Changes on Techno-Functional, Thermal, Rheological, and Microstructural Properties of Tef Flours Induced by Microwave Radiation—Development of New Improved Gluten-Free Ingredients

Abstract

Tef [Eragrostis tef (Zucc.) Trotter] flour is a gluten-free cereal rich in fiber, minerals, vitamins, and antioxidants, which offers a promising alternative for new food development. This study investigated the effect of microwave radiation (MW) on the techno-functional, thermal, rheological and microstructural properties of tef flours. White and brown tef grains were milled and microwaved at different moisture contents (MC) (15%, 20% and 25%) for a total irradiation time of 480 s. The morphological structure of tef flours was affected by MW treatment, and its particle size and hydration properties increased after the treatment. Lower peak, breakdown, and setback viscosities, up to 45%, 96%, and 67% below those of the control (untreated) samples, and higher pasting temperature, up to 8 °C in the 25% MC samples, were observed. From FTIR analysis a disruption of short-range molecular order was concluded, while DSC confirmed an increased stability of starch crystallites. Rheological analysis of the gels made from the treated samples revealed that MW had a structuring and stabilizing effect on all samples, leading to higher viscoelastic moduli, G′ and G″, and the maximum stress the gels withstood before breaking their structure, τmax. The MC of the flours during the MWT drove the modification of the techno-functional properties of the tef flours and the gel rheological and thermal characteristics. These results suggest that MW-treated tef flours are potential ingredients for improving the technological, nutritional and sensory quality of food products.

Hydrothermal Treatment via Microwave Radiation Improves Viscoelastic Properties of Native Gluten-Free Flours for Extrusion 3D Printing

“…In teff flours, the variety had an interesting impact, as the elastic and viscous moduli values of gels made with WT were always higher than BT. Similar results were observed by Calix-Riveira et al for other Spanish cultivated teff varieties [35] for native flours. Such behavior suggests firmer internal consistency, probably affected by the lower lipid content in the white variety.…”

“…Pasting temperature increased in all cases of treated samples; this resembles the slowed absorption during the heating ramp. Similar results were observed by Vincente et al and Calix-Riviera et al [34,35] for buckwheat and teff flours after MV treatment. The generalized slowed water absorption is connected to both the overall particle size distribution change in the samples as well as amylose release and melting characteristics of particle samples; this was proven by several authors for both flour and starch samples [31][32][33].…”

“…A similar behavior was observed by Vincente et al and Calix-Riviera et al [34,35] for lower initial moisture content treatments. A 30% initial water content allows amylose leaching and protein hydration, resulting in a sticky matrix causing smaller particles to adhere to bigger ones.…”

“…Hydrothermal treatment via microwave radiation has been shown to improve the viscoelastic properties of teff and buckwheat flours and resulted in increased particle size, hydration properties, and stability of starch crystallites [34,35]. These findings suggest that hydrothermal treatment via microwave radiation can enhance the viscoelastic properties of teff and buckwheat flours, making them potential ingredients for improving the technological, nutritional, and sensory quality of food products.…”

Physicochemical Characterisation of Seeds, Oil and Defatted Cake of Three Hempseed Varieties Cultivated in Spain

“…Water absorption capacity (WAC), water absorption index (WAI), water solubility index (WSI) and swelling power (SP) of the totally defatted hempseed flours were determined following the method described in Calix-Rivera et al ( 2023) [34]. Foaming capacity (FC) and foam stability (FS) were analysed according to the procedures described by Abebe et al ( 2015) [25].…”