Temperature and relative humidity during air-curing and their effects on burley tobacco quality in different curing barns

Five air-curing barns (black plastic-film barn, red tile barn, American barn, mud barn and steel frame barn) were established in Dazhou City, Sichuan Province. Differences in temperature and relative humidity during burley tobacco air-curing among the different barns were then investigated. Tobacco leaf quality after air-curing in different barns was also determined. The results showed significant differences in adjustment of temperature and relative humidity among the different barns. Average temperature in different barns was in the order of: American barn > steel frame barn > red tile barn > black plastic-film barn > mud barn. Average diurnal amplitude in temperature was in the order of: steel frame barn > black plastic-film barn > mud barn > American barn > red tile barn. Adjustment ability of temperature was in the order of: mud barn < black plastic-film barn < steel frame barn < American barn < red tile barn. On the basis of temperature, steel frame and red tile barns exhibited the best effects while black plastic-film and mud barns exhibited the worse effects. Average relative humidity in different barns was in the order of: black plastic-film barn > mud barn > American barn > red tile barn > steel frame barn. Differences in relative humidity between barns and outdoors was in the order of: black plastic-film barn > mud barn >American barn > steel frame barn > red tile barn. On the basis of relative humidity, steel frame and red tile barns showed the best effects while black plastic-film and mud barns showed the worse effects. There was no obvious effect of air-curing in the different barns on the quality of leaf tobacco appearance. The appearance of burley tobacco air-cured in 5 barns met high-quality standard appearance requirement. There were differences in the impacts of different barns on chemical compounds of tobacco. Except for high sugar in mud barn, chemical components of air-cured burley tobacco basically conformed with high-quality burley tobacco requirement. Analysis of construction cost, practicality, heat preservation and dehumidifying effects as well as the effects on chemical compounds showed that steel frame barn was most consistent with local high-quality burley tobacco requirements.