Study On The Effect Of Pectinase Treatment On The Tobacco Stalk Base

Tobacco stalk is a byproduct in the tobacco industry after the tobacco leave are harvested,most of the tobacco stalks were discarded as solid waste or burned in the field, which lead toenormous waste of natural plant resource and serious environmental pollution. The mainutilization way of tobacco stalk is reconstituted tobacco, and it has the followingcharacteristics: low yields of tars and small releasing amounts of harmful compounds. Thehigh content of pectin in tobacco stalk will lead to the increasing of harmful compounds, suchas methanol, formaldehyde, formic acid, et al. This paper is based on reconstituted tobaccotechnology, enzyme was used to hydrolyze pectin, study the effect of enzymatic hydrolysis onthe morphology of the tobacco stalk pulp, and the aromatic components from tobacco stalkpulp under optimal hydrolysis conditions were also researched. Finally, the feasibility study ofenzymatic technology applied to engineering practices were investigated. The main contentsand results of this paper are as follows:Steam explosion and thread rolling were used to pretreat tobacco stalk in order to disruptthe recalcitrant structure and improve the efficiency of enzymatic hydrolysis. Thegalacturonic acid yield was0.139g/g and0.127g/g obtained by steam explosion and threadrolling, respectively, which were much higher than the untreated one (0.042g/g). Furthermore,the SEM analysis showed that the physical and structural damage of tobacco stalk bypretreatment was more serious than untreament under the same condition of enzyme.In enzyme hydrolysis, pectin was hydrolyzed by using pectinase and the effects of pH,temperature, substrate concentrations, hydrolysis period and enzyme loading on thegalacturonic acid yield were investigated. The optimal temperature, pH, concentration pulp,enzyme loading (for every5g dry weight pulp), reaction time were50°C,3.0,10%,0.4g, and2hours, respectively.The impact of enzyme treatment on the morphology of the fiber and the physicalproperties were determined. Through a detailed comparison, we showed that pectinase canimprove pulp properties, and increase the beating degree, and the Kajaani FS-300resultsshowed the fiber length was responsible to the enzyme treatment. At the optimum conditions,the bulk increased from2.047cm3·g-1to2.361cm3·g-1, the tensile index also increased, thetear index decreased. Several different analysis techniques were used to study the surfacemodification. Variations in surface topography between untreated samples and treated sampleswere studied with SEM and AFM, SEM showed that the texture of untreated pulp appearedcompact and soomth, after pectinase treatment, the surface of pulp became rough and exhibited holes and pits, and revealed fiber skelecton. AFM images revealed difference in thefine structure of fibers, the surface of untreated pulp fibers covered with a layer of densegranular material which not seen on the treated fibers. The results of XPS analysis showedthat the O/C ratios increased and the content of C1decreased for pectinase treated fiberscompared with the control sample, which confirmed the validity of the enzyme experiment.The crystallinity of the treated pulp fiber observed by XRD was increased.The aromatic components of tobacco stalk pulp treated under the optimum conditionsand the untreated tobacco stalk pulp were analyzed by simultaneously distillation andextraction (SDE) and GC-MS. The amounts of furfural,5-methyl furfural, and furfuralalcohol were significantly increased in the treated pulp, on the contrary, the amounts oflinoleic acid, linolenic acid, and palmitic acid were decreased. The amounts ofdihydroactinidiolide, megastigmatrienone, farnesyl acetone also had some changes. In a word,the aromatic components content were increased in the treated tobacco pulp.Finally, the feasibility research were done from technical and economic aspects, and thedata showed the high potentiality of enzyme treated for reconstituted tobacco applications.