Study of the changes on the physicochemical properties of isolated lentil starch during germination.

ABSTRACT

In this work, the changes in the composition of the flours and in the morphological, structural, thermal, vibrational, rheological, and functional properties of the isolated lentil starch during the germination process were investigated. The fiber, fat, and ash content of the flours decreased and the protein content increased, while the apparent amylose content of the starch granules remained constant. Using scanning electron microscopy (SEM), the starch granules remained intact during germination, and no enzymatic activity of α- and ß-amylases was observed. X-ray diffraction shows that the starch has nanocrystals with hexagonal structure which predominate over the nanocrystals with orthorhombic structure and are classified as C-type starch. The most important result is that these nanocrystals do not play an important role during germination. As the germination time progresses, differential scanning calorimetry (DSC) shows a decrease in the gelatinization temperature (Tp) of the starch, ranging from 70.34 ± 0.25 °C for the native lentil starch to values of 67.16 ± 0.37 °C for the starch on the fourth day of germination (ILS4), this transition being related to the solvation of the nanocrystals. On the other hand, the pasting profiles show no significant changes during germination, indicating that no significant changes in starch content occur during germination. Starch degradation is essential for the production of malt for fermented beverages. This fact makes sprouted lentils not a candidate for the short-term fermentation required in the beverage industry.