Estimation of aroma precursors in radiation processed fenugreek

Bound volatile compounds of fenugreek were isolated and identified. The glycoside profile was dominated by phenyl glucopyranoside accounting for 90% of the total glycosides. The content of this glycoside as estimated both by high performance liquid chromatography (HPLC) and thin layer chromatography (TLC)-densitometry was found to be approximately 0.7 mg gm−1 of fenugreek. Gamma-radiation processing resulted in dose dependent break down of phenyl glucopyranoside with a reduction by almost 30% at a dose of 10 kGy. A corresponding increase in phenol content with dose was also observed in the steam volatile oil of the irradiated spice. Based on pulse radiolytic studies the mechanism of radiolytic cleavage was shown to occur via a carbon centred radical. Estimation of absorbed dose based on phenol released during radiation processing is proposed herein. The method is simple and rapid and could estimate absorbed dose in the range of 2.5–10 kGy within an error of 15%.