The demand for food production has been constantly increasing due to rising population. In developed countries, for example, the emergence of regional production of old grains that are rarely utilized, along with the production of commonly consumed grains, has gained importance in recent years. These grains, known collectively as ancient or heirloom grains, have offered both farmers and consumers novel ways of cultivation and products with interesting taste, characteristics and nutritional value. Among the 30 000 plant species known, only five cereals currently provide more than 50% of the world's energy intakebread wheat (Triticum aestivum), rice (Oryza sativa), sorghum (Sorghum bicolor), millets (Panicum sp.) and maize (Zea mays). The excessive utilization of these selected species has a great potential to cause genetic losses and difficulty in bridging future agricultural demands. Teff (Eragrostis tef), an ancient grain extensively cultivated in countries like Eritrea and Ethiopia, provides promising alternatives for new food uses since its nutritional value is significantly higher than most others cereal grains. The absence of gluten allows flexibility in food utilization since it can be directly substituted to gluten-containing products. The grain also offers an excellent balance of essential amino acids and minerals, which can fulfil the recommended daily intake and eliminates the need for fortification and enrichment. This review provides a general overview of the physical properties and nutritional composition of teff grains related to processing and applications in the food and feed industries. The current status of teff utilization, as well as the challenges in production and commercialization, and future opportunities is presented and discussed.

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Increasing teff (Eragrostis tef) consumption has been recorded in recent years due to its gluten‐free nature and exceptional nutritional composition. Studies on the particle level that relates to processing and handling of teff flour are limited. The effect of different milling methods (roller mill, pin mill, and hammer mill) on size distribution, shape characteristics, and flowability of teff flour was evaluated. Physical properties (angle of repose, tapped and bulk densities, size distribution, and shape characteristics) and proximate composition were investigated and correlated with flow properties. Flowability was measured in terms of bulk, shear, and dynamic flow properties using the FT4 powder rheometer. Particle size distribution significantly (p < .05) influenced the angle of repose, aeration energy, and wall friction angle while shape characteristics (circularity and aspect ratio) significantly (p < .05) affected the aerated and tapped bulk densities and basic flow energy. Hammer‐milled flour had the highest aerated (548.00 kg/m3) and tapped bulk densities (804.33 kg/m3). Pin‐milled flour had the highest compressibility index (38.46%), Hausner ratio (1.62), angle of repose (71.57°), and wall friction angle (25.92° at 3 kPa) indicating poorer flowability. Stability index and specific energy did not vary significantly (p > .05) among the milled flours. Highest basic flow (1,191.03 mJ) and aerated energies (272.32 mJ) were required to induce flow in hammer‐milled flour due to greater proportion of large particles. Based on the flow function, all flours fall under the “easy flowing” category, but the pin‐milled flour exhibited the poorest flowability.

HighlightsTempering moisture content and condition had a significant impact on waxy white sorghum kernel and flour properties.Physical sorghum kernel properties after tempering varies with efficiency of moisture penetration into kernels.Steam tempering for 15 s led to better physical kernel properties for handling, transportation, and processing.Room temperature water tempering (18%, 24 h) yielded better flour yield and protein content.Abstract. To optimize the yield and quality of waxy white sorghum flour, the effects of various tempering treatments on sorghum kernel physical properties, milling performance, and flour properties were evaluated. Waxy white sorghum kernels were tempered at different moisture levels and for different times using either room temperature water, hot water, or steam. Tempered sorghum kernels were milled into flour using a milling flowsheet developed for a laboratory-scale tabletop roller mill that consists of four break rolls and eight reduction rolls. The effects of these tempering methods on waxy white sorghum kernel properties, roller milling, and flour properties were investigated. Tempering moisture content and condition had a significant impact on the waxy white sorghum kernel’s physical and flour properties. Steam tempering for 15s led to desirable physical kernel properties that would positively impact handling, transportation, and processing: lower bulk (732.53 kg/m3), tapped (769.39 kg/m3), and true densities (1313.37 kg/m3); lower hardness index (65.01); higher abrasive hardness index (AHI) (23.73); higher angle of repose (23.60); and higher coefficients of static (0.35) and rolling friction (0.29). In terms of milling, room temperature water tempering at 18% w.b. moisture level for 24 h resulted in better bran-endosperm separation without compensating for important flour quality characteristics. It exhibited higher protein content (9.72%), low ash content (0.94%), high bran extraction (6.42%), and high brightness (80.67). Room temperature water tempering at 18% w.b. for 24 h is a more suitable pretreatment prior to the milling of waxy white sorghum kernels in terms of flour yield and quality. Keywords: Flour properties, Kernel properties, Roller milling, Tempering, Waxy white sorghum.

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