Almuhammad Mervat, Kölling Ralf, Einfalt Daniel
Yeast Genetics and Fermentation Technology, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstraße 23, 70599, Stuttgart, Germany.
Botanical Garden, Ulm University, Hans-Krebs-Weg, 89081, Ulm, Germany.
BMC Biotechnol. 2025 Sep 8;25(1):99. doi: 10.1186/s12896-025-01037-6.
This study investigates the effect of different liquefaction temperatures (50–70 °C) and four commercial enzyme formulations on glucose release and subsequent ethanol yield, using mixed waste baked products as a substrate. Among the enzymes tested, Amylase GA 500 proved to be superior in the hydrolysis of starch at lower temperatures (50 °C and 55°C). At higher liquefaction temperatures (65 °C and 70°C) all four enzyme preparations showed comparable activity. The highest glucose concentration (205.7 g/L) and the highest ethanol yield (92 g/L) were achieved with Amylase GA 500 at 65 °C. Its superior performance is attributed to the synergistic activity of α-amylase and glucoamylase, which facilitates efficient starch hydrolysis. Crucially, we discovered that the liquefaction temperature profoundly affects fermentation speed independently of the initial glucose concentration or the enzyme preparation used for starch hydrolysis. This novel mechanistic insight suggests that higher temperature treatment either makes an additional factor crucial for yeast fermentation available or depletes/destroys an inhibitor present in the complex waste bakery product matrix. These findings highlight the critical role of temperature and enzyme formulation in optimizing bioethanol production from bakery waste, supporting the development of more sustainable and efficient waste-to-biofuel processes.
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本研究以混合废弃烘焙食品为底物，研究了不同液化温度（50 - 70°C）和四种商业酶制剂对葡萄糖释放及后续乙醇产量的影响。在所测试的酶中，淀粉酶GA 500在较低温度（50°C和55°C）下对淀粉的水解表现更优。在较高的液化温度（65°C和70°C）下，所有四种酶制剂均表现出相当的活性。在65°C下使用淀粉酶GA 500时，葡萄糖浓度最高（205.7 g/L），乙醇产量也最高（92 g/L）。其卓越性能归因于α -淀粉酶和糖化酶的协同活性，这有助于高效水解淀粉。至关重要的是，我们发现液化温度对发酵速度有深远影响，且与初始葡萄糖浓度或用于淀粉水解的酶制剂无关。这一新颖的机理见解表明，较高温度处理要么使酵母发酵所需的另一个关键因素得以出现，要么消耗/破坏了复杂废弃烘焙食品基质中存在的一种抑制剂。这些发现凸显了温度和酶制剂在优化从烘焙废弃物生产生物乙醇过程中的关键作用，为开发更可持续、高效的废弃物转化生物燃料工艺提供了支持。
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