Analysis of beta-sitosterol in seeds and nuts using pressurized liquid extraction and liquid chromatography.

Pressurized liquid extraction (PLE) has been used for the extraction of beta-sitosterol from food samples. In the present work, extractions were performed by mixing ground samples with Hydromatrix celite with methanol at 50 degrees C and 110 bar, using two 5-min cycles. After extraction, beta-sitosterol was analyzed directly by liquid chromatography with diode array detection. The extraction recovery was 92%, with relative standard deviations of 3.7% for intra-day precision and 4.3% for inter-day precision. The presence of beta-sitosterol was confirmed by gas chromatography-mass spectrometry. The proposed method was validated and applied successfully to the determination of free beta-sitosterol in seed and nut samples (almonds, pistachios, peanuts, and sunflower seeds).