| 摘要: |
| 以长牡蛎（Crassostrea gigas）为研究对象，采用酶活力测定和Western blotting鉴定牡蛎不同组织中氨肽酶、胰蛋白酶型丝氨酸蛋白酶、组织蛋白酶等几种主要蛋白酶的分布，探讨牡蛎肉在4℃冷藏过程中酶活力和鲜度指标的变化规律。结果显示：在牡蛎的外套膜、鳃、闭壳肌和性腺-内脏团四种组织中，亮氨酸氨肽酶、丙氨酸氨肽酶、精氨酸氨肽酶均有较高酶活力；胰蛋白酶型丝氨酸蛋白酶主要分布于性腺-内脏团，在另外三种组织中活性较低；组织蛋白酶B和B+L绝大部分在性腺-内脏团中表达。在4℃冷藏过程中，酶活力发生明显变化，经7 d冷藏后，性腺-内脏团中亮氨酸氨肽酶的酶活力为初始值的25.15%，丙氨酸氨肽酶的酶活力为初始值的31.65%，精氨酸氨肽酶的酶活力为初始值的23.19%；组织蛋白酶B和B+L的酶活力分别是初始值的2.59和4.23倍；胰蛋白酶型丝氨酸蛋白酶酶活力上升44%。随着冷藏时间的延长，牡蛎的鲜度指标发生变化：牡蛎pH值呈现先降低，9 d后上升的趋势；氨基酸态氮含量由初始的（0.26±0.05） g/100g增加至第7 d的（0.31±0.03） g/100g；挥发性盐基氮含量从（5.60±0.64）mg/100g上升至第7 d的（17.50±0.37）mg/100g；SDS-PAGE分析显示，牡蛎冷藏过程中四种组织的蛋白质均发生了不同程度的降解。本研究揭示了牡蛎在短期冷藏过程中几种主要蛋白酶和鲜度指标的变化规律，为牡蛎的冷藏保鲜提供了参考。 |
| 关键词: 长牡蛎 酶 冷藏 鲜度 蛋白质降解 |
| DOI：10.11693/hyhz20210100016 |
| 分类号:Q956;S984 |
| 基金项目:国家重点研发计划，2018YFD0901004号；财政部和农业农村部：国家现代农业产业技术体系资助。 |
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| DISTRIBUTION OF PROTEASES IN DIFFERENT TISSUES OF CRASSOSTREA GIGAS AND CHANGES OF ENZYME ACTIVITY AND FRESHNESS DURING COLD STORAGE |
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ZHANG Qian1,2,3, CHEN Hong1, QUE Hua-Yong2,3,4, LI Yu-Jin5, SUN Le-Chang1,2,3, WENG Ling1,2,3, ZHANG Ling-Jing1,2,3, LIU Guang-Ming1,2,3, CAO Min-Jie1,2,3
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1.College of Marine Food and Biological Engineering, Jimei University, Xiamen 361021, China;2.National &3.Local Joint Engineering Research Center of Processing Technology for Aquatic Products, Xiamen 361021, China;4.Fisheries College of Jimei University, Xiamen 361021, China;5.College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China
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| Abstract: |
| The distribution of several main enzymes in different tissues of Crassostrea gigas were identified by enzyme activity assay and the Western blotting. Enzyme (including aminopeptidase, trypsin-like serine proteinase, and cathepsins) activity variation and freshness index changes during cold storage at 4℃ were investigated. The results show that the activities of aminopeptidases (leucine aminopeptidase, alanine aminopeptidase, and arginine aminopeptidase) were high in the four tissues (mantle, gill, adductor muscle, and gonad-visceral mass). Trypsin-like serine protease was identified in mainly the gonad-visceral mass, with lower activity in other three tissues, while major activities of cathepsin B and B+L were detected in the gonad-visceral mass. During cold storage at 4℃, the protease activity changed significantly. After 7 days of cold storage, the enzyme activity of leucine aminopeptidase, alanine aminopeptidase, and arginine aminopeptidase in gonade-visceral mass was 25.15%, 31.65%, and 23.19%, respectively as compared to their initial activity. However, the activity of cathepsin B and L was 1.71 and 5.66 times that of the initial value, respectively. The activity of trypsin-like serine protease increased by 44%. During cold storage, the freshness index of oysters also changed. The pH value decreased till the 9th day and then increased. The content of amino nitrogen increased from (0.26±0.05) g/100g to (0.31±0.03) g/100g and that of volatile base nitrogen increased from (5.60±0.64) mg/100g to (17.50±0.37) mg/100g, respectively in 7 days. SDS-PAGE showed that the proteins in four different tissues all degraded to different extents during cold storage. This study revealed the variation rule of several main enzymes and freshness indexes of oysters in the short-term cold storage, providing a reference for the preservation of oysters. |
| Key words: Crassostrea gigas enzyme cold storage freshness protein degradation |
