DOI: 10.35860/iarej.1262837 ISSN:

Thermal stability of fenugreek leaf extracts

Hilal İŞLEROĞLU, İzzet TÜRKER
  • Pharmacology (medical)
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In this study, thermal stability and degradation kinetics of the phenolics of the aqueous fenugreek leaf extracts were determined. Thermal degradations of total phenolics, total flavonoids, antioxidant activity and total saponins of the fenugreek leaf extracts were examined at different pH values (3.0, 6.0 and 9.0) and different temperatures (60, 70, 80, 90 and 100°C) with respect to time. Moreover, degradation kinetics of the total phenolics were explained by first-order reaction kinetics. Half-life values, free energy and activation energy of the extracts for total phenolic compounds were calculated. According to the results, the extracts showed better thermal stability at pH 3.0 than the other pH values at the selected temperatures in terms of total phenolics, total flavonoids, antioxidant activity and total saponins. Kinetic constants (k) were 0.151-0.435 h-1, 0.181-0.491 h-1 and 0.197-0.634 h-1 at pH 3.0, pH 6.0 and pH 9.0, respectively. Activation and free energy values for the degradation of fenugreek phenolics were calculated in the range of 26.02-29.97 kj/mol and 109.31-120.07 kj/mol, respectively. The half-life values of total phenolics treated at 60-100°C were 1.59-4.59 h, 1.41-3.83 h, and 1.09-3.52 h for pH 3.0, 6.0 and 9.0, respectively.

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