Optimization of ultrasonic-assisted extraction of phenolic compounds from fenugreek ( Trigonella foenum-graecum L.) seed

Abstract

© 2015 The Author(s). Published by Taylor & Francis. Fenugreek (Trigonella foenum-graecum L.) seed was used for the recovery of phenolic compounds by employing different process modifications of ultrasonic-assisted extraction (UAE). It was observed that a 3-day germination (35°C) process negatively affected the phenolic contents of seed. Preliminary studies found that maximum quantities of phenolic compounds obtained from germinated and un-germinated seed were 5.882 and 7.534 mg GAE/g when extraction was carried out at 35°C for 30 min using ethanol (30%) as solvent. Un-germinated seed was used for further studies. In order to improve total phenolic compound recovery, Box–Behnken experimental design, regression analysis and response surface methodology were applied following the initial studies. The optimum UAE conditions were established as 38°C temperature, 32 min time and 33% ethanol for the maximum total phenolics (8.41 mg GAE/g DW). Fenugreek seed extract also showed a good radical scavenging activity (62.74 ± 1.66%).