Abstract

COMPARISON OF ANTIOXIDANT ACTIVITY AND PHENOLIC CONTENT OF GARLIC, LEEK AND ONION VEGETABLES IN DIFFERENT COOKING METHODS

*Mirzaei Ali, Mirzaei Nooshin

Abstract

Epidemiological studies have shown consumption of vegetables and fruits were related with reduced risks of several age-related and degenerative human disease, cardiovascular and cancers. Among the widely consumed vegetables garlic (Allium satium L.), leek (Allium porrum .) and onions (Allium cepa L are important medicines to the ancient Iranian. Material and Methods: The vegetable samples (2.5 kg) were collected and five portions (500 g each) were prepared. One portion was kept raw as control stored at 4 ◦C in the fridge and others were subjected for four thermally treatments such as boiling, Pressurecooking, Microwave cooking and frying. Raw and cooked vegetables were analyzed by different antioxidant activity such as diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) methods and total phenol contents. All data were expressed as means ± standard deviation .For statistics analysis samples one-way analysis of variance (ANOVA) was applied.Results: The total phenolics content of onion samples was insignificantly reduced after cooking procedures . However significant reductions in leek and garlic were reported. In total phenol procedure the highest losses were reported by leek in boiling method .Leek showed highest scavenging activity (32.7 μM TE/g) whereas onion had lowest activity with 21 μM TE/g by DPPH assay .According to result of the TEAC radical scavenging activity the highest losses were reported in garlic in boiling method. The boiling cooking method in all assays was reported with maximum of % losses. Conclusion: Among spice vegetables tested, garlic had the highest phenolic contents and antioxidant activity. All antioxidant activities decrease in the vegetables except leek in thermal treatments by different methods.

Keywords: Garlic, Leek, Onion, Antioxidant Activity, cooking methods