RELATIONSHIP OF PHENOLIC CONSTITUENTS TO MATURITY, STALK POSITION, AND CERTAIN PHYSICAL CHARACTERISTICS OF FLUE-CURED TOBACCO

Abstract

Chlorogenic acids, scopoletin, and caffeic acid in green and cured leaves of flue-cured tobaccos harvested from various stalk positions at different stages of maturity were isolated and quantitatively determined. Total chlorophyll, which provided the basis of maturity classification, was measured in green samples. Lamina weight, grade index and visual lightness were determined in cured samples. Levels of the phenolics were related to chlorophyll, lamina weight, stalk position, grade index, and visual lightness.Chlorogenic acids increased from 33 to 500% during curing; levels in green and cured leaves varied from 0.1 to 1.9% (dry weight). Chlorogenic acids increased with advance in maturity and elevation in stalk position. Grade index was positively related to level of chlorogenic acids. Visual lightness was affected adversely by prolongation of the yellowing period, which was associated with both low and high levels of chlorogenic acids; therefore, visual lightness was rather poorly related to level of chlorogenic acids. Cured leaves contained less than 0.05% (dry weight) caffeic acid; none was detected in un-cured leaves. Levels of scopoletin and its glucoside were higher in cured than in green leaves; the amount of scopoletin was less than 0.03% (dry weight). Levels of caffeic acid and scopoletin in cured leaves were directly related to time of yellowing which increases with chlorophyll and lamina weight. Levels or scopoletin in green leaves increased with advance in maturity and elevation in stalk position.