Extraction of essential oil from discarded tobacco leaves by solvent extraction and steam distillation, and identification of its chemical composition
The extraction of an essential oil from discarded tobacco leaves using a combination of solvent extraction and steam distillation (SE–SD) was investigated. The effect of different parameters, such as temperature, extraction time and liquid–solid ratio, on the extraction yield was investigated using the Response Surface Method (RSM) with the Box–Behnken Design (BBD) method. The temperature and liquid–solid ratio were found to have a significant effect on the yield of extract (oleoresin). A yield of 3.38 ± 0.03% of the oleoresin (final essential oil yield was 0.89%) could be extracted under the following optimized conditions: a temperature of 41 °C, a liquid–solid ratio of 6.27 mL/g and a time of 5 h. Composition and characteristics of the discarded tobacco essential oils and oleoresins obtained by SE–SD, hydrodistillation and solvent extraction were analyzed by gas chromatography/mass spectrometric detection, to allow the extraction methods to be compared. The results showed that the same compounds were largely present in the different tobacco essential oils, but their relative concentrations differed. General characteristics of the extracts obtained from the three extraction methods showed that the SE–SD essential oil was of better quality and therefore of higher value. Thus, SE–SD is the optimum process for the extraction of high quality essential oil from discarded tobacco. âº Essential oil and oleoresin of discarded tobacco leaves were extracted by different methods. âº A combination technology of solvent extraction followed by steam distillation was performed and optimized for isolation of essential oil. âº The composition of essential oil and oleoresin were identified by GC/MS. âº The compositions of the extracts were found to be similar, quantitative differences were observed.