Quantification of Crocetin in Foods by Solid-Phase Extraction

Abstract

Crocetin, a kind of carotenoid, is a yellow pigment composition found in gardenia fruits. Owing to its multifunctional physiological benefits, crocetin is used in many foods. For quantitative analysis of crocetin by UV-Vis spectrophotometry, we developed a process involving solid phase extraction (SPE). This novel method comprises the following steps: (1) preparation of the crocetin solution from food samples by dissolving in NaOH solution; (2) first step purification of crocetin via SPE of mixed-mode (reversed-phase/strong anion-exchange) polymer; (3) second step purification of crocetin via SPE of mixed-mode (reversed-phase/strong cation-exchange) polymer; (4) absorbance measurement of the purified crocetin solution. It was found that the lower limit of detection was 75 mg/100 g in the case of tablets and 0.3 mg/100 g in the case of beverages. The crocetin solution was added to three types of commercially available health food products and one beverage, which showed recoveries in the range of 100.4 %-102.8 %. The repeatability (relative standard deviation) was 1.03 % for a test repeated seven times with a soft capsule. The specificity of this method was confirmed by the UPLC method, mass spectrum and UV spectrum. The results demonstrated that this method is convenient and useful for the quantification of crocetin in various foods.