Potato starch noodles (PSN), a characteristic gluten-free Asian food, are essentially high-concentration starch gels (about 35% starch) formed through gelatinization and retrogradation. This study systematically investigates freezing temperature effects, particularly across the glass transition temperature, on PSN texture and microstructure. We found that fresh PSN have a freezing point of −1 °C, supercooling temperature of −4.5 °C, and a T_g’ value of −3.1 °C. Freezing significantly reduced the adhesiveness of PSN and increased the hardness. During the 48 h freezing process, noodles frozen at −3 °C, the closest to T_g’, exhibited the highest hardness (14,065.77 g), springiness (0.98), cohesiveness (0.93), chewiness (11,971.06), and resilience (0.84), and the least adhesiveness. PSN frozen within the range near T_g’ (−3 °C) showed superior texture, continuous solid cross-section, and dense surface, attributed to the reverse transformation of starch, high mobility of starch chains, and smaller ice crystals. PSN frozen at −3 °C for 24 h displayed the most compact and desirable texture compared to the other samples. These findings deepen the understanding of the role of glass transition temperature in the texture formation of starch gel during freezing and provide valuable insights for optimizing the frozen processing of starch gel-based food.

Coix has gained significant research interest for its medicinal and nutritional value, yet its characteristic bitterness limits food applications. To enhance its utilization in the food industry, this study examined the impact of conventional water immersion, ultrasound-assisted immersion (10, 15, and 20 min) and heat-treated immersion (40, 50, and 60 °C) on the nutritional profile and taste properties of Coix. Germinated Coix showed reduced starch, fat, and phytic acid content, but increased protein, γ-aminobutyric acid (from 38.05 to 58.00–116.90 mg/100 g, p < 0.05), dietary fiber, soluble sugars, total phenolics, and DPPH radical scavenging activity (n = 5). Germination introduced palmitoleic, linolenic, arachidonic, myristic, and arachidic acids to Coix, increasing total amino acids and umami taste activity value from 88.09 to 104.50–141.39 (p < 0.05). The reduced bitterness and astringency of germinated Coix may be associated with lower linoleic acid content and higher levels of palmitoleic acid, aspartic acid, and glutamic acid. Ultrasound-assisted immersion for 20 min was identified as the optimal condition for enhancing GABA and amino acid contents while reducing bitterness, thereby broadening the food applications of Coix.