Effects of enzyme treatment on chemical components and aroma quality of upper leaves of flue-cured tobacco from southern Shaanxi

In order to improve the usability of upper leaves of flue-cured tobacco from southern Shaanxi, the upper leaves of cv. Yunyan 87 were sprayed with enzyme preparations (amylase, cellulase and complex enzyme) at two concentrations (30 U/g and 60 U/g) before curing. The contents (mass fraction) of routine chemical components and aroma components and sensory quality of cured leaves were analyzed. The results showed that, compared with the control, 60 U/g cellulase and 60 U/g amylase treatments were significantly effective, and the total soluble sugar, reducing sugar and potassium contents were significantly increased in the cured tobacco leaves. The potassium content was 11.5% and 17.7% higher than the control respectively. The nicotine content in the leaves after 60 U/g cellulase treatment and the starch content in the leaves after 60 U/g amylase treatment were significantly lower than those of the control. The flue-cured tobacco under the 60 U/g cellulase treatment had the highest total sensory score, followed by that under 30 U/g cellulase treatment. The GC-MS test results indicated that compared with the control, the degradation products of plastid pigment of flue-cured tobacco treated with the 60 U/g cellulase were significantly increased by 52.5%. In addition, Maillard reaction products and the content of cembrane aroma substances also increased to varying degrees. Therefore, spraying 60 U/g cellulase before curing can improve the quality of the upper tobacco leaves through harmonizing the chemical components, improving the sensory quality and increasing the content of aroma substances.