Effect of Different Fermentation Methods on the Physicochemical, Bioactive and Volatile Characteristics of Wolfberry Vinegar

Wolfberry (<i>Lycium barbarum</i> L.) as a functional food is rich in nutrients and bioactive substances. However, the fresh wolfberry is difficult to preserve, and its deep-processing products are required to improve. In the present study, single-strain fermentation vinegar (SFV) and mixed-strain fermentation vinegar (MFV) were prepared, and the physicochemical, bioactive compounds, antioxidant capacities and volatile characteristics were examined to obtain an optimal method. The results showed that reducing sugar was sufficiently utilized during mixed-strain fermentation, and more acid substances were produced compared with single-strain fermentation. Meanwhile, total phenols content (2.64 ± 0.04 mg GAE/mL), total flavonoids content (1.81 ± 0.01 mg GAE/mL) and antioxidant activities in MFV were significantly increased compared with those in SFV. Rutin, p-hydroxycinnamic acid, and 4-hydroxybenzoic acid presented higher contents in MFV than those in SFV. The contents of total organic acids (88.13 ± 0.13 mg/mL) and total amino acids (6.50 ± 0.17 mg/mL) in MFV were significantly improved compared with those in SFV. Proline, alanine and serine were the top three amino acids in MFV. Moreover, acids, eaters, and alcohols were the pre-dominant volatile organic compounds in MFV, which were higher 9.49%, 55.27%, 18.72% in MFV than those in SFV, respectively. The results suggest that MFV efficiently enhances potential health benefits and flavor, which increases the economic value of wolfberry.