Effect of pearl millet and cowpea pre-treatments on rheology, digestible starch, and molar mass distribution of soluble starch fragments in composite porridge

• Composite porridges exhibited shear-thinning behaviour and tan δ <1. • All porridges contained rapidly digestible starch. • Germinated pearl millet porridges exhibited the lowest viscosity. • Fermented porridges had higher concentrations of solubilised starch fractions. • Blends with fermented and germinated samples may help combat undernutrition. This study investigated the rheological behaviour, digestible starch fractions, and molar mass distribution of solubilised starch fragments in composite porridges made from soaked, germinated, and fermented pearl millet and cowpea. All formulations exhibited shear-thinning behaviour at the consumption temperature of 40°C and demonstrated viscoelastic characteristics, balancing between solid-like (elastic) and liquid-like (viscous) properties. Composite porridges containing germinated pearl millet exhibited the lowest apparent and final viscosities, as measured by both rheometer and Rapid Visco Analyser. All composite porridges were classified as rapidly digestible starch (RDS), with 60–62% of DM hydrolysed within the first 20 min, and minimal change observed throughout the 240 min digestion period. RDS is a desirable attribute in composite porridges, as it provides a readily available source of dietary energy to support growth and promote weight gain. Formulations containing fermented pearl millet and fermented cowpea, either together or in combination with germinated pearl millet or cowpea (FMFP, FGMFP, and FMFGP), showed higher intrinsic viscosity and greater concentrations of degraded solubilised starch fragments than those made with soaked cowpea (FMSP, FGMSP and FMSGP). These molecular characteristics are consistent with the lower viscosities and the RDS observed across samples. The findings demonstrate that simple, low-cost pre-treatments influence the molecular characteristics of solubilised starch fraction and, consequently, the functional properties of composite porridges. These modifications may contribute to the development of nutrient-dense, culturally acceptable porridge for feeding undernourished children in Mozambique and other low-income counstries facing similar challenges.