Rational Control of Temperature and Humidity in Flue-cured Tobacco Barn

- May 07, 2019 -

China is a big tobacco producer, and its annual average output accounts for one third of the world's total. Flue-cured tobacco is the most important tobacco leaf in China, accounting for 93% of the total output. At present, the annual planting area of tobacco leaves in China is more than 20 million mu.

Tobacco curing is the coordination and unification of the physical process of continuous dehydration and drying of tobacco leaves under artificial temperature and humidity conditions and the physiological and biochemical processes of decomposition, transformation and consumption of tobacco leaves under the action of respiratory enzymes, hydrolytic enzymes and oxidation-reductase, so as to ensure that the internal and external changes of tobacco leaves are in the desired direction. Development, that is, to achieve the purpose of drying, roasting yellow, roasting fragrance.

Firstly, the moisture content of fresh tobacco leaves is 80% & mdash; 90% and 15% & mdash; 17% after baking. The water content of the lower leaves was the highest, followed by the middle leaves and the upper leaves. The water in tobacco leaf tissue is divided into free water and bound water. The bound water is tightly adsorbed by hydrophilic colloidal nuclei. It is difficult to evaporate and remove in the process of baking. It can only be partially eliminated in the case of high temperature in the middle and later stages of baking. Free water, also known as free water, exists in cell protoplasm and intercellular space, accounting for the majority of water content in tobacco leaves. The free water content affects the physical properties and enzyme activities of protoplasm, and restricts the physiological and biochemical processes of tobacco leaves. The more free water content, the smaller the concentration of protoplasm, the smaller the viscosity of bio colloid and the stronger metabolic activity. Conversely, the free water content decreases, the protoplasm will change from sol to gel, the viscosity will increase, and the metabolism of life will be greatly weakened; if the protoplasm is too dehydrated, It will cause the destruction of biocolloids and the termination of life activities.

Second, yellowing: The humidity and temperature of air in the barn have a close influence on the yellowing degree and speed of tobacco leaves. (1) The relationship between yellowing and humidity: tobacco leaves must have moisture in order to yellowing, but the water should be appropriate. It is necessary to lose water during baking, and the rate of loss must be coordinated with the rate of yellowing. When the temperature is 37 C, the water content is lower than 75%, the yellowing is very slow, and the edge of the dry tip is withered; when the water content is 85%, the yellowing is normal and withered at the same time; when the water content is higher than 95%, although the yellowing is normal, the leaves do not wither, and there is “ hardening-yellowing-rdquo;. (2) The relationship between yellowing and temperature: Under normal conditions, the fastest and most suitable temperature for leaf yellowing is 38-mdash and 42 C. The lower leaves are generally yellow at about 38 C because of their sufficient water content and less contents; the middle leaves are moderate in water content, with more contents, generally at 38-mdash; the upper leaves are yellow at 39 C; and the upper leaves are less water, thicker and richer in contents, usually at 42 C. The optimum temperature for yellowing of tobacco ribs was 42-mdash in lower leaves, 42-mdash in middle leaves, 42-mdash in upper leaves, and 49-c in 47-c.

Third, roasting aroma: The research showed that the unique aroma of flue-cured tobacco began to appear when the roasting temperature reached 50 (?) C, which was mainly produced by the condensation reaction of sugar and amino acid. At present, it is generally believed that 50-mdash and 55 C are the key period for the mass production of aroma-producing substances in Flue-cured tobacco. Appropriately prolonging the baking time in this temperature zone is very helpful to improve the aroma quality of tobacco leaves. The temperature control range of dry tendon stage is generally 56-mdash and 68 C. However, many aroma substances have low boiling point and thermal instability. Excessive ambient temperature is disadvantageous to maintain the aroma of tobacco leaves, which can easily cause volatilization loss of some aroma components. Therefore, it is advisable to adopt & ldquo; ladder & rdquo; heating method in order to shorten the curing time under high temperature and reduce the aroma loss of tobacco leaves. Please visit /products/kaoyanfang.html or dial 400-998-9229 for more information.

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