Germinated Cereal Flours Exhibit Distinct Technological Properties, Water Sorption Behaviours, and Bioactive and Mineral Profiles

Abstract Germination is a low-cost bioprocess that modifies the composition and functionality of cereal grains, but its integrated effects on flour properties remain poorly understood. This study evaluated the technological properties, water adsorption behavior, thermodynamic properties, phenolic profile, antioxidant activity, and mineral composition of flours obtained from germinated maize, rice, and rye. Germinated rye flour showed the highest bulk density, solubility (7.53%), oil absorption capacity (144.47 g/100 g), and emulsion stability (44.97%), whereas maize flour had the highest water absorption capacity (165.96 g/100 g) and cohesiveness. The water adsorption isotherms were Type II and were best described by the Peleg and Guggenheim–Anderson–de Boer models (R² > 0.99), with monolayer moisture content decreasing as temperature increased. The integral isosteric heat of sorption decreased with increasing equilibrium moisture content, negative Gibbs free energy values indicated spontaneous adsorption, and enthalpy–entropy compensation showed that the process was enthalpy-driven. Twenty phenolic compounds were identified. Maize flour had the highest free phenolic content (121.05 mg/100 g), dominated by procyanidin A2, but the lowest antioxidant activity in all assays. Rice flour showed the highest radical scavenging activity, and rye flour the highest ferric reducing power. Multivariate analysis indicated that antioxidant activity was associated with the qualitative phenolic profile, particularly epigallocatechin gallate, rather than with free phenolic content. Rice flour had the highest contents of most minerals, including iron and zinc. Overall, controlled germination yielded flours with distinct technological and bioactive profiles, supporting their potential use as functional ingredients in bakery and gluten-free products.