Area de Biotecnología, CIATEJ Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Av. Normalistas 800, Col. Colinas de la Normal, Guadalajara, Jalisco, Mexico.
J Sci Food Agric. 2010 Jul;90(9):1423-8. doi: 10.1002/jsfa.3957.
Continuous cultures have been used since the 1950s in beer and wine fermentations due to their higher productivities compared to traditional batch systems; nevertheless, the tequila industry has not taken advantage of the possible improvements that continuous fermentations could offer. In this work, the effect of pH, aeration and feeding of non-sterilized medium, on the fermentative capability of two Saccharomyces cerevisiae strains (S1 and S2) cultured in continuous fermentation, using agave juice as the fermentation medium, were studied.
In continuous cultures, the control of the medium pH (set point at 4) did not have a significant effect on fermentation efficiency compared to fermentations in which the pH was not controlled (pH 2.5 +/- 0.3). Conversely, aeration of the cultures of both strains improved biomass production and consumption of reducing sugars and ammonium. The aeration also significantly augmented ethanol production only for S1 cultures (P < 0.05). Furthermore, the feeding of medium, either sterilized or not, did not show significant differences on the production of ethanol for S1 cultures. Higher concentrations of acetoin, succinic acid and diacetyl were found in the cultures fed with non-sterilized medium.
Compared to S2, S1 has a better fermentative performance in continuous non-sterilized medium fermentations. Not controlling the pH during the cultures could prevent the possibility of microbial contamination as a result of the extreme medium acidity (pH 2.5 +/- 0.3). This work showed the possibility of scaling up agave juice continuous fermentation feeding non-sterilized medium with no control of pH.
自 20 世纪 50 年代以来，连续培养已在啤酒和葡萄酒发酵中得到应用，因为与传统的分批系统相比，其具有更高的生产力；然而，龙舌兰酒行业并未利用连续发酵可能带来的改进。在这项工作中，研究了 pH 值、通气和非灭菌培养基进料对两种酿酒酵母（S1 和 S2）在连续发酵中使用龙舌兰汁作为发酵培养基时的发酵能力的影响。
在连续培养中，与未控制 pH 值（设定点为 4）的发酵相比，控制培养基 pH 值对发酵效率没有显著影响（pH 值为 2.5 +/- 0.3）。相反，两种菌株的培养物通气均提高了生物量的产生以及还原糖和铵的消耗。通气也显著增加了 S1 培养物的乙醇产量（P < 0.05）。此外，对于 S1 培养物，无论是灭菌还是未灭菌的培养基进料，对乙醇的生产均无显著差异。在未灭菌培养基中进料的培养物中发现了更高浓度的乙酰醇、琥珀酸和双乙酰。
与 S2 相比，S1 在连续非灭菌培养基发酵中具有更好的发酵性能。在培养过程中不控制 pH 值可以防止由于极端培养基酸度（pH 2.5 +/- 0.3）而导致微生物污染的可能性。这项工作表明，可以在不控制 pH 值的情况下，对龙舌兰汁连续发酵进行非灭菌培养基的进料放大。
