Study On The Far-infrared-hot Air Drying Combined With Humectant On The Moisturizing Performance And Quality Of Tobacco

Tobacco products generally have a large change in moisture content due to environmental temperature and humidity,which seriously affects the sensory quality of cigarettes.Tobacco moisturizing technology solves the problem of insufficient water holding capacity of tobacco products.There are two main parts that affect the moisture retention performance of tobacco: chemical composition and organizational structure.In this paper,the technology of far-infraredhot air combined compound humectant is proposed to improve the performance and quality of tobacco.In terms of chemical composition,the hydrophilic compound humectant formed by propylene glycol and polysaccharides is mainly used to improve the tobacco shreds.Moisture binding capacity;in terms of organizational structure,the far-infrared-hot air drying is used to improve the organizational structure of tobacco and improve the moisture retention and quality of tobacco.The results were as followed:(1)Due to compact microstructure,small pore size and holes less than tobacco(1)and(2),tobacco(1)had the best quality,with better moisture retainment and higher contents of total sugar and sugar/nitrogen ratio.Compared to propylene glycol(PG),algal polysaccharide(AP)and tea polysaccharide(TP),moisturization effect of coriolus versicolor polysaccharide(CVP)was the best and it showed no negative impacts on cigarette quality.Dehydration experiments showed that dehydration rate of tobacco(1)added with CVP was the least and its equilibrium water content was the highest.PG,TP and CVP had positive impacts in increasing saliva secretion and decreasing dryness and harshness.Humectant recombined with PG and CVP can influence hydration/dehydration equilibrium and slow down hydration process,leading to increase in cigarette moisturization and thus sensory quality,which can be applicable in practical cigarette production.(2)Three selected sources all can emit far infrared and their irradiation power density ranged from high to low in the following sequence: far infrared sintered material(FISM)> ceramic debris > glass debris.Adding metal baffle can increase infrared energy efficiency.Material weight and irradiation area were positive related to power density.Heating can induce infrared emission and higher power density.Power density were more affected by wavelength and its peaks corresponded with 6 μm and 10 μm.Further researches targeting distribution of far infrared sources displayed that radiation attenuation was pretty low in the range(L = 0-3 cm,r = 0-1 cm)and well fitted by a mathematical model(E = I *exp(-σ*L)/L~2)describing relation between power density(E)and normal distance(L).Therefore,loose-located patches of far infrared sources were designed with inter-spacing of 2 cm and irradiation distance of 3 cm,in which case,uniform power density distribution and high energy efficiency can be realized,thus presenting theorical assistance in the development of far infrared drying technology.(3)Further,loose-located patches of far infrared sources were selected for quality investigation of tobacco(1)during the process of far infrared radiation assisted hot air drying(FIR-HA).Far infrared technology improved moisturization effects and sensory properties of tobacco(1).Dehydration rate was showed as the following sequence: FIR-HA + recombined humectant < FIR-HA control < HA + recombined humectant < HA control,while sensory quality as: FIR-HA + recombined humectant < FIR-HA control ≈ HA + recombined humectant < HA control.Therefore,synergistic effects of far infrared radiation and recombined humectant on moisturization improvement can be observed.Besides,far infrared had positive impacts on the chemical components of cigarette,especially on reduction in protein and amino acid: it led to increase in Cys,Leu,Gln,etc.and decrease in Asn,Ala,Gly,Tyr,etc.From the aspect of water distribution,far infrared can change water binding status inside tobacco,increase proportion of bound water and thus increase water holding capacity.Moreover,far infrared can also change capillary microstructure of tobacco,by increasing the number of inner pores(diameter: 0-1 μm)which normally had positive correlation with water capillary absorption.Therefore,far infrared can improve water retainment and then cigarette quality.