| The characterized of starch gels and structure of tobacco starch in different stage were studied during flue-curing in order to provide theoretical basis for optimization of curing technology.The changes of light transmittance, viscosity, proximate composition and content of tobacco starch by using the electric-heated flue-curing barn designed and made by Henan Agricultural University in the different temperature and humidity yellowing conditions. Its main conclusion is as follows:1.During the process of flue-curing, from the result of the change of four basic components of tobacco starch leaves, the basic tobacco starch composition changes concentrated in the yellow stage, the relative change in dramatic.The basic components of tobacco starch were analyzed. The result show that the fat of fresh tobacco leaves was 0.74%, the moisture content of starch was 14.73%, the ash content of starch was 0.63%, the content of starch phosphorus was 0.19%. Including fat, moisture and ash were smaller along with the flu-curing, but phosphorus content is gradually increasing. To the yellow stage is completed, water, fat, ash reductions were 71.41%, 17.56%, 22.22% ,which were greater than the degradation of fix color and stem-drying stage.The biggest reduce of ash appear in fix color stage.2. During the process of flue-curing, the basic components of tobacco starch showed a decreasing trend, except ash. From the four temperature and humidity treatment, high temperature (40℃) and humidity (relative humidity 95~90%) in the yellow stage, the water of tobacco starch in the fast heating and color fixed (from 42℃to warm up, 1℃/h, to 52℃after the extension of 12~20h) decreased quickly, while no matter slow heating and color fixed (from 42℃to warm up, 1℃/3h, at 54~55℃do not stop), or fast heating and color fixed (starting from 42℃temperature, 1℃/h, reached after the extension of 52℃12~20h) the ash content were decreased in the most significant. Slow heating and color fixed setting (from 42℃to warm up, 1℃/3h, at 54~55℃do not stop) in the yellow stage, changes in fats were greater than the margin of 2 other treatment can be effective in tobacco loose combination of starch and fat, so the lower the protein content of starch to fat more easily separated, to reduce odors, and very useful for the tobacco contains substances conducive to accumulation of decomposition and transformation, the formation of good quality tobacco.3.Through biological microscope to observe of the granular structure and non-crystallized granule of tobacco starch, it can be seen that amorphous granular starch and starch of tobacco compared to non-crystallized granule is destroyed, although the particles remained the basic shape of starch granules loose tobacco amorphous structure, but the particle surface has changed dramatically, showing network-like structure, there are obvious holes burst, greatly increased the reactivity of microbial degradation.During the process of flue-curing, the microbial particles have an good effect on the non-crystallized granule of tobacco starch, With the extension of time of flue-curing, the granular structure of tobacco starch was reduce, 2h after the starch granules completely disappear more completely degraded. Curing process of microbial degradation of starch content in flue-cured tobacco 2h and four deal with the size of the overall degradation of T3> T4> T1> T2.4. The sample of light transmittance in seven hours at 40~70℃in the test temperature rises along with the tests temperature showed "flat-increasing" trend during flue-curing. After the test temperature at 70℃, the overall light transmittance rate was significantly increased. At the test temperature is 95℃, the light transmittance of tobacco starch paste in the seven hours of close to 100%. In the yellowing stage, all the test temperature of light transmittance of tobacco starch was significantly lower and then increased until lead to the end yellow stage(60h), in addition of 60℃. The other test temperatures of light transmittance of tobacco starch compare to light transmittance of tobacco starch of the early of yellow stage (12h) were not significantly different. During the fix color stage (60~72h), the test temperature of light transmittance of tobacco starch was significantly higher, and then show the trend of slow growth. In the stem-drying stage (95~125h), the test temperatures (except 50℃, 80℃and 85℃outside) starch were significantly higher light transmission and maximum. The test temperature at 80℃and 85℃, the starch does not significantly increase light transmission rate, the difference was not significant.5. Add the the different chemical composition analysis of the impact on the light transmittance during flue-curing, it can be seen that NaCl reduced the light transmittance of tobacco starch, sucrose. On the other hand citric acid can enhance their transparency. In addition, the starch is also a serious impact on the aging effect of light transmittance of tobacco starch, this experiment also proved that the process of curing showed light transmittance is closely related to the retrogradation. With the rise of tobacco starch high, the effect of retrogradation of tobacco starch was significantly decreased.6. By adding different chemical composition analysis of the impact on starch viscosity during flue-curing, It can be seen that each time the viscosity of starch increased with NaCl, NaHC03 added volume increases. With the increase in the amount of sucrose, starch viscosity also increased. In the process of curing, the two treatment of speed 60r/min and 30r/min viscosity of tobacco starch along with the curing temperature and higher, in which the speed 30r/min treated starch viscosity was significantly greater than the overall speed 60r/min. The treatment of pH4 and pH6 of tobacco starch viscosity shown inverted "U" trend in the yellowing phase were gradually increased, respectively, 42℃and 48℃at the highest point, and then declined sharply until the end during the process of curing.7. The results show that the tobacco starch gel elasticity and adhesion were decreased gradually during flue-curing. In this process, NC89 and Yunyan87 difference is not significant, At 42℃, NC89 was significantly higher than,after 42℃it lower than the content of Yunyan87. During flue-curing the restorative of NC89 and Yunyan87 were decreased, and the differences between them were large. especially in the 38~42℃,the recovery of Yunyan87 was significantly higher than NC89. In the late of fix color stage and cured ,The restorative tobacco were small value, the difference value between restorative of NC89 at 54℃and cured was 0.01, and Yunyan87 restorative at this stage the difference between the value show and the same stiustion. |
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