Study on Constituents of Pummelo Peel Oil and Antibacterial Activity of It's Emulsion for S. aureus and E. coli

Autor: Yu-Hsin Lin, 林雨欣
Rok vydání: 2005
Druh dokumentu: 學位論文 ; thesis
Popis: 93
Pummelo peel oil was extracted by steam distilation and the constituents were analyzed by GC-MS. There were thirty-three compounds identified from the essential oil. The main compound was limonene (940.07 mg/g), the second was myrcene (23.65 mg/g), and the third was β-pinene (13.53 mg/g). In order to find the effect of endogenous enzymes on composition of pummelo peel oil, the oil was extracted by water distillation after reacting with endogenous enzymes for 15 days at 30oC. The yield of the essential oil decreased from 2.5 to 2.04%. The amount of hydrocarbon monoterpenes in the essential oil decreased from 911.68 to 828.19 mg/g, while the oxygenated terpenes increased from 9.46 to 12.43 mg/g. If the pummelo peel oil was extracted by steam distillation after reacting with endogenous enzymes for 2 days at 50oC, the yield of the essential oil significantly decreased from 2.48 to 1.64%. The hydrocarbon monoterpenes in the oil decreased from 982.15 to 864.35 mg/g and the oxygenated terpenes increased from 10.95 to 13.92 mg/g. The antibacterial effect of emulsified pummelo peel oil (without homogenization) on S. aureus and E. coli increased as the concentration of the oil raised. The plate counts of S. aureus and E. coli were lower (1.03 and 0.85 CFU/mL, respectively) than the control when 0.4% essential oil was used. The antibacterial effects of emulsified pummelo peel oil, which had been homogenized at 24000 rpm, on S. aureus and E. coli were higher than that homogenized at 13500 rpm as well as that without homogenization for E. coli. The MIC (minimum inhibitory concentration) value for E. coli decreased from 0.49 to 0.25%. The mean partical size of the emulsified pummelo peel oil was 1383.5 nm after being homogenized with 1 time of microfluidizing treatment. The size decreased to 216.6 nm while the microluidizing treatment increased to 3 times. The inhibitory effect of S. aureus was the best when 0.4% emulsified pummelo peel oil was homogenized with 1 time of microfluidizing treatment, of which the plate count of S. aureus was 1.13 Log CFU/mL lower than the control. The same concentration of emulsified pummelo peel oil also had significant inhibitory effect on E. coli after the essential oil was homogenized with 1 and 3 times of microfluidizing treatments, of which the plate counts of E. coli were respectively 1.12 and 1.16 Log CFU/mL lower than the control. The emulsified pummelo peel oil with lower concentration (0.1%) could increase its inhibitory effects on both S. aureus and E. coli after the essential oil was homogenized with 1 time of microfluidizing treatment, of which the plate counts of S. aureus and E. coli were respectively 0.88 and 1.02 Log CFU/mL lower than the control. The antibacterial effect raised by adding water-souble chitosan (DA=54.8%) alone when the concentration increased. The inhibitory effect on S. aureus reached to the maximum when the concentration of water-souble chitosan was 500 ppm, of which the plate count of S. aureus was 1.12 Log CFU/mL lower than the control. The plate count of E. coli was only 1.07 Log CFU/mL lower than the control as the concentration of water-souble chitosan increased to 1000 ppm; hence, the water-souble chitosan exhibited higher inhibitory effect on S. aureus than on E. coli. The 0.4% emulsified pummelo peel oil (homogenized at 24000 rpm) adding different concentrations of water-souble chitosan (100, 300, 500 and 1000 ppm) was found to have higher antibacterial effect than both water-souble chitosan and emulsified pummelo peel oil without adding chitosan. The inhibitory effects on S. aureus and E. coli increased significantly when 300 and 500 ppm of water-souble chitosan was added in 0.4% emulsified pummelo peel oil. The plate counts of S. aureus and E. coli were respectively 2.40 and 2.55 Log CFU/mL lower than the control. As for the pH effect, the inhibitory percentage of S. aureus for the 0.4% emulsified pummelo peel oil increased as the values of pH raised. The water-souble chitosan (300 ppm) had higher inhibitory percentage for S. aureus and E. coli at pH 5.5 than at pH 7.4 and 8.5. The 0.4% emulsified pummelo peel oil which had been added with 300 ppm water-souble chitosan showed the best inhibitory effects on both bacteria when the value of pH was 7.4. The inhibitory percentages were 99.48 and 99.06% for S. aureus and E. coli, respectively.
Databáze: Networked Digital Library of Theses & Dissertations
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