Optimization of Extraction Conditions of Citrinin from Red Yeast Rice by Orthogonal Design and Quantification of Citrinin by High-Performance Liquid Chromatography

Abstract

An orthogonal experimental design was utilized to optimize extraction condition of mycotoxin citrinin from red yeast rice. The results showed that the combination of the following conditions was the optimum extraction condition: 50 % ethanol as extraction solvent, 1:5 as the solid-to-liquid ratio, and vortex for 5 min followed by 20 min ultrasonication as extraction manner. Under the optimum extraction condition, citrinin in 11 commercial red yeast rice products was extracted and quantified by optimized high-performance liquid chromatography (HPLC) conditions which consisted of acetonitrile and acidic water (pH 2.5) as mobile phase, flow rate of 1 mL/min, and fluorescence detector. The quantification results showed that seven products contained citrinin; the highest content of citrinin was 57.28 μg/g. The citrinin contamination rate in collected red yeast rice samples was 63.6 %. This investigation indicates that the optimized extraction method followed by HPLC fluorescence detection is a sensitive and effective method to quantify citrinin. The results also indicate that most red yeast rice products in China contain citrinin. However, there are no national criteria about citrinin limit in red yeast rice and the related products. Therefore, a national regulation standard in terms of quantification method should be set up to limit citrinin contamination and to control the circulation of red yeast rice products in China.