Changes in Physicochemical Properties and Flavor Characteristics of Rosa roxburghii Tratt. Fruit Vinegar during Fermentation

This paper investigated the compositional changes of Rosa roxburghii Tratt. fruit vinegar during fermentation. By using Rosa roxburghii Tratt. as raw material and using the whole liquid fermentation technique, fruit vinegar was prepared by fermenting alcoholic and acetic acids simultaneously. The physicochemical properties of the fermentation process were dynamically monitored. Headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and the odor activity value (OAV) were utilized to analyze volatile flavor components. As fermentation proceeded, soluble solids, pH, total sugars, and reduced sugars decreased, while total acid and V_C contents increased. From the original juice to the end of acetic acid fermentation, the total acid and V_C contents ranged from 1.86 g/100 mL and 956.82 mg/100 mL to 6.79 g/100 mL and 1275.88 mg/100 mL. Oxalic acid, quinic acid, pyruvic acid, ascorbic acid, lactic acid, acetic acid, and fumaric acid showed varying degrees of increasing (P<0.05). By contrast, formic acid, citric acid, maleic acid, and succinic acid exhibited little variation. A total of 92 volatile compounds were detected in the Rosa roxburghii Tratt. fruit vinegar, and with the addition of OAV analysis, ten volatile compounds were identified as key aroma compounds, which included nonanal, acetaldehyde, ethyl isobutyrate, ethyl butyrate, ethyl 2-methylbutyrate, ethanol, isoamyl alcohol, leaf alcohol, linalool, and phenyl ethanol. Among these components, ethyl butyrate and leaf alcohol contributed most to the aroma of Rosa roxburghii Tratt. fruit vinegar. Green grass and green apples were characteristic aromas of this vinegar. The results of the study would provide a theoretical basis and practical guidance for the effective control of fermentation conditions, revealing the physicochemical characteristics and flavor features of fermented Rosa roxburghii Tratt. fruit vinegar, forming a method for quality evaluation of Rosa roxburghii Tratt. fruit vinegar, and formulating quality standards.