Effect of rice flour extrusion on α-dicarbonyl compounds, protein glycation products, and the formation of acrylamide and 5-hydroxymethylfurfural in bread crust-like system

Extrusion conditions and particle size significantly influenced the formation of Maillard reaction products (MRP) in rice flour and bread crust-like model system. In extruded rice flour ( 132-200 μm; barrel temperatures 80 °C and 120 °C; feed moisture 15% and 30%), 3-deoxyglucosone and methylglyoxal were the predominant α-dicarbonyl compounds. In rice flour samples, higher feed moisture (30%) combined with elevated temperature increased 3-deoxyglucosone and furosine concentrations, while N-ε-carboxymethyllysine and N-ε-carboxyethyllysine levels declined. In crust-like model systems, lower feed moisture (15%) markedly elevated both acrylamide and 5-hydroxymethylfurfural (5-HMF), whereas higher temperature selectively enhanced 5-HMF formation. Flour particle size had a negligible influence on acrylamide and 5-HMF in the crust-like model. These findings demonstrate that feed moisture is the dominant processing factor controlling hazardous MRP formation, with temperature acting as a secondary modulator specific to 5-HMF.