Abstract:  Bayberry (Myrica rubra) wine usually loses its red color, because its naturally-existing anthocyanins (CA) would be faded to a large extent during its free yeast cells fermentation (FCF). Anthocyanins are metabolically degraded by β-D- glucosidases that are widely expressed in fungi, yeasts and plants. To overcome this problem, aluminum (III) alginate-immobilized yeasts, instead of free ones, were utilized in the wine fermentation tests. Four commercially available Saccharomycesc erevisiae strains, Angel, Lalvin D254, Lalvin BM45, and Lalvin L2323 were evaluated. The CA stability in ICF (immobilized cells fermentation) of four yeast strains after 20 days was dramatically enhanced with the retaining rates as 50.0% (L.D254), 46.4% (Angel), 45.5% (L.L2323), and 42.7% (L.BM45), respectively, whereas, those corresponding values in FCF were only 22.7%, 20.9%, 24.5%, and 26.3%, respectively. The enhanced property of ICF on anthocyanins stability was due to the lower diffusion effect occurring in the compact outer layers of Al-alginate beads, the inhibition of β-D-glucosidases as ethanol to accumulate in medium, as well as the stabilization of the aluminum (III) in complex with anthocyanins. Moreover, during the early stage of the tests, ICF provided more stable fermentation rate as well as more slowly releasing of sulfur dioxide in medium, very important to the final retaining rate of CA.

Key words: Aluminum (Ⅲ)-alginate, anthocyanin stability, β-D-glucosidase, bayberry (Myrica rubra) wine