Changes in total phenolic and flavonoid contents and antioxidant activities of the fruit from Elaeagnus angustifolia during an 80-day study period
In the paper, we found the total phenolic (TP) of the fruit from Elaeagnus angustifolia increased from 12.65% on July 26 to 15.20% on August 16, which was followed by a gradual downward trend. After September 26, the TP had only slight increasing. The change in total flavonoid (TF) exhibited the same trend during entire study period. Moreover, the antioxidant activities of the fruit was gradually reduced during the tested early period, after September 26, the antioxidant activities began to slowly increase. In addition, strong correlations were observed between the content of TP and TF and antioxidant capacity. The observations also demonstrated that the suitable harvest time of the fruit is during the first 10 days of October.
Antioxidants are compounds that inhibit chemical reactions with oxygen. These reactions, which occur in many contexts, include oxidation reactions that cause cell damage in humans and other animals, as well as degradation of fatty foods, resulting in undesirable color changes or rancidity. Antioxidants are widely used in the food industry as potential inhibitors of lipid peroxidation. However, recently, many synthetic antioxidants are used in foods, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT). Their application has been restricted because these synthetic antioxidants possess some side effects and toxic properties to human health (1). Therefore, there has been a great interest in finding natural antioxidants from plant materials to replace synthetic ones.
The antioxidative effect of plants is mainly attributed to phenolic components, such as flavonoids, phenolic acids and phenolic diterpens. Flavonoids, exceeding four thousand in number, are phenolic compounds that are ubiquitous in nature and are categorized, according to chemical structure, into flavonols, flavones, flavanones, isoflavones, catechins, ant ...