The enzymatic hydrolysis of tilapia waste by flavourzyme combined with papain was optimized by combinedly using Plackett Burman (PB) design, steepest ascent design and central composite design. Firstly, PB design was applied to identify hydrolysis time and solid-to-liquid ratio as the most significant of 6 factors influencing the hydrolysis degree of tilapia waste. Then the center points of the two factors were determined based on steepest ascent design. Finally, the optimization of the two factors was carried out by using central composite design. The results showed that the optimal hydrolysis conditions were as follows: solid-to-liquid ratio 1:6.25, hydrolysis temperature 45 ℃, hydrolysis time 4 h, enzyme dosage 0.3% and the ratio of flavourzyme to papain 1:3. Under such conditions, the experimental degree of hydrolysis was 22.38%, which was in good agreement with the predicted one of 21.50%. In conclusion, the optimized process has good reliability.

Soluble dietary fiber (SDF) was prepared by twin-screw extrusion of defatted corn spermoderm, and the extrusion conditions were optimized by response surface analysis. On the basis of one-factor-at-a-time experiments, the optimal extrusion conditions for maximizing SDF content in final products were determined by using a 3-variable, 3-level Box-Behnken experimental design combined with response surface analysis as follows: material moisture content 138%, material granularity 0.175 mm and extrusion temperature 169 ℃, resulting in an SDF yield in final products of 10.75%, which is in basic agreement with the predicted value of 11.01%. Thus, the optimal process is reliable.

The demulsification of soybean emulsion, prepared by aqueous enzymatic method, was investigate by microwave treatment under varying conditions of treatment time, microwave power, pH and sample concentration. The optimal demulsification conditions were found to be: microwave treatment time 49 s, microwave power 700 W, pH 4.66, and emulsion concentration 82%. Under these conditions, the demulsification rate was 75.88%. Consequently, microwave treatment can be applied for aqueous enzymatic production of soybean oil as a very effective demulsification approach.

Component A was obtained from Fructus Momordicae extract by tandem AB-8/ADS-7 column chromatography followed by thin layer chromatography (TLC) using n-buttoanol-CH3COOH-water (4:1:2) as the development solvent. The component was separated into fractions A1, A2 and A3 by preparative high performance chromatography (HPLC) on ODS column (Ф 20 mm ×250 mm) using 30% aqueous methanol as the mobile phase at a flow rate of 8 mL/min, in which the detection wavelength was set as 210 nm. Fraction A2 was identified by HPLC as mogroside. Fractions A1 and A3 were unknown compounds.

Orthogonal array design was used to optimize the extraction of protein from almond (Amygdalus communis L.) seed kernel by alkaline extraction and acid precipitation method or ultrasonic-assisted alkaline extraction method. The optimal conditions for protein extraction by alkaline extraction and acid precipitation were obtained as follows: material/liquid ratio 1:25, pH 10.0, extraction time 40 min, and extraction temperature 60 ℃. The optimal ultrasonic-assisted alkaline extraction conditions were material/liquid ratio 1:20, pH 9.0, extraction time 15 min, and ultrasonic power 125 kW, resulting in an extraction efficiency of 37.16%. Therefore, the ultrasonic-assisted alkaline extraction method revealed the advantages of shorter extraction time and higher extraction efficiency over the alkaline extraction and acid precipitation method.

Response surface methodology was employed to optimize the ultrasonic-assisted extraction of polyphenols from grape skin as a byproduct of wine making. On the basis of one-factor-at-a-time experiments, through which the optimal ultrasonic power and ethanol concentration were found to be 100 W and 40%, respectively, polyphenol yield was investigated by response surface methodology with respect to liquid-to-material ratio, extraction time and temperature at three levels. The optimal levels of liquid-to-material ratio, extraction time and temperature were determined to be 16:1 (mL/g), 57 min and 50 ℃. Under such conditions, the yield of grape skin polyphenols was (42.51 ± 1.21) mg/5 g. The antioxidant activity in vitro of the obtained extract was evaluated by DPPH free radical scavenging assay and potassium ferricyanide reduction assay using water-soluble VE as the control. Grape skin polyphenols were found to have powerful DPPH free radical scavenging capacity and reducing power in a linear dose-dependent manner.

Objective: To isolate and purify water soluble protein from giant mealworm beetle (Zophobas morio) larvae and evaluate its antioxidant activity. Methods: The water soluble protein in giant mealworm beetle larvae was extracted with pH 7.4 phosphate buffer, purified by ammonium sulfate precipitation, and fractionated by Sephadex G-100 column chromatography to obtain fractions P1, P2 and P3. Fraction P2 was further fractionated by DEAE-Sepharose FF column chromatography into subfractions P2M1, P2M2 and P2M3. The antioxidant activities of each fraction and each subfraction were investigated by DPPH and hydroxyl free radical scavenging assays. Results: Subfraction P2M2 presented the highest DPPH and hydroxyl free radical scavenging rates, which were 99.42% and 55.11%, respectively.

Parameter optimization for the superfine comminution of Astragalus membranaceus root by vibration-milling was carried out based on cumulative distribution rate of 400 mesh superfine powder (Va). The physical properties of superfine Astragalus membranaceus root powder were studied at different levels of granularity. Results showed that superfine comminution increased the fluidity, water binding capacity, expansibility and bulk density of Astragalus membranaceus root. The maximum dissolution rate of total flavonoids from superfine A. membranaceus root powder of 400 mesh was 0.26 g/100 g. The optimal superfine comminution of Astragalus membranaceus root was achieved through dry comminution on high-speed pulverizer for 1 min, sieving through a 60 mesh sieve, moisture content adjustment to 6.7% and superfine comminution at － 20 ℃ for 20 min. As a result, a Va of 86.9% was obtained. Moisture content had the greatest effect on Va, followed by comminution time and temperature. Moreover, a regression model for Va (Y) as a function of temperature (A), comminution time (B) and moisture content (C) was obtained as follows: Y = 85.62 + 0.085A + 1.22B － 3.48C + 1.05AB + 0.35AC + 0.63BC － 2.28A2－ 4.18B2 － 2.73C2.

The essential oil of Semen Abutili was extracted by petroleum ether under ultrasonic assistance and microencapsulated using β-cyclodextrin (β-CD) as the wall material. Based on one-factor-at-a-time experiments, Box-Behnken experimental design combined with response surface analysis was applied to optimize process conditions for the extraction and microencapsulation of the oil. The optimal process conditions were determined as follows: 75 W ultrasonic power, 62.3℃ encapsulation temperature and 88 min encapsulation time. Under the optimal conditions, the observed value of encapsulation rate was 81.35%, which was in good agreement with the predicted value. Encapsulation rate was highly significantly affected by encapsulation temperature (P＜0.01) and time (P＜0.01). Ultrasonic power presented a significant effect (P＜0.05).

In this work, the enzymatic hydrolysis of squid ink was investigated to prepare natural melanin. Squid ink was hydrolyzed by papain, neutral protease, acidic protease, pepsin and tyrpsin, respectively, and pepsin was found to have the strongest ability to hydrolyze squid ink. Based on one-factor-at-a-time experiments, an L9(34) orthogonal array design was used to optimize the hydrolysis of squid ink by pepsin. The degree of hydrolysis of squid ink was investigated with respect to pH, hydrolysis time, temperature and enzyme amount. The four conditions were optimized as follows: pH 1.5, temperature 37 ℃, reaction time 5 h and pepsin amount 1.5%. Under the optimized conditions, the degree of hydrolysis of squid ink exceeded 13.50%. Ultraviolet-visible spectral analysis revealed the characteristic absorption of melanin derived from squid ink at 220 nm wavelength. High-intensity absorption peaks at 3384.54 cm-1 and 1617.35 cm-1, assigned to the structure of indole ring were observed in the infrared spectrum.

In order to improve the stability of pectin-protein-phenolics complex in cloudy apple juice, a model system was made by dissolving catechin, gliadin and apple pectin in water. The effects of relative molecular mass, degree of esterification (DE) of pectin and pH of the system on the stability of the ternary complex, evaluated based on turbidity retention rate were studied by one-factor-at-a-time and orthogonal array design methods. Results showed that as the relative molecular mass and DE of pectin and the pH of the system increased, turbidity retention rate initially increased and then decreased. Maximum turbidity retention rate was achieved by adding pectin with relative molecular mass of 84700 and DE of 62.95% and adjusting the pH of the system at 3.7.

Radix Actinidiae Chinensis from cultivar Miliang No. 1,, grown in west Hunan province was used as the raw material to extract triterpenoids by means of supercritical CO2. The effects of material growth period, material particle size entrainer type, entrainer amount and four extraction parameters on extraction rate of triterpenoids were investigated by one-factor-at-a-time method, and four extraction parameters were optimized by orthogonal array design method. The optimal extraction conditions were determined as follows: material growth period 3 years, particle size 60 mesh, 70% (V/V) ethanol as entrainer, material-ethanol ratio 1:3 (g/mL), extraction temperature 40 ℃, extraction pressure 22 MPa, extraction time 3 h, and CO2 flow rate 300 kg/h. Under the optimal conditions, the extraction rate of triterpenoids was 1.994%.

Broken rice starch was modified with octenyl succinic anhydride in aqueous slurry system. The modification process was optimized by one-factor-at-a-time and orthogonal array design methods to achieve maximum degree of substitution (DS). The results showed that the optimal process conditions were found to be: starch slurry concentration 30%, pH 8.5, reaction time 5 h, and reaction temperature 35 ℃. Under the optimal conditions, the degree of substitution was 0.01445.

In the present work, the extraction conditions for flavonoids from pubescent holly roots were optimized by response surface methodology (RSM) for achieving maximum extraction rate and DPPH radical scavenging rate of flavonoids. Two polynomial regression models for the extraction rate or DPPH radical scavenging rate of flavonoids as a function of three variables temperature, extraction time and material-to-liquid ratio were established. According to the models, each variable had a significant impact on the extraction rate and DPPH radical scavenging rate of flavonoids from pubescent holly roots. The optimal extraction conditions for simultaneously achieving extraction rate and DPPH radical scavenging rate of flavonoids were extraction time of 90 min, material-to-liquid ratio of 1: 21, and extraction temperature of 79 ℃. Under the optimal extraction conditions, the extraction rate and DPPH radical scavenging rate of flavonoids were 0.419% and 98.8%, which were close to the predicted values. Therefore, RSM optimization can provide a reliable process for extracting flavonoids from pubescent holly roots.

The scavenging effect of hydrolyzed corn gluten meal (HCGM), prepared by hydrolyzing defatted corn gluten meal with alkaline protease, against hydroxyl free radicals generated in Fenton system was determined by rhodamine B oxidative assay. The development of a honey suckable jelly was investigated using HCGM and honey as the main ingredients with the addition of citric acid, malic acid and gelatin, and the optimal production formula for achieving maximum comprehensive sensory score was determined by one-factor-at-a-time and orthogonal array design methods to consist of 2% HCGM, 8% honey, 0.1% citric acid, 0.05% malic acid and 2% gelatin. The prepared HCGM honey suckable jelly exhibited a smooth and refreshing mouth-feeing and a delicately balanced sweet-tart flavor.

Porous arrowroot starch was prepared by simultaneous hydrolysis with α-amylase and glucoamylase. The effects of enzyme dosage, glucoamylase-to-α-amylase ratio, pH, hydrolysis time and hydrolysis temperature on the oil-absorbing capacity of porous arrowroot starch were investigated. The optimal hydrolysis conditions for preparing porous arrowroot starch were determined by orthogonal array design method to be 3:1 glucoamylase-to-α-amylase ratio, 0.6% total enzyme amount, pH 5.0, 12 h hydrolysis time and 50 ℃ hydrolysis temperature. Under these conditions, the maximum oil-absorbing rate of 3:1 and excellent pore formation were achieved.

In order to optimize the extraction of pectin from citrus peel as an agricultural waste by simultaneous hydrolysis with cellulase and hemicellulase, the effects of three key factors including extraction time, temperature and total enzyme amount on the extraction rate of pectin were explored by Box-Behnken experimental design based on Placket-Burman design, by which the optimal initial pH, mass ratio of cellulase and hemicellulase, ratio of solid to liquid and material granularity were determined to be 4.5, 1:1, 1:20, 60 mesh, respectively. As a result, a mathematical model describing the relationship between the above three factors and the extraction rate of pectin was established. Based on canonical analysis of the model, the optimal extraction conditions were determined to be 0.46% total enzyme amount, 5.1 h extraction time and 41 ℃ extraction temperature. Under the optimal extraction conditions, the predicted maximum yield of pectin was 12.35%, which was close to the actual value of 12.22%. Meanwhile, each tested physical and chemical index of obtained pectin reached or even exceeded the requirements of the national standards.

In order to improve the product quality and production efficiency of modified shellac, ultrasonic enhancement was introduced in the washing of modified shellac. On the basis of one-factor-at-a-time experiments, response surface methodology was employed to optimize ultrasonic power, ultrasonic treatment time, ultrasonic pulse transit time and material/liquid ratio. The results indicated that the optimal ultrasonic-enhance washing conditions were ultrasonic treatment power of 1200 W, ultrasonic treatment time of 8 min, ultrasonic pulse transit time of 5.6 s, and material/liquid ratio of 1:9 (g/mL). The ash content of modified shellac could reach National Grade I after third repeated washing.

Lotus root slices was quick boiled in four different media such as water, acetic acid, sodium chloride and sodium bicarbonate solution and as a result, acetic acid was identified as the best medium through comprehensive considering VC content and sensory score of quick-boiled lotus root slices as well as dry matter dissolution rate. Further, on the basis of one-factor-at-a-time experiments, Box-Behnken design combined with response surface methodology was used to optimize process conditions for the quick boiling of lotus root slices in acetic acid. The results indicated that the optimal quick boiling conditions were acetic acid concentration of 0.35%, temperature of 68.4 ℃ and quick-boiling time of 2.4 min. After quick boiling under the optimal process conditions, the content of vitamin C in lotus root slices was 30.185 mg/100 g fresh weight, and better eating quality was also achieved. The results of variance analysis showed that acetic acid concentration, quick-boiling temperature and quick-boiling time had significant effects on the content of vitamin C in quick-boiled lotus root slices (P＜0.01). Moreover, the cross-interactions between acetic acid concentration and temperature and between temperature and quick-boiling time also revealed a significant effect on the content of vitamin C in lotus root slices (P＜0.05).

Objective: To optimize the fermentation of Gracilaria lemaneiformis for the preparation of dietary fiber. Methods: A mixed strain of Trichoderma viride and Aspergillus oryzae was used for fermentation. Fermentation process optimization was carried out using orthogonal array design for maximizing dietary fiber yield. Results: The optimal fermentation conditions were material/liquid ratio of 1:5, temperature of 28 ℃, pH of 6.0, fermentation time of 7 d, and the ratio between Trichoderma viride and Aspergillus oryzae of 1:1. Dietary fiber with a yield of 71.36% and better physical properties was gained by fermentation under the optimal conditions. The expansibility and water-holding capacity of dietary fiber were14.5 mL/g and 6.23 g/g, respectively.

The supercritical carbon dioxide extraction of capsaicin was systematically investigated. Four factors including extraction pressure, extraction temperature, separation pressure and separation temperature were optimized by uniform design method. Capsaicin was quantitatively analyzed by HPLC. In the present study, multifactor and multilevel visual analysis method (m2VA) was proposed to analyze experimental data. As a result, the best extraction pressure, extraction temperature separation pressure and separation pressure were found to be in the ranges of 10－21 MPa, 41－52 ℃, 8－11 MPa and 53－60 ℃, respectively.

The chelation between amino acids from shiitake mushroom, extracted by acid hydrolysis and purified by amino acid resin adsorption, and cupper ion was preliminarily investigated. Using orthogonal array design, the optimal chelation conditions were determined to be reaction at 70 ℃ for 70 min at pH 11.0 and a molar ratio between cupper ion and amino acids of 1:2. The obtained product was characterized by infrared spectroscopy and its stability constant was also determined.

Acid extraction followed by ethanol precipitation was used to extract pectin from citrus peel in the present work. Four factors that affect the extraction yield of pectin including material-to-liquid ratio, temperature, extraction time and pH were systematically investigated by one-factor-at-a-time method and response surface analysis. Further, the four factors were optimized and their significance was analyzed. As a result, the optimal conditions for pectin extraction were determined as follows: material-to-liquid ratio 19.7:1, temperature 87.5 ℃, extraction time 84 min, and pH 1.51. Under these conditions, the actual pectin yield was 7.294%, which was close to the predicted value of 7.316%. Thus, the optimized process can provide useful guidance for industrial pectin preparation.

In this study, orthogonal array design was employed to optimize thermal reaction conditions for the preparation of coffee flavor. This was followed by reaction product analysis by gas chromatography-mass spectrometry (GC-MS).When the reaction system was composed of 5 g of amino acids, 4 g of reducing sugar, 100 g of propylene glycol, 10 g of 95% ethanol and 40 g of deionized water at pH 6－8, the optimal reaction conditions were glucose/fructose ratio of 1: 1.5, arginine/lysine ratio of 2.5: 1, reaction temperature of 115 ℃, and reaction time of 4.5 h. The reaction resulted in the generation of 25 volatile flavor compounds such as furfuryl alcohol, maltol, dimethyl pyrazine, acetyl pyrrole and mercaptans. Moreover, pyrazine, pyrrodine, furan, phenol and their substitutes were the major volatile flavor compounds.

The depolymerization of gum derived from Gleditsia sinensis was performed by enzymatic hydrolysis with β- mannanase. The optimal hydrolysis conditions were investigated by using an L9 (34) orthogonal array design to explore the effects of substrate concentration, enzyme dosage, hydrolysis time and hydrolysis temperature on average polymerization degree of hydrolysates and reducing end glycosyl group yield. The results showed that the optimal conditions for depolymerization of the gum were substrate concentration of 50 g/L, enzyme dosage of 1300 U/g, reaction temperature of 65 ℃, and reaction time of 11 h. Under the optimal hydrolysis conditions, the reducing end glycosyl group yield was 49.92% and the average degree of polymerization 2.00. In addition, fed batch operation at the beginning could increase substrate concentration, and he reducing end glycosyl group yields in 100 g/L and 150 g/L reaction solutions after reaction for 24 h were 50.89% and 46.97%, respectively. The addition of surfactants such as gleditsia saponin and T-ween 80 could improve reducing end glycosyl group yield by 5.25% and 9.40%, respectively. Moreover, HPLC analysis indicated that the hydrolysates of Gleditsia sinensis gum mainly consisted of mannotetraose (17.25%), mannotriose (28.68%), mannobiose (4.55%) and monosaccharide (1.81%).

In the present work, alcalase was identified as the most suitable enzyme for enzymatic hydrolysis of Antarctic krill among 7 commonly used enzymes based on simultaneous consideration of chloroacetic acid-nitrogen soluble index (TCA-NSI) and degree of hydrolysis (DH). In order to optimize the hydrolysis of Antarctic krill by alcalase, the effects of the hydrolysis conditions enzyme dosage, substrate concentration, pH, temperature and hydrolysis time on TCA-NSI and DH were studied by one-factor-at-a-time and orthogonal rotary composite design methods. Two regression models with TCA-NSI or DH as a function of each hydrolysis condition were established. The optimal process conditions for hydrolyzing Antarctic krill with alcalase were 50.7 ℃ hydrolysis temperature, pH 8.01, 3010 U/g alcalase dosage and 239 min hydrolysis time. Under the optimal conditions, the TCA-NSI and DH were 73.02% and 42.33%, respectively. Meanwhile, peptides with an average length of 2.36 and a molecular mass of 277.9 were obtained.

Response surface methodology was used to optimize microwave inactivation of myrosinase in maca. Firstly, the effects of three factors such as microwave intensity, microwave treatment time and material-to-liquid ratio on myrosinase activity and glucosinolate content of maca were investigated by one-factor-at-a-time method. Subsequently, a mathematical model for myrosinase activity in maca was established based on a three-variable, three-level central composite design. Finally, response surface analysis was carried out to optimize the above three factors for minimizing relative myrosinase activity. The results showed that the myrosinase in maca could be inactivated completely after 60 s microwave treatment at a microwave intensity of 14 W/g and a material/liquid ratio of 2:1 (g/mL). The losses of glucosinolates and vitamin C in maca subjected to microwave treatment revealed the decrease by 28% and 21% when compared with conventional hot water blanching. Meanwhile, no significant difference in protein loss between both treatment methods was observed.

Purple sweet potato pigment (PSPP) is a kind of natural pigment and has gained extensive concern in recent years. In this study, response surface methodology was employed to optimize the extraction conditions of PSPP. The results showed that the optimal extraction conditions were extraction temperature of 60 ℃, extraction time of 1 h, solid-to-liquid ratio 1:30, and acidic ethanol concentration of 80%. Under the optimal extraction conditions, the yield of PSPP was up to 12.4688 mg/g. In addition, the stability of PSPP was also investigated. Increasing temperature and extension of heating time could result in a decrease in PSPP stability. Similarly, the stability of PSPP revealed an obvious decrease in neutral and alkaline environments. Fe3+ and Al3+ could increase the stability of PSPP; on the other hand, Cu2+, Zn2+ and Pb2+ could lead to a decrease in PSPP stability. Moreover, ascorbic acid could significantly improve the stability of PSPP and Na2SO3 did harm to the stability of PSPP.

Gas chromatography was used to determine the trans fatty acid composition of common commercially available milk tea, cream and fruit powder. The results showed that trans fatty acid content was 0.5－3 g per 300 mL of milk tea, 8.6 g per 100 g of cream, and 1－2.2 g per 100 g of fruit powder, respectively. Most trans fatty acids in milk tea arose from cream and fruit powder and the major trans fatty acids were trans C18, among which, trans C18:1 exhibited the largest content, followed by trans C18:2. In addition, small amounts of trans C16 fatty acids were identified in milk tea. The results also indicated that trans fatty acid contents of milk tea, cream and fruit powder were high and varied significantly in products and brands.

A method for the simultaneous determination of 6 phthalic scid esters (PAEs) aquaculture in water by solid phase extraction (SPE) and gas chromatography detection was developed. The SPE conditions were optimized using orthogonal array design as follows: n-hexane-acetone (30:1, V/V) as elution solvent at a flow rate of 2.0 mL/min, elution volume 6 mL, and sample loading rate 6.0 mL/min. Enriched samples were determined using a capillary gas chromatograph with flame ionization detector. The ldetection limits of 6 PAEs were in the range of 1.4－3.6μg/L. The method displayed a good linearity over the range of 1 to 80 mg/L, with a correlation coefficient of larger than 0.995. The recoveries of the 6 PAEs across low, medium high spike levels were 72%－117% and the relative standard deviations all lower than 10%. The PAEs in 12 samples from typical aquatic breeding areas in Guangdong province were detected by the established method. All samples were found to be polluted by total PAEs concentration in the range of 4.2－171.5 μg/L. Moreover, the contaminations of PAEs were closely associated with geographic areas.

Objective: To establish a method for determining naringin, hesperidin, and neohesperindin in Citrus paradisi cv. Changshan Huyou fruit and compare their contents in different parts such as peel, pulp and seeds. Methods: The contents of naringin, hesperidin and neohesperindin were determined by a reversed-phase HPLC method. Methanol extracts of samples and the standard substances were separated on a YMC C18 column (4.6 mm × 250 mm, 5μm) using a mobile phase made up of acetonitrile and water (23:77 , V/V) at a flow rate of 1 mL/min and detected by a UV detector at a wavelength of 283 nm. The column temperature was set at 25 ℃. Results: The calibration curves were linear in the range of 3.22－1030μg/mL for naringin, 0.59－380μg/mL for hesperidin, and 0.077－990μg/m for neohesperindin, respectively. The average recoveries of naringin, hesperidin and neohesperindin were 98.43% (RSD = 4.07%), 98.70% (RSD = 4.30%) and 99.90% (RSD = 3.47%), respectively. The contents of naringin, hesperidin, neohesperindin were the highest in the peel and the lowest in the seeds of Citrus paradisi cv. Changshan Huyou fruit. Conclusions: This method is simple, accurate, reliable and reproducible and can therefore be used for the quality control of Citrus paradisi cv. Changshan Huyou fruit.

The volatile compounds in the fresh fruit bodies of pine-mushroom (Tricholoma matsutake Sing.) collected from Linzhi, Yajiang and Xiaojing in Southwest China were extracted by organic solvent extraction-distillation method and analyzed by gas chromatography-mass spectrometry (GC-MS). Twenty-eight, 22 and 27 volatile compounds were identified in samples from Linzhi, Yajiang and Xiaojing, respectively, with a total number of 66. Nine volatile compounds were contained in both inzhi and Xiaojin samples and the predominant compounds were 1-oct-3-ol (28.43%) and linoleic acid (33.86%). Nevertheless, only 2 compounds, linoleic acid methyl ester (16.58%), and 2-ethyl hexanal (16.54%), were found simultaneously in the two samples and Yajiang sample. C8 alcohols and aldehydes such as 1-octen-3-ol (mushroom-like aroma) in both Linzhi and Xiaojin samples, 3-octanol (mushroom and butter-like aroma), phenyl acetaldehyde (floral honey-like aroma) in Xiaojin sample and 2-ethyl hexanal (green grass-like aroma) in Yajiang sample mostly contributed to the variation of pine-mushroom flavor. These compounds may be used for the classification of pine-mushrooms from different areas in Southwest China.

Objective: The aim of this study was to develop a PCR assay for the detection of tyramine-producing Enterococcus faecalis and Enterococcus faecium. Methods: The tyrosine decarboxylase genes (tdc gene) of Enterococcus faecalis and Enterococcus faecium were compared with those published in GenBank database, and specific primers were designed based on their nonconservative sequences to develop a PCR assay. Results: Each primer pair could only amplified their target gene from the associated ones of 27 bacterial strains tested. The detection limit of this assay was 1.0×102 CFU/mL. Conclusion: The developed PCR assay has good specificity, stability and sensitivity.

In order to establish a reversed-phase HPLC method for the determination of 8 biogenic amines, mobile phase composition, elution mode, detector type and detection wavelength were optimized. Gradient elution using a mobile phase composed of acetonitrile, ammonium acetate and ultra-pure water proved optimal, and 8 biogenic amines were completely separated within 30 min, showing symmetrical peak shapes without tails and extension. The optimization resulted in a time-saving analytical method. Moreover, fluorescence detector (FLD) presented higher selectivity and sensitivity when compared with diode array detector (DAD) so that it can meet the requirements for accurate determination of biogenic amines.

The phospholipids in rape, chrysanthemum, and lotus bee pollens were separated and purified by TLC, and were quantitatively determined by HPLC. The results indicated that the total phospholipid contents in three bee pollens were from 1.19 to 3.98 g/100 g with a significant difference (P＜0.01). Phosphatidylchuline (PC) was the predominant phospholipid in bee pollen, representing 34.30%－59.69% of total phospholipids. Phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidyl ethanolamine (PE), phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) were detected in rape bee pollen, but no PI in chrysanthemum bee pollen, and neither PI nor LPC in lotus bee pollen. As a conclusion, rape bee pollen contains the most phospholipids with the largest total content among the three sources investigated.

The variation of volatile aroma compounds in Rongchang pork at different roast temperature was investigated in this study. Partial least squares regression analysis showed pyrazine compounds revealed considerable variation and greatly contributed to the flavor of roasted pork during processing. Volatile compounds extracted by simultaneous distillation extraction (SDE) and solid-phase micro-extraction (SPME) demonstrated obvious differences. The aroma compounds extracted by SPME represented the true flavor of roasted pork more accurately.

The phospholipids in bee pollens from different flowers such as tea, sunflower, rose, seed melon and motherwort were extracted, separated by TLC and analyzed by HPLC. The fatty acid profiles in purified phospholipids were further analyzed by GC-FID. The results showed that all the bee pollens under investigation were rich in polyunsaturated phospholipids. Tea bee pollen exhibited the highest content of phospholipids, which mainly consisted of phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidyl ethanolamine (PE), phosphatidylcholine (PC) and lysophosphatidylcholine (LPC). Polyunsaturated fatty acids with higher relative contents of linoleic acid and linolenic acid were found in bee pollen phospholipids. The content of polyunsaturated fatty acids was more than 50% in bee pollen from each source. The highest relative content of linolenic acid was found in tea bee pollen as 56.0%. Therefore, bee pollen can have a broad application prospect owing to the presence of phospholipids.

The volatile composition of bamboo vinegar was qualitatively analyzed by each of the pretreatment methods purge and trap-thermal desorption (P＆T-TD) and liquid-liquid extraction (LLE) combined with gas chromatography-mass spectrometry (GC-MS) and quantified by peak area normalization method. A total of 50 compounds including acids, phenols, ketones, esters, aldehydes, etc. were identified in bamboo vinegar based on both pretreatment methods, of which 28 were identified by P＆T-TD/GC-MS, and 29 by LLE/GC-MS. The major components with a relative content of more than 2% were acetic acid methyl ester, methyl propionate, acetic acid, 1-hydroxy-2-butanone, cyclopentanone, furfural, phenol, 2-hydroxy-3-methyl-2-cyclopenten-1-one, and 2,6-dimethoxy-phenol. The volatile composition of bamboo vinegar identified by both methods revealed considerable differences and complementarities. So, the combination of both methods can result in a complete determination of the volatile composition of bamboo vinegar.

An analytical method was developed to simultaneously determine roxarsone, arsanilic and nitarsone in chicken by high performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Samples were extracted with methanol/water solution. The chromatographic separation was performed on a Phenomenex Luna C18 using methanol and water (containing 0.05% trifluoroacetic acid) as the mobile phase. Identification and quantification were achieved by using ICP-MS. Good linearity was observed in the range of 1 to 50 μg/kg with correlation coefficients above 0.99. The method was validated at the spike levels of 1, 2, 10 μg/kg. The validation results indicated that the average recoveries of arsenicum praeparatum ranged from 85.4% to 103.1% with a relative standard deviation of 3.3%－7.2%. The quantification limits of 3 arsenicum praeparatum were 1μg/kg. The method had good reproducibility, high sensitivity and simple pre-treatment. Its performance could meet both domestic and international legislation requirements. This method is applicable for simultaneous determination of arsenicum praeparatum in chicken.

In the present work, after being saponified and methyl esterified, the fatty acid composition of 97 camellia oil samples was analyzed by gas chromatography. Meanwhile, the near-infrared spectra of all samples were acquired in the transreflection mode. Calibration models for the relative contents of saturated fatty acids (C16:0 + C18:0), oleic acid (C18:1) and linoleic acid (C18:2) were established by partial least-squares regression method were applied. Additionally, the pretreatment of spectra was optimized. The results showed that the root mean square errors of cross-validation (RMSECV) for C16:0 + C18:0, C18:1 and C18:2 were 0.180, 0.598 and 0.269, respectively. The root-mean-square errors of prediction (RMSEP) for C18:0, C18:1 and C18:2 were 0.180, 0.598 and 0.269, respectively. The correlations of determination (Rp2) of the three components were 0.996, 0.999 and 0.999, respectively. These findings indicate that near-infrared spectroscopy can be used to identify the authenticity of camellia oil as a simple, rapid, nondestructive and reliable method for analyzing fatty acid profile.

The distribution and elimination of ractopamine residues in edible pork tissues were investigated. At a dosage of 26 mg/ kg, ractopamine was added to the feed for 60 healthy pigs. Three pigs were slaughtered at 1, 2, 3, 4, 5, 6, 7, 8, 9, 14, 21 and 28 d after withdrawal, respectively, and edible tissues and urine were collected to determine ractopamine residues in them by rapid pretreatment kits and ultra performance liquid chromatography coupled with tandem mass spectrometry (UPLC/MS-MS). Ractopamine showed an average residue of 96.3, 67.7, 15μg/kg and 8.9μg/kg in kidney, liver, rump and tenderloin at 1 day after withdrawal, respectively. The ractopamine residues in kidney, liver and tenderloin decreased to less than the detection limit on the 9th day compared to the 7th day observed for rump.

A method was developed to determine catechins, purine alkaloids and gallic acid in tea by HPLC-PDA. The optimum condition was achieved by separation on a Welchrom C18 column kept at 30 ℃ using phosphate buffer-acetonitrile as the mobile phase at a flow rate of 1.0 mL/min through gradient elution and detection at 278 nm. This method showed a good linearity for all 12 tested compounds. The results demonstrated high accuracy and stability of this method.

The contents of cadmium in tea samples including green tea, oolong tea, jasmine tea, and Pu,er tea were determined using microwave digestion followed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The linear range was from 0 to 100μg/L (R2 = 0.9998). The limit of detection (LOD) for cadmium was 1.88μg/L. The spike recovery was ranged from 95.7% to 102.3% with a relative standard derivation (RSD) of 1.1%. In conclusion, the method is a rapid, convenient, and highly sensitive method to determine cadmium content in tea samples. The contents of cadmium in randomly sampled forty tea samples were between 0.017 mg/kg and 0.138 mg/kg with an average of (0.082±0.028) mg/kg. The average content of cadmium in green tea showed a significant difference when compared with other tea samples (P＜0.05).

A rapid and sensitive direct competitive enzyme-linked immunosorbent assay (ELISA) using anti-AFM1 mAb with horseradish peroxidase (HRP) to measure aflatoxin M1 (AFM1) in milk was described. Using AFM1 contaminated milk ERMI-BD282 (zero), ERMI-BD 283 (0.11 μg/kg) and ERMI-BD 284 (0.44μg/kg), the sensitivity and accuracy of the developed assay was validated. The optimized assay conditions regarding sensitivity and stability were found to be: coating AFM1-BSA antigen concentration 0.25 μg/kg and dilution factor of anti-AFM1 mAb-HRP conjugate 2000. Assays of ERMI-BD282 samples spiked with AFM1 at the level of 0.45 μg/L revealed an average recovery of around 80%. The developed method showed an IC50 of 0.75μg/L and a linear range of 0.015－4.05 μg/L. This assay may be used in rapid screening of contaminated milk at AFM1 ＞0.5μg/L.

An ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) method was established to characterize phenolic compounds in domestic olive (Olea europaea L.) leaf. UPLC separation was performed on a Waters BEH-C18 column (10.0 mm×2.1 mm, 1.7 μm) using a mobile phase consisting of 0.1% formic acid water solution (A) and acetonitrile (B). The gradient program used was as follows: 0－10 min, 10% B－30% B; 10－12 min, 30% B－33% B; 12－17 min, 33% B－38% B. The flow rate was set at 0.25 mL/min and the detection wavelength at 280 nm. The mass spectrometer used was a Waters ACQUITY Q-TOF-MS equipped with an electrospray ionization (ESI) interface in negative mode. Fifteen phenolic compounds were identified from the extracts of domestic olive leaf by analyzing the total ion current (TIC) chromatograms and MS fragmentation patterns.

The quality characteristics of aquatic products of geographical indication in Guangxi autonomous region, such as Guiping sand turtle, Guandong grass carp, Quanzhou Chinese ink carp and Qinzhou Crassostrea rivularis were analyzed by determining the contents of protein, fat, Ca, Fe and Zn. The results demonstrated that among the four species of aquatic products, Guiping sand turtle contained the highest protein content of 20.8 g/100 g compared with the lowest of 9.2 g/100 g in Qinzhou Crassostrea rivularis. However, fat content was the lowest (0.3 g/100 g) in Guiping sand turtle but showed a similarity in other three species. The highest contents of Ca, Fe and Zn were all found in Qinzhou Crassostrea rivularis, particularly the content of Zn being 1055.6 mg/kg. Ca content revealed an increase in Quanzhou Chinese ink carp when compared with Guiping sand turtle and Guandong grass carp. Both Fe and Ca showed the lowest contents in Guandong grass carp, which were 5.0 mg/kg and 4.1 mg/kg, respectively. Similar contents of Fe and Zn were observed in Guiping sand turtle and Quanzhou Chinese ink carp. From the above data, it could be concluded that Guiping sand turtle is an aquatic product of higher protein content and lower fat content as compared with other three species. In addition, Guandong grass carp was more abundant in protein than ordinary grass carp and carp. The contents of Ca, Fe and Zn in Quanzhou Chinese ink carp were substantially higher than those in ordinary grass carp and carp. Qinzhou Crassostrea rivularis was rich in Ca, Fe and Zn, especially Fe and Zn with the highest content. Therefore, the contents of protein, fat, Ca, Fe and Zn of the above four species of aquatic products are basically superior to those of other similar products. Further, the 4 indicators can provide significant guidance for the identification of aquatic products of geographical indication in Guangxi.

A method to determine melamine deaminase activity by catalytic spectrophotometry was developed based on Berthelot colour reaction. The melamine deaminase activity was calculated by the amount of ammonia released per minute. The reaction conditions for melamine deaminase were optimized by one-factor-at-a-time experiments combined with an orthogonal experiment design L9(34). Optimum coloration reaction condition was obtained when the reaction was allowed to proceed for 40 min in a system composed of 0.3 mL of sodium hypochlorite and 1.2 mL of salicylic acid solution and detection at a wavelength of 650 nm. The optimal enzymatic reaction conditions was found to be 0.2 mL melamine solution, 60 μL crude enzyme and 40 min reaction time. Under the optimized conditions, the melamine deaminase activity was 132.41 U/L with inter-assay and intra-assay coefficients of variation of 0.81%－1.19% and 1.27%－1.69%, respectively.

An analytical method for the simultaneous determination of 17 amino acids in Chinese wolfberry fruit and pollen was proposed using high performance cation exchange chromatography (HPCEC) with post-column derivatization. The results showed that the total content of 17 amino acids determined in dry Chinese wolfberry fruit was between 7.788% and 8.820%, including 8 essential amino acids accounting for 28.9%－30.0% of total amino acids and semi-essential amino acids accounting for 4.5%－4.8%. The total amino acid content of fresh Chinese wolfberry fruit was between 1.960% and 2.036%, in which essential amino acids were 29.2%－30.3 % and semi-essential amino acids approximately 5.2%. Chinese wolfberry pollen contained 21.62%－22.08% of total amino acids, of which essential amino acids accounted for 37.9%, and semi-essential amino acids for approximately 4.9%.

The content of cadmium in flour was determined by graphite furnace atomic absorption spectrometry (GFAAS), and the sources of uncertainty were evaluated. Each parameter in mathematic model was analyzed to evaluate the type A and type B uncertainties in the method. To obtain the uncertainty evaluation, each uncertainty component was synthesized and extended by the current international method. The results showed that the major source of the uncertainty in the method was the sample solution volume and the standard curve.

A method to determine prochloraz in orange peel by electrochemistry analysis after derivatization was developed. Prochloraz was stepwise extracted by acetone and ethyl acetate, and hydrolyzed into electrochemical active 2,4,6-trichlorophenol by pyridine hydrochloride. Differential pulse stripping voltammetry (DPSV) was utilized to determine prochloraz under the optimized conditions pH 4.0 and accumulation at 0 V potential for 300 s. The results showed that oxidative peak current of 2,4,6-trichlorophenol was positively linearly correlated with its concentration within the range of 9.0 × 10-9－8.0 × 10-5 mol/L. The detection limit was 9.7 × 10-10 mol/L, and the recovery between 98.5% and 113.0%.

A method to determine 9 penicillin residues in milk and milk powder by high performance liquid chromatography- tandem mass spectrometry (HPLC-MS/MS) was established. Samples were extracted by acetonitrile-water, cleaned by solid-phase extraction, detected by HPLC-MS/MS and quantified by external standard method. The detection limit was 1 μg/kg for ampicillin and nafcillin, 2 μg/kg for amoxicillin, piperacillin, penicillin G, penicillin V and cloxacillin, 4 μg/kg for oxacillin and dicloxacillin in milk, and was 8μg/kg for ampicillin and nafcillin, 16 μg/kg for amoxicillin, piperacillin, penicillin G, penicillin V and cloxacillin, 32 μg/kg for oxacillin and dicloxacillin in milk powder, respectively. The linearity was satisfactory with a correlation coefficient ＞ 0.9997 at concentrations ranging from 1.0 to 50 ng/mL. Spike average recoveries for the 9 penicillins in milk was in the range of 77.58% to 97.77% with a RSD of 4.24% to 16.59% (n = 10), and Spike average recoveries in milk power in the range of 85.95% to 96.78% with a RSD of 2.71% to 13.98% (n = 10). In conclusion, the established method is convenient, rapid, accurate and sensitive so that it may be applied to determinate penicillin residues in milk and milk powder.

An ion exclusion chromatographic method for the determination of gallic acid in green tea was described. The optimal chromatographic separation was investigated on Metrosep Organic Acids (250 mm×7.8 mm) column with conductivity detection. The optimal separation was achieved using 0.006 mmol/L sulfuric acid as the eluent, 50.0 mmol/L lithium chloride as the regenerated liquid at a flow rate of 0.5 mL/min. Fluoride and 8 common acids in green tea had no interference on the determination. The total analysis time was 19 minutes. The detection limit of gallic acid was 0.1 μg/mL. The RSD of peak area for six replicate determinations was 1.34%. The recovery percentages in 4 green teas were 87.1%－96.7 %. So, the method has the advantages of simplicity, rapidity and satisfying results.

Objective: To determine cyanidin-3-O-glucoside (C3G) content in black soybean hulls grown in different regions of China by HPLC. Methods: The chromatographic separation was performed on Phenomenex Luna Su C18 (250 mm × 4.60 mm, 5 μm) column by gradient elution using 0.5% phosphoric acid solution as mobile phase A and water: acetonitrile (50:50, V/V) as mobile phase B at a flow rate of 0.8 mL/min. The column temperature was set at 30 ℃and the detection wavelength at 520 nm. Results: The developed regression equation of cyanidin-3-O-glucoside standard is: Y ＝ 2 × 107X － 33120 (r＝ 0.9998). A good linearity was shown in the range of 0.1041－1.041 μg. The average recoveries at three spike levels were 92.4%, 92.5% and 95.5%, respectively. The contents of cyanidin-3-O-glucoside in samples from Northeast China and Shandong, Hubei and Anhui provinces were in the range of 5.263－12.829 mg/g. Conclusions: The method is simple and reliable, and may be used for the quality control of black soybean hull from different geographic origins.

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was proposed to determine ochratoxin A (OTA) in foods. Samples were extracted by methanol-2% sodium bicarbonate solution (60:40, V/V) or methanol-water (80:20, V/V), followed by clean-up on OchraTest affinity cartridge using methanol-5 mmol/L ammonium acetate solution in the presence of 0.1% formic acid as the mobile phase. OTA was detected in the in positive ion mode. The average spike recoveries for ochratoxin A in 4 food samples were 82.3%－ 98.5% (n ＝5). The limit of detection was 0.1 μg/kg, which can meet the latest requirement of the EU. Moreover, this method proved suitable for a broad range of sample matrices with high accuracy, sensitivity and disturb resistance.

A specific and sensitive PCR method for the detection of Vibrio was established. The ctxA, zot and RS1 genes of CTX genetic element, tcpA and toxT genes of VPI pathogenic island, rtxC gene of RTX cluster, and toxR, T139, tcpH, toxRS, toxS and ctxAB genes in 6 Vibrio isolates reported in the literature were used to design specific primers for PCR. The results indicated that the established method was simple, easy, specific and time-saving. As a result, it can effectively and efficiently detect virulence genes of Vibrio strains.

An analytical method for the rapid determination of 50 pesticides residues in citrus by gas chromatography-mass spectrometry (GC-MS) with QuEChERS was established in a selected ion-monitoring (SIM) mode. The pesticide residues in samples were extracted into acetonitrile and salted out by anhydrous MgSO4 and NaCl. Then, the pesticide residues in the supernatant after clean-up on N-propyl ethylenediamine (PSA) cartridge were subjected to GC-MS analysis. Under the optimal conditions, the limits of detection (RSN ＝ 3) of the established method were in the range of 0.0038－0.066 mg/kg, and the average recovery rates (ｎ＝6) for 50 pesticide residues in a blank sample were 72.0%－118.2% with a relative standard deviations (RSDs) of 1.7%－19.7%.

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to determine the volatile compounds and aroma compounds in stewed pork broth. A total of 42 volatile compounds including aldehydes, acids, alcohols, hydrocarbons and furans were identified. Meanwhile, 19 aroma compounds were identified by GC-O. According to aroma intensity, hexanal, (E,E)-2, 4-nonadienal, 2-undecenal, 1-octen-3-ol, 1-octanol and an unknown compound of RI (retention index) 912 were identified as the critical aroma compounds in stewed pork broth.

Graphite furnace atomic absorption spectrophotometry (GF-AAS) coupled with direct injection was used to establish a determination method for manganese in edible oil. The formation conditions of microemulsion and the effects of C12H25NaO4S concentration, ashing temperature and atomization temperature on absorbance were explored. Based on one-factor-at-a-time experiments, the optimal determination conditions were determined by orthogonal array design to be C12H25NaO4S concentration of 4.0 mg/mL, ashing temperature of 900 ℃ and atomization temperature of 1900 ℃. Under the optimal conditions, the content of manganese in edible oil was determined to be 37.49 ng/mL with a relative standard deviation of 1.86% and the detection limit of the method was 0.88 ng/mL. The average recovery rate for manganese in edible oil across three spike concentrations was 101.8% with a relative standard deviation of 3.27%. Therefore, this method is rapid, accurate and applicable without pollution and complex sample pretreatments.

A test strip for the detection of cadmium was developed by immobilizing 1-(4-nitrophenyl)-3-(3- methyl-pyridyl) triazene, a chromogenic agent specific for cadmium, onto a supporting pad. After the test strip was inserted into a self-made photoelectrical sensor, the reflectivity was recorded as the sensor signal. A standard calibration curve was established between reflectivity and cadmium concentration in standard solution. The results showed that this photoelectrical sensor could detect cadmium over the concentration range of 0.0179－0.2857 mmol/L within 2 min and revealed a detect limit of 0.00348 mmol/L. This technique exhibited the advantages of short assay time and convenient operation. Therefore, this photoelectrical sensor has the potential to apply in the on-site detection of cadmium.

A high performance liquid chromatography coupled with evaporative light-scattering detection (HPLC-ELSD) method for analyzing cerebroside content in aquatic products was developed. The separation was performed on a TSKgel CN-80Ts column by using hexane-2-propanol and dichloromethane-methanol as the mobile phase at a flow rate of 1.0 mL/min. The temperature of drift tube was kept at 50 ℃ and the flow rate of nitrogen was 2.4 L/min. The aquatic products sea cucumber, sea urchin, sea starfish, fish liver and fish brain were selected as experimental subjects. Under optimal conditions, effective separation of cerebrosides was completed within 14 min. The linear range of the established cerebrosides calibration curve was 0.05－5μg, and the limit of detection was 0.01μg with a regression correlation coefficient of 0.99. The average recovery rate for cerebrosides in sea cucumber across three spike levels was 94.28% with a relative standard deviation of 4.90%. An excellent stability of this method was observed. In these aquatic products, the content of cerebrosides in sea starfish was the highest, which was up to 11.21 mg/g; in contrast, sea cucumber had the lowest content of cerebrosides, which was 0.35 mg/g. These results demonstrate that the proposed method is feasible, rapid, simple and accurate. Meanwhile, aquatic products such as sea cucumber can be used as a potential source of functional sphingolipids.

An electrochemical method was developed for the sensitive and selective determination of melamine in milk samples. The sample preparation involved extraction with acetocaustin and clean-up on a solid phase extraction column. The cyclic voltammetry was used to determine melamine in 1.0 mol/L H2SO4 solution, and a strong and stable current of reduction and oxidation peak was observed in the presence of melamine. Under optimal experimental conditions, the glassy carbon electrode (GCE) offered a highly sensitive and rapid response to melamine at the potential of 0.7 V for Ag/AgCl/saturation KCl in 1.0 mol/L H2SO4. The developed method displayed a good linearity over the range of 15－345 mg/kg with a detection limit of 5 mg/kg. The relative standard deviation (RSD) and recovery rate of this method were 3.5%－4.5% and 97.3%－101.2%, respectively. Compared with other reported methods, this method had multiple advantages, such as a broader linear range, a lower detection limit, easier sample pretreatment, quicker determination, lower cost and no requirements for complicated equipments.

A method was established to determine difenoconazole residues in vegetables by high performance liquid chromatography-mass/mass (HPLC-MS/MS). Difenoconazole residues were extracted from vegetables by acetonitrile and cleaned up by carbon/amino solid phase extraction (GCB/NH2-SPE) cartridge. The chromatographic separation was achieved by HPLC and the determination was performed by tandem mass spectrometry in a multiple reaction-monitoring mode. The external standard method was used for the quantification of difenoconazole. A good linear relationship was established in the difenoconazole concentration range of 1－500 ng/mL. The recovery rates of difenoconazole from different spiked samples were in the range of 79.3%－108.0% with relative standard deviations (RSD) of 2.7%－8.5% and the limit of detection for difenoconazole was 0.001 mg/kg. Therefore, the developed method can be used to qualitatively and quantitatively analyze difenoconazole residues in vegetables with satisfactory sensitivity, accuracy and precision.

Objective: A reversed-phase high performance liquid chromatographic (RP-HPLC) method was developed to determine the contents of chlorogenic acid, caffeic acid, p-coumaric acid and ferulic acid in potato tuber from Jiangxi, Beijing and Xinjiang. Methods: The contents of phenolic compounds were measured by RP-HPLC using YMC-C18 column (250 mm × 4.6 mm, 5μm) as the sationary phase and CH3OH: H2O: CH3COOH (30:70:1, V/V) as the mobile phase at a flow rate of 1.0 mL/min. Results: A good linear relationship of this method was achieved in the ranges of 7.80－1000μg/mL for chlorogenic acid, 0.78－100μg/mL for caffeic acid, 0.312－40μg/mL for p-coumaric acid and 0.078－10μg/mL for ferulic acid with a correlation coefficient of 0.9968－0.9999. The average recovery rates of this method were 92.38%－101.73%. Conclusion: The developed RP-HPLC method is characteristic of fast determination, accurate results, high sensitivity and good reproducibility. In addition, different growth environments of potato tuber have an important impact on the contents of phenolic acids.

Fast qualitative and semi-quantitative detection methods to distinguish hogwash oil in edible oil were developed by measuring conductivity. The effects of oil type, temperature, oscillation time, and oil/water ratio on conductivity were explored to establish optimal detection conditions. Through determining the conductivity of all kinds of hogwash oil and edible oil, a quantitative adulteration model of hogwash oil in edible oil was established and validated. The results indicated that the conductivities of crude hogwash oil, refined hogwash oil and edible oil in water phase were determined to be 30.15－130.80, 22.37－44.61μS/cm and 3.18－9.18μS/cm, respectively, under the conditions: room temperature, oscillation time of 30 s, oil/water ratio of 1:4 (g/mL) and phase separation time 10 min. When the conductivity of an edible oil sample was higher than 10μS/cm, the adulteration of this edible oil could be concluded and the semi-quantitative analysis can be completed by the established model.

A sensitive method based on cloud point extraction (CPE) coupled with thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) was proposed for the determination of trace lead and cadmium in litchi and longan samples. Factors affecting the cloud point extraction of lead and cadmium, such as sodium diethyldithiocarbamate (DDTC) concentration, pH, TritonX-100 concentration, extraction time and interference ions were investigated. Results indicated that the optimal extraction parameters were pH 5.0, extraction temperature of 100 ℃, extraction time of 15 min, Triton X-100 concentration of 0.3%, DDTC concentration of 0.02 g/100 mL and sample flow rate of 0.3 mL/min. Under the optimal conditions, Pb and Cd were enriched by 30 folds and 26 folds, respectively. The limits of detection of Pb and Cd were 2 ng/mL and 0.1 ng/mL, and the relative standard deviations (RSDs) were 5.2% and 3.6%, respectively. The proposed method was successfully applied to the determination of lead and cadmium in litchi and longan samples.

The contents of 5 anions including F－, Cl－, NO2, NO3 and PO4 in edible mushrooms such as Tricholoma giganteum, Boletus tomentipes and Leccinum rugosiceps were determined by ultrasonic-assisted extraction (UAE)-ion chromatography (IC) method. The results showed that the contents of other anions in each mushroom were ranked in the order of NO3 ＞ PO4 ＞ F－＞ Cl－, except that no NO2 was detected. The contents of each anion in different mushroom samples were different. This investigation can provide a reference for the determination of anions in edible mushrooms and guidance for the safety supervision of other species.

The contents of fat, non-fat milk solid, protein, casein and calcium in fresh milk from different areas of Liaoning province such as Shenyang, Benxi, Anshan and Jinzhou were determined and compared with the corresponding national standards. Meanwhile, the correlation between major nutritional components from different areas was analyzed. The results indicated that the contents of fat, non-fat milk solid, protein in all milk samples were in line with the corresponding national standards. However, a significant difference in the contents of fat, non-fat milk solid and protein in fresh milk from different areas was observed. In contrast, no obvious difference in casein-total ratio and free calcium-calcium ratio was observed among all samples. The casein in total protein was in the range of 77.0%－78.5% and the ratio between free calcium and total calcium was in the range of 62.73%－66.38%. Moreover, the contents of fat and non-fat solid revealed a significantly negative correlation, whereas the content of protein was positively correlated with calcium complex.

The catalytic activity of polyphenol oxidase (PPO) from Agaricus bisporus towards the substrate catechol was spectrometrically investigated at 420 nm under the influences of temperature, pH, substrate concentration and heating time. The results showed that the optimal temperature, pH and substrate concentration for the reaction of the enzyme were 30 ℃, 5.5 and 0.05 mol/L, respectively. The complete enzyme activity was almost lost after 80 s of thermal treatment at 90 ℃. All four enzyme inhibitors investigated indicated inhibitory effects on the enzyme, especially ascorbic acid as the strongest factor, followed by citric acid, sodium chloride and EDTA-Na.

In order to determine the optimal conditions for preserving postharvest strawberry fruits by hot air coupled with methyl jasmonate (MeJA), the effects of different combinatorial treatments on fruit decay and major quality parameters were investigated by response surface methodology (RSM). The results indicated that the optimal preservation conditions were treatment temperature of 45.18 ℃, treatment time of 2.86 h and MeJA concentration of 10.74 μmol/L. Validation experiments indicated that the optimal combinatorial treatment was more effective in inhibiting fruit decay and maintaining quality than hot air or MeJA alone.

In order to explore the effects of temperature and chitooligosaccharide on storage quality of sea urchin, the quality changes of Hemicentrous pulcherrimus treated with chitooligosaccharide at various concentrations during storage at 0 or 4 ℃ were evaluated by sensory quality, total bacterial count, total volatile base nitrogen (TVB-N), pH. The quality of Hemicentrous pulcherrimus without chitooligosaccharide treatment was also determined in the same manner. The results indicated that each quality index of Hemicentrous pulcherrimus stored at 0 ℃ was significantly lower than that of Hemicentrous pulcherrimus stored at 4℃ (P ＜0.05). Moreover, chitooligosaccharide treatment at 0 ℃ significantly enhanced the preservative effect of Hemicentrous pulcherrimus (P ＜0.05). However, the change of chitooligosaccharide concentration did not exhibit obvious impact on each quality index of Hemicentrous pulcherrimus during storage (P ＞ 0.05). The shelf-life of Hemicentrous pulcherrimus treated with chitooligosaccharide at the concentration of 0.1 g/100 mL during storage at 0 ℃ showed an extension of 5－6 days as compared with storage at 4 ℃.

The effect of cold shock treatment at 0 ℃ for 4 or 12 h on the quality and antioxidant defense system of hot peppers at room temperature (22 ℃ was explored. The results showed that cold shock treatment at 0 ℃ for 4 h could result in a decrease of disease incidence in hot peppers by 20% after 16 days of storage at room temperature, and an increase of chlorophyll, vitamin C and soluble protein contents in pericarps by 66.7%, 17.6% and 11.3%, respectively, as well as the inhibition of soluble sugar when compared with the control group. Moreover, cell membrane permeability of pericarps revealed a reduction by 20.9% for the hot peppers treated with cold shock at 0 ℃ for 4 h. However, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in the hot peppers treated with cold shock at 0 ℃ for 4 h were higher than those in the control group. On the other hand, cold shock treatment at 0 ℃ for 12 h exhibited an opposite effect in comparison with the cold shock treatment for 4 h. Therefore, the appropriate duration of cold shock treatment could reduce the disease occurrence of hot peppers after harvest, attenuate the deterioration of hot pepper quality and prolong the storage and transportation time of hot peppers at room temperature. These actions can be helpful for improving disease resistance and postponing the maturation and senescence of hot peppers.

The effects of chitosan, licorice extract and their mixture on physiological and biochemical changes of Laiyang pear fruits during at room temperature ( (22 ± 2 ) ℃) were investigated. The results showed that all the three preservative treatments could significantly (P＜ 0.05) inhibit the respiration intensity, decrease weight loss rate and decay rate, and delay the reduction of vitamin C, titratable acidity and soluble solids when compared with the control group.

The fresh-keeping effects of chitosan, alginate, nisin and lysozyme on Malu grapes during 4 ℃ storage were compared by determining their sensory quality, weight loss, hardness, respiration rate, vitamin C content, soluble solid content and SOD activity. The results indicated that chitosan-coating treatment had the best preserving effect on the sensory quality of Malu grapes. The weight loss, vitamin C content, soluble solid content, hardness and SOD activity of chitosan-treated grapes after 25 days of storage were 9.34%, 2.3 mg/100 g, 12.1%, 1027.59 kg/cm2 and 87.3 U/g, respectively. Meanwhile, the respiration intensity exhibited a significant decrease when compared with other treatment groups.

In the present work, low-salt solid-state fermentation was carried out to produce soy sauce using corn gluten as the main material and soybean meal as the auxiliary material. The optimal process conditions for achieving maximum amino nitrogen content were determined by one-factor-at-a-time and orthogonal array design methods to be 4:2 ratio of main to auxiliary materials, 12°Bén salinity, 60% moisture content in soy sauce mash, and 50 ℃ fermentation temperature. Under the optimal conditions, the amino nitrogen content in soy sauce was 0.8375 g/100 mL and the yield of soy sauce with strong and unique flavor and excellent quality 326%.

Objective: Researches on Gracilaria lemaneiformis-based seasoned instant marine vegetables processing methods were performed. Method: Utilizing the microagae Gracilaria lemaneiformis (Rhodophta) as the raw material, focused on the application of licorice solution and ozonized water to remove the off-flavour; acetic acid to soften the microagae; ZnCl2 to protect the decoloration; CaCl2 to guarantee the crispness; multi-seasoning to develop four products with different flavours under modified atmosphere storage whereas the shelf-life of the developed products predicted by kinetic model. Result: The optimum off-flavour removing conditions were: 4% licorice solution, sinking period 15 min, 0.2 mg/L ozonized water and treatment time 15 min. The shelf-life of the products reached to 7 months under the optimical modified atmosphere storage condition, i.e. CO2:O2:N2=6:1:3. Conclusion: Quality attruibutes of the developed products met the national food quality standard with excellent quality, which providied reference information regarding to the Gracilaria Lemaneiformis seasoned instant food processing industry.

In the production of yacon juice beverage with pulp, key technologies, such as color fixation, product formulation and stabilizer formulation were optimized by one-factor-at-a-time and orthogonal array design methods. The optimal color fixative formula (per 100 mL)was composed of VC 0.20 g, citric acid 0.20 g and Na2SO3 0.15 g. The optimal beverage formula (per 100 mL) consisted of yacon juice 25.0 g, yacon pulp 6.0 g, citric acid 0.15 g and sucrose 7.0 g. The optimal stabilizer was carrageenan-gelatin at a ratio of 1:2, added at a ratio of 0.25 g/100 mL.