EFFECT OF GAMMA RADIATION ON PHYTOCHEMICAL COMPOUNDS IN FABA BEAN (Vicia faba L.)

Abstract

The objective of the present study was to investigate the effect of gamma radiationon phytochemical compounds in faba bean. Samples of faba bean seeds were exposed to gammaradiation at doses of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 kGy. Then the contents of total phenolic andflavonoid compounds in non-irradiated and irradiated samples were determined. The contents of totalphenolic compounds in samples of non-irradiated faba bean was found to be 220.55 ± 0.040 μg gallicacid equivalent/g dry matter, while the total flavonoids in non-irradiated samples were found to be106.33 ± 0.450 μg quercetin equivalent/g dry matter. Exposing faba bean seeds to ascending doses ofgamma irradiation induced significant gradual increases in the contents of total phenolic and flavonoidcontents. The maximum increases were observed in samples irradiated at dose of 9 kGy showingincrease by about 183% and 283% in phenolic and flavonoid contents, respectively. Based on theseresults, phenolic and flavonoid compounds in the ethanolic extracts of non- irradiated faba bean seedsand those irradiated at dose of 9 kGy were fractionated and quantified by High Performance LiquidChromatography (HPLC). The results showed that 21 phenolic and 14 flavonoid compounds couldbe separated and quantified from the extract of non-irradiated faba bean seeds by HPLC. The samecompounds were identified in the extract of seeds irradiated at 9 kGy dose but at increasedconcentrations. The effect of gamma irradiation on the contents of macronutrients in seeds as well astheir water absorption properties was also determined. Significant differences were observed in theproximate chemical composition between samples of non-irradiated faba beans and those irradiated atdoses up to 10 kGy. However, irradiation treatments generally induced slight, but statisticallysignificant, increases in the values of water absorption properties as measured gravimetrically(hydration properties) and volumetrically (swelling properties). From the obtained results for totalphenolic and flavonoid contents in non-irradiated and irradiated faba bean, it is clear that irradiationdose of 9 kGy can be selected as an optimal dose for increasing of these phytochemicals in faba bean.