Study On Key Techniques Of Flue - Cured Tobacco Leaves

Based on the study to tobacco leaf’s harvest maturity, curing barn’s loading density, loading mode and curing technology of loose tobacco leaves, etc. 4 loose leaf bulk curing key technologies, as well as appearance quality, chemical compositions, smoking sensory quality, economic benefitearningss of flue-cured tobacco afterleaves, this paper seeks the best ‘harvest maturity, loading density, loading mode and curing process’, etc. supporting technologies on flue-cured tobacco loose leaf bulk curing, to provide technical reference and theoretical basis for the region’s tobacco leaf production and research of flue-cured tobacco loose leaf bulk curing technology. Main research results of the paper are as follows:(1) Research on harvest maturity: ① Appearance quality, for the leaf at the same place, after-curing color is gradually dark from ‘slight green to more orange’ with the improvement of harvest maturity, the oil content is gradually increased from ‘a little to a lot’, the body is from ‘slightly thin’ to ‘medium’, the structure is gradually loose from dense, the chroma is gradually strong from ‘weak to strong’, the maturity shows ‘green, yet ripe, mature, mature’ in turn; After curing, the leaf’s high class leaf rate, high and secondary leaf rate, orange leaf and average price increased at first and then decreased with the increase of maturity, the high class leaf rate of middle leaf process harvest maturity yellowing(means comprehensive yellowing degree) 60%(M3) is 72.86%, respectively higher 13.4%, 9.24% and 5.42% than mature harvest yellowing 40%(M1), mature harvest yellowing 50%(M2) and mature harvest yellowing 70%(M4); The high class leaf rate of upper leaf M3 is 56.33%, very significantly higher than M1(41.50%), M2(44.62%) and M4(47.49%), respectively increased 14.83%, 11.71% and 8.84% ② With the increase of leaf harvest maturity, the middle leaf shows: the stimulus of process increased at first and then decreased gradually, the combustibility of leaf increased at first and then decreased, the energy gradually increased and then decreased, among them, the combustion effect of M3 is the best, aroma quantity and quality are better and the energy is the largest. The upper leaf shows: the combustion effect of process appears wave change and the combustion effect of M3 is the best; The stimulus and energy appear the trend of gradual rising, and change to be steady when at M3 and M4; The content of reducing sugar and total sugar is gradually decreased, and steady when at M4. ③ Smoking sensory quality, the middle leaf shows M3﹥M4﹥M2﹥M1 and the upper leaf shows M3﹥M4﹥M2﹥M1.(2) Research on loading density: ① Appearance quality, with the increase of loading density, after-curing leaf’s color is gradually dark from ‘lemon yellow to reddish brown’, the body is gradually thick from ‘slightly thin to slightly thick’, the structure is gradually dense from ‘loose to dense’, the maturity is gradually improved, the chroma is gradually thickened and the oil content shows the trend of incr eased at first and then decreased; The high class leaf rate, high and secondary leaf rate, orange leaf and average price of the leaf at the same place increased at first and then decreased, after curing, the level quality of leaf shows: for the middle leaf, the loading density 85 kg/m2(D2) is the best, the second is 80 kg/m2(D1) and the worst is 90 kg/m2(D3); For the upper leaf, the loading density 90kg/m2(D2) is the best, the second is 85 kg/m2(D1) and the worst is 95 kg/m2(D3); ② Chemical composition, for loading density D1 of middle leaf and loading density D3 of upper leaf, the aroma quality is poor, odor is heavy, stimulus is larger and combustibility and aftertaste are poor; For middle leaf D3 and upper leaf D1, petroleum ether extract is slightl y more and aroma quality is slightly better.③ Smoking sensory quality, the total score of middle leaf process is 62.74-63.09; The total score of upper leaf’s process is 61.76-61.87, the difference is not significant. ④ Curing costs and earnings, with the increase of loading density, the curing earnings increased at first and then decreased, middle leaf’s loading density D2(85 kg/m2) and upper leaf’s loading density D2(90kg/m2) are the best loose leaf bulk curing loading density of the experiment.(3) Research on loading mode: ① Appearance quality, after process and curing, the middle and upper leaf’s color shows ‘more orange’, the oil content respectively shows ‘more’, ‘more- exist’ and the maturity shows ‘mature’. The partial difference is: after curing, the body of loose-leaf accumulation(W1) is thin and chroma is relatively weak, after curing, the body of bundled loose-leaf(W3) is thick, structure is dense and chroma is strong. After curing, the body, structure and chroma of loose-leaf with frame(W2) are moderate; The high class leaf rate of middle leaf W2 is 77.53%, higher 15.7% and 7.11% respectively than W1(61.83%) and W3(70.42%); The high class leaf rate of upper leaf W2 is 45.31%, higher 10.75% and 8.17% respectively than W1(34.56%) and W3(37.14%). ② Chemical composition, in the comparison of single chemical composition content and coordination, although individual processing data or ratio has difference, all meet the requirements of high-quality tobacco, what shows that three loading mode have no significant effect to chemical composition’s coordination of after-curing leaf. ③ Smoking sensory quality, the effect of three loading modes to smoking sensory quality of leaf is little, we can know from total score that, the middle leaf is W2﹥W3﹥W1, the upper leaf W2 is the highest, the second is W3 and the lowest is W1. ④ Curing costs and earnings, different loading mode has different effect to curing workload, every curing one unit tobacco, W1, W2 and W3 respectively consumes 6.5 workload, 6 workload and 7.5 workload; Different loading mode has little effect to kg dry tobacco’s power consumption and kg dry tobacco’s coal consumption.The curing earnings of different loading modes show: loose-leaf with frame are the highest, the second is bundled loose-leaf and loose-leaf accumulation is the lowest.(4) Research on curing technology: ① Appearance characteristics of leaf, for middle leaf, the appearance characteristics of key temperature and humidity 38℃/34.5 ℃(namely, dry-bulb temperature 38 ℃ and wet-bulb temperature 34.5 ℃, similarly hereinafter) in curing yellowing stage and key temperature and humidity 52℃/34.5℃ in leaf-drying stage will be the best if they show ‘more orange, more, medium, loose, strong and mature’, in key temperature and humidity of yellowing stage, the body is thin, in leaf-drying stage 52℃/35℃, 54℃/35℃, the more color is ‘lemon yellow’, and the structure is slightly dense; For upper leaf, after curing, the appearance characteristics will be the best if they are yellowing stage 36℃/34.5℃ and leaf-drying stage 52℃/34.5℃, in yellowing stage 36℃/34℃ and 38℃/34℃, after-curing leaf shows ‘more lemon yellow’ color, the body is ‘slightly thin’, structure is ‘loose’ and chroma is ‘medium’, in leaf-drying stage 52℃/34℃, 54℃/34℃, the color of after-curing leaf shows ‘orange – reddish brown’, after-curing leaf 52℃/35℃, 54℃/35℃, shows ‘slightly thick’ body and ‘slightly dense’ structure.②Leaf’s chemical composition is similar with appearance quality, for middle leaf, the chemical composition and coordination after processing and curing under key temperature and humidity in different curing stage show that: after curing in yellowing stage 38℃/34.5℃ and leaf-drying stage 52℃/34.5℃, the stimulus is moderate, taste is good, the mellowness is better and aroma and aftertaste are good. For upper leaf, the chemical composition and coordination after processing and curing under key temperature and humidity in different curing stage show that: after curing in yellowing stage 36℃/34.5℃ and leaf-drying stage 52℃/34.5℃, the stimulus is moderate, combustibility is good, energy is enough, taste is good and aroma quantity and quality are better. ③ Smoking sensory quality, for middle leaf curing, the 38℃/34.5℃ in yellowing stage and 52℃/34.5℃ in leaf-drying stage is the best;for upper leaf curing, the 36℃/34.5℃ in yellowing stage and 52℃/34.5℃ in leaf-drying stage is the best.(5) Best key technology supporting and combination, the best loose leaf bulk curing supporting technology of middle leaf is ‘harvest maturity comprehensive yellowing 60%,loading density 85 kg/m2,loose-leaf with frame mode,curing yellowing stage key temperature and humidity(dry-bulb temperature 38℃ and wet-bulb temperature 34.5℃), and leaf-drying stage key temperature and humidity(dry-bulb temperature 52℃ and wet-bulb temperature 34.5℃)’; The best curing technology of upper leaf is ‘harvest maturity comprehensive yellowing 80%, loading density 90 kg/m2, loose-leaf with frame mode,curing yellowing stage key temperature and humidity(dry-bulb temperature 36℃ and wet-bulb temperature 34.5℃), and leaf-drying stage key temperature and humidity(dry-bulb temperature 52℃ and wet-bulb temperature 34.5℃)’.In a word, the key of saving costs and increasing earnings to flue-cured tobacco loose leaf is to fully grasp suitable harvest maturity, loading density, loading mode and curing key temperature and humidity.