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Miao X.-D.,Shanghai Ocean University | Liu Y.,Shanghai Ocean University | Ma L.,Shanghai Ocean University | Li L.,Shanghai Ocean University | And 3 more authors.
Modern Food Science and Technology | Year: 2015

Previous studies conducted on the taste of obscure pufferfish have mainly focused on content of free amino acids, inorganic ions, nucleotides and other related compounds, but the peptides contributing to the flavor as well as the sensation of mellow, creamy taste has rarely been studied. Therefore, the enzymatic extraction of flavor peptides responsible for prominent taste characteristics of obscure pufferfish has significant research and economic value for the food industry. Cultured obscure pufferfish muscle was used as to extract flavor peptides using neutral protease, flavorzyme, proteolytic enzyme, and protamex. A method combining the degree of hydrolysis (DH), oligopeptide content, taste sensor outputs from an electronic tongue, and sensory evaluation was used to identify the optimal enzyme and hydrolysis conditions. The results indicated that the DH of hydrolysates from flavorzyme and oligopeptide content of the hydrolysates from proteolytic enzyme showed the highest values. Electronic tongue could clearly differentiate different hydrolysates and correlated with the results from sensory evaluation to some extent. However, there were some differences between the relative intensities of umami, saltiness, and sourness between theresults from electronic tongue and sensory evaluation. Finally, neutral protease was identified as the optimum protease for the enzymatic hydrolysis to produce flavor peptides from cultured obscure pufferfish muscle. ©, 2015, South China University of Technology. All right reserved.

Ni Y.,Jiangnan University | Wen L.,Jiangnan University | Wang L.,Jiangnan University | Dang Y.,Institute of Health Food of Zhejiang Academy of Medical science | And 3 more authors.
International Dairy Journal | Year: 2015

Protein aggregation occurs in biological systems and industrial processes, affecting protein solubility and functional properties. In this study, whey protein isolate (WPI) obtained from bovine milk was used as a model to study the dependence of aggregation on pre-heating temperature and on protein and calcium concentrations. WPI solutions (0.1-5.0%, w/v) were heated at 25-85°C for 30min prior to cooling and calcium addition. Tryptophan shifted to a more hydrophilic environment as WPI concentrations and pre-heating temperatures increased. Pre-heated WPI solutions yielded soluble particles, which aggregated to form porous gel-like particles by addition of calcium chloride. WPI microgel particles could be prepared by using a cold gelation method and preheated the protein above 65°C. The particle size was monodisperse with sizes of about 190nm and 255nm, respectively in solutions pre-heated to 75 or 85°C and containing 5m. m calcium. © 2015 Elsevier Ltd.

Dang Y.,Institute of Health Food of Zhejiang Academy of Medical science | Gao X.,ACEA Inc | Ma F.,Liaoning University of Traditional Chinese Medicine | Wu X.,Institute of Health Food of Zhejiang Academy of Medical science
LWT - Food Science and Technology | Year: 2015

Peptides are critical to the taste of dry-cured ham. To isolate and identify umami peptide fractions from the water-soluble extractions (WSEs) of Jinhua and Parma hams, separation procedures utilizing Sephadex G-25 and reversed-phase high-performance liquid chromatography (RP-HPLC) were combined with sensory evaluations (taste dilution analysis and an electronic tongue). The amino acid sequences of the umami peptides, Cys-Cys-Asn-Lys-Ser-Val (CCNKSV) from Jinhua ham and Ala-His-Ser-Val-Arg-Phe-Tyr (AHSVRFY) from Parma ham, were identified by MALDI-TOF-MS; subsequently, both were synthesized, and their umami taste properties were evaluated. The results indicate that the tastes of the umami peptides were similar to those of the hams' WSEs. © 2014 Elsevier Ltd.

Dang Y.,Institute of Health Food of Zhejiang Academy of Medical science | Gao X.,ACEA Inc | Xie A.,Southwest University | Wu X.,Institute of Health Food of Zhejiang Academy of Medical science | Ma F.,Liaoning University of Traditional Chinese Medicine
Cell Biochemistry and Biophysics | Year: 2014

The umami taste receptor is a heterodimer composed of two members of the T1R taste receptor family: T1R1 and T1R3. The homology models of the ligand binding domains of the human umami receptor have been constructed based on crystallographic structures of the taste receptor of the central nervous system. Furthermore, the molecular simulations of the ligand binding domain show that the likely conformation was that T1R1 protein exists in the closed conformation, and T1R3 in the open conformation in the heterodimer. The molecular docking study of T1R1 and T1R3 in complex with four peptides, including Lys–Gly–Asp–Glu–Ser–Leu–Leu–Ala, Ser–Glu–Glu, G1u–Ser, and Asp–Glu–Ser, displayed that the amino acid residue of SER146 and Glu277 in T1R3 may play great roles in the synergism of umami taste. This docking result further validated the robustness of the model. In the paper, binding of umami peptide and the T1R1/T1R3 receptor was first described and the interaction is the base of umami activity theory. © 2014, Springer Science+Business Media New York.

Fugang X.,Xuchang University | Juntao S.,Xuchang University | Deguo W.,Xuchang University | Yali D.,Institute of Health Food of Zhejiang Academy of Medical science | Songming L.,Sichuan Agricultural University
Analytical Methods | Year: 2014

An immuno-antigen of nodularin was prepared, and then a polyclonal antibody against nodularin was obtained from Japanese white rabbits immunized with the immuno-antigen. Immunoaffinity cartridges were prepared using CNBr-activated Sepharose 4B and the polyclonal antibody against nodularin and their coupling rate ranged from 77.5% to 90.2%. The cartridge load for nodularin and the recovery ranged from 70 ng to 98 ng and 71.8% to 97.2%, respectively. A method for trace level analysis of nodularin in water using the immunoaffinity cartridge and HPLC was established, its detection limit was 3 ng L-1 and the linear range was from 10 to 500 ng L-1. © the Partner Organisations 2014.

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