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

Petra Kavalcová,Jolana Karovičová,Veronika Kuchtová,Ján Tomáš,Judita Bystrická

doi:10.5219/394

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%).

Highlights

Vegetables are important components in the human diet and protect against many diseases of civilization especially cardiovascular diseases, high blood pressure, stroke, neurodegeneration, cancer, obesity and diabetes
Garlics and leeks are an essential part of the human diet and they are of considerable interest due to their antioxidant properties
The total content of polyphenolic compounds contained in onion, garlic and leek are quite variable, may be affected by post-harvest and climatic conditions

Summary

Introduction

Vegetables are important components in the human diet and protect against many diseases of civilization especially cardiovascular diseases, high blood pressure, stroke, neurodegeneration, cancer, obesity and diabetes. Garlics and leeks are an essential part of the human diet and they are of considerable interest due to their antioxidant properties. The total content of polyphenolic compounds contained in onion, garlic and leek are quite variable, may be affected by post-harvest and climatic conditions. In this work the content of total polyphenols in onion, garlic and leek was watched and evaluated.

Results

Conclusion