High Gravity and Very High Gravity Fermentation of Sugarcane Molasses by Flocculating Saccharomyces cerevisiae : Experim
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High Gravity and Very High Gravity Fermentation of Sugarcane Molasses by Flocculating Saccharomyces cerevisiae: Experimental Investigation and Kinetic Modeling Cristiane Vieira Camargos 1 & Vitória Demétrio Moraes 1 & Liliane Maciel de Oliveira 1 & Carla Zanella Guidini 1 & Eloízio Júlio Ribeiro 2 & Líbia Diniz Santos 1 Received: 27 July 2020 / Accepted: 9 November 2020/ # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
Substantial progress has been made in ethanol fermentation technology under high gravity (HG) and very high gravity (VHG), which offer environmental and economic benefits. HG and VHG processes increase the productivity of ethanol, reduce distillation costs, and enable higher yields. The aim of the present study was to evaluate the use of sugarcane molasses as the medium component along with flocculating yeasts for fermentation in a fed-batch process employing this promising technology. We evaluated fed-batch fermentation, HG, and VHG involving a molasses-based medium with high concentrations of reducing sugars (209, 222, and 250 g/L). Fermentation of 222 g/L of total reducing sugars achieved 89.45% efficiency, with a final ethanol concentration of 104.4 g/L, whereas the highest productivity (2.98 g/(L.h)) was achieved with the fermentation of 209 g/L of total reducing sugars. The ethanol concentration achieved with the fermentation of 222 g/L of total reducing sugars was close to the value obtained for P’max (105.35 g/L). The kinetic model provided a good fit to the experimental data regarding the fermentation of 222 g/L. The results revealed that sugarcane molasses and flocculating yeasts can be efficiently used in HG fermentation to reduce the costs of the process and achieve high ethanol titers. Keywords Bioethanol . Fed-batch system . Mathematical modeling . Sugarcane molasses . Flocculating yeasts
* Líbia Diniz Santos [email protected] Extended author information available on the last page of the article
Applied Biochemistry and Biotechnology
Introduction Due to the rising oil prices, concerns regarding fossil fuel emissions, and the need for energy security, biofuels have attracted the attention of both the public and scientific community. Brazil, France, England, Austria, Norway, and Holland plan to ban the sale of cars run on diesel and gasoline in the near future, which will lead to an increased demand for biofuels and the need for greater global biofuel production. In the last three decades, substantial progress has been made in ethanol fermentation technology under high gravity (HG) and very high gravity (VHG), which offer environmental and economic benefits [1, 2]. Brazil is one of the largest and most competitive ethanol producers. The country’s current bioethanol plants have high yields and preserve cell viability. They also use a low concentration of sugars, from X to Y g/L of sugars, to ensure the completion of fermentation within a short period (8 to 12 h). The process produces wines with ethanol concentration of 7 to 12% v/ v, and, therefore, a large vo
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