What are the baking methods of tobacco leaves?

Tobacco leaves with the same cultivation techniques, different soil and climate conditions and different growth parts have different nutritional development levels and different curing characteristics. The main points of several different types of tobacco curing processes are introduced below. (1) Tobacco leaf baking under different cultivation techniques: Here, the main points of baking three kinds of tobacco leaves are summarized as follows: 1. Baking of Malnourished Tobacco Leaves in Hilly Land (1) Fresh tobacco leaves are characterized by small and yellow leaves, low water content, rich inclusions, strong water retention capacity and slow yellowing and dehydration. (2) Technical essentials: the dry bulb temperature should be low but not high, and the wet bulb temperature should be high and not low. Pay attention to moisturizing without yellowing, stabilize heat and slow fixation, and strive to bake high-quality cigarettes. (3) Harvesting and loading cigarettes: mature harvesting is not suitable for raw or over-ripe. Because of the slow maturity, the harvesting interval should be longer, and the smoke should be thick but not thin. (4) Wet bulb temperature: It should be slightly higher. Pay attention to moisturizing during the yellowing period, appropriately reduce the difference between dry and wet, and add water to humidify when necessary. (5) Starting temperature: about 32 ~ 36℃, which can be lower after autumn or shed fashion. (6) Heating speed: the heating should be slow rather than fast, and the curing time and patience should be appropriately extended. (7) Yellowing degree: Before the temperature is 40℃, the tobacco leaves will turn yellow by more than 80%, before the temperature is 42℃, by more than 90%, and before the temperature is 46℃, the tobacco leaves will turn yellow, but they will not turn blue after baking. 2. Flue-cured tobacco leaves with good water, fertilizer and nutrition in plain areas (1) Features of fresh tobacco leaves: the leaves are large and yellow, with rich contents, good maturity, normal yellowing and dehydration, but it takes a long time, and it is easy to be baked green and dusty. (2) Technical essentials: The dry bulb temperature should not be high and the wet bulb temperature should not be low. Pay attention to full yellowing, stable heating, slow discoloration, and do not bake green smoke to ensure high-quality tobacco leaves. (3) Harvesting and loading tobacco: Harvesting when it is mature or completely mature, preferably not raw, and green picking is forbidden. The upper pole should be slightly thinner, and the cigarette loading should be slightly thicker (not too thick). (4) Wet bulb temperature: The wet bulb temperature is slightly higher, and an appropriate wet-dry difference should be maintained during the yellowing period (too much water is added for humidification and too little drainage). (5) Starting point temperature: The starting point temperature is about 36 ~ 38℃, and attention should be paid to prevent the bottom shed from baking green due to excessive temperature. (6) Heating speed: heating should be slow, steady and unpleasant, and the baking time should be prolonged to ensure the tobacco leaves to change fully. (7) Yellowing degree: Before the temperature is 40℃, the tobacco leaves turn yellow by more than 70%, before the temperature is 42℃, the blue veins turn yellow, and before the temperature is 48℃, the yellow veins do not contain green. 3. Baking of tobacco leaves with excessive nitrogen application and bad yellowing (1) The characteristics of fresh tobacco leaves are: large and thin leaves, plenty of water, insufficient inclusions, not easy to turn yellow and dehydrate, and easy to turn green and black. (2) Technical essentials: the dry bulb temperature should be high, the wet bulb temperature should be low, and the temperature should be raised faster. Pay attention to the water discharge, bring water first and then color to prevent yellowing, insufficient baking and over-baking. (3) Harvest and smoke loading: harvest from ripe to ripe, neither raw nor over-ripe, the rod should be thin, and the smoke loading should be slightly thin (avoid being too thick). (4) Wet bulb temperature: The wet bulb temperature is slightly lower, so a large difference between wet and dry should be maintained during yellowing period, and water drainage should be strengthened to facilitate tobacco softening. (5) Starting temperature: about 38 ~ 40℃. Pay attention to prevent the temperature from being too low, which will harden and turn yellow. (6) Heating speed: heating should be slightly faster. It is necessary to ensure that tobacco leaves turn yellow and prevent tobacco leaves from baking green or black. (7) Yellowing degree: Before 40℃, tobacco leaves turn yellow about 30%, before 42℃, about 50%, before 45℃, about 70%, before 48℃ and before 50℃. (2) Tobacco leaf baking under different climatic conditions: Different climatic conditions affect the accumulation and transportation of substances in tobacco leaves, thus affecting the coordination of nutritional status and chemical components in tobacco leaves at harvest, which will inevitably affect the baking process and final baking results. The main points of tobacco leaf baking in dry and rainy weather were summarized. 1. Flue-cured tobacco leaves in rainy days (1) The characteristics of fresh tobacco leaves are: more water, less dry matter, insufficient inclusions, yellow but suitable, difficult to fix color, easy to bake black or green. (2) Technical essentials: the dry bulb temperature is higher, the wet bulb temperature is lower, and the temperature rises quickly, so as to strengthen the water discharge and prevent excessive yellowing, black baking and green baking. (3) Harvesting and loading cigarettes: Harvesting should be ripe, not raw, and not over-ripe. It is advisable to release the rod and draw thin. (4) Wet bulb temperature: the wet bulb temperature should be low, the difference between wet and dry should be large in yellowing stage, and the wet bulb temperature should be low but not high in fixing stage. (5) Starting point temperature: higher to prevent hard yellowing. The smoke in the bottom shed should be pretreated (turn 30% yellow before entering the kang) to prevent the bottom shed from baking green.

(6) Heating speed: be faster to prevent black smoke, and at the same time, consider (properly control) the yellowing of tobacco leaves to prevent green curing. (7) Yellowing degree: Yellowing should not be too high in the low temperature stage, and the fire should be turned earlier, and yellow stripes should be reached before 50℃ to prevent blackening in the later stage. 2. Tobacco leaf baking in dry days (1) The characteristics of fresh tobacco leaves are: less moisture, more dry matter, fullness, late yellowing and dehydration, and easy to bake green or hang ash. (2) Technical essentials: the dry bulb temperature should be low, the wet bulb temperature should be high, and the temperature rise should be slow. Pay attention to moisturizing, fully turn yellow, and prevent scorching and ash hanging. (3) Collecting and loading cigarettes: the maturity should be high, avoiding leaves and collecting exposed smoke. The upper pole should not be too thick, and the loading of cigarettes should be thick. (4) Wet bulb temperature: it should be a little higher, and the difference between wet and dry in yellowing stage should be smaller. If it is too large, add water in time, which can moisturize and promote yellowing. (5) Starting point temperature: it should be low but not high to prevent baking. (6) Heating speed: it should be slow rather than fast, so as to ensure that the tobacco leaves turn yellow fully and prevent the rapid heating from turning green and hanging ash. (7) Yellowing degree: Yellowing at low temperature is better than yellowing at low temperature. When the temperature changes, it will reach the blue veins or yellow veins, and it will turn yellow completely before 48℃. 3. Dry yellow tobacco leaves are baked (1). Fresh tobacco leaves are characterized by immature leaves, insufficient inclusions, low water content, strong water retention, not easy to turn yellow and dehydrate, and easy to bake green, black and gray. (2) Technical essentials: the wet and dry balls should be slightly higher to promote yellowing, and the fire should be turned early, but the color should be fixed slowly to prevent baking green, hanging ash and baking black. (3) Harvest and smoke loading: It is appropriate to harvest truly mature leaves, but it should not be harvested when the scorch is too heavy. Cut tobacco should be thick, not thin. (4) Wet-bulb temperature: The wet-bulb temperature should be slightly higher. In the yellowing period, the difference between wet and dry should be appropriately reduced, and the slightly higher wet-bulb temperature should be maintained to promote yellowing. (5) Starting point temperature: it should be slightly higher, and the temperature can be appropriately lowered after the leaves become soft to prevent baking. (6) Heating speed: the yellowing time is faster and the fixation time is slower, so that the tobacco leaves turn yellow completely during fixation. (7) Yellowing degree: about 70% yellow. Turn the fire, slowly raise the temperature, slowly fix the color, and then use a higher temperature to completely yellow the tobacco leaves. (3) Baking of different parts of tobacco leaves: Different parts of tobacco leaves are affected by space and time, and there are great differences in dry matter enrichment, leaf tissue compactness, leaf tissue water content and water retention capacity, so the baking technology is also different. The main points of baking the upper, middle and lower parts of tobacco leaves are as follows. 1. Lower leaf baking (1) Fresh tobacco leaves are characterized by thin and loose leaves, insufficient inclusions and high water content, but their water retention capacity is not strong, and they are easy to turn yellow, difficult to fix color and easy to bake black or green. (2) Technical essentials: The wet bulb temperature should be slightly lower, the dry bulb temperature should not be higher, but the temperature should be slightly faster. Pay attention to the coordination between yellowing and drying, strengthen water discharge, and prevent baking from blackening. (3) Collecting and loading cigarettes; It is easy to bake green when harvesting, and it is easy to bake black when overcooked. When it is ripe, it should be harvested early, and the cigarette packaging should be thin and not thick, which is beneficial to moisture removal and color fixation. (4) Wet bulb temperature: it should be slightly lower, and there is a big difference between wet and dry during yellowing, which is beneficial to leaf softening. (5) Starting temperature: about 32 ~ 37℃, which should not be too high to prevent premature dehydration.

2. Baked middle leaves (1) Fresh leaves are characterized by moderate thickness, sparse structure, rich inclusions, normal yellowing and fixation, and easy baking. (2) Technical essentials: You can basically refer to the basic baking mode, and do everything possible to bake more high-quality cigarettes. (3) Harvest and tobacco filling: mature harvest, not raw, reduce smoke, and tobacco filling should not be too coarse and too fine, but moderate. (4) Wet bulb temperature: it should not be too high or too low, and it should not be too high or too low. The difference between wet and dry is moderate during yellowing. (5) Starting temperature: about 34 ~ 38℃, not too high or too low. (6) Heating speed: With the change of tobacco leaves, the temperature should be increased and the time should be extended by 45 ~ 47℃ to promote the full yellowing of tobacco leaves. (7) Yellowing degree: When the veins turn yellow, they turn to fire. Before 47℃, blue smoke such as yellow smoke will reach the whole kang yellow, so do everything possible to prevent baking. 3. The upper leaves are baked (1). The characteristics of fresh leaves are: dense leaf thickness, rich contents, less water, strong water retention, slow yellowing, difficult dehydration, and easy to bake and hang ash. (2) Technical essentials: The wet bulb temperature is higher, and the dry bulb temperature is also higher, but the temperature should be raised slowly, fully yellow, and the color should be fixed slowly to prevent the baking green from hanging ash. (3) Harvest and smoke loading: fully mature harvest, with yellowing as the degree, not over-ripe, in case of ash hanging, and smoke loading should be thick and not thin. (4) Wet bulb temperature: it should be slightly higher, and the Huang Shi dry-wet difference should be slightly smaller. If it is too large, it should be replenished and humidified in time. (5) Initial temperature: about 36 ~ 39℃, which should not be too low to promote water evaporation. (6) Heating speed: it should be slower than faster to prevent turning green and hanging ash, and extend the time by 46 ~ 48℃ to make the tobacco leaves turn yellow completely. (7) Yellowing degree: pulse Huang Shi turns to fire, and blue smoke such as yellow smoke reaches the whole kang yellow before 48℃, and the color is stable, so as to prevent baking paste from hanging ash. (4) Baking of several special tobacco leaves 1. Black storm smoke: The so-called black storm smoke refers to the tobacco leaves that grow in the field. The leaves are fat and thick, and even if they are not baked well, it is difficult to turn yellow and mature. Black storm smoke often contains a lot of water, little dry matter, and its internal chemical composition is not harmonious. Black tobacco leaves are thick and extremely thin after baking. It is not easy to yellow and dehydrate during baking, and the relationship between yellowing and drying is difficult to synchronize, so it is easy to bake blue and black. Black smoke can be divided into old black smoke and young black smoke. For black smoke, comprehensive control methods such as strengthening field management and improving spatial nutrition should be adopted to improve the baking quality as much as possible. (1) Old black storm smoke: The upper leaves were formed under the conditions of high water and fertilizer and excessive helium application. The leaves are large and thick, dark green and old green are not easy to turn yellow, the tissue is dense and the water retention is strong. The water content is not too high, but it is rich, but the proportion of protein is high. Baking is slow in yellowing, difficult to dehydrate, easy to brown due to insufficient yellowing, too long delay time, easy to ash or brown due to excessive consumption of dry matter, and easy to ash or burn due to sudden increase of temperature due to excessive water content, which is unfavorable to baking. Even if baked, it is dark yellow, red yellow, reddish brown yellow, with dark color and poor oil content. Wait patiently for the old black smoke to mature and turn yellow to prevent it from turning yellow and dehydration during baking. But don't overcook it, so as not to hang ash or bake it black. Under normal circumstances, the leaves are obviously yellow and yellow, and it is appropriate to harvest them when they are about eighty or ninety years old. The density of kang should be moderate, and the tobacco should be evenly packed to prevent overlapping and squeezing between tobacco leaves in upper and lower sheds. The technical essentials of modulating old black smoke are: selecting traditional baking technology and using it flexibly according to specific conditions. Usually, the dry bulb temperature is higher and the wet bulb temperature is slightly lower, which makes the tobacco leaves soften in time during yellowing. The yellowing degree is lower before the fire turns. Turn the fire ahead of time, slowly raise the temperature, stabilize the color, promote the tobacco leaves to slowly lose water and turn yellow completely at a higher temperature, and prevent the tobacco leaves from being green, gray and black. The technical points are as follows: the initial temperature of dry bulb is about 39℃ or higher (the darker the storm, the higher), the wet bulb temperature is about 36℃ when the dry bulb reaches the initial temperature, and the difference between wet and dry is controlled at about 3℃, so as to promote the tobacco leaves to turn yellow while slowly losing water and softening. With the increase of yellowing degree, the temperature should rise gradually, not too fast. It should be kept at 47 ~ 48℃ for a period of time, so that the tobacco leaves turn yellow by about 90% and yellow before 50℃ (100% yellow). The wet bulb temperature shall not exceed 38℃ before the tobacco leaves are fixed. Burn the fire accurately, raise the temperature steadily, don't rise and fall sharply to prevent ash hanging. (2) Blue-black explosion: The lower tobacco leaves were formed under the conditions of multi-line high water and fertilizer, high density, uncoordinated nutrients and excessive nitrogen content. Leaf fertilizer (thin after drying), dark green and light green are not easy to yellow, the tissue is loose, the water content is high, the dry matter content is low, the inclusion is insufficient, and the water retention capacity is stronger than that of ordinary normal tobacco leaves and weaker than that of old black smoke. When baking, it often turns yellow too slowly in the early stage, turns yellow quickly in the later stage, and turns black soon after turning yellow, which makes it difficult to fix color and easy to bake black. At the same time, it is easy to be afraid of baking black, turning yellow and baking green. It is not difficult to dehydrate tobacco leaves, but it is difficult to remove water (from inside the kang to outside the kang) because of its high water content, which is easy to evaporate and evaporate. In a way, tender black cigarettes are more difficult to bake. We should pay attention to the harvest of tender black tobacco to prevent over-ripening. The experience of "70% harvest and 80% loss" circulating in production is derived from this tobacco leaf. The tobacco rod should be thin, not too thick, and one large leaf can be used (60 ~ 80 pieces per rod). The density of kang should be thin, but not thick, to prevent moisture from blocking. At the same time, kang should be installed evenly to prevent overlapping and squeezing. The technical essentials of preparing tender black explosive smoke are: adopting traditional baking technology and using it flexibly according to specific conditions. Generally speaking, it is advisable to control the dry bulb temperature to be high and the wet bulb temperature to be low, so as to promote the tobacco leaves to soften first and then change color. When the fire turns, the yellowing degree should be low but not high to prevent it from being burnt black. After changing the fire, strengthen the burning and ventilation to remove moisture, and promote the faster drying of tobacco leaves. As long as most tobacco leaves can be cured yellow, it can be considered as reaching the expected standard (a certain amount of green smoke is allowed after curing). If one-sided emphasis is placed on "burning all yellow", it will be counterproductive and easy to bake into black smoke. The term "healthy tobacco leaves are green and green and easy to dry" in production refers to this kind of tobacco leaves. The technical points are as follows: the starting temperature of dry bulb is about 40℃ or higher (the darker the storm, the higher the temperature), sometimes it can reach 42℃ or higher, the wet bulb temperature is controlled at about 36℃, and the difference between wet and dry is maintained above 4℃, so as to promote the tobacco leaves to soften first and then turn yellow in the early stage of yellowing. When diagnosing the yellowing degree of tobacco leaves, we should pay attention to both leaves and leaf bases, both leaf edges and veins, so as to prevent local yellowing from occurring too fast or too slow and causing operational errors. As the tobacco leaves turn yellow, it should be heated in time, and it is not advisable to stay at a certain temperature for a long time. "It is better to call it fire and smoke than smoke and fire." When the tobacco leaves turn yellow by about 50%, the temperature should be raised to 45℃. The yellowing speed of tobacco leaves may be obviously accelerated from 50% yellowing, so attention should be paid to drying and fixing color in time. Therefore, it is necessary to strengthen the fire after 45℃, and at the same time strengthen the ventilation and dehumidification, that is, "big fire, big ventilation and big dehumidification" to prevent the baking from being black due to the untimely drying and color fixation. During the whole yellowing and fixing process, the wet bulb temperature should be controlled at 36 ~ 37℃, generally not exceeding 38℃. 2. Rain-drenched smoke (1) ① Baking characteristics: refers to tobacco leaves with clear water attached to their leaves under the influence of short-term rainfall (for example, within 24 hours) when they are harvested. Because the influence of rainfall is still relatively small, only some attached moisture is added, so the baking characteristics have not changed much. (2) Technical measures: Immediately after ignition, open the skylight and underground hole to remove moisture, first remove the attached moisture of tobacco leaves, then close the skylight and underground hole and switch to normal baking. This kind of tobacco leaves are not affected by rainfall, but they should be baked as yellow as possible. (2) Green-returning tobacco ① Baking characteristics: Tobacco leaves are affected by long-term rainfall, which makes mature and yellow tobacco leaves turn green and tender before rain. This kind of tobacco is called green tobacco. Not only the moisture in the leaves has changed, but also the contents have changed. The content of carbohydrates such as starch decreased and protein increased. It is difficult to turn yellow and dehydrate when baking, and the dried leaves are easy to brown, which is not conducive to baking. (2) Technical measures: After the weather clears up, it's best to let the returned smoke bask in the sun for a few days and let it naturally fall to Huangshi for harvesting again. If the weather is cloudy, you can't wait for the weather to clear up, otherwise it will be prone to "dry water". The harvest should be ripe, and packed slightly thinly on the kang. During curing, in addition to treating tobacco leaves with high water content, we should give lower wet bulb temperature and higher dry bulb temperature, and also pay attention to extending the pre-fixation time as much as possible. Generally, it is necessary to extend the time at 45 ~ 47℃ and discharge a lot of water to make the tobacco leaves smaller. Then, the temperature can continue to rise and turn to normal baking. If the temperature rises rapidly above 48℃ after the fire is switched, the tobacco leaves will easily deteriorate gradually. When the moisture content of tobacco leaves is high, the temperature rises faster and higher, which is easy to cause scald and dehydration difficulty. 3. Pale yellow smoke: Under the conditions of high water and fertilizer, high density and dark fields, pale yellow smoke is easy to appear. The main reason is that the field ventilation is seriously poor and the light is insufficient, which hinders the formation of chlorophyll. (1) Curing characteristics: This kind of tobacco leaves is seriously short of contents, rich in water, less in dry matter, loose in tissue, light and thin in leaves, yellowish white, and easy to be cured in the field. When baking, the color is fast and the black is fast. It is difficult to turn yellow normally, and it is also difficult to dry the leaves smoothly, which is easy to burn. It is the technical point of baking to pay attention to removing moisture and prevent baking from going bad. (2) Technical measures: Pay attention to early harvest in time to prevent baking in the field. The kang should not be thick, in case of bad moisture. The wet bulb should be controlled below 37℃, and the more water content, the lower it is. The dry bulb should be on the high side, controlled at about 40℃, and the higher the water content, but the dry bulb should not be too high, not exceeding 42℃, in case the yellowing degree is not high when sweating turns to fire (about 60% yellow, the more the water content, the lower). In the yellowing period, the fire should be raised in time to adapt to the characteristics of fast coloring. The temperature rise during the dead leaf period should be appropriate, neither fast nor slow, and should not be lengthened at a certain temperature. According to the yellowing and dehydration of tobacco leaves, the temperature is gradually raised and the color is fixed, so that the tobacco leaves gradually turn yellow and gradually dry and fix color in the process of gradually raising the temperature and draining a lot of water. The key to curing this kind of tobacco leaves is to turn to fire early, gradually raise the temperature, strengthen dehumidification and fixation, and prefer green to black.