Study On The Free Amino Acid Of The Flue-cured Tobacco

The free amino acid in flue-cured tobacco is important for the tobacco plants to metabolize nitrogen and to form the quality of tobacco leaves, and its content affect the quality of the tobacco and its smoke greatly. Through the analysis and research on the differences and variety regulation of free amino acid, nicotine, protein in various tobaccos and their maturing course, the theoretical basis and experimental basis can be provided for the tobacco species' selection and its plant.The test materials of this research are steamed ripen leaves from eight sorts of different genotypes, which are Yunyan87, RG11, G80, Cuibi No.1, NC82, K317, Red Flower Dajinyuan. Free amino acid is determined through reversed-phase high performance liquid chromatography derived from PITC; Nicotine is determined through ultraviolet spectrophotometry; And protein is determined through the Kjeldahl Nitrogen Determination method. With flue-cured tobacco k326 for test material, the contents of free amino acid, nicotine and protein are determined in the maturing course, and variety regulation is analyzed. The results of the research as the follow:1. To establish a set of integrated method for determining the content of free amino acid in steamed tobacco leaves through HPLC (derived from PITC), and including the methods for extracting, subliming, deriving and determining free amino acid. With this method free amino acid in the steamed tobacco leaves can be extracted furthest, and impurity that affects determining amino acid can be removed better. Better gradient elution separates every amino acid peak well. Its better repetition and higher recovery all prove the credibility of this experimental methods and results.2. To analyze and compare the differences of the contents of free amino acid, protein and nicotine in different genotype steamed tobacco leaves maturing course. In Yunyan 87 and RG11, the content of free amino acid is higher. In NC82 and Yunyan 85, the content of free amino acid is lower. In Red flower Dajinyuan and RG11, the content of protein is higher. In Cuibin No.1 and Yunyan 87, the content of protein is lower.3. It was researched that the dynamic variety of the contents of free amino acid, total nicotine and total protein in the upper, middle and lower leaves during the whole K326 maturing process. The variety of the contents of themain nitric compounds——free amino acid, nicotine and protein——hasstronger regulation. Ten days after topping, tobacco free amino acids declined rapidly, and then did slowly. But after topping, and the nicotine content continued to increase the protein content continued to decline. Regarding thetime after topping as independent variables——x, and total contents ofnicotine and protein as dependent variables——y, after analyzing them, theresult indicated that there was a positive correlation between nicotine content and the days after topping, and there was negative correlation between protein and the days after topping.