Microwave-extracted essential oil of ginger with and without solvent

• Main Author: Fitriany, Reniek
• Format: text
• Language: English
• Published: Animo Repository 2007
• Subjects: Oils and fats; Ginger; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/3500; https://animorepository.dlsu.edu.ph/context/etd_masteral/article/10338/viewcontent/CDTG004274_P.pdf
• Institution: De La Salle University

The use of ginger has a long history all over the world over the centuries. It is valued for its aromatics, volatile constituents and spicy, pungent constituents. The essential oil of ginger obtained from the root is a high value-added product. Various methods can be used for isolation of essential oils of ginger. Nevertheless, losses of some volatile compounds, low extraction efficiency, degradation of unsaturated or ester compounds through thermal or hydrolytic effect and toxic solvent residue in the extract may be encountered using conventional methods. Microwave-assisted extractions with and without solvent are new extraction techniques, which combine microwave heating and conventional extraction. The advantage of this new technology over the conventional ones is that it offers reduction of the time of extraction and higher efficiency. The comparison of the performance of the microwave-assisted extraction of the essential oils of ginger, with and without solvent, over that of the steam distillation, in terms of yield and chemical composition, was investigated in this study. In addition, the antimicrobial activity tests against gram-positive (Staphylococcus aerus, bacillus subtilis), gram-negative (Escherichia coli, Pseudomonas aeruginosa) and yeast (Candida albicans) of extracted oil were explored. A microwave extraction system was fabricated using a Whirlpool domestic microwave oven with a capacity of 1000 watts and 2,450 MHz. The same amount of 200 grams of fresh ginger was extracted using MAE with and without solvent and using steam distillation. The extraction time was set at 20 min at 70oC for MAE with solvent (ethanol) and at 100oC for without solvent using the power of 600W and 4 hours for steam distillation. Likewise, the effects of the nature of solvent (ethanol and isopropanol), extraction time (1 and 6 min), solvent/solid ratio (75/25 and 150/25 ml/gr), shape of reactor (cylindrical and v round bottomed flask reactor) and microwave power (400W and 600W) were investigated in terms of the yield of oil produced. The results of the present study were as follows: (1) MAE with solvent gave the highest yield (5.30%) compared to without solvent (0.37%) and steam distillation (0.052% for fresh and 0.18% for dried ginger). (2) The extracts of the 3 methods showed the presence of the major components of ginger oil such as sesquiterpenes and monoterpenes derivatives except gingerol, which was detected only on the MAE with solvent. (3) The oils showed the different activities against those microorganisms tested at different concentrations of 500mg/ml, 300mg/ml, 100mg/ml, 50mg/ml, 10mg/ml, and 1 mg/ml (4) Ethanol as a solvent showed higher yield over that of isopropanol. (5) The percent yield increased with an increase of extraction time, solvent/solid ratio and microwave power. (6) The shape of the reactor also had a significant effects on the yield in MAE with solvent. Keywords: Essential Oil, Ginger oil, Microwave Assisted Extraction, Steam Distillation, Ginger (Zingiber officinale).