Effect of different roasting steps on protein degradation and lipid oxidative hydrolysis, promoting flavor in Larou

Traditional Larou is typically processed in "family workshops," which results in inconsistent product quality and hampers its scientific inheritance. Consequently, a multi-step roasting technology has been proposed, which minimizes the interference of external factors and effectively enhances the flavor of Larou. However, the mechanisms underlying its flavor formation remain unclear. This study investigates how multi-step roasting promotes flavor formation by analyzing protein degradation and lipid oxidative hydrolysis. Results showed that three-step roasted Larou (TRL) exhibited significantly higher hydroxyl, acid value (AV), and phospholipase activity compared to control groups (one-step roasted Larou (FRL) and two-step roasted Larou (SRL)). Electrophoretic analysis revealed significant protein degradation during processing, particularly noticeable in TRL during later stages. And three-step roasting increased the content of free fatty acids (FFA) and free amino acids (FAA) in Larou. Furthermore, PCA-Biplot analysis and odor activity values (OVA) screened a total of 28 key flavor compounds. Quantitative results showed that TRL possessed a higher content of flavor compounds, primarily comprising phenols, aldehydes, alcohols, and ketones, and correlation analyses showed some correlations with protein and lipid oxidation. In summary, the three-step roasting process moderately promoted protein degradation and lipid oxidative hydrolysis, thus improving Larou flavor quality.