为比较几种典型番薯品种的多酚含量及抗氧化活性，以冷冻丙酮和NaOH-乙酸乙酯分别提取番薯皮及番薯肉中游离态酚和结合态酚，并采用Folin-Ciocalteu比色法，亚硝酸钠-硝酸铝-氢氧化钠比色法分别测定提取物中多酚和黄酮的含量，以氧自由基吸收能力（ORAC）指征其抗氧化活性。发现番薯皮中总多酚、总黄酮含量及ORAC值均高于相应品种的番薯肉；而在不同品种中，以紫皮紫心番薯中皮、肉中总酚含量最高，分别为（336.87±2.83）?10-2和（121.79±1.68）?10-2 mg GAE/g；紫皮紫心番薯皮ORAC值为（6917.79±672.70）?10-2 μmol TE/g，高于其他品种，但不同品种薯肉ORAC值无显著性差异。探究了不同加热条件对紫皮紫心薯肉中多酚、黄酮和ORAC值的影响，与未经加热的生薯肉相比，100 ℃下加热30 min能使其提取物中多酚、黄酮和ORAC值分别提高2倍、2.6倍及5.7倍，表明热加工有利于提高番薯中多酚类物质的释放，提高其抗氧化活性。

To compare the phenolic contents and antioxidant activities of extracts from different sweet potato cultivars, cold acetone, and sodium hydroxide-ethyl acetate were used to extract the free and bound phenolics from sweet potato skin and flesh, respectively. Folin-Ciocalteu assay and the sodium nitrite-aluminum nitrate-sodium hydroxide colorimetric method were applied to measure the phenolic and flavonoid content, and the antioxidant activities were evaluated by the oxygen radical absorbance capacity (ORAC) method. It was found that total phenolic and total flavonoid content of peels were higher than those of corresponding flesh. Among different cultivars, the purple skin-purple flesh (PP) sweet potato had the highest phenolic content of （336.87±2.83）?10-2 and （121.79±1.68）?10-2 mg GAE/g in skin and flesh, respectively. The ORAC value of PP skin extract was the highest at （6917.79±672.70）?10-2 μmol TE/g, while the ORAC values of flesh extracts from different cultivars showed no significant difference. The effects of heat treatment on the phenolic and total flavonoid content and the ORAC value of PP flesh were also investigated. The phenolic content, flavonoid content, and ORAC values of samples heated at 100 ℃ for 30 min were 2-fold, 2.6-fold, and 5.7-fold higher than those of the unprocessed sweet potato, respectively, indicating that heat treatment could favor the release of phenolic compounds in sweet potatoes and enhance their antioxidant activities.

广东省科技计划项目（2013B090600129，2014A010107007）；广州市科技计划项目（2012J5100024）