1. Functional properties of gonad protein isolates from three species of sea urchin: a comparative study
- Author
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Yunsheng Xu, Hai-Tao Wu, Jia-Run Han, Xiao-Fan Cui, Changfeng Xue, Tie-Tao Zhang, Yi-Nan Du, Jia-Nan Yan, Sheng-Yi Su, Wen-Hui Shang, and Beiwei Zhu
- Subjects
Gonad ,030309 nutrition & dietetics ,03 medical and health sciences ,chemistry.chemical_compound ,0404 agricultural biotechnology ,biology.animal ,medicine ,Animals ,Denaturation (biochemistry) ,Food science ,Sodium dodecyl sulfate ,Gonads ,Polyacrylamide gel electrophoresis ,Sea urchin ,Essential amino acid ,Strongylocentrotus ,chemistry.chemical_classification ,0303 health sciences ,biology ,urogenital system ,Proteins ,04 agricultural and veterinary sciences ,040401 food science ,Amino acid ,Isoelectric point ,medicine.anatomical_structure ,chemistry ,Sea Urchins ,Food Science - Abstract
Sea urchin Mesocentrotus nudus, Glyptocidaris crenularis, and Strongylocentrotus intermedius gonad protein isolates (mnGPIs, gcGPIs, and siGPIs) were extracted by isoelectric solubilization/precipitation (ISP) from the defatted gonads, and their functional properties were compared. Sodium dodecyl sulfate polyacrylamide gel electrophoresis results showed the similar protein pattern between each protein isolate and defatted gonad, indicating the high efficiency of ISP processing for protein recovery. Amino acid profileconfirmed that the mnGPIs and siGPIs could be potential sources of essential amino acid in nature. As regard to functional properties, mnGPIs showed higher water- and oil- holding capacities followed bysiGPIs and gcGPIs and all protein isolates presented great foaming property. As for emulsifying activity index (EAI), mnGPIs, gcGPIs, and siGPIs showed the minimum solubility and EAI at pH 5, 3, and 4, respectively, and behaved a pH-dependent manner. The gcGPIs revealed the highest EAI from pH 6 to 8 among the samples. In addition, circular dichroism showed increased content of β-sheet at the expense of α-helix and β-turn, suggesting the structure denaturation of the protein isolates. Indeed, no statistical difference was observed between secondary structure of mnGPIs and siGPIs. Moreover, ISP processing increased free sulfhydryl content of sea urchin protein isolates, but no difference was observed among the samples. Furthermore, siGPIs revealed the highest amount of total sulfhydryl and disulfide bonds, whereas both defatted gonads and protein isolates from G. crenularis presented the maximum surface hydrophobicity. These results suggest that gonad protein isolates from three species of sea urchin possess various functionalities and therefore can be potentially applied in food system. PRACTICAL APPLICATION: Sea urchin M. nudus, G. crenularis, and S. intermedius gonads are edible, whereas the functional properties of protein isolates from sea urchin gonad remain unknown. In this case, the extraction and comparison of three species of sea urchin gonad protein isolates will not only confirm functional properties but also screen food ingredients with suitable functions. In this study, functionalities of protein isolates derived from M. nudus, G. crenularis, and S. intermedius gonads would provide potential application in bakery food and meat products or as emulsifier candidates in food system.
- Published
- 2020