贮藏温度对潍县萝卜肉质根抗氧化能力的影响

Effects of storage temperature on antioxidant capacity of Weixian radish taproots

【目的】明确不同贮藏温度下潍县萝卜肉质根中H_(2)O_(2)含量、O_(2)^(-·)产生速率、抗氧化能力及各抗氧化成分的变化规律,探讨萝卜肉质根抗氧化能力的关键影响指标。【方法】以潍县萝卜为试材,研究常温(15℃)和低温(4℃)贮藏40 d,潍县萝卜肉质根皮和肉中的H_(2)O_(2)含量、O_(2)^(-·)产生速率、抗氧化成分(抗坏血酸(AsA)、谷胱甘肽(GSH)、类黄酮、总酚、叶绿素、类胡萝卜素、花青素、原花青素)含量、抗氧化酶(超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸氧化酶(AAO)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、脱氢抗坏血还原酶(DHAR)、单脱氢抗坏血酸还原酶(MDHAR))活性及抗氧化能力的变化,并分析潍县萝卜肉质根H_(2)O_(2)含量、O_(2)^(-·)产生速率及抗氧化能力与各抗氧化成分间的相关性。【结果】随着贮藏时间的延长,潍县萝卜肉质根皮和肉中的H_(2)O_(2)含量和O_(2)^(-·)产生速率整体上均呈先升高后下降再升高的变化趋势;抗氧化能力则正好相反,整体上呈先下降后升高的变化趋势;抗氧化成分的变化趋势则因物质种类、贮藏温度和皮肉部位的不同而存在显著差异。不同贮藏方式下,低温贮藏萝卜肉质根皮和肉中的H_(2)O_(2)含量、O_(2)^(-·)产生速率及AAO活性显著低于常温贮藏,其他抗氧化成分及抗氧化能力显著高于常温贮藏;相同贮藏方式下,潍县萝卜肉质根皮中的H_(2)O_(2)含量、O_(2)^(-·)产生速率及AAO活性显著低于萝卜肉,其他抗氧化成分及抗氧化能力则显著高于萝卜肉。相关分析表明,潍县萝卜肉质根H_(2)O_(2)含量、O_(2)^(-·)产生速率及抗氧化能力与AsA、花青素含量及POD、APX、AAO活性间均分别存在显著或极显著的相关关系。【结论】低温能够有效延长萝卜的贮藏期;与萝卜肉质根的皮相比,肉质根肉中的活性氧积累更多,抗氧化成分损失更快,更不耐贮藏;AsA、花青素含量及POD、APX、AAO活性能较为准确地反映萝卜肉质根的抗氧化能力,可作为判断萝卜肉质根抗氧化能力的便捷指标。

【Objective】This study aimed to assess changes of H_(2)O_(2) content,O_(2)^(-·) production rate as well as antioxidant capacity and components in Weixian radish taproots under different storage temperatures and determine key indicators affecting antioxidant capacity in radish taproots.【Method】Fresh Weixian radish taproots were stored at room temperature(15℃)and low temperature(4℃)for 40 d,and skin and flesh tissues were sampled with ten-day interval.Antioxidant capacity,contents of H_(2)O_(2) and O_(2)^(-·) production rate,AsA,GSH,flavonoids,total phenols,chlorophyll,carotenoids,anthocyanins,and procyanidins were assessed,and activities of eight antioxidant enzymes including SOD,POD,CAT,AAO,APX,GR,DHAR and MDHAR were measured.Correlation analysis was also used to determine relationships between H_(2)O_(2) content,O_(2)^(-·) production rate and antioxidant capacity with antioxidant components.【Result】With the extension of storage time,H_(2)O_(2) content and O_(2)^(-·)production rate in skin and flesh of Weixian radish taproots showed a trend of increasing,decreasing and increasing in sequence.Antioxidant capacity presented a decreasing trend from 0 d to 20 d,followed by an increasing trend from 20 d to 40 d.The change trends of antioxidant components were significantly different due to substance types,radish parts and storage conditions.H_(2)O_(2) content,O_(2)^(-·) production rate and AAO activity at 4℃were significantly lower than those at 15℃.On the contrary,other antioxidant substances,enzyme activity and antioxidant capacity were at low temperature(4℃)compared to room temperature(15℃).H_(2)O_(2) content,O_(2)^(-·) production rate and AAO activity were significantly lower in skin than in flesh under same storage condition,while other indicators exhibited opposite trends.Correlation analysis showed that H_(2)O_(2) content,O_(2)^(-·) production rate and antioxidant capacity had significant or extremely significant correlations with AsA,anthocyanins,POD,APX and AAO.【Conclusion】Low temperature could effectively extend storage period of radish.Compared with skin,radish flesh had more accumulations of active oxygen and faster loss of antioxidant components,resulting in quick decay during storage.Contents of AsA and anthocyanin and activities of POD,APX and AAO could be used as convenient indicators for antioxidant capacity of radish taproots.