Optimization of ohmic heating assisted hydrodistillation of cinnamon and bay leaf essential oil

Abstract

In this work, optimum ohmic heating assisted hydrodistillation (OAHD) conditions for extraction of cinnamon (CEO) and bay leaf (BEO) essential oil were determined by response surface methodology (RSM). OAHD were compared with conventional hydrodistillation (HD). Hydrodistillation time (30-120 min), mass of sample (20-40 g) and voltage gradient (7.5-12.5 V/cm), were varied to maximize essential oil (EO) yield and minimize energy consumption. Optimized OAHD conditions were determined as 119.90 min, 8.83 V/cm and 40 g, and 120 min, 8.53 V/cm and 40 g for CEO and BEO, respectively. EO yields of cinnamon and bay leaves at optimum conditions were found 3.98 +/- 0.25% and 1.36 +/- 0.14%, respectively. Energy consumptions were found 0.42 +/- 0.02 and 0.86 +/- 0.09 kWh/g EO for CEO and BEO, respectively. EO yield of OAHD was found to be higher when compared with HD methods for both plant materials. Energy consumptions and emitted CO2 values of OAHD method were significantly (p < 0.05) lower than HD methods. Cinnamaldehyde (CEO) and eucalyptol (BEO) contents of essential oils extracted with OAHD were higher when compared with HD methods. Antioxidant activities of essential oils extracted with different methods were not significantly different. CEO and BEO formed inhibition zones against all tested microorganism strains. Practical Applications Essential oils of cinnamon bark and bay leaf are commonly used for food and pharmaceutical industries and, have important economic value. Conventional hydrodistillation method to extraction essential oils is time consuming, requires more energy and has more CO2 emission rates. Ohmic heating assisted hydrodistillation as a novel technology, is a promising method to extraction of essential oils from different plant materials with lower process times and energy consumption when compared with conventional hydrodistillation. Ohmic heating assisted hydrodistillation method can developed with regard to scale up as a green technology to essential oil production. This work provides a knowledge about the effects of different OAHD process variables on essential oil yield and energy consumption for cinnamon bark and bay leaf essential oils. It is expected that the outcomes of this study will be useful for the designing of large scale ohmic heating assisted hydrodistillation units.