Application And Evaluation On Enzymatic Degradation Of Tobacco Stem

Tobacco is a kind of important agricultural crop in many areas of the world. In China, theacreage and yield of tobacco is most all over the world, and the stem is a kind of mainby-product in tobacco industry. Currently, most of the stem is buried or burned afterharvesting, only a little was used as animal feed or made into cigarette paper, which caused theserious waste of resources. In tobacco industry, the main utilization way of tobacco stem is ascutting stem tobacco added into cigarette. Benefit from the development of biotechnology, itput forward a new direction for the deep development and comprehensive utilization oftobacco stem resources. After examining the degradation effect of enzymes on stem, abiotechnology way for making full use of tobacco stem was proposed.On the premise of actual production process and optimum condition of enzymes, rawmaterials (washing stem and cutting stem tobacco) and enzymes, including pectinase, cellulaseand hemicellulose enzymes, were sifted. Results showed that it was better for cutting stemtobacco than washing stem under the same enzyme catalysis and pectinase I, pectinase II andcellulase I showed better ability of catalysis than others.The effects of temperature, moisture, pectinase I dosage, pectinase II dosage andcellulase I dosage on the contents of reducing sugar, cellulose as well as pectin weresystematically analyzed. The above factors, including temperature, moisture and enzymedosage all had highly significant impact on the content of reducing sugar. Results revealed thatthe primary and secondary sequence of influence factors were in the following order ofmoisture> cellulase I> pectinase II> temperature> pectinase I and a significant effect ofmoisture content was observed. Through variance analysis, we came to the conclusion that allsynergistic effects between variables were not significant under non-solution system, thedegradation of pectin and cellulose were more depended on individual parameter rather thanthe synergistic effect between each other.The uniform design of experiments was introduced in order to reduce cost of productionon the basis of response surface method. By the content of chemical compositions,coordination of chemical compositions, statistical analysis and method of selection sensory, abetter parameters meeting the requirements of actual production process was determined:temperature45℃, moisture40%, pectinase I20U/g, pectinase II230U/g, cellulase I0.9%,time6h. Results showed that the sensory quality evaluation was best compared with othertreatments as well as the check under the conditions, the improvements were mainly embodiedthe reduction of irritation (23.53%) and the increase of of aroma quality (18.75%) and aromaamount (18.75%). Based on the above results, the fermentation process of cutting stem tobacco wasanalyzed. Results revealed that the balance of reducing sugar, total sugar content was achievedwithin6h, while the content of pectin and cellulose was significantly reduced within2h.During reaction process, the concentration of glucose, fructose and galacturonic acid increased.On the contrary, the content of sucrose decreased sharply within2h. The activity of bothpectinase and cellulase could maintain about80%in the whole process under non-solutionsystem, in which the thermal stability of enzymes was also improved. Insulated for60min at100℃, the activity of cellulase could still maintain about40%.So the residual activity ofcellulase could be monitored as a standard that the inactivation of pectinase and cellulase wascompleted. The surface of cutting stem was greatly changed before and after hydrolys is, andcellulose that previously coated by pectin was exposed. However, the crystalline of cellulosewas only slightly damaged.The contents of resultants from phenylalanine, browning reaction and carotenoid changedowing to enzyme complexes. The results of instrument analysis revealed that the total contentsof neutral aroma components after treatment was higher (approximately3times) than that ofthe check. While the contents of small molecule compounds, such as hydrocarbon compounds,small molecules alcohols, volatile organic acids (C<10), esters and phenolic substances etc,decreased more obviously.According to the experimental results, it is feasible for biologicalenzymes to improve the industrial availability of tobacco stems on the basis of existingproduction process.