of ripening wine grape (Cabernet Sauvignon, Merlot and Cabernet Franc) berries were compared for the difference in the contents of C6 aldehydes and alcohols determined by the developed HS-SPME-GC-MS method. Results showed that hexanal, hexanol, trans-2-hexenal, trans-2-hexen-1-ol and cis-3-hexen-1-ol were prominent compounds in the three varieties of grapes. The regression curves developed for the determination of the C6 aldehyde or alcohol compounds displayed good linearity with a correlation coefficient of more than 0.99. The analytical method exhibited limits of detection of less than 5μg/L for these compounds. Mean recoveries for the compounds in either Cabernet sauvignon, Merlot or Cabernet Franc grape juices spiked at one level were within the range of 85%－110%, with a RSD range of 3%－9%. This method demonstrates the advantages of simplicity, rapidity and accuracy and therefore is most suitable for the analysis of grapelike samples. There was a significant difference in the contents of hexanal, hexanol, trans-2-hexenal, trans-2-hexen-1-ol and cis-3-hexen-1-ol among Cabernet Sauvignon, Merlot and Cabernet Franc. Cabernet Sauvignon contained even more hexanol, trans-2-hexenol and cis-3-hexen-1-ol than other two varieties. The lowest contents of hexanol and cis-3-hexen-1-ol were observed in Merlot. The orders of contents of hexanal and trans-2-hexen-1-ol from highest value to lowest value were both Cabernet Franc, Cabernet Sauvignon and Merlot. Odour activity value (OVA) analysis indicates that C6 aldehyde compounds including hexanal and trans-2-hexenal make greater contribution to the aroma of grapes than C6 alcohol compounds including hexanol, trans-2-hexen- 1-ol and cis-3-hexen-1-ol.

To evaluate the fresh-keeping effect of limonene as a natural preservative, the emulsification of limonene with various emulsifers and the changes in physicochemical and microbiological and sensory attributes of freshly squeezed sweet orange juice added with emulsified limonene during storage at (36 ± 1) ℃ were investigated. The attendance of sucrose ester SE-15 at the concentration of 20 g/L in the aqueous solution gave the best emulsification of limonene, with an absorbance difference at 420 nm of the emulsion before and after centrifugation. The addition of SE-15 emulsified limonene at the level of 0.25 g/L had no obvious fresh-keeping effect on sweet orange juice. However, the treated sweet orange juice exhibited a much lower total number of bacteria than the control without the addition of SE-15 emulsified limonene after 3 days of storage. There were no obvious differences in pH and sensory attributes between the treated and untreated sweet orange juices throughout the 8-day storage period. When the amount of added emulsified limonene was no less than 0.50 g/L, an obvious fresh-keeping effect on sweet orange juice was observed. Moreover, the treated sweet orange juice was better than the control in terms of total number of bacteria, pH and sensory attributes.

To explore the effect of harvesting time on browning of ‘Okubo’ peach pulp, the changes in total content of phenolic compounds and activities of polyphenol oxidase (PPO) and peroxidase (POD) in ‘Okubo’ peaches collected at different harvesting times were examined during storage at 0 ℃ or 25 ℃‘. Okubo’ peaches harvested earlier exhibited higher total content of phenolic compounds and PPO and POD activities and more severe browning. This indicates that an appropriate delay of harvesting time attenuates the browning of ‘Okubo’ peach pulp. The lowest degree of browning was observed in ‘Okubo’ peach pulp with 80% degree of maturity (harvested on July 22 in Xinji City, Hebei Province).

Konjac glucomannan (KGM) as a film-forming agent and Chinese traditional herbal extract as an antibacterial agent were mixed to form a compound coating agent. To evaluate the fresh-keeping effect of the compound coating agent, the weight loss rate, decay index and harness of ‘Gala’ apples treated with the compound coating agent were determined after 108-day storage at (0 ± 1 )℃. To achieve an optimal compromise among low weight loss rate, low decay index and high firmness, the optimal formulation of the compound coating agent and the optimal treatment time were investigated using orthogonal array design. Results showed that the optimal compound coating agent formula was that 1 L of the finished compound coating agent contained 3 g of KGM, water extract from 6 g of Flos Caryophyllata, 0.3 mL of Tween-20 and the optimal treatment time was 20 min. The treatment with the compound coating agent delayed the decrease of fruit firmness and the degradation of titratable acids, total soluble solids and vitamin C, postponed the appearance of respiratory peak and ethylene release peak, lowered the values of respiratory peak and ethylene release peak, weight loss rate and decay index.

To achieve better fresh-keeping of the fruits of Vitis vinifera L. cv. Chaoteng (Chaoteng grape), chitosan coating combined with chlorine dioxide fumigation was used to treat them. Results showed that the treatment increased the firmness and good-fruit rate and lowered the browning index of Chaoteng grapes to a certain extent. Treatment with a coating containing 1.5% (g/100 mL, final concentration) chitosan and 0.5 g/100mL calcium chloride followed by chlorine dioxide fumigation at 0.3 g/kg fruit weight dosage reduced the loss of soluble sugars, vitamin C and titritable acids, effectively suppress the activities of POD and PPO and the accumulation of MDA and increased the activity of SOD in Chaoteng grapes.

Citrus fruits were treated for 10 min with propolis extract dissolved in a small amount of absolute ethanol and diluted with water to a concentration of 0.1%, inoculated with Penicillium italicum suspension (1 × 106 CFU/mL) at different posttreatment time points and stored at 26 ℃. After 72 h storage, the inhibitory effect of propolis extract treatment against lesion diameter of citrus fruits inoculated with Penicillium italicum was measured to determine the optimal expression time for resistance to blue mold disease. Besides, the changes in biochemical and physiological parameters of treated citrus fruits were examined. Results showed that treated citrus fruits exhibited the strongest resistance to blue mold disease at 48 h post-treatment. Propolis extract treatment increased the content of total phenolic compounds and enhanced the activities of enzymes related to induced disease resistance such as phenylalanine ammonia-lyase, polyphenol oxidase, peroxidase, and chitinase in citrus fruit peels. This demonstrates that propolis extract treatment has the ability to strengthen the defense system and reduce the blue mold disease incidence in citrus fruits, thereby providing an effective approach for the fresh-keeping of citrus fruits.

Fresh ‘Chester’ blackberry fruits with different degrees of maturity (DM) were stored at 20 － 25 ℃ or 2 －5 ℃ and the changes in their physical and chemical quality characteristics were determined at 3-day intervals during a storage period of 24 days. Results showed that DM and storage both had a remarkable effect on the storage life of ‘Chester’ blackberry fruits. ‘Chester’ blackberry fruits with lower DM stored at lower temperatures (more than 0 ℃) displayed longer storage life. Fully ripe blackberry fruits were most easy to decay, had a very short storage life, which only was 2－3 days at 20－25 ℃, and exhibited rapidly deteriorated quality characteristics during storage. Therefore, they are unsuitable to be sold in the market. Initially ripening blackberry fruits displayed perfect storage resistance and a storage life of 15－18 days at 2－5 ℃, whereas their appearance was small in size and their quality was bad. Thus, they are also unsuitable to be sold in the market. Blackberry fruits with a medium DM had a storage life of 8－11 days at around 4 ℃, and post-ripening occurring during storage made their main quality parameters basically reach the levels of fully ripe blackberry fruits. So, they are suitable to be sold in the market.

To solve the problem of short shelf life of Chinese conventional fish cake, 3 preservatives including Nisin, ε - polylysine and potassium sorbate, which exhibited better respective preserving effect than other 3 preservatives including pimaricin, ethylparaben and sodium benzoate, were simultaneously added to the fish cake formula. To minimize total number of bacteria in fish cake, the optimal amounts of added Nisin, ε-polylysine and potassium sorbate were investigated using response surface analysis based on quadratic general rotation design. Results showed that the fish cake with 0.023%－0.034% of Nisin, 0.04%－0.06% of potassium sorbate and 0.022%－0.028% ofε-polylysine exhibited a minimum total number of bacteria and its shelf life at 0 － 4 ℃ was up to around 10 weeks.

Unheated or microwave heated channel catfish byproducts with a central temperature of 90 ℃ were used as raw material to prepare fish silage. Both fish silages obtained were stored for 40 days at 6, 10, 15, 20, 30, 40 ℃ and were measured for basic chemical composition, amino acid composition, trace element composition, degree of hydrolysis and acid soluble protein content at different storage time points. Results showed that 40-day storage at 40 ℃ resulted in an increase by 12 g/kg of protein content in fish silage prepared from unheated channel catfish byproducts compared with freshly prepared fish silage, whereas the contents of fat, ash and water were decreased by 3, 3 g/kg and 31 g/kg, respectively. However, no obvious changes in amino acid composition and inorganic element composition were observed. Storage conditions such as temperature and time made a big difference to the degree of hydrolysis and acid soluble protein content of fish silage prepared from unheated channel catfish byproduct, whereas there were no obvious changes in the degree of hydrolysis and acid soluble protein content of fish silage prepared from microwave heated channel catfish byproducts with changing storage conditions.

A new solid-state chlorine dioxide preservative was designed based on the fact that chlorine dioxide gas is generated from chlorate exposed to sulphur dioxide gas donated by sulfates. The respective effects of diatomite, sodium carbonate and calcium oxide added to the preservative on chlorine dioxide release were explored. In addition, the applicability of the preservative in Golden Queen melon storage was evaluated. Results showed that sodium metabisulphite as a sulphur dioxide donor effectively reduced sodium chlorate to generate chlorine dioxide. The respective additions of diatomite, sodium carbonate and calcium oxide gave an effective regulation on the amount and time course of chlorine dioxide release. Golden Queen melons treated with the preservative consisting of sodium chlorate and sodium metabisulphite (1:1.5, m/m) exhibited a commodity rate of up to 85% after 3 months of storage under the conditions of 4－7 ℃ and 80%－90% relative humidity. This demonstrates an excellent preserving effect of the preservative on Golden Queen melons.