Study On Improving The Water-holding Capacity And Sensory Quality Of Tobacco With Potassium Lactate

The moisture content of tobacco can influence its physical properties, processingcharacteristics, combustion, flavor and sensory quality. When placed in a dry envrioment, themoisture content of tobacco decreased and “dry” cigarettes can yield harsher and moreirritating smoke. With the improvement of people’s life, the requirement for the cigarette wasundergoing some changes, shifted from physiological satiation to the sense of comfort andenjoyment. Therefore, enhancing the water-holding capacity and sensory quality of cigarettesbecame the primary cancern of people. In this research, a new humectant was applied toincrease the water holding capacity of tobacco. Meanwhile, the mouth dryness was improvedby the addition of humectant. The main research contents and results are as follows:Differences in hygroscopicity may be observed not only between tobacco varieties butalso within different grades of the same variety. But the influence of physical structure andchemical composition of tobacco on the water holding capacity is still unclear. At first, thekinetic model of moisture migration was studied, and the evaluation index was established torepresent the water-holding capacity. The physical structure (specific surface area and porevolume) and chemical components (total nitrogen, protein, pectin, starch, water-soluble sugar,and total sugar) of tobacco were determined. Results showed that the effective diffusioncoefficient (Deff) could be a useful representation of water-holding capacity except forequilibrium moisture content (EMC).With the increasing of the relative humidity ofenvironment, the values of Deffincreased first, then decreased. Simple correlation analysisshowed that, the Deffwas significantly affected by the specific pore volume of tobacco atdesorption. Large specific pore volume was in favored of moisture diffusion. Besides, aremarkable negative correlation was found between the effective diffusion coefficient and thepectin, water-soluble sugar, and total sugar content.Adding humectants to the tobacco was used to improve its water holding capacity in thestudy. At first, the moisturizing efficiency of polysaccharide, plant extracts and organic saltswere determined at RH=40%and70%. They were polysaccharide: hyaluronic acid (HA),Schizophyllum, chitosan and arabic gum; plant extracts: extracts of apple peel, orange peel,Chinese yam, reed rhizome and tremella; organic salts: potassium lactate (PL) and sodiumlactate, respectively. The results showed that the HA, extract of reed rhizome and PLexhibited better moisture keeping performance. After added to the tobacco, HA, extract ofreed rhizome and PL could increase the EMC of tobacco, decrease the drying rate constantand Deff. The drying rate constant and Deffdecreased with the increasing of the adding amountof humectants. The effects of the three kinds of humectants on the mainstream chemisty andsensory quality of tobacco were investigated. The results demonstrated that HA, extract ofreed rhizome and PL had no effect on the total particulat matter and tar in the mainstreamsmoke, but increased the moisture content and sensory quality. The effect of PL on themoisture content in the mainstream smoke was the most obvious. The cigarettes treated withextract of reed rhizome exhibited the best sensory quality.PL could be a new humectant due to its perfect performance to enhance the water holding capacity of tobacco. At first, the effects of different added amounts of PL on mainstreamsmoke chemistry, components distribution were determined. The mainstream smokechemistry detection of the cigarettes presented that PL had no effect on the content of TPM,NFDPM, puff number, nicotine and volatile carbonyl compounds, while increased themoisture content and decreased the CO content and the pH of smoke. Adding PL in thetobacco could increase the yield of alcohols, lactons, miscellaneous oxygenated compoundsand amides, but decrease the yield of aldehydes, acids, pyrroles and pyrazines. A small addedamount (0.2%) could lead to the reduction of the content of semi-volatile substancescompared with the control. However, when the added amount was beyond0.2%, the totalcontent of semi-volatile substances was not affected by the presence of PL. The same resultswere also achieved during the generation of ketones, esters, phenols, hydrocarbons, pyridines,tobacco alkaloids, and nitrogenous compound. Finally, the effect of potassium latate on thecombustion behavior and ash morphologies from tobacco were elucidated by TG–FTIR andSEM analysis. The results revealed that the maximum weight loss rate was decreased by theaddition of PL. The peak and end-point temperature of the combustion stage slightly movedtowards higher temperature. PL altered the ash morphology in a way that bonded the ashstronger and restricted the air flow. The alteration of ash morphology may be one of thereasons for the change of combustion behavior.The moisture formation mechanism during the combustion of tobacco was firstlyresearched. DTG analysis revealed that tobacco thermal degradation occurred in four stepsand the H2O evolution was found to have three major peaks for the combustion of bothflue-cured and burley tobacco. About36%-38%of the H2O genterated at first step (from25℃to140℃) due to the evaporation of absorbed water;51-54%generated at140-370℃and6%-12%formed at370-600℃. The yield of moisture was not affected by the flow rateindicating that gas phase secondary reactions did not contribute to the yield of moisture at thethree stages.The radical enhancement effect caused by oxygen was dominant in the lowertemperature range（<370℃）and the oxygen promoted the generation of H2O. While theoxygen played the oxidative destruction effect in the higher temperature range and inhibitedthe formation of H2O. The H2O formed during the pyrolysis or combustion of carbohydrate,organic acid and lignin. The yield of H2O from monosaccharides was the highest, indicatingthe monosaccharide was the main potential precursor.The effects of PL on the generation of H2O at different temperature ranges andprecursors were studied. The results showed that PL increased the moisture content inmainstream smoke by increasing EMC and affecting the combustion behavior of tobacco. Theincrease of EMC was due to the potassium ion and lactate group. During the process ofcombustion, the lactate group promoted the generation of H2O, while the potassium ionpresented in organic salts hindered the formation of H2O. PL increased the yield of H2O fromthe pyrolysis and combustion of monosaccharide, starch and cellulose, showed no effect onthe formation of H2O from the pyrolysis of disaccharide and pectin, but promoted thegeneration in the process of combustion. The yield of H2O from organic acids was notaffected by PL. PL increased the yield of H2O from the pyrolysis of lignin, but prevented thegeneration of H2O from the combustion of lignin.