College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China; National Engineering Research Center for Fruits and Vegetables Processing, Beijing 100083, China; Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture, Beijing 100083, China.
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China; National Engineering Research Center for Fruits and Vegetables Processing, Beijing 100083, China; Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture, Beijing 100083, China.
Int J Biol Macromol. 2018 Jul 15;114:1056-1063. doi: 10.1016/j.ijbiomac.2018.03.145. Epub 2018 Apr 4.
This study determined the optimal conditions for ultrasound-assisted extraction of a water-soluble polysaccharide, Raw Okra Polysaccharide, from the fruit of okra using response surface methodology. The optimal extraction temperature, extraction time and ultrasonic power were 59°C, 30min and 522W, respectively, giving a yield of 10.35±0.11%. ROP was further isolated, lyophilized and purified using a DEAE-Sepharose Fast Flow column and Sepharose CL-6B column, revealing three elution peaks subsequently designated ROP -1, -2, and -3, respectively. Of these, ROP-2 showed the highest yield, and was therefore selected for physicochemical analysis and evaluation of antioxidant activity. Gas chromatography, fourier transform infrared spectroscopy, and high-performance liquid chromatography were used to characterize the primary structural features and molecular weight, revealing that ROP-2 is composed of glucose, mannose, galactose, arabinose, xylose, fructose, and rhamnose (molar percentages: 28.8, 12.5, 13.1, 15.9, 9.2, 13.7, and 6.8%, respectively) and has an average molecular weight of 1.92×105Da. A superoxide radical scavenging assay and DPPH radical scavenging assay further revealed the significant in vitro antioxidant activity of ROP-2. These findings present an effective technique for extraction of the natural antioxidant ROP-2, warranting further analysis of its potential application in the food industry.
本研究采用响应面法确定了从黄蜀葵花果实中超声辅助提取水溶性多糖——生蜀葵花多糖的最佳条件。最佳提取温度、提取时间和超声功率分别为 59°C、30min 和 522W，得率为 10.35±0.11%。ROP 进一步通过 DEAE-Sepharose Fast Flow 柱和 Sepharose CL-6B 柱分离、冻干和纯化，随后分别命名为 ROP-1、-2 和 -3，三个洗脱峰。其中，ROP-2 产率最高，因此选择对其进行理化分析和抗氧化活性评价。气相色谱、傅里叶变换红外光谱和高效液相色谱用于表征其一级结构特征和分子量，结果表明 ROP-2 由葡萄糖、甘露糖、半乳糖、阿拉伯糖、木糖、果糖和鼠李糖（摩尔百分比分别为 28.8%、12.5%、13.1%、15.9%、9.2%、13.7%和 6.8%）组成，平均分子量为 1.92×105Da。超氧自由基清除试验和 DPPH 自由基清除试验进一步揭示了 ROP-2 的体外抗氧化活性。这些发现为提取天然抗氧化剂 ROP-2 提供了一种有效技术，值得进一步分析其在食品工业中的潜在应用。
