Abstract: In this study, rye, black rice and black bean were subjected to extrusion or drum drying, and their physicochemical properties and storage stability were investigated. The aim was to evaluate the effect of the two treatments on the nutrient composition, solubility characteristics, flowability, rheological properties and storage stability of the three kinds of black grains. The results showed that both the treatments significantly decreased the contents of crude fat, starch and anthocyanin (P < 0.05), and improved the solubility (P < 0.05), but they did not markedly change protein contents. After either treatment, the flowability of black rice and black bean did not change noticeably, while that of rye was improved. All samples showed a non-Newtonian fluid shear thinning behavior. During 45-day accelerated storage, the free fatty acid content and peroxide value of each kind of unprocessed grain were higher than those of the drum-dried and extruded counterparts, and all the unprocessed and processed samples showed similar changes in carbonyl value change. Either treatment could alleviate grain quality deterioration caused by lipid oxidation and improve storage stability. Our research results provide theoretical data for developing ready-to-eat black grain products.

Key words: rye; black rice; black bean; extrusion; drum drying; nutrient contents; storage stability