Comparative Evaluation of Germination Methods on the Nutritional and Sensory Profile of Coix

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.