Study On Improving The Quality And Flavor Of Lower Tobacco Leaves By Enzymolysis And Cased With Herbal Extracts

Tobacco, as special hobby product, is an important economic crop in China. During theprocessing of harvesting, storage, manufacturing process, large amounts of low-grade tobaccoare produced. The abandoned low grade tobacco with poor quality and low utilization causedgreat waste of resources, as well as serious environmental pollution. Meanwhile, the provisionof high grade tobacco was inadequate, since the restructuring policy of Chinese cigarettesblends. It will be of great importance for the industry and environment if the low-gradetobacco could be improved as supplement raw materials for low-tar cigarettes manufacturing.In this resrerch, the low-grade tobacco of poor flavoring quality, poor usability, and lowutilization were improved by different means, with the aims of improving the intrinsic qualityand organoleptic characteristics of low-grade tobacco. The main research contents and resultsare as follows.At first, the differences of basic chemical compositions and macromolecule substancesbetween the upper, middle and lower leaves were compared, due to the the lack of appropriatephysical and chemical indicators support defects in currenent Chinese flue-cured tobaccoquality evaluation system. Thereafter, Principal Component Analysis (PCA) was applied toinvestigate the differences of neutral voltiles in tobacco flavor between different positions oftobacco stalk. The results obtained showed that: the upper leaves had low contents of totalsugar and reducing sugar, high levels of nicotine, which led to poor components coordinationand strong irritant feeling; All of the chemical composition index examined in the middleleaves were in an moderate range, which led to middle leaves with the best sensory qualitybetween different positions of tobacco; the lower leaves had low contents of nicotine andneutral volatiles but high cell wall material contents, which led to the low mainstream smokevolume and poor aroma quality. PCA results showed that: the main differences between upperleaves and middle leaves were the content of carotenoids degradation products, while thedifference between the middle and lower leaves were releted to the cembratriendid alkyldegradation products, terpenes degradation products, Maillard reaction products andphenylalanine degradation products.In order to decrease the negative effects of high content of tobacco cell wall substancesto the tobacco aroma, polysaccharide enzyme (Viscozyme), neutral protease (Protease),amylase (BAN), pectinase (Pectine) in non-solution system were applied to degrade the cellwall substances of lower position tobacco. Cell wall degradation ratio and sensory scoreswere used as indicators to determine the efficiency of enzymtic degradtion. The resultsindicated that Viscozyme and Protease showed the most satisfied profits. The technologyparameters of degradation with Viscozyme and Protease were optimized by using theorthogonal experiment design combined with practical process. The optimized process was asfollows: Viscozyme of490U/g, Protease of208U/g, Reaction time of4h; under thiscondition tobacco cell wall substance content was decreased to25.74%. Meanwhile, theeffects of enzymatic treatment on tobacco surface structure, the combustion property and the content of neutral volatiles were also investigated by scanning electron microscopy (SEM),GC-MS detection and TG-DSC thermal analysis, respectively. The results showed that: thetobacco surface became smoother and the contents of neutral volatiles were raised afterenzymolysis; the combustion prosperity was rarely influenced by enzymatic process.As Pectinase caused serious damage to the low-grade tobacco structure, the pectinasesolution was consequently used to extract the flavor components of low-grade tobacco forflavoring. When the Pectinase dosage was64U/g and the reaction time was2h, tobaccoextract obtained and used as low-grade tobacco flavoring showed good sensory properties.The cased cigarettes provided coordinate aroma when the addition amount of tobacco extractwas in the dosage of30～40g/g.In order to increase the TDPs content of lower leaves, the Artemisia argyi leaves rich interpenoids was applied. Simultaneous distillation extraction (SDE), solid phase microextraction (SPME) and comprehensive two-dimensional gas chromatography time of flightmass Spectrometry (GC×GC-TOFMS) were used to determine the volatiles of the Artemisiaargyi leaves. The results showed that the major volatiles of Artemisia argyi leaves weremonoterpenes (C10H16), sesquiterpenes (C15H24) and their oxygend derivatives. Smoketransfer experiments indicated that terpenes can transfer into mainstream smoke and increasethe content of neutral volatiles in tobacco smoke. Because of high volatility of essential oil,the added Artemisia argyi essential oils would lost during storage and uneven release inmainstream smoke. Therefore, the microemulsion of Artemisia argyi essential oil was appliedto solve this problem. The effects of different surfactants, cosurfacant and Km values to themicroemulsion area were examined. The results indicated that ethanol as co-surfactant, Tween80as surfactant and Km=3:1were the optimal choices for Artemisia argyi essential oilmicroemulsion system, which had high loading capacity and good water dilution. Themicroemulsion system was O/W type when the moisture content was over66%, and thephase transition temperature was47°C. The microemulsion particle size and PDI remainedstable under two months storage. The Artemisia argyi essential oil microemulsion was addedto low grade tobacco leaves and the mainstream somke puff-by-puff transfer rules werechecked. The results showed that Artemisia argyi essential oil added in embedding type couldraise the60-day essential oil holding rate in tobacco leaves from <60%up to>80%. Also,Artemisia argyi essential oil microemulsion promoted the volatiles, in a certain extent,distributed more evenly among puffs in mainstream smoke.Artemisia argyi ethanol extract was also applied for lower leaves casing. The aromaretention rates and prolysis properties of Artemisia argyi ethanol extract were determined.The results indicated that retention rate of volatiles in tobacco experiments was higher inArtemisia argyi extract than that in Artemisia argyi essential oil, but lower than that inArtemisia argyi essential oil microemulsion. The pyrolysis products at different temperatures(300℃,600℃,900℃) were identified. The results showed that most of the volatiles directlytransferred via distilling under300℃. Part of the neutral volatiles transferred to the smoke atthe range of300～600℃and most of the volatiles pyrolysed at the range of600～900℃.The terpenoids in tobacco smoke can be raised under the combustion situation. The contents ofTPN, tar were also increased slightly, while the CO, nicotine were not influenced. Sensoryevaluation results showed that the cased cigarette provided coordinate aroma when theaddition amount of Artemisia argyi extract was30g/g.