Evaluation and comparison of the content of total polyphenols and antioxidant activity in onion, garlic and leek

Abstract

Onion, leek and garlic as onion family are a great source of freely available health-promoting and chemoprotective compounds (polyphenols, flavonoids, fructooligosaccharides, thiosulfinates and other sulfur compounds, vitamins). Chemoprotective compounds belong between natural components. Onion, garlic and leek have high nutritional value. They are an important component of our human diet and we used them as a preventive factor for many diseases of civilization (cancer, coronary heart diseases, and atherosclerosis). In this work we watched and evaluated content of total polyphenols and antioxidant activity in onion, garlic and leek. Samples of plant material (onion, garlic and leek) we collected at the stage of full maturity in the area of Pružina. Pružina is area without negative influences and emission sources. Samples of fresh onion, garlic and leek were homogenized and were prepared an extract: 25 g cut onion, garlic and leek extracted by 50 ml 80% ethanol accourding sixteen hours. These extracts were used for analyses. The content of the total polyphenols was determined by using the Folin-Ciocalteu reagent (FCR). Antioxidant activity was measured by using a compound DPPH (2.2-diphenyl-1-picrylhydrazyl). In the present experiment it was detected, that total polyphenols content in samples ranges from 210.67 mg/kg (leek) - 429.58 mg/kg (onion). Statistically significant highest value of total polyphenols was recorded in onion (389.64 to 429.58 mg/kg). Statistically significant the lowest content of total polyphenols was recorded in leek (210.67 - 254.80 mg/kg). Another indicator that has been evaluated and compared was the antioxidant activity of onion, garlic and leek. Statistically significant highest value of antioxidant activity was recorded in onion (20.22 - 25.76%). Statistically significant the lowest value of antioxidant activity was recorded in garlic (4.05 - 5.07%). Based on the measured values of AOA in onion, garlic and leek samples can be classified as follows: onion (20.22 - 25.76%) > leek (8.55 - 12.92%) > garlic (4.05 - 5.07%).

Keywords

• onion
• garlic
• leek
• total polyphenols
• antioxidant activity