Study On Variation Of Important Neutral Aroma Constituents In Tobacco Leaf During Aging

In order to find out variation regularity of important neutral aroma constituents and relationshipbetween neutral aroma constituents and smoking quality during aging, we detected53neutral aromaconstituents in Zhucheng tobacco leaf with GC/MS and smoking quality in different stages of aging.Through analyzing concrete data, we could provide scientific directions and references for aging andimproved industrial availability. The specific results were as follows:(1) Variation of important neutral aroma constituents during aging.The total of neutral aroma constituents (neophytadiene excepted) was gradually increasing with theincreasing of aging time. The rate of increase slowed down and set to plateau with the increasing ofaging time after18months.A continuing increasing trend was found for the carotenoid degradation products,the Maillardreaction compounds，aromatic amino acid degradation products and other kind of aroma constituents.The content of the chlorophyll degradation products decreased with the increasing of aging time. Thecontent of cembranenoid degradation products keep stable during aging.(2) Variation of smoking quality during agingQuality aroma, concentration of aroma, aftertaste, offensive odor, irritancy and total score hadconsistent trend during aging: these indexes were continually increased with the first18months ofaging,reaching peak in18months. The smoking quality began to decrease and tend to be stable after18months. Changes in the six indexes all reached significant or very significant level.(3) Relationship between important neutral aroma constituents and smoking quality during agingTotal of neutral important constituents was positively correlation with smoking, the relationshipbetween them was influenced by way of aging and leaf position.The direct effect of carotenoid degradation products on smoking quality was detrimental, the indirecteffect of carotenoid degradation products on middle leaf smoking quality was beneficial and on upperleaf smoking quality was not significant. The direct effect and indirect effect of the Maillard reactioncompounds were all favorable for smoking quality. The direct effect and indirect effect of thecembranenoid degradation products on aroma quality and aftertaste were significantly favorable, thecembranenoid degradation products played direct role that was significantly beneficial to aroma quality,aftertaste and irritancy in middle leaf under artificial aging. The direct action of the aromatic amino aciddegradation products on smoking quality was not significant, the indirect action on offensive odor,irritancy in upper leaf and aroma quality, aroma concentration,offensive odor, total in middle leaf underartificial aging were all significant favorable, the aromatic amino acid degradation products had littleindirect action on middle leaf smoking quality under natural aging. The chlorophyll degradationproducts showed no significant correlation with smoking quality of upper leaf under artificial aging andmiddle leaf under natural aging, the direct action on aroma quality, offensive odor in middle leaf underartificial aging was significant detrimental. The indirect action on aroma quality, offensive odor,aftertaste, total in middle leaf under artificial aging and aroma concentration, offensive odor,irritancy,total were all significant detrimental. The indirect action of other kind of aroma constituents onsmoking quality was favorable, but direct action was little.There were five neutral aroma constituents associated with smoking quality,they were as follows:2-acetyl-5-methyl-furan, phenylacetaldehyde, β-damascone,2-cyclopentene-1,4-dione,1,3,7,7-tetramethyl-2-oxo-bicyclo[4.4.0]dec-5-en-9-one, the preceding four aroma constituents werestrongly positively correlated with smoking quality, and β-damascone showed negative correlations withsmoking quality.