鲜切洋葱贮藏期间多酚成分及抗氧化活性的变化

CHANGES OF POLYPHENOLIC COMPOUNDS AND ANTIOXIDANT ACTIVITY OF FRESH-CUT ONIONS DURING STORAGE

目的以鲜切洋葱为对象,研究其低温贮藏期间多酚成分和抗氧化活性的变化以及二者之间的相关性。方法采用HPLC法检测鲜切洋葱多酚组分含量,通过铁还原能力、ABTS自由基和DPPH自由基清除能力三种方法评价鲜切洋葱的抗氧化活性。结果鲜切洋葱中单体酚含量较多的为槲皮素、绿原酸和香豆酸,随着贮藏时间的延长,鲜切洋葱的总酚、槲皮素、香草酸和阿魏酸的含量呈先上升后下降的趋势,香豆酸含量则先下降后上升,咖啡酸的含量呈波浪式变化,而绿原酸无显著变化(P>0.05)。贮藏期间鲜切洋葱的铁还原能力呈现先升高后降低的变化趋势,ABTS自由基和DPPH自由基清除能力在最初1 d内显著升高(P<0.05),贮藏至第7 d时有小幅下降,随后呈现先上升又下降的变化。相关性分析表明香草酸、槲皮素和咖啡酸为主要活性单体酚。结论鲜切洋葱低温贮藏期间具有较高的抗氧化活性,其抗氧化活性与多酚含量呈正相关。

Objective Changes of polyphenolic compounds, antioxidant activity of fresh-cut onions were investigated during the storage. Methods High-performance liquid chromatography （HPLC） was used to quantify the contents of polyphenolic compounds and three assays were used to determine the antioxidant activity, including ferric reducing power, 2,2-azinobis （3-ethyl-benzothiazoline-6-sulfonic acid） （ABTS） radical scavenging activity, and 1,1-diphenyl-2- picrylhydrazyl （DPPH） radical scavenging activity. Results The main phenolic compounds in fresh-cut onions were quercetin, chlorogenic acid and coumaric acid. During the storage, total phenolic, quercetin, vanillic acid and ferulic acid contents increased at first and then decreased, while the changing trend of coumaric acid content was just on the opposite. Caffeic acid content varied greatly and chlorogenic acid content remained constant throughout storage. The ferric reducing power of fresh-cut onions increased at first and then decreased during the storage. The ABTS radical and DPPH radical scavenging activities increased at the first day of storage and followed by a progressive increase and then a decrease were observed at day 7. Correlation analysis revealed that the contents of vanillic acid, quercetin and caffeic acid were well correlated with the antioxidant activity of fresh-cut onions. Conclusion Fresh-cut onions exhibit strong antioxidant activity during the storage and there is a significant correlation between antioxidant activity and the contents of polyphenolic compounds. [ACTA NUTRIMENTA SINICA, 2016, 38（6）： 596-6001