Investigating the effect of enzymolysis and fermentation on the flavor of Laiyang pear syrup

In order to investigate the flavor quality of Laiyang pear syrup, Volatile components (VOCs) of Laiyang pear syrup were characterized using volatomics techniques combined with machine learning. 31, 32, and 47 key features were identified via Partial Least Squares Discriminant Analysis for gas chromatography–mass spectrometry, gas chromatography-ion mobility spectrometry, and comprehensive two-dimensional gas chromatography–mass spectrometry, respectively. Key VOCs were screened/verified by machine learning, with core aromas selected via aroma wheels and OAV analysis; E-nose and E-tongue supplemented flavor evaluation. Results showed TFP+GOD+F had optimal flavor. All the experimental results indicated that TFP+GOD+F exhibited the optimal flavor characteristics. In-depth studies on the flavor improvement mechanisms of β-glucanase, glucose oxidase and LD1.0010 on Laiyang pear syrup revealed that fatty acid metabolism, amino acid metabolism and monoterpenoid metabolism were the main metabolic pathways of aroma in TFP+GOD+F; the content of odor substances 1-octen-3-one and diethyl disulfide was reduced by glucose oxidase and β-glucanase respectively; the characteristic aromas borneol acetate, linalool and 1-(2-furanyl)-ethanone were produced through the complex enzyme system of glucose oxidase, β-glucanase and LD1.0010. By elucidating the mechanistic role of β-glucanase, glucose oxidase and LD1.0010 in enhancing pear syrup aroma profiles, this study establishes fundamental insights for targeted sensory quality control during processing. • Fermentation increased furfural and 1-(2-furanyl)-ethanone • Enzymolysis increased isoprene, acetic acid butyl ester and propionic acid propyl ester • Borneol acetate and linalool were main aromas in enzymatically fermented Laiyang pear syrup • Support vector machine was used to develop models of Laiyang pear syrup volatile components