Particle-Size-Sieved Fractions of <i>Caesalpinia pulcherrima</i> Seed Flour: Physicochemical, Nutritional, and Functional Properties

Flamboyant-mirim seed flour (FSF) emerges as a promising natural ingredient obtained from grains rich in proteins, carbohydrates, minerals, and bioactive compounds. This study aimed to characterize FSF and evaluate the effect of particle size on its chemical, physicochemical, technological, mineral, and functional properties. The seeds were milled using a knife grinder, and the flour fractions were separated through sieves of 0.710, 0.500, 0.355, and 0.250 mm. Analyses included proximate composition, technological, and functional parameters, and 1H NMR spectroscopy was performed only for the selected 0.250 mm fraction (chosen due to its superior proximate composition) to assess solvent-dependent compositional variability. Data were acquired through triplicate sampling and statistically treated using ANOVA, Tukey’s test, and supervised multivariate analysis (PLS-DA). All analyses were performed in triplicate (n = 3), and PLS-DA was validated by Venetian Blinds cross-validation. The 0.250 mm fraction showed higher ash, lipid, protein, fiber, and mineral contents as well as elevated water solubility index and superior oil absorption, foaming, and emulsifying capacities. The 0.500 mm fraction exhibited the highest total phenolic content and antioxidant activity. PLS-DA analysis indicated that pH, soluble solids, color parameters, phenolics, and antioxidant capacity were the main discriminant variables among the samples. Overall, the results demonstrate the potential of FSF as a functional ingredient for innovative formulations in the food industry.