Influence of Pre-extraction Leaf Modifications on Lemongrass Essential Oil Recovery and Thermo-Energetic Efficiency in Steam Distillation

Abstract

This study evaluated the influence of simple pre-extraction leaf modifications on lemongrass (Cymbopogon citratus) essential oil recovery and thermo-energetic efficiency during steam distillation. Experiments were conducted at JNKVV, Jabalpur, Madhya Pradesh, India, using a completely randomised design with four treatments and three replications, giving 12 experimental runs. The treatments were whole leaves without soaking (WWOS), whole leaves with soaking (WWS), chopped leaves without soaking (CWOS), and chopped leaves with soaking (CWS). Each run used 0.5 kg of lemongrass leaves and 2 kg of distilled water, with observations recorded at 15-minute intervals up to 120 minutes. Oil recovery, thermal energy consumption, specific gravity, refractive index, material balance and burner efficiency were assessed. No oil was recovered during the first 30 minutes. Oil extraction began at 45 minutes and increased until stabilisation. CWS produced the highest oil volume (2.4 ml), followed by CWOS (2.1 ml), WWS (1.8 ml) and WWOS (1.6 ml). Chopping reduced the optimum extraction time to 90 minutes for CWOS and CWS, compared with 105 minutes for WWOS and WWS. ANOVA indicated significant differences in oil recovery among pre-treatments (p < 0.05). The lowest thermal energy consumption per ml of oil was observed for CWS (2129.50 kJ/ml), whereas WWOS required the highest value (3654.68 kJ/ml). Specific gravity and refractive index ranged from 0.876 to 0.910 and 1.477 to 1.488, respectively. Burner efficiency ranged from 40.23% to 41.94%. The material balance confirmed conservation of the 2.500 kg input mass. Overall, chopping combined with water soaking improved oil recovery and energy use under the tested conditions.