Structural, Physicochemical, and Functional Properties of Waxy and Non-Waxy Foxtail Millet Starches

This study investigated the physicochemical, structural, and functional characteristics of foxtail millet starches (FMSs), including five non-waxy varieties (N-HXMS, N-LXMS, N-QZHS, N-JG21S, N-BLGS) and one waxy control (W-HJGS). All FMSs exhibited polygonal granules with surface pores and an orthorhombic crystalline structure (A-type X-ray diffraction pattern). Compared with the waxy FMSs, non-waxy starches exhibited higher amylose content (32.4–34.04%), reduced crystallinity (37.01–39.21%) and short-range molecular order, and lower hydration capacity and molecular weight (1.01 × 105–2.81 × 105 g/mol). The non-waxy FMSs also demonstrated enhanced resistance to mechanical shear, better structural stability, stronger recovery behavior, and reduced enzymatic susceptibility. Varieties like N-LXMS, with higher amylose and resistant starch contents (31.17%), are more suitable for functional foods targeting glycemic control, while W-HJGS, with higher swelling power (22.76 g/g) and solubility (92.30%), is well suited as a thickener. This study provides a foundation for future research on the modification of FMSs and their utilization as starch-based matrices in various applications, such as functional food development, biodegradable packaging materials, and targeted delivery systems for bioactive compounds.