Handling and Curing Characteristics of Cut-Strip Tobacco. Part 2: Effect of Yellowing Time and Drying Potential

This paper presents Part 2 of a study on comparative handling and curing characteristics of cut-strip vs. whole leaf tobacco. Part 1 considered the effect of leaf size (cut-strip size vs. whole leaf), packing density and mode of leaf orientation on cured leaf chemistry and leaf quality; whereas, the present study considers further the effect of leaf form, two yellowing times and two drying potentials during yellowing. Results showed that leaf chemistry and quality were quite similar for cut-strip (15.2 × 22.9 cm) and whole leaf. Insignificant differences were noted for cured leaf starch and sugars, although slightly lower levels of alkaloids (significant at the 0.01 level) were observed for cut strip. Curing treatments significantly affected leaf chemistry. Increased yellowing time resulted in lower levels of starch and higher levels of sugar. Sugars were also higher for tobacco yellowed under the higher drying potential. The two forms of leaf responded similarly to different curing schedules (i.e. no interaction of leaf form with schedule). Also, government grade and price data were essentially unaffected by leaf form or curing schedule over the range of variables tested. Cured leaf starch was abnormally high on the average for both leaf forms. Interestingly, starch levels were lower when intact tobacco was bulk-cured in racks rather than box cured (6.35% vs. 9.02%). Since curing schedules were similar, air velocity in the two curing methods might be a factor. Also the cured leaf starch content was about 56% lower for tobacco produced at the Oxford Tobacco Research Station (in a secondary study) than at the Central Crops Research Station. It is postulated that carbohydrate and nitrogen metabolism during growth and maturation might be affected by excess rainfall events and/or nitrogen availability, with subsequent effects on starch-to-sugar conversion during curing.