Extraction of vanillin from vanilla pods: A comparison study of conventional soxhlet and ultrasound assisted extraction

This study deals with extraction of vanillin from cured vanilla pods using conventional soxhlet extraction and ultrasound assisted extraction. Effect of various extraction parameters such as type of the solvent (6 different solvents viz. ethanol, methanol, acetonitrile, acetone, chloroform and hexane), quantity of beans (1–3 g), operating temperature (in the range 90–100 °C) for soxhlet extraction and pre-leaching time (in the range of 30–90 min) for ultrasound assisted extraction, on the extent of extracted vanillin has been investigated in this work. It has been conclusively established that the use of polar solvents resulted in maximum extent of extraction for both the types of extraction operations. For soxhlet extraction, an increase in operating temperature from 90 °C to 100 °C was found to increase extent of extraction by 30% whereas for ultrasound assisted extraction, pre-leaching stage for 30 min duration was found to be beneficial in enhancing the extent of extraction by about 20%. The use of ultrasonic irradiation resulted in intensification of the extraction operation of vanillin significantly as confirmed from the results that in soxhlet extraction, an operating temperature of 95 °C and solvent to solute proportion of 66.67 ml/g (most commonly used conditions) resulted in release of around 180 ppm in 8 h whereas ultrasonic assisted extraction required only 1 h for release of around 140 ppm vanillin concentration at similar proportions of solvent to solute and under ambient operating temperature.