Study On The Identification And Biological Charateristics Of Microorganisms Of Moldy Cigarettes

Tobacco is an important economic crop in many areas of the world. Tobacco contains carbohydrates, minerals, nitrogen compounds, organic acids and derivatives which are suitable for the growth of microorganisms. Tobacco is an important raw material for cigarettes and susceptible to microorganisms contamination from the environment after harvesting, processing, transporting, storage and other processes. As tobacco had a number of microorganisms, microorganisms can easily grow then cigarette mildew when the water content of cigarette reaches the threshold.A variety of microorganisms from market moldy cigarettes were isolated. 3 dominant moulds in the process of mildew were established by the main mildew standards according to the colony’s modality and microscope observation on spore and mycelium. 7 moulds from market moldy cigarettes and artificial acceleration mildew cigarettes were identified by morphological and molecular biology identification methods.The 7 moulds were identified by the colony’s modality and microscope observation on spore and mycelium combined with ITS molecular biology technique. The results showed that the 4 moulds from artificial acceleration mildew cigarettes were Aspergillus flavus, Penicillium citrinum,Cladosporium.sp and Aspergillus oryzae, and the 3 moulds from market moldy cigarettes were all Aspergillus.The effects of different temperatures, humidity, p H, heat treatment, carbon sources, nitrogen sources and other factors such as UV sterilization to moulds were carried on. The results showed that Aspergillus flavus had the highest adaptability, followed by Penicillium citrinum and Cladosporium.sp, whlie Aspergillus oryzae was less adaptable.The experiments of temperature and heat to 4 moulds on the tobacco were carried on. The results found that the characteristics of 4 moulds on the tobacco consistent with the characteristics on the plate culture. The results of different temperature experiment showed that Aspergillus flavus had the highest temperature adaptability which easily spread to tobacco, and Penicillium citrinum and Cladosporium.sp followed by, and Aspergillus oryzae was less adaptable. We found that spore’s heat resistance higher in the tobacco than in the bath, and lethal temperature of the 4 moulds increased from 70 ℃ to 90 ℃ when fungi spores were sprayed onto the surface of cut tobacco and the heat treatment was carried on.The effects of environmental factor to tobacco mildew were studied. These factors included moisture content, packing tightness, packaging way and simulating of different areas and different temperature and humidity to storage of tobacco. The results showed that tobacco of 13% moisture was prone to mildew, and the cigarette preserved well when the package tightness is greater than 100 mm H2 O, and the cigarettes were prone to mildew in high temperature and humid conditions.The volatiles of cigarette were analyzed by SPME-GC-MS method. The results showed that normal cigarette contained abundant esters and nicotine substances, while had less acids, aldehydes, ketones and ethers, and the moldy cigarette had lower esters, much amount of acidic substances. Thus, analysis on the changes in cigarette volatiles could be used as an important indicator of the moldy cigarettes.