Influence Of Molecular Distillation On Antioxidant And Antimicrobial Activities Of Rose Essential Oils

This thesis focused on the molecular distillation of Rosa damascene,Rosa centifolia,Rosa pomponia,Rosa chinensis Jacq“Crimson Glory”H.T.and Rosa sretata×Rosa rugosa essential oils.The molecular distillation equipment was used to study the experimental process of reducing the content of long-chain fatty alkanes in rose essential oils.Antibacterial and antioxidative activity studied on rose essential oils,fractions of molecular distillation and main functional monomer components of rose essential oils（linalool,phenylethyl alcohol,citronellol,geraniol,farnesol,eugenol and methyleugenol）,and explored the contribution and influence of antibacterial and antioxidant activities on monomeric components of rose essential oils.At the same time,the anti-oxidation applicationand in sunflower oil and the preservation in milk and antibacterial mechanism of Rosa sretata×Rosa rugosa essential oil and fractions of molecular distillation were studied.The research content of this thesis includes the following points:（1）The effects of distillation temperature,distillation pressure,scraping speed,feed flow rate and reflux water temperature on the removal of rose essential oil wax and pigment and the dissonance and irritating odor of essential oil top notes were studied.The results showed that molecular distillation could effectively reduce the wax and pigment in rose essential oil,and could remove the dissonance and pungent odor of rose essential oils,and achieved the aroma of rose essential oils,thus improved the quality of rose essential oils.（2）Gas chromatography-mass spectrometry（GC-MS）was used to analyze the components of rose oil and the distillates and residues fractions molecular distillation.The results showed that the main components of rose essential oil were linalool,citronellol,geraniol,phenylethyl alcohol,eugenol,methyleugenol,farnesol,nonadecane,1-nonadecene,eicosane,heneicosane,etc.（3）The antioxidant activities of the above five rose essential oils,the distillates and residues fractions of molecular distillation,and the main functional monomer components were determined.The results showed that rose essential oils and distillates,antioxidant capacity of D1 and R2（D1 is distillate component of primary molecular distillation,R2 is residue component of secondary molecular distillation,the same below）the same below)of Rosa sretata×Rosa rugosa essential oil by molecular distillation all were good;eugenol and methyleugenol played a major antioxidant role in rose essential oils,linalool,phenylethyl alcohol,citronellol,geraniol,and farnesol may act synergistically.The experimental studied on accelerated oxidation of sunflower oil by Rosa sretata×Rosa rugosa essential oil and corresponding the distillates and residues fractions showed that in addition to R1（R1 is residue component of primary molecular distillation,the same below）,Rosa sretata×Rosa rugosa essential oil and the corresponding the distillates and residues fractions could effectively alleviate the sunflower oil.Oxidation and extending the shelf life of sunflower oil.（4）The above five kinds of rose essential oils,molecular distillation of the distillates and residues fractions and main functional monomer components for antibacterial research.The diameter of the zone of inhibition was determined by a disk diffusion method,and the minimum inhibitory concentration（MIC）of bacteria（Escherichia coli,Staphylococcus aureus,Bacillus subtilis,and Pseudomonas aeruginosa）were determined by a two-fold dilution method and a large dilution method.Minimum bactericidal concentration（MBC）,the minimum inhibitory concentration（MFC）and minimum bactericidal concentration（MBC）of fungi（Aspergillus niger,Rhizopus oryzae and M.gingivalis）were determined by agar dilution method.The results showed that in addition to Pseudomonas aeruginosa,rose essential oils and distillates and D1 and R2 had strong antibacterial and bactericidal effects.（5）Studied on the antibacterial mechanism of the fractions of Rosa sretata×Rosa rugosa essential oil by molecular distillation from the biofilm activity,membrane permeability,membrane integrity and cell morphology of the bacteria and antiseptic applications in milk.Based on the MIC value determined by dilution methods,the biofilm inhibition rate was measured at a concentration of 0.5×MIC,1×MIC,and 2×MIC.At 1×MIC concentration,except for R1,the biofilm inhibition rate of Rosa sretata×Rosa rugosa essential oil,D1,D2 and R2 reached 60%or more,and the biofilm inhibition rate of D1 and R2 reached 80%or more.At 2×MIC concentration,the biofilm inhibition rate of Rosa sretata×Rosa rugosa essential oil,D1,D2（D2 is distillate component of secondary molecular distillation）and R2 reached 90%or more.Except R1,the Rosa sretata×Rosa rugosa essential oil and the fractions of molecular distillation increased the permeability of the cell membrane,leading to the leakage of intracellular components,especially the loss of electrolytes such as K⁺,Ca²⁺,Na⁺,etc.So that the relative conductivity increased rapidly,reached a stable value after 6 h.Except R1,due to the action of Rosa sretata×Rosa rugosa essential oil and fractions of molecular distillation,the integrity of Escherichia coli cell membrane was destroyed,and a large amount of protein,reducing sugar and other components were released,and the growth and reproduction of the bacteria were seriously affected.Scanning electron micrograph was used to observe the effects of Rosa sretata×Rosa rugosa essential oil and fractions of molecular distillation on the morphology of Escherichia coli.After treatment,the surface of the cells was broken,distorted or sunken,and the original cell morphology was lost.To determine the bactericidal and bacteriostatic effect of Rosa sretata×Rosa rugosa essential oil and fractions of molecular distillation in milk,that was,the number of bacteria surviving with time.Rosa sretata×Rosa rugosa essential oil and fractions of molecular distillation were applied to milk preservation.Under the MIC,the milk treated with D1 and R2 for 12 h,the concentration of Escherichia coli was below 10³CFU/mL,while the antibacterial effect of Rosa sretata×Rosa rugosa essential oil and D2were both Lower,the concentration of Escherichia coli was about 10⁴-10⁵ CFU/mL,whowever,R1 had almost no bacteriostatic effect,and the increase in the number of Escherichia coli was similar to the control.