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Zhang Z.,Sun Yat Sen University | Zhang Z.,Fujian Engineering College | Li G.,Sun Yat Sen University | Luo L.,Zhanjiang Institute of Supervision and Test on Quality and Measure | Chen G.,Fujian Engineering College
Analytica Chimica Acta | Year: 2010

Seafood volatile profile characteristics at different storage phases are various and can be used for freshness evaluation during storage. It is imperative to obtain the full volatile information prior to the further study of seafood volatile profile characteristics during storage. Also, the efficient data-processing method is another important factor for the interpretation of seafood volatile profile characteristics during storage and related potential volatile markers. In this work, a new analytical strategy, including the efficient sampling technique, sensitive detection and suitable data-processing method, for seafood freshness evaluation was developed based on the volatile profile characteristics during storage. First, the study of volatiles of seafood samples including razor clam, redspot swimming crab and prawn at different storage phases were conducted by headspace solid phase microextraction (HSSPME) followed by gas chromatography-mass spectrometry (GC-MS) detection. Then, seafood volatile profile characteristics at different storage phases were statistically interpreted by a combination data-processing method including normalization, principle component analysis (PCA) and common model strategy. The different seafood volatile profile characteristics and potential volatile markers were attempted to be distilled. The results tentatively suggested that the different seafood volatile profile characteristics during storage could reflect the transitional changing seafood freshness and provide more precise warning information for seafood spoilage during storage than any single chemical markers. This work developed an analytical method for study of seafood volatile profile characteristics and tentatively proposed a new idea of using seafood volatile profile characteristics during storage for the freshness evaluation from the point of view of analytical chemistry. © 2009 Elsevier B.V. All rights reserved. Source


Liu C.,Henan University of Technology | Teng Z.,South China University of Technology | Lu Q.-Y.,Henan University of Technology | Zhao R.-Y.,Henan University of Technology | And 3 more authors.
Food Research International | Year: 2011

The mechanism of soy protein fractionation was explored. A Focused Beam Reflectance Measurement (FBRM) technique was used to study the effects of Ca2+ and Mg2+ concentrations on the aggregation/precipitation processes of soy globulins. An electrophoretic technique was used to provide information about the electrical charge of the resulting individual protein precipitate. FBRM measurements demonstrated the presence of a two-step process for glycinin (around 90% purity) aggregation. First, in the absence of Ca2+ and Mg2+, about 9730 counts of the primary particles (~3.33μm) per second were formed immediately, with the pH being adjusted to 5.8 for glycinin precipitation. Second, more than 90% of the primary particles aggregated slowly within approximately 15min into larger secondary particles (~54.72μm). The addition of Ca2+ and Mg2+ significantly increased the amount of the primary aggregate of soy globulins and altered their aggregation process. However, the number of primary particles induced by Ca2+ was smaller than that by Mg2+. The aggregation kinetic pattern for soy globulins in the second precipitation step (mainly β-conglycinin) significantly differed from that of the first precipitation step (mainly glycinin) in the stability of secondary particles. Electrophoretic measurements showed that, as Ca2+ and Mg2+ concentrations were increased, the net ζ-potential of the glycinin-rich fractions decreased, and the reduced effect by using Ca2+ was greater than that by using Mg2+. The different influences on the ζ-potential for soy protein between Ca2+ and Mg2+ were probably due to their different influences on phytate precipitation, respectively. The combined effects of Ca2+ and Mg2+ and phytate led to the reduction in the ζ-potential and thus to colloidal stability for soy globulins, resulting in more protein precipitation. © 2011 Elsevier Ltd. Source


Liu C.,Henan University of Technology | Liu C.,South China University of Technology | Yang X.-Q.,South China University of Technology | Lin M.-G.,Henan University of Technology | And 4 more authors.
International Journal of Food Science and Technology | Year: 2011

The effect of pHs and heating on the protein-polysaccharide complexation between the 0.5wt% soy globulin (7S or 11S) and 0.1wt% chitosan was studied. Electrophoretic and light scattering techniques were used to examine the electrical charge and aggregation of the individual biopolymers and complexes. At pH 3.0-6.5, 7S (or 11S) globulin in the presence of chitosan had significantly higher ζ-potentials and lower particles size than 7S (or 11S) globulin alone did (e.g. 600-6000nm at pH 5.5), indicating the formation of complexes. After heating 7S (or 11S)-chitosan mixtures had higher positive value of ζ-potential. 7S (or 11S)-chitosan mixtures exhibited a significant increase in positive value of ζ-potential and stability after heating at lower pH values (pH 3.3 instead of pH 4.5). Compared with other mixtures, at pH 2.5-6.0, the most remarkable decrease in aggregation was obtained for 11S-chitosan mixtures after heating at pH 3.3. © 2011 The Authors. International Journal of Food Science and Technology © 2011 Institute of Food Science and Technology. Source


Tao X.,Guangdong Ocean University | Huang H.,Guangdong Ocean University | Liao J.,Zhanjiang Institute of Supervision and Test on Quality and Measure | Gao P.,Zhanjiang Institute of Supervision and Test on Quality and Measure | And 2 more authors.
Journal of Chinese Institute of Food Science and Technology | Year: 2014

A high performance liquid chromatography-tandem mass spectrometry method was developed for simultaneous determination of Chloramphenicol (CAP), Thiamphnicol (TAP), Florfenicol (FF) and Florfenicol amine (FFA) in shrimp muscle and pork. The samples were extracted with 2% basic ethyl acetate. Concentrated extracts were no liquid-liquid partition and solid phase extraction (SPE) procedure. The gradient elution solvent of methanol and 5 mmol/L ammonium acetate at a flow rate of 0.25 mL/min. Identification was achieved by electro spray ionization (ESI) in negative mode using selected reaction monitoring. The calibration curves were good linear between the peak areas and the concentrations of 0.1-20 μg/L, and the correlation coefficients (R2) were between 0.9997~0.9998. The average recoveries and relative standard deviations (RSDs) for the analysis of all samples fortified over the range of 1.00-5.00 μg/kg were in the range of 78.17%~99.86% and 2.18%-9.27%, respectively. The limit of detection of chloramphenicol, thiamphenicol, florfenicol and florfenicol amine were 0.001, 0.020, 0.002 μg/kg and 0.003 μg/kg. Source

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