Influences of Roasting Treatments on Nutritional Properties and Characteristic Aroma Compounds in GABA-Enriched Germinated Highland Barley Flour
Description
Roasting is a critical step affecting the nutritional quality and flavor of germinated highland barley flour. This study evaluated three roasting conditions (80°C/10 min, 130°C/5 min, and 160°C/3 min) on high-γ-aminobutyric acid (GABA) germinated flour. Results showed that increasing roasting intensity reduced GABA content (up to 85% loss at high temperature) but increased total phenolics and flavonoids. Quantitative descriptive analysis revealed a progressive decline in grassy aroma and enhancement of roasted, nutty, and caramel notes, with smoky character emerging at high temperature. Using HS-SPME-GC-MS-O combined with rOAV and AEDA, 42 key aroma-active compounds were identified among 138 volatiles; 2,5-dimethylpyrazine (FD=256, rOAV=223.7), trimethylpyrazine (rOAV=110.8), and maltol (rOAV=408.6) were the most significant contributors. Precursor analysis confirmed that reducing sugars and free amino acids accumulated during germination were largely consumed during roasting, showing strong negative correlations (r<−0.88) with Maillard reaction products, verifying Maillard reaction and Strecker degradation as core pathways for flavor formation. Considering nutrient retention, key aroma formation, and sensory quality, medium-temperature roasting (130°C, 5 min) effectively eliminated grassy off-flavor and achieved optimal balance, receiving the highest overall sensory score (87.5). This study provides a theoretical foundation for flavor-oriented processing of germinated barley products.