# Functionality and Appearance of Sorghum‐Pearl Millet Composite Flour Fortified With Oyster Mushroom for Thin Porridges

## TL;DR

This study shows that adding oyster mushrooms to sorghum-pearl millet flour improves its nutritional value and physical properties for making porridges in sub-Saharan Africa.

## Contribution

The study demonstrates that oyster mushroom fortification enhances cereal flours' functionality and nutritional value without negative effects.

## Key findings

- Fortified flours showed higher water, oil, and swelling properties due to oyster mushrooms' absorption capacity.
- Color lightness and yellowness improved with increased oyster mushroom levels in the composite flours.
- Rheological tests showed gel-like behavior in porridges, indicating enhanced elasticity with mushroom fortification.

## Abstract

Porridges are the main staple food in sub‐Saharan Africa. They are generally starchy and are made from composite flours of various cereals. Evaluation of color, pasting, rheological, and functional properties of the composite flour samples was done, since these influence the cooking and product quality of the porridges. Sorghum‐pearl millet blends were substituted at levels from 10% to 50% using oyster mushrooms to form the composite flours. Rheometer and Rapid Visco Analyzer were used in the determination of rheological and pasting properties respectively, while Chroma Meter was used in color determination. Bulk density, water and oil absorption, and swelling qualities were also determined. The study findings indicated that fortified flours had a consistently higher water, oil, and swelling properties indicating that oyster mushrooms have a higher absorption capacity. The color parameters (L* (degree of lightness), b* (yellowness), chroma, hue angle) increased while the pasting parameters (peak, trough, breakdown, final, and setback viscosities) reduced with an increase in oyster mushroom levels; that is, final viscosity decreased with increased oyster mushroom levels in the pearl millet‐sorghum flours from 1072.7 ± 61.8 to 216.8 ± 21.2 mPas. For the dynamic rheological tests of the thin porridges prepared from the composite flours showed a distinctive gel‐like character under the measurement conditions, an indication that elastic behavior dominated over viscous behavior. The level of storage and loss moduli decreased with increasing substitution levels, which is coherent with the pasting properties. Research on physico‐functionality of sorghum‐pearl millet composite flours fortified with oyster mushrooms shows that the substitution of mushrooms has no significant negative effect on the composite flour functionality. Oyster mushrooms could therefore be used to fortify cereals without affecting their physical properties.

This study investigated the functionality, color, pasting and rheological properties of sorghum–pearl millet composite flour fortified with oyster mushroom. Fortification increased water, oil and swelling capacities, while decreasing pasting viscosities. The color lightness and yellowness improved with increasing oyster mushroom levels. Rheological tests indicated gel‐like behavior (G′ > G″), showing enhanced elasticity of thin porridges. The findings demonstrate that oyster mushroom fortification can enhance cereal‐based porridge nutrition without compromising functional quality.