Department of Chemical Engineering, Escola Politécnica, Universidade de São Paulo, Av. Prof. Luciano Gualberto, Trav. 3, n. 380, 05508-010 São Paulo, SP, Brazil.
Universidade Federal do Rio de Janeiro, Rod. Washington Luiz, n. 19593, 25240-005 Duque de Caxias, RJ, Brazil.
Lett Appl Microbiol. 2024 Sep 2;77(9). doi: 10.1093/lambio/ovae083.
Yeast immobilization in beer fermentation has recently regained attention, due to the expansion of the craft beer market and the diversification of styles and flavors. The aim of this study was to evaluate the physiological differences between immobilized and free yeast cells with a focus on flavor-active compounds formation. Three strains of Saccharomyces spp. (SY025, SY067, SY001) were evaluated in both free and immobilized (using a cellulose-based support, referred as ImoYeast) forms during static batch fermentations of 12 °P malt extract. Immobilized cells showed higher glycerol (SY025, 40%; SY067, 53%; SY001, 19%) and biomass (SY025, 67%; SY067, 78%; SY001, 56%) yields than free cells. Conversely, free cells presented higher ethanol yield (SY025, 9%; SY067, 9%; SY001, 13%). Flavor-active compounds production exhibited significant alterations between immobilized and free cells systems, for all strains tested. Finally, a central composite design with varying initial biomass (X0) and substrate (S0) concentrations was conducted using strain SY025, which can be helpful to modulate the formation of one or more flavor-active compounds. In conclusion, yeast immobilization in the evaluated support resulted in flavor alterations that can be exploited to produce different beer styles.
酵母固定化在啤酒发酵中最近重新受到关注，这是由于精酿啤酒市场的扩张以及风格和口味的多样化。本研究的目的是评估固定化和游离酵母细胞之间的生理差异，重点是风味活性化合物的形成。评估了三种酿酒酵母菌株（SY025、SY067、SY001）在游离和固定化（使用纤维素基载体，称为 ImoYeast）形式下，在 12 °P 麦芽提取物的静态分批发酵中的表现。固定化细胞的甘油（SY025，40%；SY067，53%；SY001，19%）和生物量（SY025，67%；SY067，78%；SY001，56%）产量高于游离细胞。相比之下，游离细胞的乙醇产量更高（SY025，9%；SY067，9%；SY001，13%）。对于所有测试的菌株，风味活性化合物的产生在固定化和游离细胞系统之间表现出显著的变化。最后，使用菌株 SY025 进行了初始生物量（X0）和底物（S0）浓度变化的中心复合设计，这对于调节一种或多种风味活性化合物的形成可能是有帮助的。总之，在评估的载体中进行酵母固定化会导致风味发生变化，可以利用这些变化来生产不同风格的啤酒。
