Successive grinding and sieving as a new tool to fractionate polyphenols and antioxidants of plants powders: Application to Boscia senegalensis seeds, Dichrostachys glomerata fruits, and Hibiscus sabdariffa calyx powders.

The present investigation aimed at evaluating the effect of powder fractionation based on particle size on the chemical composition in macronutrients, polyphenol contents, and antioxidant properties of powders of Boscia senegalensis seeds, Dichrostachys glomerata fruits, and Hibiscus sabdariffa calyces. Significant differences (p < 0.05) among granulometric classes of each plant were observed for the chemical composition in macronutrients. A decrease in particle size of plant powders was associated with an increase in ash, protein, and fat contents, while carbohydrate content was lowered. The following Granulometric classes, [0-180 µm] for Boscia senegalensis, [180-212 µm] for Dichrostachys glomerata, and [212-315 µm] for Hibiscus sabdariffa, respectively, were found to maximize total phenolic content and antioxidant activity. These results confirm that the grinding and controlled differential screening technology is an approach may serve as a useful guide to obtain optimum polyphenol extraction and enhance antioxidant activity of plant products.