Bioethanol production from deproteinized cheese whey powder by local strain isolated from soured milk: influence of operating parameters

ABSTRACT

In this paper, a local isolated yeast strain was studied for bioethanol production using protein-free cheese whey powder (CWP) in batch alcoholic fermentation experiments. Ethanol tolerance tests were performed with different ethanol concentrations (from 0% to 20%). The maximum ethanol tolerance obtained for our strain was 5% (v/v). The influence of initial lactose concentration, temperature and pH on fermentation kinetic was studied. For initial lactose concentration ranging from 57.5 to 260 gL⁻¹, the highest ethanol production 34.8 gL⁻¹ was obtained at 109 gL⁻¹ initial lactose concentration corresponding to 0.413 gg⁻¹ ethanol yield (Y_P/S); (While it was noticed less ethanol production, namely 0.178 g g⁻¹) at a higher initial whey sugar concentration of 260 gL⁻¹. The effect of the initial pH on the fermentation was studied at three different values: 3, 4 and 5. The ethanol production reached a maximum of 22 g L⁻¹ with a lactose consumption of 77.62% at pH 4. However, an observed decrease occurred in ethanol production and lactose consumption at pH 3, with values of 10.34 gL-1 and 24.46%, respectively. For the fermentation conducted at the three temperatures of 37°C, 40°C and 43°C, the maximum ethanol production and lactose consumption were 34.82 gL-1 and 80.75%, respectively, achieved at 37°C. The experimental data was analyzed using the Gompertz model to obtain the following kinetic parameters: the maximum ethanol concentration (P_m) was found to be 36.97 gL-1, the maximum ethanol production rate (r_p,m) was 0.402 gL⁻¹h⁻¹ and the lag phase (t_l) was 10.8 h. The comparison of the isolated Kluyveromyces marxianus TXID4911 strain with the reference strain Kluyveromyces marxianus DSM 5421, showed a relatively close ethanol yield (Y_P/S) 0.415 and 0.505 gg,⁻¹ respectively.

KEYWORDS:

• Bioethanol
• fermentation
• whey
• isolated yeast
• kinetic model
• Kluyveromyces marxianus

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Latifa Tebbouche

Latifa Tebbouche is a postgraduate in Ecole Nationale Polytechnique, And is Research at the Research Centre on Renewable Energy (CDER). Her research interest is related to biofuels production.

Majda Aziza

Majda Aziza is Research Director at the Research Centre on Renewable Energy (CDER), in Algiers. Her research interest is related to microorganism’s cultures improvement on bioreactors, biofuels production and food technology.

Sabah Abada

Sabah Abada is Research at the Research Centre on Renewable Energy (CDER), in Algiers. Her research interest is related to biofuels production.

Abdelmalek Chergui

Abdelmalek Chergui is a Professor at National Polytechnic School of Algiers. Her research interest is valorisation of agro-resources in water treatment and purification and life cycle analysis in the control of industrial and environmental risks.

Abdeltif Amrane

Abdeltif Amrane is a Professor – Exceptional class, UMR CNRS 6226 ISCR, University of Rennes. his research is entirely devoted to the development of combined processes for the removal of organic pollutants in effluent wastewater and gaseous emissions within the CIP team.

Amina Hellal

Amina Hellal is a Professor at National Polytechnic School of Algiers. Her research interest is the environmental biotechnology.