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Picrocrocin Kinetics in Aqueous Saffron Spice Extracts (Crocus sativus L.) upon Thermal Treatment

Sanchez, Ana M., Carmona, Manuel, Jaren-Galan, Manuel, Minguez Mosquera, M. Isabel, Alonso, Gonzalo L.
Journal of agricultural and food chemistry 2011 v.59 no.1 pp. 249–255
kinetics, saffron, extracts, food analysis, food composition, Crocus sativus, heat treatment, thermal properties, degradation
The kinetics of picrocrocin degradation in aqueous extracts of saffron upon thermal treatment from 5 to 70 °C have been studied, together with the degradation of purified picrocrocin in water at 100 °C. The best fits to experimental data were found for a second-order kinetics model. Picrocrocin showed high stability with half-life periods (t1/2) ranging from >3400 h at 5 °C in saffron extracts to 9 h in the experiments with purified picrocrocin at 100 °C. In saffron extracts, the evolution of the rate constant (k) with temperature showed maximum values at 35 °C, and filtration of the extracts contributed to picrocrocin stability. In the case of purified picrocrocin, the generation of safranal in the first 5 h (yield up to 7.4%) was confirmed. Spectrometric parameters used in saffron quality control (E1cm1% 257 nm and ΔΕpic) were not appropriate for documenting the evolution of picrocrocin.