A study on the physico-chemical properties and anti-bacterial activity of extracted garlic essential oil using microwave assisted extraction and steam distillation

• Main Authors: Bermudez, Sarah A., Gurtiza, Karen Joy H., Hernandez, Leon Raphael S.
• Format: text
• Language: English
• Published: Animo Repository 2008
• Subjects: Garlic; Garlic > Therapeutic use; Garlic > Health aspects; Plant extracts; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/7810
• Institution: De La Salle University

Microwave extracted garlic oil as a pharmaceutical alternative in the country was studied and compared to the conventional steam distillation extract. The main objective of the study is to determine the physico-chemical and anti-bacterial properties of the extracted Garlic essential oil and oleoresin. Garlic essential oil was extracted from air-dried garlic (Allium sativum) using two methods, steam distillation and microwave extraction. Microwave extraction at different conditions were performed by varying the solvent (ethanol and hexane), temperatures (65ºC, 70ºC and 75ºC), wattage (400 and 600 Watts), irradiation time duration (1 and 5 minutes), drying time duration of sample (1 and 3 weeks) and sample preparation (sliced and chopped). For the steam distillation, the extraction was set to 4 hours and the drying duration and sample preparation was the same with that of microwave-assisted extraction (MAE) conditions. The 120 grams of one week air-dried chopped garlic irradiated with ethanol at 70ºC for 1 minute using 600 Watts gave the best extraction condition giving a 15.47% yield of the extract. For the sliced-air-dried garlic sample for three weeks, the MAE extract gave a yield of 9.28%. In contrast, steam distillation extract which was distilled for 4 hours using sliced air-dried garlic for three weeks, yielded less, only about 6.29%. More sulfur compounds of the MAE extract were detected using gas chromatography-mass spectroscopy analysis compared to extracts derived from steam distillation. The purity of the MAE oleoresin extract is low with a refractive index of 1.46 as compared to the steam distilled oil with a refractive index of 1.58 which is comparable to that of Medichem Co. with a value of 1.579. The physico-chemical tests also showed that the MAE oleoresin has a specific gravity of 1.09 acid value of 107.338 and ester value of 177.65. The Kirby-Bauer disc diffusion technique and spot inoculation test were employed to determine the anti-microbial property of the extracts. Test microorganisms included in the test were P. aeruginosa, S. aureus, B. subtilis and E. coli. Anti-bacterial activity was observed on extracts using MAE but none on the steam distillation extracts. It was noted that P. aeruginosa was most resistant while S. aureus and B. subtilis were found to be susceptible to the extracts.