Development of an environmentally-friendly solvent-free extraction of saffron bioactives using subcritical water

Abstract

Subcritical water extraction (SWE) of saffron major bioactive compounds – picrocrocin, safranal and crocin– was conducted. The influence of extraction time (5–15 min) and temperature (105–125 °C) on the process efficiency was investigated through response surface methodology (RSM). The components were determined through spectrophotometry at 257, 330 and 440 nm, namely the wavelengths at which picrocrocin, safranal and crocin have the highest absorbance respectively. The molecular extinction coefficient(E1cm%1λmax) was measured for each component at its corresponding wavelength. Our results revealed that moderate extraction times and low temperatures had the best impact on the yields of picrocrocin and safranal indicating the partial thermal stability of these two compounds. The crocin content decreased dramatically by increasing time and temperature revealing the sensitivity of this component to subcritical conditions. Extraction temperature of 105 °C and time of 7.32 min were acquired as the optimum conditions which delivered E1cm%1λmax of 88.262, 45.482 and 145.26 for picrocrocin, safranal and crocin, respectively. HPLC analysis demonstrated that SWE process degraded most of saffron crocins. GC-MS identified only safranal with a retention time of 6.752 min and a molecular weight of 150.