Volume 29,Issue 10,2013 Table of Contents

1 Effects of Temperature on Morphology and Adsorption Capacity of CaCO3

YU Shu-juan , YU Pei , LIU Chang-zhan , MIN Ya-guang , PAN Run-quan

2013, 29(10):2325-2329.

[Abstract](1114) [HTML](0) [PDF 517.92 K](667)

Abstract:
In order to study the effect of temperature on morphology and adsorption capacity of CaCO3, the particle sizes and morphology of CaCO3 were characterized by means of FBRM and SEM, and the content of reducing sugars, color and purity of purified juice were also determined. The results showed that at low temperatures of 60 and 70 ℃, small and rod-like CaCO3 particles were formed. And the clarified juice showed low reducing sugar loss and color values (281 and 289 IU, respectively.), while the corresponding apparent purity values were high (93% and 90%, respectively.). However, at high temperature (80 and 90 ℃), the bigger and sphere-shaped CaCO3 particles were obtained. It was also found that theloss of reducing sugar was greater and color values were higher (303 and 385 IU, respectively) than those at low temperatures . The corresponding apparent purity was decreased (87% and 73%, respectively). Consequently, the morphology of CaCO3 and the content of reducing sugars were significantly affected by temperature. With lower temperature, the adsorption capacity of CaCO3 was better and the loss of reducing sugar was less which were both good for clarification.

2 Effect of Different Temperature and Packing on Fresh-keeping Quality of Litchi

LU Hua-zhong , LI Yuan-quan , LV En-li , YANG Song-xia , ZHOU Xiao-long

2013, 29(10):2330-2334.

[Abstract](1287) [HTML](0) [PDF 589.95 K](805)

Abstract:
To investigate the impact of temperature and packaging on the shelf-life of litchi, effects of different parameters on quality loss rate, browning index, marketable fruit rate, chromatic aberration, total soluble solid (TSS) content and titratable acid (TA) content of. exposed and perforated bags packed litchi of “Huizhi” at room temperature shelf and low temperature shelf were studied. The results showed that both low temperature shelf and packaging can extend litchi’s shelf life. The quality indicators of decay speed from fast to slow was as follows: exposed litchi at room temperature, packaged litchi at room temperature, exposed litchi at low temperature, packaged litchi at low temperature. Temperature showed the highest effect on litchi’s shelf life and low-temperature shelf efficiently reduced the deterioration rate of litchi. Perforated polyethylene film packaging could also reduce the decay of litchi quality, but the influence was lower than that of shelf temperature. Litchi’s marketable fruit rate on shelf at room temperature without packaging decreased to 0 after 30 hours while that at low temperature and packaging remained 9.20% after 60 hours. Compared with exposed room temperature shelf, low-temperature shelf and perforated polyethylene film packaging could extend litchi shelf life more than double. The results of this research provided reference for increase of the litchi shelf life during strorage.

3 The Antioxidant Activities of Walnut Protein and its Enzymolysis Product

ZHAO Mou-ming , CHEN Hui-ping , REN Jiao-yan

2013, 29(10):2335-2339.

[Abstract](1284) [HTML](0) [PDF 512.40 K](971)

Abstract:
The antioxidant activities of walnut dreg, walnut dreg protein extract, walnut kernel, peeled walnut kernel, defatted walnut kernel, peeled and defatted walnut kernel hydrolysates were researched. The results showed that, the order of reducing power of each hydrolysate was as follows: walnut kernel ? walnut dreg protein extract ? walnut dreg ? defatted walnut kernel ? peeled walnut kernel ? peeled and defatted walnut kernel. When the substrate concentration was 10 mg/mL, the reducing power of walnut kernel hydrolysate was 79.74% of the glutathione. The sequence of ORAC value was as followed: walnut kernel ? defatted walnut kernel ? walnut dreg protein extract ? walnut dreg ? peeled walnut kernel ? peeled and defatted walnut kernel. Walnut kernel hydrolysate had the highest ORAC value 1560.75 μmol Trolox equivalent/g peptide, which was equal to the same weight of the glutathione. All the enzymolysis products could protect PC12 cell damage induced by H2O2, compared with other hydrolysates, the walnut kernel had the best protective effect. When its substrate concentration was 0.10 mg/mL,0.25 mg/mL and 0.50 mg/mL, the cell survival rate reached 72.64%, 90.43% and 84.98% respectively. When the substrate concentration was 1.00 mg/mL, the best protective effect was defatted walnut kernel with the cell survival rate being of 85.11%.

4 nfluence of Nano-TiO2 Modified LDPE Film Packaging on Quality of Strawberry

LUO Zi-sheng , YE Qing-yang , LI Dong-dong

2013, 29(10):2340-2344.

[Abstract](1130) [HTML](0) [PDF 520.17 K](658)

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Nano-TiO2 modified low density polyethylene (LDPE) film packaging was prepared by blending LDPE with nano-TiO2. The effects of LDPE film and nano-TiO2 LDPE film packaging on quality of strawberry were investigated at 4 ℃ for 14 days. Results showed that compared with the control (LDPE ?lm), nano-TiO2 LDPE packaging significantly decreased the decay rate, weight loss and ethylene production of strawberry and also inhibited the reduction of firmness and titratable acid content. Additionally, nano-TiO2 LDPE packaging could keep ascorbic acid and total phenols contents, as well as antioxidant ability, at relatively higher level during the later storage period. At the 14th day, the decay rate and ethylene production of strawberry packaged with nano-TiO2 LDPE film were 60.72% and 40.32%, respectively, lower than those of the control. The firmness and the contents of titratable acid, ascorbic acid and total phenolic of the packaged strawberry were 24.34%, 9.02%, 29.22% and 10.73%, respectively, higher than those of the control. These results indicated that nano-TiO2 LDPE film packaging could provide a potential alternative for maintaining quality and prolonging storage life of strawberry.

5 Effect of Frozen Storage on Physicochemical Properties and Microstructure of Eggs

XIONG Jian , SU Si-ting , HE Pei-wen , HE Jun-ran , YE Jun

2013, 29(10):2345-2348.

[Abstract](1603) [HTML](0) [PDF 575.39 K](848)

Abstract:
Effect of different frozen storage time at -20 ℃ on whole egg, albumen, yolk, boiled egg and boiled yolk of fresh egg were investigated through determination of pH, viscosity, rebound height and structural change in the paper. The results showed that, at -20 ℃, the rebound height of boiled egg was decreased with increase of storage time of fresh eggs, while the bounce height of boiled yolk was increased 2~4 times after fozen-storaged from 5 to 36 h. Both pH and viscosity of egg yolk, albumin and whole egg had obviously changed with the increase of storage time, and the changes were more significant after freezing the samples for 10 h. The structures of the albumen and yolk frozen for 10 h began to change. After 24 h, yolk became smooth and tight, with gel, formed. And the change was irreversible after 36 h. Therefore, the quality of eggs can be greatly reduced to be substandard by frozen storage at -20 ℃for 10 h..

6 Physicochemical Properties of the Complex of Hesperidin and Hydroxypropyl-β-cyclodextrin

LIU Ben-guo , ZHANG Rui-ting , WU Xiao-nan , LI Jia-qi , YUAN Er-dong

2013, 29(10):2349-2345.

[Abstract](1317) [HTML](0) [PDF 622.10 K](722)

Abstract:
Hesperidin possesses many bioactivities, such as antioxidant, antibacterial, lowering blood pressure, antiviral, antitumor and improving immunity, which can be used in functional food, medicine and cosmetics. But its poor solubility in water limited its wide applications. In this study, the complex of hesperidin and hydroxypropyl-β-cyclodextrin (HP-β-CD) was prepared to improve the water solubility of hesperidin by solvent method. Meanwhile, the physicochemical properties of the complex were investigated by ultraviolet-visible spectrometry (UV), infrared spectrometry (IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). The results showed that the physical phase of hesperidin was significantly changed . It was completely dispersed in HP-β-CD matrix after inclusion. Hesperidin and HP-β-CD were combined with non-covalent bonds such as hydrogen bond and Van der Waals' force. HPLC analysis showed that the solubility of hesperidin in water at 30 ℃ was increased from 34.68 μg/mL to 2049.50 μg/mL

7 Effects of Ions on Swelling Properties and Microstructure of Chitosan and Pectin Polyelectrolyte Complexes

ZHANG Li-yan , BAO Li-kun

2013, 29(10):2353-2357.

[Abstract](1257) [HTML](0) [PDF 521.61 K](656)

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Chitosan/pectin polyelectrolyte complexes (PECs) were obtained when chitosan and pectin was mixed within 6 different kinds of ion solutions. The influences of ion type and concentration on certain characteristics such as complex yield, swelling patterns both in water and in vitro, FT-IR spectra and microstructure of the aforementioned PECs were studied. The order of ionic valence on PEC yield was trivalent ions > divalent ions > univalent ions. PEC cross-linking was promoted by the low ion concentration but prohibited by high ion concentration. The addition of FeCl3 led to a maximum in swelling degree of 56.87±0.63 in water while the minimum swelling degree of 9.21±0.13 was obtained when added with Fe2(SO4)3. The addition of MgSO4 resulted in a greatest swelling degree of 361.74±6.21, while a lowest swelling degree of 28.01±0.66 with the addition of Fe2(SO4)3 was achieved in the simulated gastro-intestinal transit solutions. FT-IR analysis indicated that ions had no effect on hybrid NH3+/COO- in PECs. SEM results showed that the chitosan/pectin PECs formed a sponge-morphic microstructure. The thickness increased from 9.76±1.03 % to 334.19±5.12%, and the layer became smooth with the interaction of ion. The porosity of PECs depended on different ions. Research showed that the addition of ions could influence the PEC complex yield, swelling ratio and microstructure, but showed little effect on PEC cross-linking pattern.

8 Effect of Stretching Temperature on Rheological Characteristics and Microstructure of String Cheese

MIAO Ying , ZHAO Zheng

2013, 29(10):2358-2362.

[Abstract](916) [HTML](0) [PDF 664.61 K](768)

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String cheeses were provided by a small-scale single screw extruder, and the effect of stretching temperature on the rheological characteristics and microstructure of string cheese was observed in this research. Scanning electron microscopy of string cheese indicated that cheese microstructure changed from amorphous three-dimensional into a near-linear parallel fibrous structure after stretching, which exhibited a more dense protein network structure at higher temperature. This microstructural change was consistent with a reduction in the level of serum expressed by centrifugation and suggested that after the stretching treatment the water holding capacity of the casein matrix increased with the rise of temperature. Dynamic measurement of the viscoelastic changes on heating the cheese from 25 to 80 ℃ showed that rheological properties of string cheese were unstable below 50 ℃. Dynamic measurement of the viscoelastic changes on the string cheese from 0.1~10 Hz frequency sweep displayed that it had stronger viscoelastic and shear thinning properties, and the performance was more obvious with increasing stretching temperature. TPA results revealed that cheese hardness was affected by the stretching temperature significantly.

9 Analysis of the Chemical Constituents of Defensive Substances from Aspongopus chinensis and their Effect on the Activity of LO2 Cells

HOU Xiao-hui , SUN Ting , LI Xiao-fei , ZHONG Ting-ting , LIU Chuan-yan

2013, 29(10):2363-2367.

[Abstract](905) [HTML](0) [PDF 508.31 K](731)

Abstract:
The volatile components and their relative contents of the defensive substances in aqueous solution from Aspongopus chinensis, and the effect of aqueous solution on the activity of normal human liver LO2 cells were studied in this research.Warm water immersion of bugs was used to obtain the defensive substances solution, and GC-MS and area normalization was employed to identify the volatile components and calculate their relative contents. MTT and flow cytometry was used to find the effect of the defensive substances solution on liver LO2 cell. The research showed that the solution contained 19 kinds of chemical compounds, and the anti -2- hexenal had the highest relative percentage content 88.54%, then followed by 2-methyl-4-pentene aldehyde (5.16%) and trudecyl (3.43%); IC50 was 3.64 μL which presented dose-dependent manner after the solutions reacted with LO2 cells. The result of flow cytometry showed that, compared with the control group, the percentage of G2/M phase cells from the drug group were reduced obviously and G0/G1 phase cells were increased significantly. The major compounds of Aspongopus chinensis defensive substances solution were enal and alkanes, which could inhibit the proliferation of normal human liver LO2 cells in vitro because of cell cycle arrest.

10 Gelation Behavior of Inulin in Ethanol Solution

LUO Deng-lin , XU Wei , XU Bao-cheng , WU Yan-huiL , IU Jian-xue

2013, 29(10):2368-2371.

[Abstract](975) [HTML](0) [PDF 454.52 K](721)

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To explore the gelling behavior and textural properties of inulin in ethanol solution, the gel was prepared by heat/cold storage. Gelling behaviors of 35%, 45% and 55% inulin solution in ethanol aqueous solution with ethanol concentrations ranging from 0~40% (V/V) were studied. Gelatin textural properties were analyzed using texture analyzer. The results showed that inulin gelling ability improved with the increase of inuiln content and was influenced significantly by ethanol concentration. When ethanol concentration was below 30%, inulin gelling ability and water holding capability were enhanced with the rise of ethanol concentration. However, they displayed a downward trend when ethanol concentration was above 30%. TPA analysis demonstrated that increasing inulin content could significantly promote gel textural properties. Gelatin textural properties climbed up at first and then dropped down as ethanol concentration increasing. The inflexion point of the effect of ethanol on hardness, strength, adhesive force and adhesiveness was 20%, while the value was 10% for cohesiveness and chewiness.

11 Impact of Different Storage Time on Antioxidant Activity of Organic Solvent Extracts of Pu-erh Teas

LIU Tong-xun , TAN Meng-zhu

2013, 29(10):2372-2377.

[Abstract](945) [HTML](0) [PDF 562.86 K](628)

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The antioxidant activity of different organic solvent extracts of pu-erh teas (raw and ripened pu-erh which produced in different years) was evaluated by half-inhibitory concentration (IC50). Results showed that the IC50 value of raw teas to scavenge DPPH free radical and superoxide radical were 0.339 mg/mL, 0.074 mg/mL and 1.206 mg/mL, respectively. And the IC50 of ripe teas to the obove-mentioned radicals were 0.554 mg/mL, 0.164 mg/mL and 1.927 mg/mL, respectively. Raw teas had higher antioxidant activity than ripe ones. The extracts by different organic solvents showed different scavenging abilities to different free radicals, which depended on the content of tea polyphenol and flavonoids. The highest content of tea polyphenol in raw teas was extracted by ethyl acetate, ranged from 7.33% to 9.57% and the extract from butyl alcohol had the largest amount of flavonoids(7.08~10.99%). For the ripe tea, the highest contents of tea polyphenol and flavonoids were 3.62% to 5.73% and 4.75% to 5.83%, respectively, which were all extracted by butyl alcohol. In conclusion, the extracts by ethyl acetate and butyl alcohol had higher capacity of scavenging free radicals due to the higher content of hydroxyl; and the storage time of teas showed little effect on the antioxidant activity from different extracts.

12 Antioxidant Effects of Fucoidan and Its Hydrolysates on Oxidative Damage Mice induced by D-galactose

WANG Ying , ZHAO Zhi-hao , GAO Meng-chu , LIU Wei-jie , LI Ba-fang , ZHAO Xue

2013, 29(10):2378-2382.

[Abstract](1009) [HTML](0) [PDF 380.40 K](624)

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To investigate the antioxidant effects of fucoidan and its hydrolysates on D-galactose-induced senescent mice, hydrolysates of Fucoidan were prepared by EQFF degradation from high molecular weight Fucoidan. Kunming male mice were randomly divided into five groups: normal control group, oxidative injury model group, fucoidan group, hydrolysates of fucoidan group, and positive control group. Each group was injected with different drugs at the same dose for successive forty-two days. Then the indices of antioxidant effects both in serum and liver were determined. The results showed that both fucoidan and its hydrolysates had significant antioxidant effects compared with the model group. The inhibiting effects of fucoidan hydrolysates on hydroxyl radical of the mice feeding reached 500.67±35.67 U/mL (serum) and 1821.34±162.02 U/mgprot (liver), and the activity of T-SOD achieved were 101.82±3.98 U/mL (serum) and 3053.36±245.88 U/mgprot (liver). Meanwhile, the activity of CAT and GSH-Px in serum reached 4.05±0.56 U/mL and 348.88±29.22 U,respectively. It was indicated that the low-molecular- weight fucoidan hydrolysates had higher antioxidant influence on D-galactose-induced senescent mice than high- molecular- weight fucoidan.

13 Antioxidant and Antiproliferative Activities of Polyphenol Extract from 12 Tropical Fruits

LI Wu , LI Yan-jun , YANG Rui-li

2013, 29(10):2383-2387.

[Abstract](1158) [HTML](0) [PDF 474.58 K](629)

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To evaluate the phenolic contents, antioxidant and antiproliferative activities of phenolic extracts from 12 tropical fruits, the total phenolic content was determined by Folin-Ciocalteu method and the antioxidant activity was measured with oxygen radical absorbance capacity activities (ORAC). The ferric reducing ability of plasma (FRAP), and the antiproliferative activity against human hepatoma cells (HepG2) were analyzed by MTT assay. It was founda that the total phenolic contents ranged from 26.17 to 229.67 mg gallic acid equivalents (GAE) per 100g fresh weight (FW). Averrhoa carambola had the highest phenolic content, being of 8.87-fold higher than Persea americana which had the lowest phenolic content. The ORAC and FRAP values were in the ranges of 607.05~2631.17 μmol TE/100g FW and 462.12~1067.92 μmol TE/100g FW, respectively. Averrhoa carambola showed the highest ORAC value which was 4.33 times higher than Carica papaya, and the higherst FRAP value which was 2.31 times higher than Persea Americana. The limits of IC50 values against HepG2 cells were from 31.79 to 66.93 mg/mL. Carica papaya had the lowest antiproliferative activity, with a 2.11-fold higher IC50 value compared to Averrhoa carambola with the highest antiproliferative activity. In addition, the total phenolic contents showed significant correlations with ORAC (R2＝0.7839), FRAP (R2＝0.7636) and IC50 values against HepG2 cells (R2＝0.8847).

14 Effects of Heat-Moisture Treatment with Water-Ethanol Mixtures on Properties of Corn Starch Granule

CHEN Fu-quan , LIU Huan-yu , ZHANG ben-shan , ZHAO Yong-qing , ZHENG Yan-na , YU Huan

2013, 29(10):2388-2394.

[Abstract](908) [HTML](0) [PDF 567.50 K](590)

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Nature corn starches treated by heat-moisture with water-ethanol mixtures were investigated in terms of polarization cross, morphology, size distribution, crystal structure and paste properties within the temperature range of 70~90 ℃. With the increase of the temperature in the treatment system, some phenomena were found as follows: the disappearance of the granules birefringence increased, and the granules broke in the end. The average radius of the starch granules was augmented from 23.6 μm to 50.4 μm and the amount of the small granules (<10 μm) decreased. Besides, the number of the medium granules (10~30 μm) and large granules (30~100 μm) increased in different degrees. Small holes and pits were observed on the surface of the granule, and the granules conglobated at high temperature in the end .After drying and grinding, the granules broke into flakes. X-ray diffraction intensity gradually reduced at the diffraction angle of 15°, 18° and 23°, but strengthened at 20°. Starting temperature of corn starch gelatinization raised from 80.5 ℃ to 90.6 ℃, and viscosity of the starch decreased, which indicated that the stability of both warm and cold paste improved while the retrogradation of the starch reduced. Determination of molecular weight of the starches displayed that molecular chains were ruptured and degraded during the heat-moisture treatment.

15 Physicochemical properties and Antioxidant Activity of Ginkgo biloba L. Nut

YANG Qiang , LI Xin-hua , WANG Lin , LU Fei , ZHANG Chun-hong , ZHENG Yu-yan , XIE Hong

2013, 29(10):2395-2400.

[Abstract](1028) [HTML](0) [PDF 570.64 K](738)

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The polysaccharides extracted by water-extract and ethanol-precipitation from Ginkgo nuts were purified by Sevag method for protein removing and macroporous adsorption resin for the de-colorization. The composition of the polysaccharide was analyzed by Ultraviolet spectrum (UV), high-performance liquid chromatography (HPLC), and infrared spectra (IR). The in vitro antioxidant activities of the polysaccharide were determined by DPPH, superoxide radicals and hydroxyl radicals scavenging assays. The effect of the polysaccharide on the content of SOD, GSH-PX, MAD and CAT in the serum and liver of the hyperlipemia mice were measured to determine the antioxidant activity in vivo. It was found that the ginkgo polysaccharide consisted of 3 kinds of monosaccharide, including glucose, galactose and xylose, with the molar ratio of 2.26:19.60:4.29, in the form of pyranose containing α-glycosidic bond. The Ginkgo polysaccharide showed the significant DPPH, superoxide radicals and hydroxyl radicals scavenging activities, with IC50 values being of 0.15 mg/L, 0.30 mg/L and 0.47 mg/mL, respectively. The antioxidant in vivo showed that the ginkgo polysaccharide could evidently increase the concentrations of SOD, GSH-Px and CAT, and decrease the concentration of MDA in serum and liver.

16 Effect of Lanthanum and Cerium on Growth and Physiological Properties of Chlorella vulgaris

CHEN Ai-mei , SHI Qing-shan , OUYANG You-sheng , CHEN Yi-ben

2013, 29(10):2401-2404.

[Abstract](1502) [HTML](0) [PDF 594.08 K](772)

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In order to study the biological effects of La and Ce on Chlorella vulgaris, growth curve was plotted, and the biomass, contents of chlorophyll a and b, carotenoid and soluble sugar were tested. The results showed that La and Ce at 10-3~10-6 mM stimulated algae cell proliferation at early stage, and their growth promoting effect weakened as time was increased. Compared with blank control, the contents of chlorophyll a and b increased by 24.46% and 28.51%, respectively, when cultured with La at 10-3 mM while they were raised by 50.76% and 38.92%, respectively, with Ce at 10-4 mM. In addition, 10-3 mM La and Ce could increase the soluble sugar content by 13.38% or 34.88%, respectively.. In conclusion, certain amounts of La or Ce could efficiently promote the algae cell growth at early stage, shorten the lag stage, and increase the contents of chlorophyll and soluble sugar.

17 Inactivation of Microorganisms in Model Fruit Juice System by Dynamic Ultra-high Pressure Combined with Dimethyl Carbonate

CHENG Yin-qi , YU Yuan-shan , WU Ji-jun , XU Yu-juan , TANG Dao-bang , WEN-Jing , ZHENG Xin

2013, 29(10):2405-2409.

[Abstract](1105) [HTML](0) [PDF 489.80 K](704)

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Inactivation of dynamic ultra-high pressure (DUHP) combined with dimethyl carbonate (DMDC) on E. Coli, Saccharomyces cerevisiae and Leuconostoc mesenteroides in model juices were investigated. The results showed that the effect of DUHP on inactivation of three strains in model juices gradually increased as the pressure increased (p<0.05). UHP had the best sterilization effect on E. Coli under the same pressure. But even under the pressure of 100 MPa, the reduction of E. Coli was not more than 1.2 Lg cycles. After 250 mg/L DMDC was added to the model juices, E. Coli and Saccharomyces cerevisiae were completely inactivation after 2 h, while Leuconostoc mesenteroides only decreased 1.7 Lg cycles. No significant reduction was displayed as treatment time increased. DUHP combined with DMDC showed a significantly synergistic effect on the inactivation of Leuconostoc mesenteroides (p<0.05), and its sterilization effect was affected by the sequence of DMDC addition.

18 Anti-Proteus mirabilis Effect of Freeze-dried Powder of Polyphenolic Enriched Berry

ZHU Hong , ZHAO Hui-fang , WU Wen-long , LI Wei-lin

2013, 29(10):2410-2414.

[Abstract](1450) [HTML](0) [PDF 543.72 K](709)

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The black berry (Rubus fruticosus) and blue berry (Vaccinium corymbosum) contain bioactive polyphenols with reported anti-bacterial properties. This study sought to investigate the anti-bacterial, cartilage-protecting and anti-inflammatory effects of freeze-dried powder of polyphenolic-enriched berry by using a plate inhibition test, a minimum inhibitory concentration (MIC) test, and an in vitro bovine nasal explant cell culture model. Results showed that both gram-positive Bacillus subtilis and gram-negative Escherichia coli were inhibited by the freeze-dried powder. And a multiply antibiotic resistant bacterium Proteus mirabilis was also susceptive to berry freeze-dried powder. After a 20-day culture, the growth inhibition rate of Proteus mirabilis reached 50.43±0.00% and 68.05±3.00% in black berry and blue berry freeze-dried powder, respectively. Casein hydrolysis activity and gelatin zymography test indicated the protease activity significantly decreased to 50.02±0.30% and 66.00±5.00% in bovine nasal explant cell culture samples after black berry and blue berry freeze-dried powder were added. The release inhibition of glycosaminoglycan (GAG), which was a signal of inflammatory, was also found in according with protease inhibition by berry freeze-dried powder.

19 Expression and Identification of Human Alpha Fetoprotein in E. coli

LI Zhen-dong , GU Hua-wei , WANG Hai-ying , CHEN Shu-yi , NING Zheng-xiang , WANG Ju-fang

2013, 29(10):2415-2419.

[Abstract](1251) [HTML](0) [PDF 654.03 K](834)

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In this study, through the application of genetic engineering techniques, the prokaryotic expression vector pET22b-AFP of full-length human alpha-fetoprotein AFP gene was recombined, constructed, encoded, and then transformed into E. coli host strain BL21 (DE3) to induce the expression of the target protein AFP. AFP coding sequence was amplified by polymerase chain reaction (PCR), and then cloned into the prokaryotic expression vector pET-22b containing His-tag. The constructed vector, verified by restriction endonuclease digestion and DNA sequencing, was then transformed into E. coli host strain BL21 (DE3) for expression by using IPTG-inducible promoters. Different concentrations of IPTG and different temperatures were optimized to induce the expression of target protein. Expression products were identified by SDS-PAGE electrophoresis and Western Blot. The results showed that AFP gene fragments were obtained by PCR amplification. By double enzyme digestion and gene sequencing methods, it was confirmed that the recombinant plasmid was constructed successfully. Expression product was revealed in the vicinity of the 66 kDa band by using SDS-PAGE and Western Blot., which was consistent with the expected value indicating that the recombinant AFP protein succeeded in expressing.

20 Fluorescence Quenching Properties of Vegetable Protein Caused by Potassium Sorbate with Non-covalent Bonding Interactions

CAI Chun-sheng , HU Yong , GAO Yong-qing , ZHANG Jie-liang , HOU Fang-li

2013, 29(10):2420-2424.

[Abstract](959) [HTML](0) [PDF 616.34 K](726)

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The interaction between potassium sorbate (PSS) and soy protein isolate (SPI) or wheat gluten (WG) under different temperatures in solution was investigated by fluorescence spectroscopy. The quenching mechanism was analyzed referring to PSS against the fluorescence of the vegetable protein. The apparent binding constants and the binding sites were also determined simultaneously based on the fluorescence. The experimental results clearly indicated that static quenching occurred in these systems because of the formation of new complexes among vegetable proteins and potassium sorbate. The apparent binding constants (KA) between PSS and SPI were 1.58×104 L/mol (281 K), 1.49×103 L/mol (291 K), and 1.11×102 L/mol (303 K), respectively. The corresponding binding sites values (n) were 1.25, 0.96 and 0.78, respectively. The apparent binding constants between PSS and WG were 2.90×104 L/mol, 2.53×104 L/mol and 5.50×104 L/mol at 281 K, 291 K and 303 K, respectively. And the, corresponding binding sites values (n) were 1.04, 1.06 and 1.15, respectively. The changes of entropy and enthalpy indicated that the interaction of PSS and SPI was driven mainly by Vander waals force and hydrogen bonding, while the interaction of PSS and WG was chiefly driven by hydrophobic interaction and electronic force.

21 Preparation and Properties of Corn Slowly Digestible Starch with Dual-enzymes Treatment

GAO Qun-yu , WANG Lin

2013, 29(10):2425-2430.

[Abstract](1104) [HTML](0) [PDF 809.64 K](694)

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The common corn starch was applied as raw material to prepare the slowly digestible starch (SDS) by using β-amylase and transglucosidase, and the physicochemical properties of the SDS were also investigated. The content of SDS was up to 16.37% with addition of 20 mL β-amylase and 20 mL transglucosidase by stirring for 4 h and 12 h, respectively. The position of maximum absorption peak of starch samples binding iodine shifted obviously with increasing SDS content. Analysis by differential scanning calorimeter showed that the onset melting temperatures, the peak temperatures, terminated temperatures and the temperature differences between beginning and ending of SDS were improved significantly and its thermal stabilities were enhanced, resulting in more difficulty for starches to gelatinize. Compared to the native corn starch displayed “A” typical diffraction pattern, no crystal structure was found for all samples modified by enzymes which represented sharp diffraction peaks at 2?=19.8° and diffuse diffraction peaks at 2?=13.1?. Scanning electron micrographs revealed that all enzyme-treated samples had more irregular fragments without granular structures as native starch.

22 Effects of Two Compound Preservatives on Agaricus bisporus

ZHANG Qiang , WANG Song-hua , ZHU Chang-wei , WANG Chen-feng , GUO Jian , ZHOU Jun

2013, 29(10):2431-2435.

[Abstract](948) [HTML](0) [PDF 578.22 K](717)

Abstract:
Effects of two compound preservatives on the preservation quality of Agaricus bisporus during refrigeration storage were investigated. The harvested Agaricus bisporus were seperately immerged in ginger compound preservative, garlic compound preservative and distilled water (control) for 3 min, then packaged with polyethylene film after drying and stored at 4 ℃. The sensory, physiological indices and nutrition quality of Agaricus bisporus were evaluated periodically. After a 18-day storage at 4 ℃, weight loss rate of Agaricus bisporus treated with ginger compound preservative and garlic compound preservative were decreased by 51.34% and 33.27%, respectively, which the browning degree of the samples were decreased by 10.15% and 15.73%, respectively, compared with control group. Their soluble solids contents (4.69%, 4.56%) and soluble protein contents (755.40 μg/g, 798.31 μg/g) were significantly higher than those in control group(P?0.01). After treated by ginger compound preservative and garlic compound preservative, the contents of cellulose of Agaricus bisporus were 35.67mg/g and 33.76 mg/g, respectively, and their nitrite contents were of 3.45 mg/kg and 3.65 mg/kg respectively, both of which were significantly lower than those of control group (P?0.01). In addition, total acidity and PPO activity of the samples remained at lower level. Therefore, the two compound preservatives greatly improved the preservation quality, prolonged storage life of Agaricus bisporus.

23 Effects of the Addition of Different Proteases on Properties of Frozen Pork in the Curing Process

CUI Chun , CONG Yi-jie , SUN Wei-zheng , YANG Yuan-yuan

2013, 29(10):2436-2441.

[Abstract](927) [HTML](0) [PDF 507.78 K](665)

Abstract:
Property changes of pork during the frozen storage (0~120 d, -18 ℃) were studied. Effects of the addition of proteases (papain, neutrase and protamex) in the curing process on properties of frozen pork were also evaluated. During the frozen storage, pork became darker. Its chewiness, elasticity and cohesiveness all decreased (p<0.01), and cooking loss rate increased (p<0.01). Curing with addition of different proteases indicated that CIE L* of minced pork rose and the degree of improvement of unfrozen pork was increased (p<0.05). CIE a* of unfrozen minced pork also rose, but no significant change or a slight decrease in frozen pork (p>0.05) was found. CIE b* of minced pork increased (p<0.05) and the degree of improvement of frozen pork was lower than the unfrozen one, whereas CIE b* of cooked minced pork decreased (p<0.01). Changes in texture properties of both pork and minced pork were similar and represented ascent. Cooking loss rate was reduced and enzyme effectiveness was improved for frozen pork (p<0.01). It was suggested that addition of proteases during the curing process of minced pork could significantly improve textural properties, inhibit products becoming dark or yellow and enhance water-retaining which provided reference for meat products processing.

24 Effects of Aging Method on Physicochemical Properties and Volatile Aroma of Mangosteen Wine

YU Li-mei , LIU Jun-mei , FENG Wei-hua , BAI Wei-dong

2013, 29(10):2442-2446.

[Abstract](1084) [HTML](0) [PDF 522.29 K](808)

Abstract:
To recognize the effect of aging method on physicochemical properties (total esters, total acid and chromaticity) and aroma components of mangosteen wine, samples were preprocessed by heating, microwave and ultrasonic, and the volatile aroma components of the samples were analyzed by headspace solid-phase micro-extraction (HS-SPME) and GC-MS. The results showed that heating and microwave treatments improved the total ester content in wine to the maximum value of 2.97 g/L. Chromaticity was 53.3% higher than that of the control wine after heating. The microwave treatment could also reduce the acidity of the wine, and the total acid content decreased from 2.21 g/L to 1.72 g/L. Aroma components analysis displayed that heat treatment decreased the content of alcohols in mangosteen wine by 11.89% and increased the ester compounds content by 11.28%, resulting in the formation of 2-methyl ethyl butyrate and other new compounds. By microwave treatment, the alcohols content reduced slightly and the ester content had a mild raise. After ultrasonic treatment, the alcohol content was descend by 7.42%, and the ester content increased by 7.1%. In addition, many new compounds such as hexyl acetate, linalool, phenyl ethyl acetate were generated, which were helpful to improve the aroma of the wine.

25 Effects of Modified Atmospheres Package with High O2 on Storage Properties of Fresh-cut Lotus Root

GUO Yan-yin , LI Ling

2013, 29(10):2447-2452.

[Abstract](905) [HTML](0) [PDF 586.29 K](713)

Abstract:
In order to study the role of modified atmospheres package (MAP) with different proportion of high O2 in controlling storage attributes, fresh-cut lotus root stored in modified atmospheres packages were analyzed with initial atmospheres of 100% O2, 90% O2+10% CO2, 80% O2+20% CO2, 70% O2+30% CO2, and air as control check (CK) at 4 ℃. The results showed that the treatments with proper concentration of high O2 lowered the respiration rate by 43.57%, delayed ethylene release by 65.14%, suppressed the decrease of ascorbic acid by 26.43%, decreased the activity of polyphenol oxidase (POD) by 68.67% and reduced the degree of brown by 17.65%; meanwhile, it could also diminish soluble sugar and starch content, minimize the loss of dry and fresh weight, maintain a higher superoxide dismutase (SOD) activity, postpone the accumulation of malonaldehyde (MDA) and effectively retain the storage qualities of fresh-cut lotus root. Among the treatments, the maximum efficacy was observed with a MAP with initial atmosphere of 90% O2 + 10% CO2, followed by 100% O2, 80% O2+20% CO2 and 70% O2+30% CO2, while CK had the poorest effect. The results suggested that an appropriate concentration of high O2 in MAP could maintain the quality of fresh-cut lotus root during storage.

26 Effects of Three Modification Methods on the Physicochemical Properties of Native Banana Starch

BAI Yong-liang , CHEN Qing-fa , ZHANG Quan-kai , YE Qiong-juan , YANG Gong-ming

2013, 29(10):2453-2460.

[Abstract](902) [HTML](0) [PDF 609.92 K](670)

Abstract:
The effects of three modification methods including compound enzymolysis, lactic acid fermentation and extrusion on physicochemical and processing characteristics were analyzed, in order to find a method that can retain the natural advantages of banana starch and improve the processing performance. The results showed that compound enzymatic modification could increase the content of resistant starch (RS) significantly. Compound enzymolysis and lactic acid fermentation increased the crystallinity of banana starch from 18.13% to 20.19% and 22.06% respectively, but the crystallinity of the starch modified by extrusion decreased to 2.16%. The effect of compound enzymatic modification could preserve the particle morphology of native banana starch which was helpful to improve the thermal stability, cold stability and the retrogradation. Besides, the compound enzymolysis had less effect on color that improved the transparency of starch paste. Lactic acid fermentation and extrusion reduced the thermal stability and retrogradation, but helped to improve the cold stability. Extrusion could also improve the transparency, solubility and hygroscopocity. The three kinds of modification methods decreased freezing and thawing stability, but the lactic acid fermentation had less effect on it. In a word, the compound enzymolysis was an ideal modification method.

27 Optimization of Preparation Conditions and Structural Properties of Microcrystalline Cellulose from Distillers Grains

REN Hai-wei , LI Jin-ping , ZHANG Yi , ZHANG Fei , LI Zhi-zhong , XIANG Shuang-quan

2013, 29(10):2461-2468.

[Abstract](1025) [HTML](0) [PDF 664.43 K](629)

Abstract:
Distillers grain (DG) is a kind of lignocellulosic biomass with high content of cellulose. In this study, the feasibility of preparing microcrystalline cellulose (MCC) by DG was observed. Dilute hydrochloric acid hydrolysis was carried out to prepare DGMCC. The prepared DGMCC samples were then characterized by FTIR, SEM, XRD, TGA and DSC, comparing with that of DG and commercial MCC (Lowa?PH101). The fineness of cellulose was 94.55%. The optimum conditions for the preparation of DGMCC were solid-liquid ratio of 1:15 (g/mL), hydrochloric acid concentrations of 6% (V/V), temperature of 70 ℃ and time of 60 min, under which the DP and the yield of DGMCC were 288 and 27.01%, respectively. FTIR spectroscopy showed that the main component of DGMCC was cellulose. SEM and XRD indicated that the DGMCC samples appeared an irregular but overall spherical shape, the crystallinity and particle sized of which was 62.47% and 54.95 nm, respectively. In addition, TGA and DSC revealed a sharp endothermic peak at 365.3 ℃. In a word, DGMCC particles showed higher thermal stability than that of DG and similar structural properties to Lowa?PH101.

28 Effect of Micro-vacuum Storage Conditions on The Preservation of Fresh-cut Broccolis

MU Qi-yun , LI Wen-xiang , KOU Xing-kai , FAN Ming-cong

2013, 29(10):2469-2473.

[Abstract](909) [HTML](0) [PDF 549.37 K](714)

Abstract:
In order to study the preservation effect of micro-vacuum storage conditions on the fresh-cut broccoli, the broccoli was disinfected with 100 mg/L sodium hypochlorite, rinsed clean with water, cut into flower ball about 3~4 cm in diameter, loaded into the 30 cm×20 cm×8 cm plastic baskets, placed in vacuum pressure of 66.65~79.98 KPa, storage temperature of 4 ± 1 ℃ micro vacuum storage facilities, atmospheric freezer storage was as the control experiment under the same temperature and the effect of different storage conditions on the sensory quality, respiratory intensity, weight loss, titratable acid, Vc and chlorophyll contents was investigated .The results showed that compared with the same temperature atmosphere storage, micro-vacuum storage could obviously improve the sensory quality, significantly inhibit the respiratory intensity, reduce weight loss, delay the decrease of titratable acid, Vc and chlorophyll contents (P<0.05) of fresh-cut broccoli. It indicated that the micro-vacuum storage conditions could visibly heighten the preservation effects of fresh-cut broccoli.

29 Physical Properties and Volatile Compositions of Jackfruit Seeds under Different Processing Methods

LIN Li-jing , ZHANG Wen-hua , JING Wei , YUAN Yuan , HUANG Xiao-bing , GONG Xiao , LI Ji-hua

2013, 29(10):2474-2479.

[Abstract](947) [HTML](0) [PDF 535.05 K](798)

Abstract:
The water binding ability, oil-holding capacity, particle size, swelling capacity and volatile compositions from drying, cooking and shattering were analyzed and compared. The results showed that the average surface area diameter of cooked seed was 116.13 ?m, which was larger than that of fresh seed (74.15 ?m) and dried seed (29.22 μm). Fresh seed had the biggest average volume diameter 550.26 ?m and dried seed had the largest specific surface area 0.21 m2/g. Dried jackfruit seed had stronger water binding capacity (5.25) and swelling capacity (4.0) than other two processed seeds while the greatest oil-holding capacity belonged to fresh seed, being of 1.66. 31 kinds of volatile compounds were detected in fresh seed, accounting for 77.37% of the total volatile compositions. 24 and 32 kinds were tested in dried and cooked seed individually, occupying 63.32% and 35.74% of the total compounds, respectively. It was indicated that the dried and cooked methods could decrease the total relative content of the volatile ingredients in jackfruit seed. However, cooked seed contained more esters (16 kinds) than those from fresh seed (8 kinds) and dried seed (9 kinds). Moreover, compared with fresh seed, some toxic components such as methanol were removed through drying or cooking. Thus, this research could provide certain theoretical foundation for eating and processing jackfruit seed.

30 Aroma Components of Zijuan Tea Processed by Four Different Methods

CHEN Bao , JIANG Dong-hua , LUO Fa-mei , MAN Hong-ping , LUO Zheng-gang , HU Yan-ping , YANG Liu-xia

2013, 29(10):2480-2486.

[Abstract](1029) [HTML](0) [PDF 659.67 K](756)

Abstract:
The aroma components of Zijuan tea processed by different methods (sun-dry tea, baked green tea, black tea and fermented tea) were extracted by solid phase micro-extraction (SPME), qualitified by gas chromatography/ mass spectrometry (GC-MS) and quantified by area normalization method. The results showed that 146 compounds were identified from different processed Zijuan Tea, including 81 compounds from sun-dry tea, 80 from baked green tea, 68 from black tea, 69 from fermented tea, and 30 from all the samples tested. The main aroma compounds of sun-dry tea were 1-Octen-3-ol, 2-ethyl-Hexanol, Hotrienol, and β-Terpineol, etc. The main aroma compounds of baked green tea were linalool, 2-ethyl-hexanol, benzyl alcohol, 1-octen-3-ol, etc. The main aroma compounds of black tea were linalool, epoxylinalol, cis-linalool oxide, and benzyl alcohol. The main aroma compounds of fermented tea were 1,2,3-trimethoxybenzene, epoxylinalol, cis-linalool oxide, and 2-ethyl-hexanol. In summary, there were significant differences in composition and content of aroma compounds of different processed Zijuan tea extracted by SPME.

31 Covalent Immobilization of Pancreas Porcine Lipase on Aminated Mesoporous Silica

WEN Xiao-rong , XIA Xiao-le , YANG Hai-lin , XIN Yu

2013, 29(10):2487-2491.

[Abstract](1100) [HTML](0) [PDF 551.03 K](786)

Abstract:
In this study mesoporous silica gel was activated by epoxy-group and amino-group for covalent immobilization of pancreas porcine lipase (PPL) using water-soluble carbodiimide. At the optimum conditions (molar ratio of EDC to protein 50:1, weight ratio of support to rude enzyme 10:1, pH 6.0 and immobilization time 8h), the maximum enzyme activity (86.67 U/g) was obtained, which was much higher than that of PPL immobilized onto silica gel without modification (33.33 U/g). The immobilization PPLs were also characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Many filiform substances were observed on the surface of enzyme-immobilized support. Moreover, the absorption peak at 1543 cm-1 (amideⅡ) could be seen in the spectra of immobilized PPL, which confirmed that the PPL had been successfully immobilized onto the supports. In addition, the properties of immobilized PPL were studied. The optimum pH of the immobilized PPL was shifted to a more alkaline range, and the optimum temperature was determined to be 5 ℃ higher than that of free enzyme. Meanwhile, the thermal stability of modified PPL was significantly improved.

32 Freshness of litopenaeus vannamei Based on Mole Ratio of TMA and TMAO

HU Jin-xin , LI Jun-sheng , YAN Liu-juan , HUANG Guo-xia

2013, 29(10):2492-2497.

[Abstract](1026) [HTML](0) [PDF 543.47 K](746)

Abstract:
Picric acid colorimetric method was conducted to measure TMA and TMAO of Litopenaeus vannamei in this research. Variations as the mole ratio of TMA and TMAO, total volatile basic nitrogen (TVB-N), pH value and sensory evaluation were detected to determine the freshness of Litopenaeus vannamei at the store temperature of 0, 5 and 15 ℃. The result showed that TMA, TMAO and pH values grew unsteadily which were hardly to detect the freshness of sample whereas the mole ratio of TMA and TMAO and TVB-N increased steadily with the increasing storage time. Moreover, the mole ratio of TMA and TMAO and TVB-N were significantly correlation (p＜0.01), and all the correlation coefficients were greater than 0.936. Thus the mole ratio of TMA and TMAO was a feasible index for detection of the freshness of Litopenaeus vannamei simply and exactly.

33 Produce of Low Trans Fatty Acids Soybean Oil by Electrochemical Hydrogenation in a Diaphragm Reactor

XIAO Fei-yan , FU Hong

2013, 29(10):2498-2503.

[Abstract](948) [HTML](0) [PDF 520.04 K](666)

Abstract:
The proton transfer membrane electrochemical hydrogenation reaction system was designed for soybean oil to hydrogenate under moderate processing temperature, atmospheric pressure and low current density. The formate ion was regenerated at the cathode and acted as a mediator during the hydrogenation process. The effect of various processing parameters such as temperature, agitation speed, the amount of EDDAB and the oil-water ratio on the fatty acid profile, iodine value, trans fatty acid content, the specific trans isomerization index and hydrogenation selectivity were investigated. The optimum technological parameters of hydrogenation were as follows: the reaction temperature 60 ℃, speed of agitation 850 r/min, the content of EDDAB 3 g in 100 g soybean oil and the oil-water ratio 0.3 g/g. Under the optimal technical conditions, the hydrogenated soybean oil was obtained, which contained 13.3% TFAs, IV of 82.73 g I2/100 g oil, AV of 0.15 mg KOH/g oil and PV of 0.070 g/100 g oil. Compared to the traditional hydrogenation process, the application of the diaphragm electrochemical hydrogenation technique resulted in up to 71% reduction in trans fatty acid when the same level of hydrogenation was accomplished.

34 Determination of Bitertanol and Diniconazole in Food by Virtual-template Molecularly Imprinted Solid Phase Extraction-HPLC

GAO Wen-hui , LIU Bo , PANG Jun , LI Xing-feng , JIA Ying-min

2013, 29(10):2505-2508.

[Abstract](1158) [HTML](0) [PDF 539.46 K](748)

Abstract:
Myclobutanil molecularly imprinted polymer (MMIP) was prepared by bulk polymerization using myclobutanil as template molecule, methacrylate acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EDMA) as crosslinker and acetonitrile as pore-foaming agent. The solid phase extraction (SPE) column was produced with MMIP as SPE agent. Fungicides of Bitertanol and diniconazole in food could be separated and enriched by SPE column, and then residuals were determined by HPLC. The sample was separated by the C18 column with a mobile phase of methanol and water (90:10, V/V) at the rate of 1mL/min and the wavelength was 210 nm. Their contents were quantified by external standard method. The average recoveries of bitertanol and diniconazole were 89.40~90.88% and 81.37~83.26%, respectively. The detection limits were all 0.20 μg/g. RSDs were 1.08~2.04% for bitertanol and 1.29~2.52% for diniconazole. In conclusion, the polymer had a good adsorption capacity for the two fungicides and the virtual template molecularly imprinted solid phase extraction technology could be used for the separation and detection of the two fungicides.

35 Determination of K Value for Fish Freshness by Filter Paper Electrophoresis

TAO Zhi-hua , SATO Minoru

2013, 29(10):2509-2511.

[Abstract](1189) [HTML](0) [PDF 467.19 K](613)

Abstract:
In order to monitor the freshness level of fish, a simple filter paper electrophoresis was developed for the analysis of K value in fish meat. ATP and its breakdown products were extracted and homogenized from fish meat samples by 1N HCl. Each homogenate was centrifuged at 8000 xg for 15 min, then the paper disc (6 mm in diameter) containing 10 ?L supernatant was set at the electrophoresis paper which immersed in the pyridine–acetic acid buffer solution (acetic acid:pyridine:water﹦1:10:289, pH 3.7), ATP and its breakdown products were separated by electrophoresis paper and analyzed under UV light at 254 nm. The visualized sample colored spots was digitized and calculated by image processing software. Successful separation of HxR and Hx from ATP and other ATP breakdown products were thus achieved And the linearities of the mixture of ATP, ADP and IMP, AMP, and the mixture of HxR and Hx were within 0.001~0.01 ??mol (R2＝0.99). The average recoveries of ATP and its breakdown products were 98%, 96% and 103%, respectively, with the relative standard deviations (RSD) being of 0.75~5.8%. The method was simple, effective and accurate that could be applied to determinate K value for fish freshness.

36 Isolation, Identification and Amino Acid Composition of Proteins in Soy Sauce Residue

GAO Xian-li , ZHAO Si-wei , SUN Peng-fei , LU Jian

2013, 29(10):2512-2516.

[Abstract](1660) [HTML](0) [PDF 587.42 K](894)

Abstract:
In this paper, the soy sauce residue was prepared by filtration-lyophilization, and the supernatant of soy sauce was used as control. The proximate indices of soy sauce residue were comparatively analyzed. The molecular weight distribution, variety and source and characteristics of amino acid composition of proteins in soy sauce residue and the supernatant were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), matrix-assisted laser desorption ionisation-time of flight/time of flight mass spectrometry (MALDI-TOF/TOF MS) and high-performance liquid chromatography (HPLC). Results showed that soy sauce residue (wet) was mainly composed of carbohydrate (15.98%), proteins (10.19%), NaCl (10.10%) and water (59.50%). Analysis of SDS-PAGE and MALDI-TOF/TOF MS results demonstrated that proteins in soy sauce residue primary consisted of molecular weights of 19.3 kDa (a, 59.40%), 31.8 kDa (b, 12.91%) and 12.3 kDa (c, 27.69%) subunits, and proteins with molecular weights of 19.3 kDa (a) was identified as the basic polypeptide B3 of soy glycinin G4. Research on amino acid composition indicated the hydrophobic amino acid content and the average hydrophobicity of proteins in soy sauce residue were significantly higher than those in the supernatant proteins. The differences were the chief characteristics in amino acid composition of proteins in soy sauce residue, and could explain the low solubility and formation of soy sauce residue proteins.

37 Simultaneous Analysis of Six Water-soluble Sugars in the Main Stream Smoke of Cigarettes by Ion Chromatography with Pulsed Amperometric Detection

HUANG Yi-fei , HU Jing

2013, 29(10):2517-2521.

[Abstract](965) [HTML](0) [PDF 501.06 K](820)

Abstract:
Arabinose, galactose, glucose, xylose, mannose and fructose are the six major water-soluble monosaccharides in the main stream smoke of cigarette. These sugars were separated and determined by high-performance anion exchange chromatography with pulsed integrated amperometric detection. Soluble sugars of the main stream smoke trapped in a Cambridge filter were extracted with 20 mg/L sodium azide by ultrasonic wave for 45 minutes. Six sugars were effectively separated by using 2.5 mmol/L NaOH as eluent on an anion exchange column -CarboPac PA20. The detection limits were between 2.47~9.82 ?g/L and the linear correlation coefficients were above 0.999 in all cases. The intra-day and inter-day precision were below 5.0% and 6.9%, respectively. The recoveries of three spiked levels ranged from 97.1% to 102.4%. The established method was successfully applied in the detection of cigarette samples of various brands. The total contents of six sugars within the tested samples were 36.17~119.5 ?g/cigarette. Fructose had the highest content with the values between 24.63~74.66 ?g/cigarette. And glucose showed the second highest content, which took up 8.09 to 38.09 ?g/cigarettes. Both fructose and glucose accounted for 90.5~94.7% of the total contents of six sugars.

38 Establishment of Mutton Characteristic Flavor Fingerprint

ZHAN Ping , TIAN Hong-lei , LI Wei-guo , MA Yong-guang , ZHANG Xiao-ming

2013, 29(10):2522-2527.

[Abstract](1084) [HTML](0) [PDF 568.21 K](763)

Abstract:
Fifteen mutton samples from different districts were analyzed by gas chromatography-mass spectroscopy (GC-MS) and gas chromatography-olfactometry (GC-O), among which 14 samples were selected to establish a flavour fingerprint according to the results of clustering analysis. Thirty-four compounds were identified as odor-active compounds of characteristic information of mutton flavour fingerprint. The validation of method for fingerprint establishment was evaluated by the test of precision, repeatability and stability, and the similarities of the 14 mutton samples were more than 0.80, indicating that the samples from different batches were relatively consistent. These results also indicated that the method was reliable and applicable to establish chromatographic fingerprint of mutton flavor. Based on the fingerprint, it could be easily to differentiate mutton from other meats a0nd fraud samples by principal component analysis (PCA).

39 Determination of Iodine in Food by Isotope Dilution Inductively Coupled Plasma Mass Spectrometry

WAN Yu-ping , PAN Hong-hong , XIAN Yan-ping , LIANG Run , LI Shao-bo , LUO Dong-hui , GUO Xin-dong

2013, 29(10):2528-2532.

[Abstract](945) [HTML](0) [PDF 580.00 K](698)

Abstract:
A method for the determination of iodine in food by isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) was established, combined with sealed glass tube extraction technology. After addition of the isotopic labeled Tellurium (128Te) and tetramethylammonium hydroxide (TMAH) as extraction solution into a sealed glass tube, the homogenized sample was shocked in a water bath to obtain an extract suitable for analysis by ICP-MS, and the internal standard was used for quantitative analysis. Under the optional conditions, the linear range was between 0.025 μg/L and 50 μg/L with the linear correlation coefficients of 0.9999, and the linear equation was y = 1.0506x +1.2511. The detection limit was 1.8 μg/kg when the sample mass was 0.1 g. The mean recoveries for food samples at three spiked concentrations levels of 2.50, 5.00 and 10.00 mg/kg were ranged from 80.29% to 104.70% with relative standard deviation (RSD, n=6) less than 5.0%. The ID-ICP-MS method for determination of the iodine in standard material GBW08517 of kelp presented no significant differences between measured values and certified values. Due to the simplicity, accuracy and high sensitivity, this method was suitable for the determination of iodine in various of food.

40 Detection of Arcobacter butzleri in Animal Derived Food by a PCR Method

YOU Shu-zhu , WANG Xiao-yu , HU Song-nan , TANG Shi-ming , KUANG Xiao-shan , FENG Jia-wang

2013, 29(10):2533-2537.

[Abstract](1087) [HTML](0) [PDF 623.67 K](722)

Abstract:
Arcobacter spp. are newly emerging human foodborne pathogens, of which A. butzleri has the highest contamination rate PCR method amplifying 23S rRNA gene was applied to specifictly detect Arcobacter butzleri in this study, and the sensitivity of the method was 103 CFU/mL. Both of the 2 different reference strains of A. butzleri amplified and formed a band with length of 2061 bp, while A. cryaerophilus, A. skirrowii, Campylobacterjejuni and other different strains, 18 strains in total, didn’t produced any band. The results proved the PCR method had high specificity and could be used to identify A. butzleri at the species level. The comparative experimental results showed the PCR method also had advantage over the API CAMPY test kit, as the latter could only be used to identify A. butzleri at the genus level. 55 animal derived food samples containing the strains were enriched in Johnson-Murano broth and then detected by the PCR method, of which 5 samples were detected positive for A. butzleri, with the positive ratio of 9.1%. It suggested that the method was specific, easy to operate and timesaving, which could be used for rapid detection of A. butzleri in animal derived food.

41 Determination of Collagen Content in Livestock and Poultry Ossein by Spectrophotometry

DONG Xian-bing , LI Xia , ZHANG Chun-hui , SUN Hong-mei , LI Yin

2013, 29(10):2538-2541.

[Abstract](1312) [HTML](0) [PDF 487.52 K](821)

Abstract:
The paper provided a rapid, simple, accurate and low cost method to determine collagen content in ossein. Collagens from livestock and poultry bone were extracted by acid and thermal processes, and then calculated the ratio of collagen protein and hydroxyproline content in order to obtain collagen conversion factors from different bones. However the results indicated that fewer differences of collagen conversion factors between water-soluble and acid soluble collagen could be seen. According to the actual production, water-soluble collagen was taken as the conversion factor in ossein. The hydroxyproline in ossein was measured by spectrophotometry and then the collagen contents of pig, bovine and chicken ossein were calculated as 9.19%, 7.92% and 9.78%, respectively. The relative standard deviation (RSD) was between 0.01% and 0.03% and coefficient variation (CV) changed from 0.44% to 2.26%. The average recovery rate ranged from 99.36% to 100.44%. In conclusion, the method was appropriate to detect of collagen content in livestock and poultry ossein.

42 Determination of Organic Acids in Fermentation-silage of Citrus Peel Wastes by RP-HPLC

LEI Xing , PENG Rong , DU Ruo-yu , YIN Zhong-yi , PENG Ya , WANG Song-lin , ZHENG Xu-xu

2013, 29(10):2542-2546.

[Abstract](1113) [HTML](0) [PDF 617.48 K](727)

Abstract:
Reversed phase high performance liquid chromatography (RP-HPLC) was used to detect six different organic acids from fermentation-silage of citrus peel wastes. The organic acids were extracted by heated water from samples and analyzed by RP-HPLC on an applied Welch Materials XB-C18 column (4.6 mm×250 mm, 5 μm) at 214 nm using the mixture of 0.05 mol/L monopotassium phosphate (pH 2.70) and methanol (97:3, V/V) as mobile phase at a flow rate of 0.80 mL/min. The injection load was 20μL and the column temperature was 20 ℃. Under these conditions, the six organic acids had a good separation within 20 minutes and the recovery rates ranged from 94.96 % to 103.43%. Each organic acid presented a good linear relationship between concentrations and chromatographic peak area with the correlation coefficient higher than 0.99 (R2 > 0.99) and relative standard deviation less than 3% (RSD < 3%). The lowest detection limit was between 0.53 to 2.51 mg/L. Consequently, the determined concentrations of six organic acids (oxalic acid, formic acid, lactic acid, acetic acid, citric acid and propionic acid) were 0.84, 3.69, 51.13, 20.61, 1.76 and 1.06 mg/g respectively. In conclusion, RP-HPLC was a convenient, rapid and accurate method for analysis of organic acids in fermentation-silage of citrus peel wastes.

43 Determination of 10 Pesticide residues in Fruits by HPLC with SPE and UV Double Wavelength

SHAO Jin-liang , WANG Lu-xiang , MEI Wen-quan , DU Li-juan , CHEN Xing-lian , FAN Jian-ling , LIU Hong-cheng

2013, 29(10):2547-2553.

[Abstract](1070) [HTML](0) [PDF 558.74 K](743)

Abstract:
HPLC with solid-phase extraction (SPE) and UV double wavelength was presented to analysis of imidacloprid, acetamiprid, carbendazim, thiophanate-methyl, primigravida, diflubenzuron, chlorbenzuron，phoxim, difenoconazole and abamectin pesticide residues in strawberry, peach and apple. Sample preparation involves extraction with acetonitrile, and then purification and enrichment by LC-NH2 solid. Chromatographic analysis was performed on Shiseido CAPCELL PAK MG ⅡC18（250 mm×4.6 mm, 5 μm）HPLC column using methyl alcohol, water and acetonitrile as gradient eluents. Dual wavelength at 270 nm and 245 nm was conducted to detect target compounds. All the ten pesticides ranging from 0.05 mg/kg to 1.0 mg/kg had a good linear relationship (0.9834~0.9992). And the limits of detection and quantification for the ten pesticides were 0.005~0.030 mg/kg and 0.020~0.098 mg/kg, respectively. The average recoveries obtained from samples spiked with standards at concentrations of 0.05, 0.10 and 0.20 mg/kg were in the range of 69.82~88.95%，86.77~110.61% and 89.74~110.62%, respectively, with relative standard deviations (RSD) of 6.52~13.24%, 5.21~10.32% and 3.56~9.88%, respectively. This method can be applied to determine and quantitative analysis of 10 pesticide residues in fruits, which was more convenient operation, higher sensitivity, higher accuracy and better repeatability than other methods.

44 Change of Main Chemical Components of Bead Tea during Spreading

SHEN Qiang , PAN Ke , ZHANG Jian , ZHENG Wen-jia

2013, 29(10):2554-2558.

[Abstract](984) [HTML](0) [PDF 470.16 K](810)

Abstract:
Fresh leaves of bead tea were processed bydifferent spreading method and their leaf appearance, color and main chemical compositions were investigated by sensory evaluation, Hunte-Lab color space method, high performance liquid chromatography and chemical analysis. SPSS (Statistical Product and Service Solutions) statistical software was used for significant difference analysis and correlation analysis. The results showed that during spreading processing of the tea leaf, their moisture content decreased significantly and color was gradually deepened. The leaf became soft and showed delicate fragrance. The most suitable moisture contents and -b / a value for bead tea processing were 74% and 3.66, respectively. Moisture content, (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), (-)-gallocatechin gallate (GCG), total amount of catechins and ester type catechins showed a decreasing trend. Tea polyphenols, phenol ammonia ratio, (-)-epicatechin (EC), total amount of catechins presented a downward trend at first then went up with prolonging the processing time. (-)-Epigallocatechin (EGC) decreased first then increased, but decreased again at last period of the spreading processing, while the catechin (C) content increased first, decreased then and increased again lastly. Change of moisture content had a positive correlation with EC, but a negative correlation with soluble sugar content, neither of which was significant. Significant positive correlations of moisture content with phenol ammonia ratio, EGC, EGCG, GCG, ECG, total amount of catechins and ester type catechins, however were found. In particular, the correlation coefficient with EGCG could reach 0.99. In addition, moisture content showed extremely significant negative correlation with contents of amino acids and C.

45 Preparation of Monoacylglycerol and Diacylglycerol through Glycerolysis of Triacylglycerol

ZHONG Nan-jing , LI Lin , LI Bing , LU Qi-yu , LIU Guo-qin

2013, 29(10):2559-2565.

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Abstract:
Monoacylglycerol (MAG) and diacylglycerol (DAG) were widely used in food, pharmaceutical and organic synthesis industries. Their preparation has been therefore paid much attention. Glycerolysis of triacylglycerol (TAG) is the primary reaction route for MAG and DAG preparation due to the easy access of TAG and glycerol. In this paper, production of MAG and DAG through glycerolysis of TAG was reviewed; merits and drawbacks of chemical glycerolysis and enzymatic glycerolysis were compared. Enzymatic glycerolysis of TAG was generally carried out at about 60 ℃ in which TAG and glycerol were immiscible, leading to the difficult proceed of the reaction. Suitable reaction medium could greatly enhance the reaction speed, and some reaction mediums also played a great role in the selectivity of the target product. Presently, ion liquid had proved potentially for glycerolysis of TAG, in terms of reaction progress and reaction selectivity.

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