Compositional characteristics of water-soluble sugars and Amadori compounds and their effects on sensory quality of Shandong flue-cured tobacco

【Objective】To determine the composition and content distribution characteristics of water-soluble sugars and Amadori compounds in B2F and C3F leaves from the upper and middle portions of Shandong flue-cured tobacco leaves, and to analyze the impact of these compounds on the sensory quality of flue-cured tobacco. The study would provide reference for improvement and precise regulation of the sensory quality of Shandong flue-cured tobacco. 【Method】The leaves of B2F and C3F flue-cured tobaccos produced in the main production areas of Shandong were selected as experimental materials, and water-soluble sugars and Amadori compounds in flue-cured tobaccos were analyzed by gas chromatography-mass spectrometry(GC-MS) and high-performance liquid chromatography-mass spectrometry(HPLCMS/MS), orthogonal partial least squares discriminant analysis(OPLS-DA) was conducted on B2F and C3F flue-cured tobacco samples, and evaluation of smoke samples of flue-cured tobacco was conducted, the main chemical components with positive/negative correlation with sensory quality indices of Shandong flue-cured tobacco were revealed by simple correlation analysis. 【Result】A total of 16 water-soluble sugars and 8 Amadori compounds were qualitatively and quantitatively analyzed in flue-cured tobacco, the contents of glucose and fructose were high, followed by sucrose, and the content of the rest of water-soluble sugars were low, among which the contents of arabinitol, psicose and mannitol were significantly different between B2F and C3F(P<0.05, the same below), the arabinitol content of C3F was as 1.50 times as that of B2F, and the psicose and mannitol contents of B2F were as 1.26 and 48.85 times as those of C3F, respectively.The main Amadori compounds in B2F and C3F tobacco leaves were 1-deoxy-1-L-proline-D-fructose(Fru-Pro)(14-45mg/g), followed by 1-deoxy-1-L-alanine-D-fructose(Fru-Ala), 1-deoxy-1-L-glutamic acid-D-fructose(Fru-Glu), 1-deoxy-1-L-phenylalanine-D-fructose(Fru-Phe), glucosamine(GLU), and 1-deoxy-1-L-tryptophan-D-fructose(Fru-Trp)(1-20 mg/g). The compounds that significantly contributed to B2F and C3F differentiation were revealed, and the following compounds were ranked in order of contribution: mannitol>psicose>ributol>lyxose>ribose>1-deoxy-1-L-valine-Dfructose(Fru-Val)>GLU>fructose>Fru-Ala. The scores for each sensory quality index of C3F leaves were greatly higher than those of B2F leaves. In B2F leaves, arabinitol, Fru-Pro, arabinose, xylitol, psicose, Fru-Ala were significantly or extremely significantly(P<0.01, the same below) positively correlated with partial sensory evaluation indexes, while FruGlu and GLU were significantly or extremely significantly negatively correlated with partial sensory evaluation indexes.In C3F leaves, ribose, psicose, fructose, glucose and maltose showed significant or extremely significant positive correlations with partial sensory evaluation indexes, and lyxose, ribitol, Fru-Glu and Fru-Phe showed significant or extremely significant negative correlations with partial sensory evaluation indexes. 【Conclusion】The contents of water-soluble sugars and Amadori compounds in Shandong flue-cured tobacco vary greatly among different parts, which in turn have different effects on the sensory quality of the tobacco.