Comparison of different isolation methods of essential oil from Citrus fruits: cold pressing, hydrodistillation and microwave ‘dry’ distillation

Abstract

Traditional hydrodistillation (HD), cold pressing (CP) and innovative microwave 'dry' distillation or microwave-accelerated distillation (MAD) methods have been compared and evaluated for their effectiveness in the isolation of essential oil from fresh Citrus peels. The microwave method offers important advantages over traditional alternatives, viz. shorter extraction times (30 min vs. 3 h for hydrodistillation and 1 h for cold pressing); better yields (0.24% vs. 0.21% for HD and 0.05% for CP); environmental impact (energy cost is appreciably higher for performing HD and for mechanical motors (CP) than that required for rapid MAD extraction); cleaner features (as no residue generation and no water or solvent used); increases antimicrobial activities; and provides a more valuable essential oil (with high amounts of oxygenated compounds). It also offers the possibility for better reproduction of the natural aroma of the essential oil from Citrus fruit compared with CP, but more than the HD essential oil. Further, the microwave procedure yields essential oils that can be analysed or used directly without any clean-up, solvent exchange or centrifugation steps. Scanning electron microscopy provides more evidence of the cleanness of microwave extraction, in contrast to the huge perforations on the external surface of the Citrus fruit peel in the case of conventional hydrodistillation. Finally, a mechanism of microwave 'dry' distillation is proposed and discussed.

Effect of microwaves on the in situ hydrodistillation of four different Lamiaceae

“…As previously reported, with our instrumentation the energies required for HD and MGH are 1.5 kWh and 0.25 kWh respectively, these figures correspond to a carbon footprint of 1200 and 200 g CO2 for HD and MGH, respectively [11,15]. As reported by Chemat et al [9] the energy required to perform an extraction with MHG is 0.2 kWh and the calculated quantity of carbon dioxide emitted is 160 g. In a recent paper we successfully experimented a 75 L-pilot MW reactor demonstrating the scaling up feasibility of MGH and MGH extractions [16].…”

Production of Pectin-Cellulose Biofilms: A New Approach for Citrus Waste Recycling

“…In both cases, the length of the lag phase and the exponential phase of the microorganisms were the same for blanks and for the samples containing the films. One reason could be that orange oils were removed during the sugar removal pretreatment step, which was similarly performed as the cold pressing method, a preferred method for extracting essential oils from citrus fruits [27], and is usually done by soaking the citrus fruit in warm water and pressing the rind with a sponge to collect the oil.…”

Chemical composition of essential oil of Indonesia sandalwood extracted by microwave-assisted hydrodistillation

“…Substantially high amounts of oxygenated compounds and low amounts of monoterpene hydrocarbons were present in the essential oils of the aromatic plants and spices extracted by MAHD [8]. The oxygenated terpenes (α-santalol, β-santalol, etc.)…”