Changes in Non-volatile Metabolites of Elaeagnus multiflora Fruit Vinegar during Fermentation

This study aimed to understand the changes in quality characteristics of <italic>Elaeagnus multiflora</italic> fruit vinegar according to the fermentation period. During the fermentation of <italic>E. multiflora</italic> fruit vinegar, pH decreased, and total acidity and yellowness increased. The total phenolic compound and total flavonoid contents of <italic>E. multiflora</italic> fruit vinegar gradually increased during fermentation. 2,2-Azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS⁺) radical scavenging activity and ferric reducing antioxidant power of <italic>E. multiflora</italic> fruit vinegar increased to the 35 day of fermentation and then decreased. In the liquid chromatography-mass spectrometry metabolite result, 59 main compounds, including organic acids, leucic acid, phenolic acids, flavonoids, and tricoumaroyl spermidine were detected in <italic>E. multiflora</italic> fruit vinegar. The partial least squares discriminant analysis score plot indicated that <italic>E. multiflora</italic> fruit vinegar samples were clearly distinguished according to different fermentation periods. Flavonoids and amino acid derivatives decreased, and phenolic acids and organic acids increased during the fermentation of <italic>E. multiflora</italic> fruit vinegar. The metabolomic result suggests that flavonoid glycosides and tricoumaroyl spermidines might be considered as marker compounds in of <italic>E. multiflora</italic> fruit. It also provides useful information for understanding the fermentation property of <italic>E. multiflora</italic> fruit vinegar.