Effects of Different Yeasts on the Physicochemical Properties and Aroma Compounds of Fermented Sea Buckthorn Juice

Sea buckthorn juice (SBJ) has a sour taste and can lead to the demineralization of tooth enamel when consumed over a long period of time, whereas fermentation reduces the acidity of sea buckthorn juice, improves its taste, and enhances its antioxidant activity. Flavor components are important factors that affect the quality of fermented beverages. Yeast is one of the most important factors affecting the flavor of beverages during the fermentation process, where yeast converts sugars into alcohol and produces flavor substances. Therefore, two commercial yeast strains, Angel RW and Angel RV171, were selected in this study for the single and mixed bacterial fermentation of sea buckthorn juice (FSBJ). Physicochemical analyses showed that RV171-FSBJ had the highest total reducing sugar (0.069 ± 0.02 g/L) and total acid content (1.86 ± 0.03 g/L), as well as the highest fermentation efficiency and free radical scavenging capacity (1,1-diphenyl-2-picrylhydrazyl (DPPH) 98.54 ± 0.03%, 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) 88.35 ± 0.14%, ·OH 48.61 ± 0.4%). RWRV-FSBJ had the highest content of functional compounds (total flavonoid content (TFC): 176.09 ± 0.44 μg/mL; total phenolic content (TPC): 157.9 ± 1.35 μg/mL; total anthocyanin concentration (TAC): 0.04 ± 0.004 μg/mL) and good color (L* 50.53 ± 0.04, a* 27.98 ± 0.04, b* 173.64 ± 0.34). Among the three FSBJs, a total of 54 volatile compounds were identified, with RV171-FSBJ having the highest content of volatile compounds. OAV analysis showed that 15, 14, and 11 volatile compounds of RW, RV, and RWRV, respectively, were greater than 1. Among them, ethyl hexanoate had the highest OAV, followed by ethyl isovalerate, phenylethyl alcohol, and 3-methylbutyl 3-methylbutanoate, which are characteristic flavor substances common to FSBJ.