Natural fermentation of lentils. Influence of time, flour concentration, and temperature on the kinetics of monosaccharides, disaccharide, and alpha-galactosides

Lentil seeds (Lens culinaris var. Vulgaris cv. Magda 20) were left to ferment naturally at different initial lentil flour concentrations (79, 150, and 221 g/L) and different temperatures (28, 35, and 42 degrees C). During fermentation, samples were taken at 24 h intervals. Changes in pH, titratable acidity, monosaccharides (fructose and glucose), disaccharide (sucrose), and alpha-galactosides (raffinose, ciceritol, and stachyose) were investigated. A large decrease in pH was observed after 24 h of fermentation, which continued more gradually in every experiment for 96 h. This drop in pH was accompanied by a rapid increase of titratable acidity. During the preparation of the lentil flour suspension the initial concentration of the lentil flour-water suspension had an important influence on the levels of fructose, glucose, sucrose, and alpha-galactosides, while temperature had a minor effect. Once fermentation occured, it was observed that both flour concentration and temperature modified the soluble sugar content and that the higher the initial flour concentration the greater the sugar content and the higher the temperature the greater the decrease in soluble sugar content.