Determination of total safranal by in situ acid hydrolysis in supercritical fluid media: Application to the quality control of commercial saffron

A procedure allowing hydrolysis reactions to be conducted in a dynamic supercritical-CO₂ medium was developed for quantifying total safranal (viz. free safranal present in the sample + safranal resulting from picrocrocin hydrolysis), which are the main component of the essential oil and responsible for the characteristic aroma of saffron. The proposed method allows total safranal amounts over the ranges 0.05-1.5 mg mL⁻¹ to be determined. The standard deviation achieved was 2%. This method was applied to the determination of safranal in natural saffron samples. The results obtained were compared with the “safranal value” total index, which is widely used as a quality measure of saffron products. The comparison revealed that the proposed method provides useful information not contained in the safranal value, based on the fact that, some samples with a high “safranal index” contain low concentrations of safranal. The proposed method is very useful for quality control in commercial saffron samples.     

A quantitative high-performance liquid chromatographic method to analyse commercial saffron (Crocus sativus L.) products.

An HPLC method to check components and purity in commercial saffron by photodiode array detection has been developed. The method was suitable for the standard analysis of commercial saffron. Therefore, 10 saffron metabolites responsible for the taste, flavour and colour were identified and quantified with high selectivity, precision and accuracy. Also, some artificial colorants, which can be used as adulterants, were also detected and identified. Three different saffron types were studied and their metabolite concentrations determined at different wavelengths.     

Ultrasound-assisted extraction of saffron bioactive compounds; separation of crocins,picrocrocin, and safranal optimized by artificial bee colony

In this work, a four-factor five-level full factorial central composite design (CCD) was used to optimize the ultrasound-assisted extraction (UAE) of saffron major components, namely picrocrocin, safranal and crocin. The process parameters included ethanol concentration (0–100%), extraction time (2–10 min), duty cycle (0.2–1.0) and ultrasonic amplitude (20–100%). The extracted compounds were measured both by spectrophotometry and chromatography techniques. The results revealed that the middle concentrations of ethanol and relatively long process durations along with high duty cycles and ultrasonic amplitudes had the most profound impact on the yields of the extracted bioactives. UAE was optimized using response surface methodology (RSM) and artificial bee colony (ABC); a comparison between these methods indicated their optimization power was approximately the same. According to the RSM analysis, an ethanol concentration of 58.58%, extraction time of 6.85 min, duty cycle of 0.82 and amplitude of 91.11% were the optimum extraction conditions, while the optimal conditions resulting from ABC were 53.07%, 7.32 min, 0.93 and 100% for the UAE variables respectively. Finally, HPLC analysis was carried out on the UAE optimum extract resulting from RSM. Four crocetin esters were detected in the optimal extract.     

Use of volatile organic solvents in headspace liquid‐phase microextraction by direct cooling of the organic drop using a simple cooling capsule

A low‐cost and simple cooling‐assisted headspace liquid‐phase microextraction device for the extraction and determination of 2,6,6‐trimethyl‐1,3 cyclohexadiene‐1‐carboxaldehyde (safranal) in Saffron samples, using volatile organic solvents, was fabricated and evaluated. The main part of the cooling‐assisted headspace liquid‐phase microextraction system was a cooling capsule, with a Teflon microcup to hold the extracting organic solvent, which is able to directly cool down the extraction phase while the sample matrix is simultaneously heated. Different experimental factors such as type of organic extraction solvent, sample temperature, extraction solvent temperature, and extraction time were optimized. The optimal conditions were obtained as: extraction solvent, methanol (10 μL); extraction temperature, 60°C; extraction solvent temperature, 0°C; and extraction time, 20 min. Good linearity of the calibration curve (R² = 0.995) was obtained in the concentration range of 0.01–50.0 μg/mL. The limit of detection was 0.001 μg/mL. The relative standard deviation for 1.0 μg/mL of safranal was 10.7% (n = 6). The proposed cooling‐assisted headspace liquid‐phase microextraction device was coupled (off‐line) to high‐performance liquid chromatography and used for the determination of safranal in Saffron samples. Reasonable agreement was observed between the results of the cooling‐assisted headspace liquid‐phase microextraction high‐performance liquid chromatography method and those obtained by a validated ultrasound‐assisted solvent extraction procedure.