Changes of Electrical Properties of and Chemical Components in Flue-cured Tobacco During Bulk Curing

Abstract

To determine nondestructively and real-timely the moisture content and chemical components in tobacco leaf dependent on its electrical property during curing and further regulate the humidity and temperature in the curing barn on a scientific basis, the capacitance and resistance of and chemical components in leaves were measured and analyzed with capacitance meter, resistance bridge, and routine physical and chemical analytic methods. The results showed that: with the degradation and transformation of macro molecular substances and water dissipation during curing, the capacitance value dropped steeply at the end of the stage when dry-bulb temperature raising from 38 to 48 ℃, then decreased very slowly afterwards. The resistance value presented a rising trend, which raised steadily at the dry-bulb temperature range from 36 to 42 ℃(yellowing stage). The differences of resistance value were not significant(P0.05) at the temperatures of 36, 38, and 42 ℃. The resistance values of leaves increased quickly at color fixing stage(after dry-bulb temperature raising to 42 ℃). Correlation analysis showed that the values of capacitance and resistance obviously correlated to the contents of major chemical components in tobacco. The capacitance value extremely significantly correlated to moisture content and significantly correlated to the contents of total sugar, total nitrogen, protein, β-carotene, xanthophyll, neoxanthin and soluble pectin. Though there was a certain correlation between the resistance value and the moisture content and chemical components in leaves, it was not significant.