Drying and analytical determination of moisture content change of tobacco leaf lamina and midrib

Abstract

Of the countries that produce highly aromatic oriental tobacco varieties, Kyrgyzstan ranks third in the world in terms of production volumes, and one of the best in terms of quality; therefore many foreign companies are interested in Kyrgyz tobacco. For the natural and climatic conditions of Kyrgyzstan, the following optimal regimes of various stages of tobacco leaf drying were experimentally determined: at yellowing, temperature 25-35°C, moisture content 80-85%; at leaf lamina drying, temperature 35-45°C, moisture content 65-75%; at final midrib drying, temperature up to 50-55°C, moisture content – initial 50-60% and final 35-40%. The methods for reducing the time of final midrib drying are recommended by applying a device to tobacco sewing machines for slitting leaf stems and midribs with simultaneous alignment of bunches. It was also found that when tobacco leaves are sun-dried, the leaf lamina dries for 72-120 hours (3-5 days). It takes from 168 to 264 hours (or 7-11 days) for the midrib to dry depending on tobacco leaf picking (leaf size). Extending the drying time leads to the fact that the dry matter yield is reduced by 5.4%, the product range of higher grades (1 and 2) is deteriorating by 15.7%, the Schmuck ratio which determines the quality of raw materials is reduced by 0.12. All this indicates the need to find ways to reduce the duration of the midrib drying. The equations have been derived that make it possible to determine the moisture content at leaf lamina and midrib drying under natural conditions. This makes it possible to obtain equations for determining the change of moisture content of leaf lamina and midrib for other drying methods which is practically important for controlling the entire drying process of tobacco leaves.