Involvement of hydrolytic reactions in the deterioration of Moringa oleifera Lam. seeds during storage
Natural aging; Seed quality; Biochemical markers; Deterioration reactions.
The aim of this work was to investigate the deterioration of Moringa oleifera Lam. (moringa) seeds stored in a growth chamber (27 ± 2ºC and RH 65%) and under refrigeration (4 ± 2ºC and RH 25%) for twelve months. The harvests were performed prior to storage and every three months. Moisture content, germination percentage and average time, seedling length and dry weight, and content of neutral lipids, starch, soluble proteins, total soluble sugars, non- reducing sugars, and total free amino acids, as the activity of lipases, amylases and acid proteases were evaluated. Only seeds stored in the growth chamber showed an increase of moisture content and germination average time, followed by a decrease of germination percentage and seedling dry mass at the end of twelve months. In both environments, the content of neutral lipids remained unchanged, whereas the content of starch and soluble proteins decreased over time. Curiously, the activity of lipases increased, while the activities of amylases and acid proteases did not follow the decrease of starch and soluble protein content, respectively, during the experimental period. Furthermore, in both environments, there was no accumulation of soluble sugars, non-reducing sugars, and total free amino acids. Therefore, it is possible to conclude that moringa seeds keep viability and vigor when stored by twelve months under refrigeration. It is likely that non-enzymatic hydrolysis of starch and soluble proteins may contribute to start the process of deterioration in moringa seeds during the period of storage, regardless the environment.