林塬 吴毓炜 王焱 吉哲蓉 乐学义

摘  要：为了更好地了解市售椰浆中椰子蛋白质量状况，本研究以市售的10种椰浆为样品，采用反向高效液相色谱（reversed-phase high performance liquid chromatography，RP-HPLC）及十二烷基磺酸钠-聚丙烯酰胺凝胶电泳（sodium laurylsulfonate-polyacrylamide gel electrophoresis，SDS-PAGE）对提取蛋白进行分析，采用基质辅助激光解吸电离飞行时间串联质谱（matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry，MALDI-TOF/TOF-MS）对蛋白进行鉴定。结果表明：椰浆RP-HPLC约在10.4 min和11.9 min分别出现1个色谱峰，大多数样品峰面积大小都与蛋白标签含量一致，SDS-PAGE条带数量和颜色的深浅与RP-HPLC得到的峰面积结果一致，个别样品标签含量高，SDS-PAGE能分离出的蛋白条带数量也较多，但RP-HPLC的椰子蛋白峰面积小，经MALDI-TOF/TOF-MS鉴定，部分条带没有鉴定出椰子有关的肽段或蛋白。研究结果为椰浆蛋白的食品安全与质量控制提供了方法参考和示范。

关键词：椰浆;蛋白分析;鉴定;RP-HPLC;SDS-PAGE;MALDI-TOF/TOF-MS

中图分类号：S667.4      文献标识码：A

Extraction， Isolation and Identification of Coconut Protein from Coconut Milk

LIN Yuan1， 2， WU Yuwei2， WANG Yan2， JI Zherong2， LE Xueyi1*

1. Department of Applied Chemistry， South China Agricultural University， Guangzhou， Guangdong 510642， China; 2. Products Quality Supervision and Testing Institute of Hainan Province / National Quality Supervision and Inspection Center for Tropical Agriculture Products， Haikou， Hainan 570203， China

Abstract： In order to better understand the quality of coconut protein in commercially available coconut milk， 10 types of coconut milk were used as the samples bought from the market. Reversed-phase high performance liquid chromatography （RP-HPLC） and sodium laurylsulfonate-polyacrylamide gel electrophoresis （SDS-PAGE） were used to analyze the extracted proteins， identified through matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry （MALDI-TOF/TOF-MS）. There were two peaks in RP-HPLC of coconut milk at 10.4 min and 11.9 min， the peak area of most samples were consistent with the protein label content. The number of SDS-PAGE bands and intensity were consistent with the peak area results obtained by RP-HPLC. Some samples had high label content， and SDS-PAGE could separate more protein bands， but the peak area of coconut protein from RP-HPLC was small. The protein bands were identified with MALDI-TOF/TOF-MS and no coconut-related peptides or proteins were identified. This method could be used for the isolation and identification of coconut protein in coconut milk.

Keywords： coconut milk; protein analysis; identification; RP-HPLC; SDS-PAGE; MALDI-TOF/TOF-MS

DOI： 10.3969/j.issn.1000-2561.2021.04.029

椰子（Cocos nucifera L.）是棕櫚科（Palmae）椰子属（Cocos）植物[1]，是世界上重要的果树之一[2]。椰肉富含蛋白，易于被人体吸收，有较好的保健效果，如具有抗糖尿病活性[3]、抗氧化活性[4]和降低血脂[5]等作用，近年来引起了人们的兴趣[6]。椰子肉中蛋白质的种类包括球蛋白、谷蛋白、白蛋白和醇溶蛋白等[7]。椰子全身是宝，但其可食部分比例较小、加工麻烦，不宜直接将其作为生产原料。椰子果肉被加工成纯椰浆，在保持其营养物质和天然风味的同时解决了运输麻烦的问题，降低贮存费用，便于广泛使用。

椰浆目前的研究主要集中在挥发性风味成分及脂肪酸的类型和含量[8]、浓缩方法（常压、真空）对椰浆各指标的影响[9]、真空浓缩椰浆的护色工艺[10]和真空浓缩椰浆形成稳定乳状液的乳化剂配比[11]等。……