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Table of Content

25 September 2017, Volume 38 Issue 18
Bioengineering
Optimization of Fermentation Process for the Production of Intracellular Polysaccharide from Chlamydomonas sp. 212 and Its Antimicrobial Activity
SUN Jianrui, FU Dandan, ZHAO Junfeng, WANG Dahong, GU Shaobin
2017, 38(18):  1-7.  doi:10.7506/spkx1002-6630-201718001
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Response surface methodology was applied to optimize the fermentation process of intracellular polysaccharide production from Chlamydomonas sp. 212. Then, the antibacterial activity of intracellular polysaccharide was studied by filter paper disc method. The optimum fermentation medium was found to consist of NaNO3 305.01 mg/L, NaCl 93.66 mg/L, and NaHCO3 2.12 g/L. The bacterium grown in the optimized medium yielded 91.182 3 mg/L of intracellular polysaccharide, which was increased by 160% compared to that obtained using the unoptimized medium. The intracellular polysaccharide from Chlamydomonas sp. 212 had strong antibacterial activity against Salmonella typhimurium and weak antimicrobial activity against Escherichia coli, Staphylococcus albus, Staphylococcus?aureus and Aspergillus niger. This study may provide a theoretical basis for the screening of new natural antimicrobial substances and for the comprehensive utilization of oleaginous microalgae.
Optimization of Bacterial Cellulose Production by Fermented Soybean Molasses with Komagataeibacter intermedius
YIN Yuan, MA Jiage, NI Chunlei, CHENG Jianjun, XU Su
2017, 38(18):  8-16.  doi:10.7506/spkx1002-6630-201718002
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In this study, Komagataeibacter intermedius CGMCC12562 was employed to produce bacterial cellulose (BC) from soybean molasses. The fermentation process was optimized to improve BC yield. Through one-factor-at-a-time experiments, the soluble solids content (SSC) of soybean molasses, and corn gluten meal, ZnSO4 and malic acid were selected as the factors with a significant influence on BC production for optimization by response surface methodology. It was found that the optimized culture medium consisted of soybean molasses with an SSC level of 14.13 °Brix, 1.6% corn gluten meal, 0.11% ZnSO4 and 0.41% malic acid. The BC yield was as high as (15.68 ± 0.82) g/L after 7 days of culture at 30 ℃ for in a 250-mL conical flask containing 16% of the medium with an inoculum size of 10% at an initial pH of 6.0 under static?cultivation?conditions.
Kinetic Modeling of Quality Changes of Low-Salt Shrimp Sauce during Fermentation
YU Hui, LIU Haimei, WANG Jing, YI Dong, ZHAO Qin, LI Haiyan
2017, 38(18):  17-21.  doi:10.7506/spkx1002-6630-201718003
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In order to explore the influence of fermentation temperature and salt content on quality kinetics of low-salt shrimp sauce during fermentation, changes in total volatile basic nitrogen (TVB-N), free amino nitrogen (FAN) and sensory quality were investigated during fermentation at different temperatures (5, 15, and 25 ℃) with the addition of different amounts of salt (12%, 16%, and 20%). The kinetics of these quality changes was modeled. The lower salt content increased the fermentation rate, shortened the ripening time and elevated the TVB-N value at the end of the ripening period. Kinetics of FAN value was fitted to exponential model. At the beginning of fermentation, kinetics of TVB-N value was fitted to a linear model, but it was also fitted to an exponential model at the end of fermentation. The higher fermentation temperature shortened the ripening time, which was 28, 38, and 49 days at 25, 15, and 5 ℃, respectively. For each temperature, both FAN and TVB-N values were linearly correlated with fermentation time. All the models developed could accurately simulate the kinetics of quality changes in shrimp sauce during fermentation.
Effect of Kojic Acid on Enzymatic Activity and Structure of Phenoloxidase from the Shrimp Penaeus vannamei
Lü Yanfang, ZHANG Yanping, CAI Luyun, LI Jianrong, YANG Mingduo
2017, 38(18):  22-28.  doi:10.7506/spkx1002-6630-201718004
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The effect of kojic acid on the enzymatic activity and structure of phenoloxidase (PO) from Penaeus vannamei was investigated. The PO enzyme purified from shrimp heads was treated with different concentrations (0–1.5 mmol/L) of kojic acid. Kojic acid was found to be able to inhibit PO activity. The type of inhibition was determined and the effect of different concentrations (0–1.1 mmol/L) of kojic acid on the spatial structure of the PO enzyme was examined by measuring changes in the intrinsic fluorescence spectrum, surface hydrophobicity and secondary structure contents. The results showed that the residual PO activity gradually decreased to 9.8% of the initial activity with increasing kojic acid concentration up to 1.5 mmol/L, and the change in browning index was 3.02, suggesting prominent browning inhibition. Kojic acid could effectively inhibit PO activity, and the type of inhibition was competitive. The intrinsic fluorescence intensity of PO continuously decreased with increasing kojic acid concentration and the maximum emission wavelength (λmax) was red shifted. The surface hydrophobicity of PO decreased after an initial increase. In addition, as the concentration of kojic acid increased, the α-helix and β-sheet contents decreased, but β-turn and random coil increased. It was speculated that the spatial structure of PO was changed due to its reaction with kojic acid.
PCR-DGGE Analysis of Bacterial Community Structure in Stinky Mandarin Fish (Siniperca chuatsi)
LI Yan, WU Jiajia, ZHANG Jing, DAI Zhiyuan
2017, 38(18):  29-34.  doi:10.7506/spkx1002-6630-201718005
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Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to study the bacterial community composition in stinky mandarin fish during fermentation. Stinky mandarin fish was fermented for 8 days and sampled every two days for DNA extraction. The V6–V8 region of bacterial 16S rDNA was amplified by PCR and analyzed by DGGE. The results of DGGE showed that Enterococcus sp., Shewanella putrefaciens, Macrococcus caseolyticus and Exiguobacterium acetylicum gradually became dominant strains during the fermentation process, especially in the later stage of fermentation. The comparative analysis of DGGE fingerprints showed that the bacterial community of stinky mandarin fish was similar in later stage of fermentation, and became stable. These findings may provide helpful guidance for screening an industrial fermentation starter, controlling the growth of spoilage organisms and foodborne pathogens and consequently improving the quality and safety of stinky mandarin fish.
Screening of Strains of Adjunct Culture for Improving Bitterness of Low-Sodium Cheese
SONG Lanlan, MA Chunli, QU Qian, ZHANG Rui, SHI Jingwen
2017, 38(18):  35-41.  doi:10.7506/spkx1002-6630-201718006
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With the aim of counteracting the bitterness of low-sodium cheese, 21 Lactobacillus strains isolated from raw milk and Cheddar cheese were evaluated for low-temperature growth, acid-producing capacity, autolytic activity, aminopeptidase activity, proteolytic activity and gamma-aminobutyric acid (GABA) content. The isolated strains were analyzed further by multivariate statistical method. The results showed that strain C5 presented not only low acid-producing activity, high aminopeptidase activity and high autolytic activity, but also high proteolytic capacity; strain C8 displayed higher aminopeptidase activity; strain C9 exhibited higher proteolytic capacity in addition to higher autolytic activity. In addition, the fermentation broth of all the three strains contained lower than 5 μmol/L GABA. Therefore, they had the potential to improve the bitterness of low-sodium cheese, and could be the good candidates of adjunct cultures for low-sodium cheese production.
Component Analysis
Chemical Constituents and α-Amylase Inhibitory Effect of Crude Ethanol Extract and Fractions of Tartary Buckwheat
ZHOU Xiaoting, ZHANG Genyi
2017, 38(18):  42-47.  doi:10.7506/spkx1002-6630-201718007
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The purpose of this study was to investigate the chemical composition and α-amylase inhibitory activity of the crude ethanol extract of tartary buckwheat and its fractions obtained by successive extraction with organic solvents of different polarities including petroleum ether, ethyl acetate and N-butyl alcohol. An ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) method in the negative ion mode was established to analyze the major constitutions in the extracts. Results showed that the majority of the extracts were the flavonoids rutin, quercetin, quercetin-3-rutinoglucoglucoside, isoquercetin and kaempferol-3-O-rutinoside as well as some phenols such as hydroxybenzoic?acid. The inhibition rate against α-amylase and the inhibition type were determined and fluorescence quenching experiments were used to study the α-amylase inhibitory activity of the extracts. Results revealed that the crude extract, and the ethyl acetate-soluble and N-butyl alcohol-soluble fractions all significantly inhibited α-amylase activity whereas the petroleum ether-soluble fraction could not. Therefore, it can be inferred that the inhibition of α-amylase by tartary buckwheat extracts likely resulted from the combined action of different fractions in a noncompetitive manner, as indicated by the kinetic analysis. Fluorescence quenching experiments revealed that the fluorescence of α-amylase was statically quenched as it formed a complex with the extracts of tartary buckwheat.
Analysis and Comparison of Volatile Flavour Compounds in Kazakh Dry-Cured Beef from Different Feeding Systems and Muscle Cuts
SHA Kun, SUN Baozhong, ZHANG Zejun, LI Haipeng, SONG Huanlu, LEI Yuanhua, LI Hongbo, ZHANG Yang,
2017, 38(18):  48-53.  doi:10.7506/spkx1002-6630-201718008
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The aim of this study was to analyze the differences in the volatile flavor components of Kazakh dry-cured beef from two different feeding systems and three different muscle cuts. The volatile components were analyzed by an electron nose and solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). The results of electronic nose analysis showed that there were significant differences in flavor components between the two feeding systems, but no difference was found between different muscle cuts. A total of 26 volatile compounds were detected by SPME-GC-MS, including 8 aldehydes, 7 alcohols, 6 aromatic benzene compounds, 3 aliphatic hydrocarbons, 1 ketone and 1 furan. The results of analysis of variance showed that the muscle cuts had a significant effect on the total amount of fat oxidation products (P < 0.05), while the feeding systems had a significant effect on the total amount of feed ingredients (P < 0.01).
Functional Components and Activities of Different Dark Tea Extracts
CAO Yong, ZHAO Mouming, ZHAO Tiantian, CUI Chun, ZHAO Qiangzhong, FENG Yunzi
2017, 38(18):  54-59.  doi:10.7506/spkx1002-6630-201718009
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The functional components of different dark tea extracts (Tianjian tea, Fuzhuan tea, Bailiang tea, Liubao tea and Pu-erh tea) were quantified and the functional properties, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, oxygen radical absorbance capacity (ORAC), and the protective effect against injury in PC12 cells, were evaluated. Then the relationship between functional components and properties in tea extracts was analyzed. The results showed that the contents of tea polyphenols, polysaccharides and catechins in Fuzhuan tea, Tianjian tea and Bailiang tea extracts were significantly higher than those in Pu-erh tea and Liubao tea extracts, while Puer tea extract contained the highest contents of caffine, gallic acid and theanine. Fuzhuan tea, Tianjian tea and Bailiang tea extracts had higher ORAC and DPPH radical scavenging activities, whereas Fuzhuan, Puer and Liubao extracts had stronger protective effects against injury in PC12 cells. Correlation analysis indicated that DPPH radical scavenging activity and ORAC activity were significantly influenced by the contents of tea polyphenols, especially the contents of epicatechin?gallate (ECG) and epigallocatechin gallate (EGCG), while the protective effects against glutamate-induced injury in PC12 cells were significantly related to the content of theanine.
Effect of Heating Temperature on the Volatile Compounds of Lateolabrax maculatus Meat Analyzed by Electronic Nose and GC-MS
KANG Cuicui, SHI Wenzheng,, DIAO Yuduan, WANG Hui
2017, 38(18):  60-66.  doi:10.7506/spkx1002-6630-201718010
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The volatile flavor components of Lateolabrax maculatus meat extracted at different temperatures by headspace solid phase microextraction were identified by an electronic nose and gas chromatography-mass spectrometry (GC-MS).This study amied to explore the relationship between volatile components of L. maculatus meat and heating temperature. The results indicated that the electronic nose could distinguish L. maculatus meat samples heated at different temperatures. Principal component analysis (PCA) showed that the odor components of L. maculatus meat heated at different temperatures exhibited distinct differences and showed the minimum differences between 45 and 60 ℃. The results of GC-MS analysis showed that a total of 25, 40, 52, 56 and 59 volatile compounds were detected in L. maculatus meat extracted at 35, 45, 60, 80 and 95 ℃, respectively. The number of volatile components extracted from L. maculatus meat increased with increasing heating temperature. Meanwhile, there was a significant change in the contents of aldehydes, ketones, alcohols, hydrocarbons and aromatic compounds. Among the volatile flavor compounds identified, hexanal, nonanal, heptanal, decanal, undecanal, 2-octenal, 2,4-decadienal, heptanol,1-octen-3-ol, xylene made important contributions to the flavor of L. maculatus meat.
Nutritional Changes of Brown Rice during Germination and Their Effects on Pasting Properties of Germinated Brown Rice
WU Xiaojuan, CONG Jingyuan, WU Wei, WU Yue
2017, 38(18):  67-72.  doi:10.7506/spkx1002-6630-201718011
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Twenty four brown rice varieties were investigated for the changes in the contents of main nutrients during germination and their effect on the pasting properties of germinated brown rice. The results indicated that germination of brown rice led to a significant decrease in total starch content (P < 0.01) and a significant increase in soluble protein, cellulose, and γ-aminobutyric acid contents (P < 0.01), while not significantly changing the contents of amylose, total protein, and crude lipids (P > 0.05). Peak viscosity, minimum viscosity, final viscosity, and setback of starch from germinated brown rice were significantly positively correlated with amylose content (P < 0.01), and significantly negatively correlated with amylopection content and the ratio of amylopection to amylose (P < 0.01). The peak time of starch from germinated brown rice was significantly and positively correlated with amylose content (P < 0.01), and negatively correlated with amylopection content and the ratio of amylopection to amylase (P < 0.05). In addition, peak viscosity of germinated brown rice was significantly negatively correlated with total protein content (P < 0.01). Minimum viscosity, final viscosity, and setback of starch from germinated brown rice were negatively correlated with total protein content (P < 0.05).
Determination of Tetramethylpyrazine-4-Methyl Guaiacol and 4-Ethyl Guaiacol in 67? Chinese Baijiu Samples by Vortex Assisted Liquid-Liquid Microextration Combined with Gas Chromatography-Mass Spectrometry
SUN Xiaotao, WANG Zongyuan, LIU Miao, AO Ling, SUN Baoguo, SUN Jinyuan, ZHENG Fuping, HUANG Mingquan, LI Hehe
2017, 38(18):  73-79.  doi:10.7506/spkx1002-6630-201718012
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Tetramethylpyrazine, 4-methyl guaiacol and 4-ethyl guaiacol in 67 Chinese Baijiu samples were detected by vortex assisted liquid-liquid microextration (VALLME) combined with gas chromatography-mass spectrometry (GC-MS). The analytes were extracted with CH2Cl2, using a vortex agitator for 1?min, and then centrifuged at 6 000?r/min for 5?min. After that, the CH2Cl2 phase was directly injected into GC-MS for analysis. The results indicated that the calibration curves for the three analytes displayed a good linearity (R2 > 0.99) in the ranges of 0.5–2 500, 1.0–2 500, and 1.0–2 500?μg/L, respectively. The limits of detection (LODs) for tetramethylpyrazine, 4-methylguaiacol and 4-ethyl guaiacol were 0.25, 0.5 and 0.5?μg/L, respectively. The recoveries were in the range of 80.1%–88.0%. The method was successfully employed to detect the analytes in 67? Chinese Baijiu samples and the results showed that all the samples contained 1.5–2 434.3?μg/L tetramethylpyrazine, of which 51 contained 2.8–1 709.0?μg/L 4-methylguaiacol, and 53 contained 1.3–1 167.5?μg/L 4-ethyl guaiacol. The differences in the contents of the health-beneficial ingredients in Chinese Baijiu may be related to the raw materials and manufacturing process.
Changes in the Release of Salty and Umami Taste during Mastication of Stewed Pork with Brown Sauce
DENG Yajun, LIU Dengyong, GUO Chen, HAN Yaohui
2017, 38(18):  80-86.  doi:10.7506/spkx1002-6630-201718013
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A trained sensory panel consisting of 10 judges was requested to masticate stewed pork with brown sauce, and boluses were collected at different stages of mastication for dynamically monitoring moisture, fat, sodium chloride, nucleotides, nucleotide degradation products and pH and detecting changes in the taste profile of the food boluses were measured during mastication and the changes in taste were monitored using an electronic tongue. The results obtained indicated that moisture content of boluses during mastication increased significantly, and fat content decreased continuously. Moisture and fat contents reached 55.65% and 19.40% at the swallowing point, respectively. There was no significant change in pH except during the early stage of mastication. The contents of sodium chloride and flavor-enhancing nucleotides gradually decreased during mastication but both of them were slightly elevated at the swallowing point, reaching 1.07% and 79.90 mg/100 g, respectively. Furthermore, the sodium chloride content of bolus was significantly negatively correlated with its pH, and there was a significantly negative correlation between flavor-enhancing nucleotide and fat contents. The electronic tongue analysis showed that the release of saltiness and umami during mastication of stewed pork with brown sauce increased first and then decreased, attaining the highest value at the middle and late stages.
Isolation and Identification of Monoterpene Glucosides from Seed Cake of Paeonia rockii
LIU Pu, XU Yifan, LIU Peipei, QIU Saixi, ZHANG Huifang, WU Ke, DENG Ruixue
2017, 38(18):  87-92.  doi:10.7506/spkx1002-6630-201718014
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Objective: To isolate and identify monoterpene glucosides from the seed cake of Paeonia rockii. Methods: Monoterpene glucosides were isolated and purified by successive column chromatographies on silica gel and Sephadex LH-20 and semi-preparative high performance liquid chromatography (semi-pre-HPLC). Spectroscopic methods were used to elucidate their structure. Results: Eight monoterpene glucosides were isolated from the seed cake of Paeonia rockii. They were identified as β-gentiobiosylpaeoniflorin (1), abiflofin (2), oxyalbiflorin (3), 1-O-β-D-glucopyransoyl-paeonisuffron (4), abiflofin R1 (5), paeonifanin (6), 8-O-debenzoyl-albiflorin (7), and mudanpioside F (8). Conclusions: All of these compounds were isolated from the seed cake of P. rockii for the first time in this study. These compounds and their derivatives were of significant interest for drug research and development. The study may provide important evidence supporting the exploitation of the seed cake of P. rockii.
Nutritional Components and Gelling Properties of Three Brands of Commercial Ready-to-Eat Fish Tofu
XU Zudong, DAI Zhiyuan,, CHEN Kang, MA Xuting, XUE Jing
2017, 38(18):  93-98.  doi:10.7506/spkx1002-6630-201718015
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Three brands of commercial ready-to-eat fish tofu (A, B, and C) were purchased and evaluated for their nutritional components and gelling properties. The results showed that the moisture contents of brands A, B and C were 65.94%, 69.34% and 67.20%, respectively, crude protein contents were 25.63%, 22.02% and 23.81% respectively, and crude fat and ash contents were low. All three brands contained a variety of amino acids with ratios of essential to total amino acids of 39.43%, 39.64% and 39.57%, and ratios of umami taste to total amino acids of 37.11%, 36.06% and 36.32% respectively; the first limiting amino acid was leucine (Leu) for all three samples, and the essential amino acids index (EAAI) scores for brands A, B and C were 43.81, 53.14 and 49.57, respectively. A total of 21, 22, and 21 fatty acids were detected in these three brands, and the contents of polyunsaturated fatty acids (PUFAs) were high in them (59.14%, 63.39% and 44.59%, respectively). Water holding capacity of these fish tofo samples were high, which were 84.61%, 86.36% and 82.98% respectively. Moreover, pH values were 6.04, 6.06 and 6.23 and gel strengths were 320.17, 203.63 and 212.71 g?cm, respectively. Accordingly, this study demonstrated that fish tofu is a ready-to-eat food containing a variety of amino acids and having good gel performance. Data from this study may provide the foundation for further evaluation of the quality of commercial fish tofu products.
Effects of Blanching Time on Nutritional Quality and Antioxidant Activities of Walnut (Juglans sigillata) Male Inflorescences
ZHANG Wen’e, WANG Changlei, LI Xue, SHI Binbin, PAN Xuejun
2017, 38(18):  99-105.  doi:10.7506/spkx1002-6630-201718016
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The effects of blanching time on the nutritional quality and antioxidant activities of walnut male inflorescence (Juglans sigillata ‘Qianhe No. 7’) were investigated. The results indicated that blanching reduced obviously the contents of proximate components such as ash, fat and crude protein. The contents of soluble sugars, starch, titratable acid and ash dropped significantly after blanching for only 3 min. However, the fat content decreased remarkably at 6 min, and significant declines in the crude fiber and protein contents were observed at 9 and 12 min, respectively. The contents of mineral elements including potassium (K), iron (Fe), manganese (Mn) and zinc (Zn) lost seriously during blanching, followed by copper (Cu), phosphorus (P) and boron (B). However, the contents of magnesium (Mg) and calcium (Ca) were increased obviously during the whole blanching period of 15 min. Our results also showed that the essential amino acids lost more than non-essential amino acids and total amino acids during blanching and the loss rate of Phe and Val was the highest of all amino acids. Both total phenolics and total flavonoids were also significantly reduced with blanching time, which led to a reduction of antioxidant activities, but ferric reducing antioxidant power (FRAP) dropped more dramatically than 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity. Thus, the blanching time should be controlled within 3 min during the processing and cooking of walnut male inflorescences process in order to maximally retain nutrients.
Isolation, Purification and Structural Characterization of a Water-Soluble Polysaccharide from the Flower of Hylocereus undatus (Haw.) Britton & Rose
HE Muxue, MENG Fancheng, WANG Chunming, LI Shaoping, WANG Ying, YE Wencai, ZHANG Qingwen
2017, 38(18):  106-112.  doi:10.7506/spkx1002-6630-201718017
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Objective: To extract and purify polysaccharide fractions from the flower of Hylocereus undatus (Haw.)(H. undatus) Britton & Rose and investigate their physicochemical, spectroscopic, and structural properties. Methods: The crude water-soluble polysaccharide (HUP) was extracted, precipitated, deproteinized and lyophilized from flower of H. undatus. A homogeneous polysaccharide fraction, designated HUP0, was obtained by consecutive DEAE-cellulose and Sephadex G-100 column chromatography. Structural characterization of the polysaccharide fraction was conducted using high performance size exclusion chromatography coupled with multi-angle laser light scattering and refractive index detection (HPSEC-MALLS-RID), Fourier transform infrared (FT-IR) spectroscopy, high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectroscopy. Results: The weight-average molecular mass, intrinsic viscosity, specific rotation and mean diameter of HUP0 were measured to be 33.24 kD, 47.16 mL/g, +69°, and 196.96 nm, respectively. The FT-IR spectra showed that HUP0 was a neutral polysaccharide, which mainly contained β-configuration. Methylation, HPLC and NMR analyses indicated that HUP0 was a (1→4)-β-D-galactan.
Amino Acid Composition and Nutritional Quality Evaluation of Different Germplasms of Chinese Prickly Ash (Zanthoxylum bungeanum Maxim)
HOU Na, ZHAO Lili, WEI Anzhi, YANG Tuxi
2017, 38(18):  113-118.  doi:10.7506/spkx1002-6630-201718018
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The amino acid composition of 13 germplasms of Chinese prickly ash (collected from 13 different areas) was analyzed by using an automatic amino acid analyzer and the nutritional value was evaluated by ratio of amino acid (RAA), ratio coefficient of amino acid (RC), score of ratio coefficient of amino acid (SRCAA) and ratio between amino acid content and taste threshold (RCT). The results showed that each sample contained 17 amino acids, including all essential amino acids except tryptophan, with total amino acid contents ranging from 5.82% to 10.9%. The ratios of essential to total amino acid (EAA/TAA) were in the range of 0.17–0.33, and the ratios of essential to non-essential amino acid (EAA/NEAA) ranged from 0.21 to 0.48, which were lower than the FAO/WHO reference values of 0.4 and 0.6, respectively. The medicinal amino acids accounted for about 58% of the TAA content in Chinese prickly ash peel, which was the highest (6.70%) in the pericarp of Chenjiagelao thornless prickly ash (ZB1), accounting for 61% of the TAA content. The content of medicinal amino acids in prickly ash peel varied depending on the germplasms, but the proportions of medicinal amino acids in TAA were identical. According to the amino acid scores, methionine and cysteine were the first limiting amino acids in the pericarp of Chinese prickly ash, and aspartic acid, a umami amino acid, and had a significant effect on the flavor of Chinese prickly ash. The 13 germplasms of Chinese prickly ash were classified into 3 categories by using cluster analysis, and Chenjiagelao thornless prickly ash had the highest nutritional value. Therefore, Chenjiagelao thornless prickly can be used as an ideal source of protein in the development and utilization of Chinese prickly ash.
Variations in Umami Amino Acids of Defatted Silkworm Pupa Protein during Enzymatic Hydrolysis
YANG Bo, LIU Xiaoling, ZHAO Mouming,
2017, 38(18):  119-125.  doi:10.7506/spkx1002-6630-201718019
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In this study, alcalase and flavourzyme were applied in combination at a ratio of 1:1 to hydrolyze defatted silkworm pupa protein and the hydrolysates collected at different hydrolysis times were assayed for total sugar, amino nitrogen, soluble nitrogen, peptide nitrogen and peptide and amino acid compositions. The results showed that the optimum concentration of substrate, temperature, enzyme dosage (relative to the mass of defatted silkworm pupa protein powder) and hydrolysis time were 8?g/100 mL, 50?℃, 1?g/100 g, and 9?h, respectively. The enzymatic process promoted the release of total sugar. Nitrogen was mainly existed in the form of peptide nitrogen, and the molecular masses of most peptides in the hydrolysates were lower than 1?kD. The main free amino acids in the hydrolysates were threonine, histidine, leucine, tyrosine, lysine and cysteine, accounting for about 60% of the total free amino acid content, and they contributed to the taste of the hydrolysates. Umami and sweet amino acids accounted for approximately 50% of the total amino acids in the hydrolysates with a ratio of hydrophilic to alkaline amino acid of about 1. The contents of peptide-derived amino acids were strongly linearly correlated with the umami of the hydrolsates..
Analysis of Key Aroma Components in Three Wuliangye Liquors of Different Ages
NIU Yunwei, CHEN Xiaomei, XIAO Zuobing,, MA Ning, ZHU Jiancai
2017, 38(18):  126-130.  doi:10.7506/spkx1002-6630-201718020
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The aroma components of three Chinese Wuliangye liquors of different ages (1 year, 15 years and 30 years) were analyzed by headspace-solid phase?microextraction (HS-SPME) coupled with gas chromatography-olfactometry-aroma extract dilution analysis (GC-O-AEDA) and gas?chromatography-mass?spectrometry (GC-MS). A total of 30 aroma compounds were identified, including 18 esters, 2 alcohols, 5 acids and 5 aldehydes. Among them, 9 aroma compounds were detected in all three liquors, which could be regarded as key aroma components since their flavor dilution (FD) factors were equal to or higher than 256. Quantitative analysis indicated that the total content of aroma compounds decreased along with wine age. Sensory evaluation was also conducted. The analysis of variance (ANOVA) revealed that there were statistically significant differences in all seven sensory attributes evaluated among three liquors (P < 0.05). Duncan’s multiple comparison test indicated that aging, floral, sweet, caramel and grain aroma were most distinct from each other.
Effect of Drying Methods on Aroma Components of Jujube Fruits (Ziziphus jujube Mill. cv. Dongzao)
SHEN Jing, DU Ruoxi, WEI Ting, JI Xiaolong, WANG Min
2017, 38(18):  131-137.  doi:10.7506/spkx1002-6630-201718021
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The effects of microwave vacuum freeze drying (MVFD), microwave vacuum puffing (MVP), short- and medium-wave infrared drying (ID) and vacuum freeze drying (VFD) on the aroma properties of Chinese jujube were determined. The results showed that a total of 70 aroma compounds including alcohols, acids (29), aldehydes (31), esters, hydrocarbons and other miscellaneous compounds were identified by gas chromatography-mass spectrometry (GC-MS) coupled with solid phase micro-extraction in four dried jujube chips. Acids were the major volatile compounds in VFD, MVFD and MVP dried jujube chips, while aldehydes were the major volatile compounds in ID dried samples. There were significant differences in aroma quality among four dried jujube chips. Principal component analysis (PCA) was used to establish a model for aroma quality assessment. The MVP dried product showed the highest sensory scores and best aroma quality, followed by the VFD and MVFD dried products, and the ID dried product was the worst. The aroma quality of jujube chips could be evaluated by PCA method.
Effects of Withering Duration on the Aroma Profile of Yinghong No. 9 White Tea
CHEN Wei, MA Chengying, WANG Wenwen, HU Haitao, CHEN Haiqiang, PANG Shi, MIAO Aiqing
2017, 38(18):  138-143.  doi:10.7506/spkx1002-6630-201718022
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The aroma compounds of white tea samples produced from the cultivar Yinghong No. 9 with different withering durations were extracted by headspace-solid phase micro-extraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that the total aroma content of white tea rose to a maximum level of 858.40 ng/g at 24 h and then declined with withering time. The aroma components identified included alcohols, esters, aldehydes, ketones and hydrocarbons with alcohols being the most abundant ones. All tea samples shared similar aroma components. A total of 17 aroma compounds, including (Z)-3-hexen-1-ol, linalool, (Z)-3-hexen-1-yl acetate, (Z)-3-hexen-1-yl butyrate, methyl salicylate, (Z)-3-hexen-1-yl hexanoate, hexanal, benzaldehyde, (E,E)-2,4-heptadienal, nonanal, (E,E)-3,5-octadien-2-one, 3,5-octadien-2-one, β-ionone, β-myrcene, D-limonene, (E)-β-ocimene and β-ocimene were found in relatively high levels in most of the samples, together accounting for 67.3%–76.0% of the total aroma components. The 17 compounds were the main contributors to the aroma of white tea, most of which such as linalool and methyl salicylate demonstrated an initial rise followed by a decline while a few of them such as benzaldehyde and β-myrcene increased continuously during the withering process.
Proximate Composition and Flavor Substances of Chinese Toon (Fresh Young Leaves and Shoots of Toona sinensis) from Different Growing Areas of Henan Province
WANG Xiaomin, SHI Guanying, YANG Hui, ZHANG Le, ZHAO Shouhuan, ZHAO Hongyuan, WANG Zhaogai
2017, 38(18):  144-149.  doi:10.7506/spkx1002-6630-201718023
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In this study, the proximate nutrient composition and flavor substances of Chinese toon (fresh young leaves and buds of Toona sinensis) from different growing areas of Henan province were investigated. The contents of total proteins, total saponins, total alkaloids, and total flavonoids were determined by routine methods. Amino acid composition was determined by using an amino acid analyzer. Volatile compounds were determined by gas chromatography-mass spectrometry (GC-MS). The results showed that Chinese toon from Luoyang exhibited the highest contents of total proteins, total saponins, total alkaloids and total flavonoids among the four areas. A total of 17 amino acids were detected, including 7 essential amino acids. Chinese toon from Luoyang showed the highest contents of both total amino acids and essential amino acids, which were 274.82 and 86.09 mg/g, respectively. A total of 75 aroma compounds were identified, 52, 48, 47 and 46 of which were detected in Chinese toon from Yuanyang, Zhongmou, Anyang and Luoyang, respectively. Terpenes were present as the dominant compounds in all four samples, and the number of terpenes detected in Chinese toon from Luoyang was the largest. Thus, Chinese toon from four growing areas have significant differences in proximate composition and flavor substances. All the above results suggested that the quality of Chinese toon from Luoyang was better. The geographical origin of Chinese toon should be taken into account when processing it into various products.
Fluorescence Magnetic Surface Molecularly Imprinted Polymer Nanospheres to Detect Naringin by Fluorescence Polarization
ZHAO Chen, MENG Xiangyan, LU Wenzong, GUO Xing
2017, 38(18):  150-155.  doi:10.7506/spkx1002-6630-201718024
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A fluorescent magnetic surface molecular imprinting method was used to detect narigin by fluorescence polarization technology. By using TiO2-coated magnetic particles as substrate and methlacrylic acid and acrylamide as monomers, a surface molecular imprinting polymer with both fluorescence and magnetic characteristics was prepared and loaded with fluorescein isothiocyanate. The binding ability of the prepared polymer was tested by fluorescence polarization and ultraviolet (UV) spectrophotometry. Compared two other methods, the fluorescence polarization method was more sensitive, and its limit of detection (LOD) was 0.1 mg/L. The recovery of the fluorescence polarization method was higher than 81.3%. It was shown that the fluorescent magnetic surface molecular imprinting technique could be a new method to quickly and efficiently detect naringin in food.
Effect of Ultra-High Pressure (UHP) on the Flavor of Solenocera melantho Meat
WANG Zhiyan, GUAN Aiyan, Lü Liangyu, ZHOU Guo, YANG Wenge, LOU Qiaoming
2017, 38(18):  156-162.  doi:10.7506/spkx1002-6630-201718025
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This study was an attempt to investigate the effect of ultra-high pressure (UHP) treatment on the flavor compounds of shrimp. Solenocera melantho was subjected to UHP treatments at 100, 200, and 300 MPa held for 3 and 5 min at room temperature, respectively. The contents of ATP-related compounds and free amino acid contents in shrimp samples were determined and the freshness indicator K value and equivalent umami concentration (EUC), the concentration of?monosodium glutamate (MSG) equivalent to the umami intensity given?by?the?mixture?of?MSG-like amino acids?and the flavor?50-nucleotides, were calculated. Meanwhile, the volatile compounds were detected by an electronic nose and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Results indicated that the concentration of AMP increased after UHP treatments and 5 min holding treatment obviously improved the content of umami amino acids compared with the control group. UHP treatment at 200 MPa held for 3 and 5 min resulted in higher EUC values of 13.04 and 13.81 g MSG/100 g, respectively. The results of electronic nose showed an obvious difference between the control and 300 MPa treatment groups rather than comparison with 100 and 200 MPa treatments. As the primary key flavor component, 1-octen-3-ol was retained after 100–300 MPa treatments. GC-MS analysis demonstrated that the key odor components were 1-octen-3-ol, 2-nonanone and linalool for all control and treatment groups. Taking into consideration changes in non-volatile and volatile flavor compounds, treatment at 200 MPa for 5 min could better remain the flavor of Solenocera melantho.
Determination of Lycopene in Ketchup Using Attenuated Total Reflection Infrared Spectroscopy
ZHUANG Yang, TIAN Panpan, XIA Dongmei, SHAN Changhai, CHEN Meilin, CHENG Chao, WANG Xingping
2017, 38(18):  163-167.  doi:10.7506/spkx1002-6630-201718026
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In this study, the feasibility of using attenuated total reflection infrared spectroscopy to determine lycopene in ketchup was examined. The results obtained were as the follows: The wavenumber region between 1 700 and 950 cm-1 was chosen for the infrared spectrum analysis of samples and the spectrum data were analyzed by partial least squares regression after denoising using the 2nd derivative pretreatment. A regression equation was established with a coefficient of determination of 0.970, and the root mean square error of prediction of the model was 3.78. The coefficient of determination of linear fitting between the predicted and real values was 0.959 8, suggesting that the regression equation can accurately predict the content of lycopene in ketchup.
Taste Characteristics of Keemun Black Tea
CHEN Dong, MA Tao, SAN Weilin, WANG Chang, LI Quanhong
2017, 38(18):  168-174.  doi:10.7506/spkx1002-6630-201718027
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In this study, the tasty characteristics of three kinds of premium Keemun black tea, Teming Keemun Gongfu black tea (the top grade), Teji Keemun Xiangluo (the top grade) and Teji Keemun Maofeng (the top grade), were studied by sensory evaluation, electronic sensory analysis and chemical analysis. The results of sensory evaluation showed that the three samples showed different taste attributes. Teming Keemun Gongfu black tea had higher sensory scores for sweetness, freshness and briskness, bitterness, astringency, and sweet aftertaste than the other two samples. Electronic tongue could distinguish the three samples effectively. The chemical analysis showed that there were significant differences in tea polyphenols, caffeine and free amino acids among the three samples (P < 0.05), while no significant difference in pH was seen (P ≥ 0.05). Caffeine was positively correlated with bitterness and astringency. Free amino acids had positive correlation with freshness and briskness. These correlations were due to the different taste attributes among the three samples.
Effect of UV-C Irradiation on Quality and the Contents and Resveratrol and Its Derivatives in Muscat Grape
LI Yifan, WANG Fengling, ZHAO Qiqing, YANG Dan
2017, 38(18):  175-179.  doi:10.7506/spkx1002-6630-201718028
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In this study, ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to determine the contents of resveratrol and its derivatives in Muscat grapes. After being irradiated with 4.5 kJ/m2 UV-C, Muscat grapes were stored at 20 ℃. The experimental results showed that the contents of resveratrol and resveratrol glucoside increased to their maximum values of 90.29 and 163.28 μg/g,?respectively, after 48 h of storage. After 72 h of storage, the content of pterostilbene increased to its maximum level (38.67 μg/g). At the same time, UV-C radiation also decreased the?rate of reduction in soluble solids, vitamin C and titratable acid.
Change in Composition and Content of?Oligosaccharides?in Human Milk from Chinese Lactating Mothers
WEI Yuan’an, ZHENG Huiling, WU Shaohui, WU Jiayi, HUO Jinhong
2017, 38(18):  180-186.  doi:10.7506/spkx1002-6630-201718029
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Twenty two human milk oligosaccharides (HMOs) in 163 milk samples collected from 22 Chinese mothers during different stages of lactation were measured by high-performance anion-exchange chromatography (HPAEC). Levels of 15 neutral HMOs were highest at the early stages of lactation (in colostrum) and decreased later (in mature milk), but?3-fucosyllactose level continuously increased throughout the sampling period. Levels of six sialylated HMOs decreased during the course of lactation, and LSTa was detected only in some samples. Based on the Lewis blood types, the?volunteers were divided into secretor mother group and non-secretor mother group. Milk samples from secretor mothers were rich in α-1-2-linked fucosylated oligosaccharides (such as 2’-FL, LNFP Ⅰ, LDFT, and LNDFH Ⅰ). Specifically, the concentrations of the α-1-2-linked fucosylated oligosaccharides ranged from 1 211 to 7 272 mg/L in milk from secretor mothers and from 100 to 920 mg/L in milk from non-secretor mothers. In contrast, the contents of α-1-3/4-linked fucosylated oligosaccharides (such as LNDFH Ⅱ, DFLNH, 3-FL, and LNFP Ⅱ) was 476–4 931 mg/L in milk from non-secretor mothers, compared to 181–2 722 mg/L for milk from secretor mothers. Generally, this study showed that the composition and contents of HMOs in milk from secretor and non-secretor mothers varied continuously and were different significantly during the lactation period.
Processing Technology
Optimization of Purification by Ammonium Sulfate Precipitation of the Major Allergen Tropomyosin from Shrimp (Litopenaeus vannamei)
FU Linglin, FU Shujie, WANG Yanbo, WANG Chong, ZHANG Yan, WU Qi, MA Aijin
2017, 38(18):  187-192.  doi:10.7506/spkx1002-6630-201718030
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Tropomyosin (TM), the major shrimp allergen, is one of the serious food safety problems throughout the world and has drawn much attention. It has been reported that the isolation and purification of TM is of very importance in the identification and control of allergy. In the present study, tropomyosin was purified from Litopenaeus vannamei by an improved method. The results indicated that TM could be purified effectively by adjusting the extraction buffer to pH 6.5 to 7.5 and then adding ammonium sulfate to approximately 30% saturation. The concentration of TM was about 43 μg/μL, as determined by a BCA Protein Assay Kit. The improved method avoided further purification of TM using high performance liquid chromatography (HPLC) or another chromatographic technology. In addition, the process of TM isolation was simplified and TM loss and dilution were avoided during further purification. High concentration of purified TM solution obtained in the present study could be directly used to study its physicochemical properties and allergenicity without being freeze-dried.
Optimization of Extraction and Composition of Sterols from Lotus Seed Plumule
CHEN Jiali, BI Yanlan, CHEN Shuai, WEI Maolin, HUANG Zhenwei
2017, 38(18):  193-199.  doi:10.7506/spkx1002-6630-201718031
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The objective of this study was to optimize the extraction of sterols from lotus seed plumule with acetone as the extraction solvent using one-factor-at-a-time method and response surface methodology. The independent variables were extraction time, temperature, solid-to-solvent ratio and number of extractions, while the response variable was the yield of total sterols. This study also determined the sterol composition of lotus seed plumule by gas chromatography-mass spectrometry (GC-MS). The highest yield of total sterol (1.67 ± 0.11)% was achieved under optimal conditions: extraction time, 12 min; temperature, 44 ℃; solid-to-solvent ratio, 1:12 (g/mL); and three extraction cycles. The extract was composed of esterified and free sterols, accounting for 84.97% and 11.95%, respectively. Besides, seven sterols were identified, among which, sitosterol (58.27%), Δ5-avenastero (22.99%) and campesterol (12.64%) were predominant. Additionally, both glyceride and sterol ester had high level of unsaturated fatty acids (77%), especially linoleic acid. Sterol ester contained higher levels of long chain fatty acids, such as behenic acid and lignoceric acid than glyceride.
Optimization of Vacuum Freeze-Drying of Tofu by Response Surface Methodology
ZOU Xiaoshuang, LI Jiani, JIANG Nan, JIANG Lianzhou, LI Yang, SUI Xiaonan, QI Baokun, WANG Zhongjiang
2017, 38(18):  200-207.  doi:10.7506/spkx1002-6630-201718032
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The purpose of this study was to develop a new freeze-drying procedure for tofu. The processing conditions were optimized using response surface methodology. The rehydration ratio and mass of freeze-dried tofu were 9.42 and 0.073 1 g, respectively under the optimized conditions: slice thickness 9.00 mm (12 mm in both length and width), pre-freezing rate, 0.70 ℃/min, cold trap temperature, ?48.7 ℃, pressure in drying chamber 70 Pa, and temperature of heat plate 51.9 ℃. The optimized procedure can establish a theoretical foundation for the production of freeze-dried tofu and other related products.
Optimization of Extraction and Purification of Polysaccharides from Patinopecten yessoensis
LIU Yu, FANG Zhiqiang, LIU Yuxin, LOU Yadi
2017, 38(18):  208-213.  doi:10.7506/spkx1002-6630-201718033
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In this paper, the ultrasonic-assisted enzymatic extraction and purification of polysaccharides from Patinopecten yessoensis were optimized using one-factor and orthogonal array design methods. For the deproteinization of crude polysaccharides, D-glucono-δ-lactone (GDL) was used in this study for the first time and its performance was evaluated in comparison with trichloroacetic acid (TCA). The results showed that the optimum conditions for extraction were as follows: solvent/solid ratio, 40:1 (mL/g); enzyme dosage, 2.5%; and 3 h extraction at 60 ℃, resulting in the highest polysaccharide yield of 10.90%. The optimum conditions for TCA deproteinization were as follows: deproteinization time, 5 h; final TCA concentration, 5%; and 3 deproteinization cycles. The optimal conditions for GDL deproteinization were as follows: deproteinization time, 1 h; reaction temperature, 45 ℃; and final concentration, 0.3%. Three parallel experiments conducted under the optimized conditions gave an average deproteinization rate of 88.654% and 99.062% with relative standard derivation (RSD) of 0.905% and 0.679% for TCA and GDL, respectively. Comparison of the two deproteinization methods showed that the deproteinization efficiency of GDL method was higher and more stable.
Optimization of Ultrasonic-Assisted Cellulase-Based Extraction and Anti-α-Glucosidase Activity of Polyphenols from Pomegranate Fruitlets
WANG Zhanyi, ZHANG Lihua, WANG Yuhai, DAI Bo, ZHENG Dandan, LI Zhuowa
2017, 38(18):  214-221.  doi:10.7506/spkx1002-6630-201718034
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This study aimed to optimize the ultrasonic-assisted cellulase-based extraction of polyphenols from pomegranate fruitlets. The factors with a significant influence on the yield of polyphenols were selected using a combination of one-factor-at-a-time method and Plackett-Burman (PB) design for the optimization experiments which were carried out using Box-Behnken design combined with response surface methodology. The anti-α-glucosidase activity and kinetics?characteristics of the polyphenols were determined by using α-glucosidase inhibition model in vitro. Results showed that under the following conditions: ultrasonic power, 318 W; enzyme dosage, 23 U/mL; hydrolysis temperature, 46 ℃; and hydrolysis time, 2.7 h, the average yield of polyphenols from pomegranate fruitlets was 11.65%, close to the predicted value. The polyphenols had a strong anti-α-glucosidase activity. The percentage inhibition of α-glucosidase by the polyphenols at a concentration of 1.20 mg/mL reached 70.3% and the half inhibitory concentration (IC50) was 0.747 mg/mL. There was a positive relationship between the anti-α-glucosidase activity and polyphenol concentration in the range of 0.24–1.20 mg/mL. The inhibition was reversible and non-competitive.
Optimization of Ultrasonic-Assisted Alkaline Extraction of Duck Liver Protein Using Response Surface Methodology and Its Antioxidant Activity
WANG Li, ZOU Ye, ZHANG Kun, YU Hai
2017, 38(18):  222-228.  doi:10.7506/spkx1002-6630-201718035
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The ultrasonic-assisted alkaline extraction of duck liver protein was optimized by response surface methodology, and the antioxidant activity of duck liver protein extracted with and without ultrasonic treatment was compared. For the ultrasonic-assisted extraction, the optimum conditions were determined as follows: ultrasonic power, 256 W; ultrasonic exposure time, 43 min; and pH value, 11, where the maximum yield of duck liver protein equal to 73.1% was achieved. Antioxidant activity tests showed that IC50 values for scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate (ABTS+·) and hydroxyl free radicals were 1.97, 0.168 and 0.529 mg/mL of the ultrasonically extracted duck liver protein, respectively, suggesting stronger scavenging activity against ABTS+· than other free radicals, which also had high reducing power. Moreover, its antioxidant activity was significantly higher than that of the conventional alkali-extracted protein (P < 0.05). The current study may provide a scientific basis for intensive processing of duck liver.
Preparation and Oxidative Stability of Microcapsules Containing Pine Nut Oil by Complex Coacervation
GUO Yang, BAO Yihong, ZHAO Nan
2017, 38(18):  229-236.  doi:10.7506/spkx1002-6630-201718036
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Pine nut oil microcapsules were successfully prepared using gelatin and arabic gum as wall materials by complex coacervation method. The influences of the ratio of gelatin to arabic gum (V/V), the mass ratio of core to wall material, the mass fraction of wall materials, and agglomeration time on microencapsulation efficiency were determined. These processing parameters were optimized using orthogonal array design. Meanwhile, the physicochemical properties of the microcapsules were evaluated and the effect of temperature on their oxidative stability was also analyzed. The highest microencapsulation efficiency of 87.23% was achieved under the optimized conditions: gelatin/arabic gum ratio 2:1, core/wall ratio 2:3, mass fraction of wall materials 2%, and agglomeration time 50 min. The moisture content and solubility of pine nut oil microcapsules was 5.1% and 98.09%, respectively. The interaction between gelatin and arabic gum was analyzed by Fourier transform infrared (FT-IR) spectroscopy, and field emission scanning electron microscopy (FESEM). DSC analysis indicated that complete structure of microcapsules could exist stably at room temperature. The oxidative stability of encapsulated pine nut oil revealed that microencapsulation could enhance the storage stability, prolong the storage period of pine nut oil.
Dielectric Barrier Discharge Atmospheric Cold Plasma Inactivation of Microorganisms on Mackerel (Pneumatophorus japonicus) and Its Effects on Histamine Content
SHI Zihe, CHEN Jing,, CHEN Xingjie, HUANG Ju, DENG Shanggui
2017, 38(18):  237-243.  doi:10.7506/spkx1002-6630-201718037
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The aim of this work was to investigate the bactericidal efficacy of dielectric barrier discharge atmospheric cold plasma (DBD-ACP) and its effect on the histamine content of mackerel (Pneumatophorus japonicus). Direct and indirect processing modes were adopted and their anti-microbial effects were compared based on the variations of total variable counts (TVC) in the fish. The voltage and treatment time were optimized using response surface methodology (RSM) combined with central composite design. Under optimized conditions, the effect of DBD-ACP treatment on the changes in histamine contents and histamine-producing microorganisms such as Pseudomonas, Enterobacter, and Vibrio during storage were evaluated. The results indicated that direct DBD-ACP treatment was more effective in the inactivation of microorganisms, which resulted in a 35.88% decrease in TVC, compared with indirect treatment. The optimal conditions were found to be 71.5 s treatment at a voltage of 59.9 kV. Under these conditions, TVC decreased to 1.83(lg(CFU/g)), which is in good agreement with the predictive value (1.86(lg(CFU/g))), suggesting that the proposed model could fit the experimental data well. During a 14-day period of storage, Distinctly slower growth rates were observed for Pseudomonas, Enterobacter and Vibrio in DBD-ACP treated samples. On the 8th day, the counts of Pseudomonas, Enterobacter and Vibrio decreased by 25.89%, 46.23% and 45.23%, respectively, compared to those of control groups. Meanwhile, a reduced rate of increase in histamine content was determined for DBD-ACP treated group, whose histamine content was measured to be 72.34 mg/100 g on the 14th day, lower than the national standard limit.
Response Surface Methodology for Optimization of Preparation Process for RS3 Type Resistant Indica Rice Starch by Seed Crystal Induction Combined with Dual-Enzymatic Hydrolysis
OUYANG Mengyun, WANG Yan, WU Weiguo, LIAO Luyan
2017, 38(18):  244-250.  doi:10.7506/spkx1002-6630-201718038
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In this research, RS3 type resistant potato starch was prepared and used as seed crystal to investigate the preparation of RS3 type resistant indica rice starch by the combined use of seed crystal and sequential hydrolysis with isoamylase and pullulanase. Scanning electron microscopy (SEM) was used to characterize starch granule morphology. Besides, we also studied the resistance of starches to enzymatic hydrolysis. Using the one-factor-at-a-time method, the amounts of seed crystal, isoamylase and pullulanase added and pullulanase hydrolysis time were identified as factors with a significant influence on the yield of RS3 type resistant starch. These variables were optimized using response surface methodology with a Box-Behnken design. The maximum yield of RS3 type resistant starch of 27.42% was obtained under the following conditions: 5% seed crystal, 8 U/g isoamylase, 8 U/g pullulanase and 3.50 h hydrolysis with pullulanase. The surface of the resistant starch granules was rough, which lost the original starch granule morphology, and the crystal structure of the resistant starch was compact. In addition, its resistance to enzymatic hydrolysis was strong.
Optimization of Enzymatic Deproteinization of Polysaccharides from Cuttlefish Muscle (Sepia lycidas) and Its in Vitro Free Radical Scavenging Potential
SUN Yulin, DAI Hongjie, WEN Jing, ZHANG Wei, ZHAO Juan, TIAN Li, CHEN Daohai
2017, 38(18):  251-258.  doi:10.7506/spkx1002-6630-201718039
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The enzymatic deproteinization of polysaccharides from cuttlefish muscle (Sepia lycidas) was optimized using an orthogonal array design. Trypsin was determined to be the optimal enzyme to hydrolyze the protein in the crude polysaccharide extract. Enzyme dosage, hydrolysis temperature, pH and hydrolysis time were selected as independent variables for optimization, and the response variables were deproteinization efficiency and polysaccharide loss. The enzymatic method was compared with trichloroacetic acid (TCA) and isoelectric point (IP) methods. Meanwhile, the free radical scavenging capacity of the deproteinated polysaccharides was also studied. The results showed that the optimum deproteinization conditions were obtained as follows: trypsin dosage, 3.0 g/100 mL; hydrolysis temperature, 53 ℃; pH, 8.2; and hydrolysis time, 1.5 h, yielding a deproteinization rate as high as 89.43% and a polysaccharide loss of only 1.78%. In terms of both dependent variables, the enzymatic method was better than TCA and IP methods. The percentage scavenging of hydroxyl radical by the deproteinated polysaccharides obtained by the enzymatic, TCA and IP methods were 45.72%, 38.72% and 25.18%, with IC50 values of 12.44, 16.37 and 34.64 mg/mL, respectively, and the percentage scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical by these purified polysaccharides were 68.00%, 30.08% and 23.10%, with IC50 values of 7.62, 16.71 and 28.96 mg/mL, respectively. The free radical scavenging activities of the deproteinated polysaccharides from S. lycidas muscle were ranked as follows: enzymatic method > TCA method > IP method.
Lutein Nanoliposomes: Optimization of Preparation Conditions and Oxidative Stability
JIAO Yan, LI Dajing, LIU Chunquan, XIAO Yadong
2017, 38(18):  259-265.  doi:10.7506/spkx1002-6630-201718040
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This study aimed to optimize the preparation conditions of lutein nanoliposomes (LUT-NLP) by ethanol injection method using a combination of one-factor-at-a-time method and response surface methodology. The optimal preparation conditions were found to be as follows: lutein concentration, 0.51 mg/mL; total content of lecithin and cholesterol (4:1, m/m) in nanoliposomes, 5.0%; pH, 7.4; and hydration temperature, 62.9 ℃. Under these conditions, the entrapment efficiency of lutein in nanoliposomes was (91.20 ± 0.56)% and the average size of nanoliposomes was (226.8 ± 10.62) nm. Transmission electron microscope (TEM) showed that the shape of LUT-NLP was regularly spherical and lutein was evenly distributed in the nanoliposomes. The antioxidant activity studies showed that both lutein and LUT-NLP concentration-dependently scavenged 1,1-dipheny1-2-picrylhydrazyl (DPPH) radical. Furthermore, this study demonstrated that LUT-NLP had apparently improved antioxidant activity and stability compared with lutein .
Extraction, Composition Analysis and Functional Properties of Protein Isolate from Hydraulic Expeller-Pressed Macadamia Nut Meal
GUO Gangjun, HU Xiaojing, MA Shangxuan, XU Rong, YAN Li, ZOU Jianyun
2017, 38(18):  266-271.  doi:10.7506/spkx1002-6630-201718041
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The extraction of protein from hydraulic?expeller-pressed macadamia nut meal by alkali dissolution and acid precipitation was optimized using one-factor and orthogonal array design methods. The composition and functionality of the protein extract were evaluated. The results showed that alkaline pH, extraction time and temperature all had highly significant effects on extraction efficiency (P < 0.01), and these factors could be ranked in decreasing order of significance: alkaline pH, extraction time and temperature. The optimal extraction conditions were determined as follows: solid-to-liquid ratio, 1:50 (g/mL); pH value, 9.0; extraction time, 2 h; and extraction temperature, 40 ℃. Under these conditions, the yield and purity of protein extracted from macadamia nut meal were up to 95.40% and 65.46%, respectively. Albumin, globulin, gliadin and glutenin accounted for 7.29%, 14.58%, 14.95%, and 63.18% of the total proteins extracted from macadamia nut meal, respectively. The isoelectric point of the protein isolate was approximately 5.0. At the appropriate pH, the solubility, emulsifying capacity, emulsion stability and foam stability of macadamia nut meal protein isolate were good and the foamability was relatively poor. Its oil-binding capacity reached the maximum value of 50.10% at 70 ℃.
Ultrasound-Assisted Supercritical Carbon Dioxide Extraction of Lipids from Chinese Giant Salamander (Andrias davidianus)
REN Guoyan, SONG Ya, KANG Huaibin, XIAO Feng, SUN He, ZHAO Dong, HU Gan, WANG Songjun
2017, 38(18):  272-279.  doi:10.7506/spkx1002-6630-201718042
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The ultrasound-assisted supercritical?CO2 (UASC-CO2) extraction of lipids from the freeze-dried adipose tissue of Chinese giant salamander (Andrias davidianus) was optimized using a combination of one-factor-at-a-time method and response surface methodology and compared with conventional supercritical?CO2 extraction. The optimum conditions for UASC-CO2 extraction that provided maximum lipid yield (93.66%) were determined as follows: pressure, 36 MPa; temperature, 43.5 ℃; and time, 120 min. However, the optimum conditions for conventional supercritical?CO2 extraction that provided maximum lipid yield (75.25%) were as follows: pressure, 40 MPa; temperature, 43.5 ℃; and time, 120 min. It was observed that the yield of lipids was significantly higher by UASC-CO2 extraction method at lower pressures than by conventional supercritical?CO2 extraction at the same temperature and time. In addition, in terms of physicochemical properties and fatty acid content, no significant difference was seen between the two lipid extracts. The results showed that the yield of lipids from Chinese giant salamander could be significantly improved by ultrasound-assisted treatment, while still maintaining the product quality.
Optimization of Ultrasonic-Assisted Dilute Alkali Extraction of Trachinotus ovatus Bone Oil and Analysis of Its Fatty Acid Composition
CAO Xuan, SHEN Xuanri
2017, 38(18):  280-285.  doi:10.7506/spkx1002-6630-201718043
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In this study, the main nutritional components (moisture, crude protein, crude fat and ash contents) of Trachinotus ovatus bone was firstly determined, and then the optimization of the ultrasonic-assisted extraction of T. ovatus bone oil using dilute alkali as the extraction solvent was investigated using one-factor-at-a-time and orthogonal array design methods. The fatty acid composition of the fish bone oil was analyzed by gas chromatography-mass spectrometry (GC-MS) in order to evaluate its nutritional value. The results indicated that the moisture, crude fat, crude protein and ash contents of T. ovatus bone were 50.20%, 29.97%, 12.00% and 7.63%, respectively. Solvent-to-solid ratio, pH, hydrolysis temperature and hydrolysis time were identified as important factors that affected the extraction efficiency. The maximum oil yield of 80.51% was achieved after 30 min extraction at 60 ℃ and pH 9 with a solvent-to-solid ratio of 4:1 (mL/g) under the condition of 500 W power. The qualitative and quantitative analysis indicated that the content of unsaturated fatty acids in the oil was 68.44%, which was much higher than the content of saturated fatty acids (31.56%). Moreover, the content of monounsaturated fatty acids (37.99%) was higher than the content of polyunsaturated fatty acids (30.45%). Oleic acid (27.86%) and cetylic acid (21.46%) were the most dominant among the identified fatty acids. Additionally, the oil was rich in oleic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). It was indicated that T. ovatus bone as a fish processing waste was rich in nutrients, and had health benefits and economic value, thereby being worthy of exploitation and utilization.
Safety Detection
Tracing the Geographical Origin of Rice Grown in Different Crop Years Based on Diffuse Reflectance Fourier Transform Near Infrared Spectroscopy
SONG Xuejian, QIAN Lili, ZHANG Dongjie, WANG Xinhui, YU Guo, YU Jinchi, ZHOU Yi
2017, 38(18):  286-291.  doi:10.7506/spkx1002-6630-201718044
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In this study we identified the feature wavebands for rice samples grown in experimental fields located in Wuchang, Jiamusi and Qiqihar in 2015 to examine the application of diffuse reflectance Fourier transform near infrared (FT-NIR) spectroscopy combined with chemometrics for identifying the traceability of the geographical indication products Chahayang rice and Wuchang rice harvested in 2014 and 2015. The results showed that the rice samples from different regions were significantly different in the wavenumber region of 5 136–5 501 cm-1. The predictive accuracy of the developed qualitative analysis model was 100% for both Chahayang rice and Wuchang rice harvested in 2014, and 100% and 91.67% for Chahayang rice and Wuchang rice harvested in 2015, respectively. The accuracy of the quantitative prediction model established by partial least squares method was 90.90% and 95.83% for Chahayang rice and Wuchang rice harvested in 2014, and 91.67% and 87.50% for Chahayang rice and Wuchang rice harvested in 2015, respectively.
Synthesis and Application of a Novel Fluorescent Probe Based on 8-Hydroxyquinoline for Al3+ detection in food
XU Jian, FU Qingquan, ZHANG Hui, WANG Xiaofeng, SUN Youhong, MA Yufeng
2017, 38(18):  292-296.  doi:10.7506/spkx1002-6630-201718045
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A novel fluorescent probe L (2-((E)-((2-((4-((E)-(4-nitrophenyl) diazenyl) phenyl) amino) ethyl) imino) methyl) quinolin-8-ol) for detecting Al3+ was designed and synthesized. The structure was fully characterized by elemental analyses,1H-nuclear magnetic resonance (NMR) and electron ionization-mass spectrometry (EI-MS). The fluorescence intensity of the probe was very weak in solution, but it increased obviously after binding with Al3+. Thus, a new method for the determination of Al3+ was successfully established. It exhibited a dynamic response within the Al3+ concentration range from 1 × 10-8 to 1.4 × 10-6 mol/L. The limit of detection (LOD) of the method was 5.8 × 10-9 mol/L. The recovery of the method was 96.5%–105.9% and the precision expressed as relative standard deviation (RSD) was 5.89%. The method showed the advantages of excellent selectivity, high sensitivity, wide linear range and simplicity.
Suitability of Fully 13C Isotope Labeled Internal Standards for the Simultaneous Determination of 16 Mycotoxins in Grains by UPLC-MS/MS
WU Yu, XIN Yuanyuan, YE Jin, ZHANG Yan, XIE Gang, LI Li, LI Rui, WANG Songxue, ZHANG Tinglan
2017, 38(18):  297-303.  doi:10.7506/spkx1002-6630-201718046
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This work investigated the suitability of applying fully 13C isotope labeled mycotoxins as internal standards for the accurate determination of 16 mycotoxins in maize and wheat by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The target analytes in samples were extracted, diluted, and detected by UPLC-MS/MS after addition of internal standards. The results showed that all 16 mycotoxins displayed good linear relationships with correlation coefficients more than 0.997. Recoveries of the analytes were in the range of 83%–114.3% with relative standard deviations of 0.9%–13%. The limits of quantification (LOQs) of the method ranged from 0.5 to 200 μg/kg. Maize reference materials, and corn and wheat samples were analyzed by this method to validate its accuracy and applicability. The method could accurately, quickly detect 16 mycotoxins in grains in batch.
Determination of Diarrhetic Shellfish Poisons in Shellfish by Immunoaffinity Column Cleanup Coupled with Liquid Chromatography-Mass Spectrometry
YAN Zhongyong, ZHANG Xiaojun,, LI Qifu, CHEN Si, LI Peipei, ZHU Yin, LIU Wenjing
2017, 38(18):  304-309.  doi:10.7506/spkx1002-6630-201718047
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A new method using immunoaffinity chromatography (IAC) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established for the determination of diarrhetic shellfish poisons (DSP) such as okadaic acid (OA), dinophysistoxin-1 (DTX1), pectenotoxin-1 (PTX1) in shellfish. Samples were extracted with 80% methanol, diluted with phosphate buffer, cleaned up by immunoaffinity chromatography, and detected by LC-MS/MS. The major parameters affecting the performance of IAC, including loading amount, washing time and elution conditions, were investigated. Detection was carried out by electrospray ionization in the negative ion mode using multiple reaction monitoring (MRM). The linear range of the analytes was 1.0–100 μg/L with correlation coefficient more than 0.996. The limit of detection (LOD) and limit of quantification (LOQ) for the analytes were calculated as 0.3 and 1.0 μg/kg, respectively. The mean recoveries of the analytes were in the range of 82.7%–94.3% with a relative standard deviation (RSD) of less than 7.61%. Therefore, the method could be used to identify and quantify diarrhetic shellfish poisons in shellfish with less matrix interference and satisfactory sensitivity.
Application of Electronic Nose for Identifying the Freshness of Chinese Mitten Crab (Eriocheir sinensis) Based on Modified Unsupervised Discriminant Projection Algorithm
ZHU Peiyi, XU Benlian, LU Mingli, SHI Jian, Lü Gang
2017, 38(18):  310-316.  doi:10.7506/spkx1002-6630-201718048
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An electronic nose was designed to collect odor data of live Chinese mitten crab (Eriocheir sinensis) using a sensor array consisting of 7 commercial tin oxide gas sensors. To obtain a better feature vector for identifying different crabs, a modified unsupervised discriminant projection coupled with sample label information was proposed which could maintain the local and global structure and take advantage of the important label information to achieve optimal linear geometric projection. Then back-propagation neural network was used for modeling the quality changes of crabs during storage. At the same time, the total volatile basic nitrogen (TVB-N) of crab meat was measured and used as an indicator of crab freshness. The results showed that a high degree of accuracy in nondestructive identification of crab freshness was achieved with electronic nose based on this algorithm.
Determination of 15 Pesticide Residues in Food Matrixes by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry after Sample Cleanup Using Polyethersulfone (PES)/Multiwalled Carbon Nanotubes (MWCNTs) Composite Membrane
HE Yahui, WANG Liang, WANG Jing
2017, 38(18):  317-324.  doi:10.7506/spkx1002-6630-201718049
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In this paper, polyethersulfone (PES)/multi-walled carbon nanotubes (MWCNTs) composite membrane was prepared by phase inversion method, and its surface morphology and structure were observed by scanning electron microscopy (SEM). The results showed that the membrane displayed a finger-shaped porous structure. A simple, easy-to-operate filtration device equipped with the composite membrane was designed and used to develop a rapid sample pretreatment for the analysis of 15 pesticide residues in food by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Good sample cleanup was obtained with the composite membrane. However, due to the special planar ring structure of multi-walled carbon nanotubes incorporated in it, the composite membrane could adsorb planar pesticides. Consequently, of the 15 pesticides analyzed, the average recoveries of two planar pesticides were low while those of the other pesticides were between 71% and 118%, with relative standard deviation (RSD) between 0.73% and 12.87% (n = 6). The method reduced the overall sample preparation time from 4–7 h to 30 min. The method was simple, efficient, sensitive and environmentally friendly and could be applied widely. It was suitable for rapid analysis of non-planar pesticide residues in food.