The relationship between the color change of cigar tobacco leaf and the main nitrogen compounds and smoking quality during fermentation

【Objective】To analyze the relationship between the color change and the main nitrogen compounds(total nitrogen, nicotine, protein, amino acid, nitrate, nitrite, chlorophyll a, chlorophyll b) and the quality of smoking during the fermentation process of cigar tobacco leaves, so as to provide a reference for the improvement of the fermentation qualityof cigar tobacco leaves.【Method】Using the upper leaves of Dexue No.1 as the test material, the artificial stacking method was used for fermentation, and the changes in the color, main nitrogen compounds and the quality of smoking cigar tobacco leaves during the fermentation process were measured, and the relationship between these parameters was investigated to establish a dynamic predictive equation.【Result】The contents of total nitrogen, nicotine, protein, amino acid, chlorophyll a, chlorophyll b and color parameters L^*, a^*, b^*, and C values all showed a slow decreasing trend during the fermentation of cigar tobacco leaves. The degradation rate of nitrogen compounds was rapid and there was no significant difference between 25^th and 30^th days of fermentation (P>0.05). After 30 days of fermentation, the contents of total nitrogen, protein, nicotine, amino acid, chlorophyll a and chlorophyll b were degraded by 18.8%, 23.5%, 42.5%, 31.8%, 42.2% and 41.4%, with L^*, a^*, b^* and C values of 30.245, 8.305, 14.350 and 16.580, respectively. The contents of nitrate, nitrite and H⁰ showed a trend of first increasing and then decreasing, while the △E value showed a slow increasing trend. At 30^th d of fermentation, the nitrate content, nitrite content, H⁰ and △E values were 5.78 mg/g, 21.11 μg/g, 30.060 and 62.303, respectively. All evaluation indicators of fermented tobacco were better relative to unfermented tobacco leaves. However, when fermented for 25 days, the quality of the tobacco leaves was better than at 30 days; the cigar style was prominent, the aroma of the tobacco leaves was clear, the mellowness, fullness and cleanliness of the smoke were significantly improved, the miscellaneous gas and irritation were significantly reduced, the aftertaste was comfortable and the smoke balance was better. The results of correlation analysis showed that the correlations between the color parameters of cigar tobacco leaves and the main nitrogen compounds and the quality of smoking during the fermentation process were significant(P<0.05) or extremely significant(P<0.01). The results of regression analysis showed that the contents of total nitrogen, protein, amino acid, chlorophyll a and chlorophyll b had a direct impact on the color changes of cigar tobacco leaves during the fermentation process and the evaluation of smoking quality was closely related to the color parameters.【Conclusion】The color parameters in the fermentation process are closely related to the main nitrogen compounds and the quality of smoking. By establishing a model of the quality of smoking during the fermentation process, the controllability of the fermentation process of cigar tobacco leaves is improved and cigar leaves with better quality of smoking are obtained.