Optimization of solid-phase microextraction analysis for headspace flavor compounds of orange juice

The headspace flavor compounds of orange juice were isolated by solid-phase microextraction (SPME) fiber coated with 100 mu m of poly(dimethylsiloxane) and separated by gas chromatography. The effects of the orange juice temperature from 25 to 80 degrees C and the adsorption time from 5 to 40 min an the equilibrium of flavor compounds between the SPME coating and the orange juice indicated that the equilibrium time decreased as the sample temperature increased. The equilibrium of the flavor compounds between the SPME coating and the orange juice required 30 min at 40 degrees C or 20 min at 60 degrees C. The amount of orange flavor compounds adsorbed by SPME coating decreased as the orange juice temperature increased from 25 to 80 degrees C. The resolution of the gas chromatogram increased as the inside diameter of the injection port liner decreased from 1 to 0.75 mm. The concentrations of ethyl butyrate, octanal, decanal, alpha-pinene, and limonene in orange juice were 0.4, 1.1, 1.0, 1.4, and 254 ppm, respectively. The coefficients of variation for the analyses of ethyl butyrate, octanal, decanal, alpha-pinene, and limonene ranged from 4.4% for 0.4 ppm ethyl butyrate to 1.6% for 254 ppm Limonene.