Effect of soaking, germination, and roasting on the proximate composition, antinutrient content, and some physicochemical properties of defatted Moringa oleifera seed flour

The effect of soaking, germination, and roasting on some physicochemical properties of defatted Moringa seeds flour was studied using a 23 complete factorial design. Soaking was operated for 24 hr in water (1/10, w/v) with changing of water every 4 hr. Germination consisted of soaking seeds previously for 6 hr in water and sprouting for 8 days. Roasting was done at 140°C/50 min. A total of eight treatments were then applied to the seeds which were then dehulled, finely ground, and defatted, and the resulting flours were submitted to physicochemical analysis. The results showed that particle size of defatted flour was bimodal (13 and 300 µm). The whiteness index varied from 66.9 for the soaked–germinated–unroasted (S.G.UR) sample to 79.8 for the nonsoaked–germinated–unroasted (NS.G.UR) sample. The moringa flours (treated or untreated) were concentrated in proteins (57.21–70.45 g/100 g DW). While the protein and crude fiber (3.11–5.20 g/100 g DW) contents significantly increased with the treatment, the carbohydrate (14.56–24.67 g/100 g DW) and total dietary fibers (22.99–38.28 g/100 g DW) diminished. The antinutrients/toxicants as saponins, oxalates, phytates, and trypsin inhibitors were significantly (p < .05) reduced with treatment. While most of the antinutrients were at low level in the flour, the glucosinolates were at remarkably higher levels which may induce toxicity if consumed. Glucosinolates ranged 5.84–7.95 g/100 g DW and were not reduced above the tolerance limit (0.79 g/100 g DW). In overall, the treatments induced important improvement of the nutritional quality of the flour with combined treatment being more efficient. Novelty impact statement The combined treatments (S.G.UR., S.NG.R, NS.G.R, and S.G.R) were more efficient compared to single treatments (S.NG.UR, NS.G.UR, and NS.NG.R) with raw (untreated) sample (NS.NG.UR) as a reference. The most efficient combined treatment was S.G.R. followed by S.G.UR, NS.G.R., and S.NG.R because they promote the best increasing protein contents of defatted Moringa seed flour with 20% of increase for S.G.R., 10% for S.G.UR., and 6% for NS.G.R and S.NG.R. The maximum antinutrients reduction was observed with combined treatments; thus, the reduction rate of glucosinolates was −18% and −28% for S.G.R and S.NG.R, saponins was −37% and −66% for S.NG.R and S.G.UR., alkaloids was −71% and −66% for S.G.R and NS.G.R, oxalates was −51% and −57% for S.NG.R and S.G.UR, respectively, and trypsin inhibitor was −100% for almost all combined treatments.