Ann. Tabac, 1981-82, Sect. 2-17, p. 105-33., ISSN.0399-0354

Analytical approach of tobacco proteins. Technological implications

A first estimation of the potentiality of tobacco as a source of proteins for human and animal nutrition was made by a simple analytical approach of the protein content of the leaves and the plant as a whole, of two types of close-grown tobacco (burley and dark tobacco poor in nicotine, grown with plant populations of 250,000/ha in the field). On the one hand, this study permitted to determine exactly the distribution of the different nitrogenous substances in the plant according to the different stages of growth, and to underline the risk of over-estimating the protein levels in a global appreciation obtained through the quantification of total nitrogen or organic nitrogen (crude proteins). In another study, the problem of the extractibility of the water soluble proteins (fraction I and II proteins) was approached by comparing two modes of extraction (ïndustrial"extraction by water in the presence of Na metabisulfite and "laboratory" extraction by a Tris-HCl pH 8 buffer in presence of mercaptoethanol) on young or senescent tobaccos. The "industrial" process compared with the"laboratory"process, gave an extraction yield inferior by about 30% to 50%. The apparent beneficial influence of the stalk during the extraction was also demonstrated. In addition, the ability of the fraction I protein to crystallize which marks the originality of tobacco among the higher plants was evidenced on plants grown in the field. This property is of special interest in that it would permit, by using very simple _ therefore inexpensive _ technology, to produce large quantities of a very high quality protein.