Changes in Flavor and Quality of Pine Pollen Vinegar during Fermentation

The changes in color, taste, aroma, and quality of pine pollen vinegar during fermentation were evaluated in terms of bioactive ingredients, antioxidant capacity, color difference, electronic tongue analysis, free amino acids, organic acids, volatile compounds, and sensory scores. Principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA), and odor activity values (OAV) were then employed for differential analysis. The results indicated that the contents of total phenols, total flavonoids, vitamin C, free amino acids, and organic acids in pine pollen juice significantly increased during the fermentation process. The electronic tongue analysis showed that the bitterness of pine pollen juice decreased while its umami taste increased. By gas chromatography-mass spectrometry (GC-MS), a total of 110 volatile compounds were detected during the fermentation process, among which, aldehydes, acids, and esters were identified as the major aroma substances of pine pollen vinegar, and ethanol, 2-ethylhexanol, phenylethanol, isobutyric acid, ethyl acetate, nonanal, anisole, and acetic acid as the key differential substances during the fermentation process, conferring a pleasant aroma on pine pollen vinegar. Furthermore, sensory evaluation showed that pine pollen vinegar was superior to pine pollen juice in terms of color, flavor, aroma, and overall acceptability. These findings lay a theoretical foundation for the production of high-quality pine pollen vinegar a, hence promoting the deep processing and utilization of pine pollen.