Astudy Of Microbial Fermentation And Enzyme Hydrolysis Of Tobacco Stem Materials

The utilization of tobacco stems in the tobacco industry was not used effectively. Some substances, such as the main cell wall materials, especially the pectin, starch and protein had adverse effects on the quality of smoke. Obviously, decreasing these substances could raise the utilization rate of tobacco stems and reduce the loss of resource.Microbial fermentation and enzyme hydrolysis of tobacco stems and cut-stems were investigated in this study. The contents of pectin, cellulose, starch and the like in the tobacco stems and cut-stems were degraded partially. Thus the quality and the applicability of tobacco stems in the cigarette will be improved.A new analysis method for various pectin substances in enzyme-hydrolysed tobacco samples was established by combining the gravimetric method with HPLC method. Using this new method, the coefficient of variation of the content of the total pectin acid was lower than traditional gravimetric method. The pectin substances would be fully extracted. The new method is comprehensive and with good reproducibility, and easy operations.In order to degrade pectins, submerged fermentation of tobacco stems by Aspergillus niger was carried out. The optimized fermentation conditions were as follows: adding 20 g tobacco stems in a 500 mL Erlenmeyer flask; inoculum volume:15%(v/v); solid to liquid ratio: 1∶12; fermentation temperature: 30℃; fermentation time: 72 h.The recovery yield of tobacco stems was 40.89%. The degradation rates of the total pectin were 83.99%.The effects of the enzyme hydrolysis on various kinds of tobacco stem substances were compared. The results were described as follows: cut-stem> stem powders> tobacco stem.The enzymes suitable for enzyme hydrolysis of tobacco stems were tested. Some enzymes are useless, and some enzymes, such as pectinase, amylase, saccharifying enzyme and cellulase were appropriate for the treatment of tobacco stems.The enzyme hydrolysis conditions of cut-stems by single enzyme and the dosages of enzyme were investigated. The optimized results were as follows: for 1 gram of tobacco cut-stems, the dosage of pectinase is 300 U; enzymolysis time: 5 h; digesting temparature: 50℃; the dosage of amylase is 200 U; the dosage of cellulose is 200 U; and the dosage of saccharifying enzyme is 1000 U.The formula of compound enzymes were established. The dosage of compound enzymes and the condition of enzymolysis were as follows: for 1 gram of cut-stem, the dosage of pectinase is 200 U; the dosage of amylase is 133 U; the dosage of cellulose is 133 U; and the dosage of saccharifying enzyme is 667 U. The optimized results were as follows: enzyme hydrolysis time: 4 h; digesting temparature: 47.5℃.When the intact cut-stems were hydrolyzed by the compound enzymes, the degradation rates of the pectin were 13.08%; and the degradation rates of starch were 37.59%; and the reducing sugar was increased by 76.71%; and the soluble sugar was increased by 68.48%, respectively. Sensory assessment results showed that the quality of cut-stems in the cigarette can be improved.As the requirements of simple operation, high efficiency, lower investment and other factors, the method of enzyme hydrolysis was selected.