Study Of Cinnamon Essential Oil Inhibition On Aspergillus Flavus

Food spoilage caused by microbial growth is a great event related to national people safety and health. China is a country with a large population and great demand for food, food industry are facing a major issue of food storage,antimould and preservation. At present, deoxy-preservatives are widely used in food storage which is high cost and short aging, even if using new generation of the broad-spectrum chemical preservatives with low toxicity and little pollution, it can only inhibit but without virus-free. So food safety and health is an arduous task with serious situation.Because chemical preservatives have shortcomings such as limited condition,biological resistance and cumulative poison with long-term use, people have turned and looked to find natural antibacterial ingredients (such as essential oils)from biology as a preservative. Natural preservatives have little side effects, fast and long aging. But the researches of essential oils are still limited to the static level of partial antibacterial in china and aboard, there is little report about its antibacterial mechanism as preservatives.This subject comes from the item of "Anti-Aspergillus flavus natural flavor composite oil and its preparation" (No.[2004]514) supported by the Ministry of Agriculture of the PRC. In this paper, experiment material is cinnamon oil which is extracted from cinnamon of Litsea szemaois and spice crops. Through multi-angel observation on its inhibition effect on Aspergillus flavus which causes food spoilage and has great harm, inhibition process and mechanism of this essential oil are discussed and preliminary clarified.1. Cinnamon essential oils was extracted by steam distillation, Na₂SO₄ dehydration: Cinnamon was crushed 10～60nm particles, then cinnamon oil was extracted using steam distillation in the 280℃. In the process of separation, the speed of distillation raised gradually from initial to one hour, 80% volatile oil was distillated until 2 hours; Finally cinnamon essential oil was obtained by Na₂SO₄ dehydration, the yield is 1.8% of total sample weight. The results of GC-MS analysis showed that the major components of cinnamon oil were cinnamaldehyde and cinnamic acid.2.Compared with the similar kinds of essential oils, the effect of inhibition on Aspergillus flavus was more fast and remarkable: Through research on there inhibition on Aspergillus flavus by different diffusion method, the results showed that the effect of cinnamon oil inhibition on Aspergillus flavus is more remarkable at the same concentration. The MIC of cinnamon oil inhibition on Aspergillus flavus is 1.5μL/mL by liquid contact and 2.0μL/mL by gas diffusion method.3. Observation on changes of microscopic and submicroscopic cell structure: through observation on spores and mycelia of Aspergillus flavus effected by cinnamon oil using optical microscopy, scanning electron microscopy, TEM, the results showed that the spores of Aspergillus flavus brought aberrance, mycelia structure changeed irregular, cell wall texture structure got disorder and hard to distinguish, even disappeared, cell membrane become illegibility, some irregular bodies were formed in the cytoplasm.4. Compared with the control group, discussing dynamic process of cinnamon oil antibacterial activity: through drawing the growth curve of Aspergillus flavus spores within 15 days treated by cinnamon oil, we found that the characteristics of control group from spore germination, the colony size, color had changed significantly. Experiment group didn't enter the logarithmic growth phase, but directly got into the aging and atrophy.5. Study of this oil influencing on composition of Aspergillus flavus cell wall by gas diffusion: the results showed that protein and uronic acid content of Aspergillus flavus cell wall decreased 20% , and the amino sugar content decreased by 56%; inorganic phosphorus content decreased by 33%. HPLC analysis showed that the neutral sugar galactose for neutral sugar ratio compared to the control group decreased by 46% and the amino sugar galactose amines than the control group decreased by 88%. All of these results indicated that the cell wall structure of Aspergillus flavus was destroyed and the selective absorption to surrounding material changed.6. Cinnamon oil influencing on the Aspergillus flavus cell membrane function of fluidity and permeability: compared with the control group, Ca²⁺, K⁺ ion of Aspergillus flavus cell membrane was leaked; the content of extra and intra-cellular MDA increased; the total lipid,phospholipids and cholesterol of cell membrane had significantly changed, the total lipid content decreased by 44%, phospholipids content increased by almost 2.5 times, cholesterol decreased by 20%. Therefore, one target of cinnamon oil inhibition on the growth of Aspergillus flavus should be cell membrane.7. Through influencing key enzyme activity of respiratory metabolism pathway, metabolism process of Aspergillus flavus was inhibited by cinnamon oil: compared with the control group, we found that the glycolysis, herbs cycle, the pentose phosphate pathway of Aspergillus flavus cell respiration were inhibited, the activity of malate dehydrogenase and succinic dehydrogenase decreased by 28.3% 28.9% respectively , energy compensation of cells survive weakened. In summary, the inhibition of cinnamon oil on Aspergillus flavus was preliminary discussed at cellular, subcellular,enzyme levels. The results indicated that the mechanism of cinnamon oil inhibition on Aspergillus flavus was not the sole factor, but overall synergies through affecting the cell wall,cell membrane and cell metabolism. All results initially provided a theoretical basis of cinnamon oil such as natural essential oils used in food preservation provide.Text innovations: extracted way of cinnamon oil was initially constructed by rapid steam distillation and dehydration, its mechanism of inhibition on Aspergillus flavus which caused food spoilage and had strongly toxicity was researched by multi angle.