Chemical Composition, Functional Properties, FTIR, and TGA Analysis of White Fonio (Digitaria exilis Stapf., Poaceae) Flour

Abstract

Background: Fonio is an underutilized ancient West African cereal with promising nutritional, functional, structural, and thermal properties that support its potential application in value-added food products and large-scale industrial utilization. Aims: This study aimed to evaluate the chemical composition, functional properties, pasting behaviour, and structural characteristics of white fonio (Digitaria exilis (Kippist) Stapf., Poaceae) flour to establish its suitability for food and industrial applications. Study Design: Experimental laboratory-based study. Place and Duration of Study: Department of Industrial Chemistry Laboratory, Ekiti State University, Ado-Ekiti, Nigeria. The study was conducted using standard analytical procedures. Methodology: White fonio grains were processed into flour and analyzed using standard methods. Proximate composition and mineral profile were determined using AOAC procedures and spectrophotometric methods. Functional properties (water/oil absorption, foaming, gelation, dispersibility, pH, and swelling power), and pasting characteristics were evaluated using established techniques and a Rapid Visco Analyzer. Structural and thermal properties were assessed using Fourier Transform Infrared (FTIR) spectroscopy and Thermogravimetric Analysis (TGA). Results: The flour exhibited high carbohydrate (75.89%), moderate protein (7.61%), and low fat (2.50%) contents, with moisture (10.08%) suitable for storage stability. It showed high water (238%) and oil (120%) absorption capacities, indicating good functionality in food systems. Pasting properties revealed a peak viscosity of 280 RVU, high final (485 RVU), and setback (315 RVU) viscosities, suggesting strong paste formation and high retrogradation potential. FTIR analysis confirmed characteristic starch and protein functional groups, while TGA indicated thermal stability with two major degradation phases. Conclusion: White fonio flour demonstrates favorable nutritional composition, functional versatility, and thermal stability, making it a promising raw material for gluten-free products, value-added foods, and industrial applications.