DETERMINING SECONDARY METABOLITES AND THEIR ANTI-OXIDANT ACTIVITY IN FRUITS
The influence of extraction techniques with different solvents on the contents of total phenols, flavonoids and antioxidant activity of extracts of grape, sour cherry and black currant is analyzed in the study. Antioxidant activity of the extracts on stable 1,1-diphenyl-2-picryl hidrazyl (DPPH) radical was determined by spectrophotometry. The total phenolic content was determined by using the Folin-Ciocalteu assay while total flavonoid content was measured spectrophotometrically with the application of AlCl3. The changes in the value of these parameters after deep-freezing of these fruits were also observed.
A high content of total phenols and flavonoids was detected in extracts. Acetone proved to be the best agent for extraction of grape and sour cherry while the highest content of total phenols with black currant was obtained by methanol. The content of total phenols in fruits in frozen state increased while the content of total flavonoids and of antioxidant activity decreased. The obtained results show that the extracts of grape, cherry and black currant can be used as natural antioxidants.
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