海藻酸铝固定化酵母在杨梅果酒发酵中提高花色苷稳定性研究

杨梅果酒采用游离酵母发酵时，由于微生物所产生的β—D-葡萄糖苷酶对果汁中的呈色花色苷有脱糖作用，导致其失色或降解，从而使杨梅果酒失去鲜艳的红色。为了解决这一问题，本研究采用海藻酸铝固定化酿酒酵母（商品名分别为安琪，Lalvin D254，Lalvin BM45，and LalvinL2323）代替游离酵母发酵杨梅果酒，对四种固定化酿酒酵母的花色苷稳定作用进行了试验。结果表明四种酵母的海藻酸铝固定化发酵均表现出明显的护色效果，经过20d发酵后，呈色花色苷保存率分别为50％（D254）、46．4％（安琪）、45．5％（L2323）、42．7％（BM45），而在相应品种的酿酒酵母的游离细胞发酵时，保存率仅分别为22．7％、20．9％、24．5％、26．3％。这种保护作用主要来自于海藻酸铝固定化细胞珠致密外层的物质低扩散性、后期酒精对的抑制作用以及形成铝离子对花色苷的稳定作用。另外，在发酵前期，海藻酸铝固定化酵母的平稳发酵速度和慢速消耗酒醪中的二氧化硫对最后的呈色花色苷保存率也有重要意义。

Aluminium (Ⅲ)-Alginate Immobilized Yeasts to Enhance Anthocyanin Stability during Bayberry (Myrica rubra) Red Wine Fermentation

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 -Dglucosidases 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 Saccharomyces cerevisiae 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.