不同烹饪加工豇豆在冷藏过程中亚硝酸盐含量及抗氧化性能的变化

Changes in nitrite contents and antioxidant properties of cowpeas processed by different cooking methods during refrigerated storage

研究了水煮、蒸和油炸3种烹饪加工豇豆在4℃冷藏过程中亚硝酸盐含量及抗氧化性能的变化。采用福林酚法和TEAC法分别测定了不同烹饪加工豇豆提取物的多酚含量和抗氧化能力。结果表明:烹饪加工豇豆的亚硝酸盐含量显著高于新鲜豇豆;在冷藏过程中亚硝酸盐含量均先升后降,在贮藏第3天时,含量最高。在整个贮藏过程中,水煮豇豆的亚硝酸盐含量均显著高于其他组的。豇豆经烹饪加工后,其游离酚含量显著下降,其中油炸豇豆下降最显著,蒸豇豆下降最少。经蒸和油炸后豇豆的结合酚含量显著增加,其中油炸后增加的量更多,而水煮后结合酚含量则显著下降。随着贮藏时间的延长,不同烹饪加工豇豆的游离酚含量均显示出先增加后下降的趋势,而结合酚含量则显著下降。总抗氧化能力与多酚含量变化趋势比较相似,它们之间存在高度相关性。

Changes in nitrite contents and antioxidant properties of cowpeas processed by three cooking methods （boiling, steaming and frying） during 4 ℃ storage were investigated. The polyphenol content and antioxidant activity of extracts from different treated cowpeas were determined by Folin Ciocalteu assay and TEAC assay, respectively. Results showed that the different cooked cowpeas had significantly higher nitrite contents than the raw cowpeas. The nitrite contents in all the samples increased at first and then decreased during storage, with the highest contents being obtained at 3 days of storage. The boiled cowpeas had significantly higher nitrite content than the other processed cowpeas throughout the storage. The free phenolics content was significantly decreased in cooking processedeowpeas. Steamed cowpea showed the highest phenolics content, whereas fried cowpea had the lowest. Increases in bound phenolics content were observed after steaming and frying, whereas a decease was noted after boiling. During storage, the free phetlofics content in cooked cowpeas increased at first and then decreased with the exten- sion of storage time, while the bound phenolics content significantly reduced. Similar trend was observed in total antioxidant activity. A high correlation was observed between the total antioxidant activity and the polyphenol content.