| Reconstituted tobacco (RT), also known as reconstituted tobacco sheet, was a sheet orfilament reconstituted product manufactured by the tobacco wastes. These tobacco wastes oftobacco stem, tobacco powder and tobacco debris were produced during the manufacturingprocess of cigarette production. The tobacco wastes of flue-cured tobacco (FCT) were theprimary source for RT in our country. However, due to the recombination process ofextraction, concentration, beating, paper making, high temperature drying and addition ofwood fiber, the qulaity of paper making RT was drastically different from FCT. In thisresearch, the quality of paper making RT was studied and compared with the FCT. The effectsof manufacturing process of RT on the formation of carbonyl compounds was studied. Then,the reason of process that improving the release of carbonyl compounds was further analyzedand discussed, with the aims of decreasing the generation of carbonyl compounds. The mainresearch contents and results are as follows.The chemical composition, thermal behavior, aroma components in tobacco andmainstream smoke and formation of harmful constituents in mainstream smoke of three kindsof RT were compared with FCT. The results demonstrated that the content of water incigarette mainstream smoke of RT was significantly higher than FCT, while the yields of tarand nicotine were signifiantly lower than FCT. There were four main weight loss stages on theweight loss curves of RT. Due to high contents of reducing sugar, FCT contained five mainweight loss stages. The maximum weight loss rates of degradation and combustion of RTwere clearly higher than FCT, which led the puff number of RT significantly lower than FCT.Therefore, the incorporation of RT into cigarette could reduce the dry sensation of smoke, andwas an effective means in reducing the tar and harmful components of cigarette smoke.However, the contents of total nitrogen, nicotine, total sugar, reducing sugar, aromacomponents in tobacco and cigarette mainstream smoke of RT were all significantly lowerthan FCT, which led to the low mainstream smoke, strong irritant feeling and poor aromaquality. Besides, the yields of carbonyl compounds in mainstream smoke of three kinds of RTwere about208μg/puff, significantly higher than153μg/puff of FCT. Because high irritantand carcinogenicity, the large incorporation of RT into cigarettes was limited.In view of higher amounts of carbonyl compounds were generated by RT than FCT, theeffects of raw material, composition of coating extracts, concentration temperature of coatingextracts, composition of cellulose web, additional pulp, softwood content and coating yield onthe formation of carbonyl compounds were analyzed. The results illustrated that theconcentration temperature of coating extracts and the composition of cellulose web showedno effects on the generation of carbonyl compounds. The raw material and the coating yieldshowed little effects on the formation of carbonyl compounds. The increase of carbonylcompounds was both less than5%. However, the softwood pulp (SP) was the main factor inthe generation of carbonyl compounds in RT mainstream smoke. The yields of carbonylcompounds were increased with the increase of adding amount. When the adding contents ofSP increased from7%to12%, the generation of carbonyl compounds increased10.2%.Besides, the effects of SP on the quality of RT were analyzed. The addiing yields of SP had no significant effects on the thickness and mass of RT, while significantly increased the fillingability, tensile strength and yields of CO in RT mainstream smoke. When the adding contentsof SP increased from7%to12%, the filling ability, tensile strength and yields of COincreased22%,31%and10%.In order to study the reason that SP promoted the formation of carbonyl compounds. Thethermal behavior and gaseous products formation of SP, TP, SP-RT and TP-RT were analyzed.The results showed that the thermal degradation start temperature of SP and TP was at284oC.The TG and DTG curves of SP-RT and TP-RT were obvious differences also start at284oC.The maximum weight loss rate of degradation of SP was94.1%/min, obviously higher than62.3%/min of TP. The maximum weight loss rate of degradation of SP-RT were also higherthan TP-RT. The areas of total FTIR absorbance curves of SP and TP were65.21and49.63.Meanwhile, the area of total FTIR absorbance curve of SP-RT was also higher than TP-RT.Therefore, the differences in the thermal behavior and gaseous products formation of SP-RTand TP-RT were mainly caused by the differences in the SP and TP. The SP-RT and TP-RTwere pyrolyzed using isothermal oxidative pyrolysis equipment. The results further validatedthat the pyrolysis of SP would increase the formation of carbonyl compounds than TP. Theyields of carbonyl compounds pyrolyzed at284oC of two RT were in the same level. While at800oC, the yields of carbonyl compounds generated by SP-RT was8.51mg/g，significantlyhigher than7.48mg/g of TP-RT.In order to study the reason that SP generated more carbonyl compounds than TP. Themonosaccharide composition of SP and TP was analyzed. Meanwhile, the yields of carbonylcompounds generated by the monosaccharide were compared. The results demonstrated thatthe monosaccharide composition of SP was greatly different from TP. TP contained five kindsof monosaccharides, while only3kinds of monosaccharides were checked in SP. Besides,fructose (13.52%) was only found in TP and xylose (23.75%) was only detected in SP. Theyield of carbonyl compounds generated by xylose was highest,17.47mg/g. The yield ofcarbonyl compounds of glucose was lowest,14.27mg/g. The yield of fuctose and mannosewas between xylose and glucose. Therefore, due to high amount of xylose and low content ofglucose, SP generated more carbonyl compounds than TP. In order to find the reason thatmore carbonyl compounds were generated by xylose than glucose, xylose and glucose wereanalyzed using TG-FTIR. The results demonstrated that the carbonyl compounds of glucoseand xylose were both mainly generated in the thermal degradation stage. There were both twopeaks on the carbonyl compounds evolution curves during the thermal degradation stage. Thearea of first peak of xylose was5.33, obviously higher than2.97of glucose. Thus, xylosegenerated more carbonyl compounds than glucose.In order to decrease the generation of carbonyl compounds in mainstream smoke of RT,five nitrogen compounds of urea, ammonium chloride, ammonium sulfate, diammoniumphosphate and monoammonium phosphate were selected as additive. The effects of these fivenitrogen compounds on the generation of carbonyl compounds were analyzed. Moreover, thereason that five nitrogen compounds could decrease the formation of carbonyl compoundswas studied. The results demonstrated that the incorporation of five nitrogen compounds intoRT could significantly decrease the yields of carbonyl compounds. Ammonium chloride generated significantly lower content of carbonyl compounds (46.2%) than the other fournitrogen compounds. The reduction of carbonyl compounds by urea was mainly ascribed tothe chemical reaction between urea and carbonyl compounds. The other four nitrogencompounds reduced the yields of carbonyl compounds not only because of the chemicalreaction, but also because they could drastically improve the thermal stability of RT andeffectively retard the combustion of the major components of RT. Besides, the incorporationof ammonium chloride into RT could increase the content of water and decrease the yields ofphenolic compounds in mainstream smoke. When1.0%ammonium chloride was added, thearoma, smoke, offensive odor and smoking quality of RT could be improved. |
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