Climate-Resilient Crops as Gluten-Free Substitutes: A Systematic Review of the Nutritional, Technofunctional, and Rheological Properties of Sorghum, Pearl Millet, and Amaranth Awaiting Galley Proofs; In Production

Abstract

Background: Gluten-free (GF) flours serve as indispensable dietary alternatives for individuals with gluten intolerance, offering various nutritional diversity. Despite the increasing global prevalence of gluten intolerance, there is limited systematic research on the potential of drought-tolerant grains specifically sorghum, pearl millet, and amaranth as viable gluten-free flour substitutes.

Aims: This study provides a systematic evaluation of the nutritional, functional, and farinographic properties of gluten-free flours derived from red and white sorghum, pearl millet, and amaranth. The primary goal is to assess their technofunctional viability as wheat alternatives in the formulation of gluten-free bakery products.

Methods: Adhering to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic review was performed on 30 peer-reviewed articles published between 2015 and 2024. The selection focused predominantly on empirical research emerging from the Asian and African continents, reflecting the regional importance of these traditional crops.

Results: Nutritional profiling revealed that white sorghum flour possessed the highest zinc concentration (13.20 mg/g), while red sorghum exhibited superior iron levels (28.93 mg/g). Amaranth flour demonstrated the most robust nutritional density, with peak values for protein (25.5%) and crude fiber (15.9%). Conversely, pearl millet displayed the lowest concentrations of iron (0.11 mg/g) and crude fiber (0.6%). Regarding technofunctional properties, pearl millet exhibited the highest water absorption capacity (359.33% ± 1.45), while white sorghum recorded the minimum (1.07% ± 0.04). Amaranth achieved the highest oil absorption capacity (1.88 g/g ± 0.01), whereas pearl millet exhibited the highest swelling index (8.17 mL/mL ± 0.01). Within the context of baking performance, pearl millet yielded the highest specific volume (4.87 cm³/g). However, amaranth flour emerged as the most comprehensive gluten-free candidate, demonstrating superior performance in loaf volume, porosity, and crumb firmness.

Conclusion: The findings underscore the significant potential of traditional, underutilized grains to satisfy the escalating market demand for nutritious gluten-free products. Future research should prioritize the optimization of composite flour blends to enhance both nutritional bioavailability and crumb structure. This may be achieved through the integration of novel processing techniques to effectively replicate the viscoelastic network typically provided by gluten.

Keywords: Gluten-free; Climate-Resilient Grains; Baking Technology; Nutritional Composition; Sorghum; Pearl Millet; Amaranth.