Research at the Cyprus University of Technology is evaluating the potential of a hybrid bioprocess for the production of green solvents from naturally derived feedstocks. The concept is based on fermenting the organic content of a renewable resource into the targeted alcohol and acid, transfer of the two intermediate products into a suitable solvent via liquid-liquid extraction and esterification into the desired ester employing lipases. The paper exemplifies this idea through effective production of ethyl lactate from cheese whey using the experimental framework developed.
Bioresource Technology, Volume 165, 2014, Pages 343-349. Michalis Koutinas, Maria Menelaou, Evrydiki N. Nicolaou.
Department of Environmental Science & Technology, Cyprus University of Technology, 30 Archbishop Kyprianou Str., 3036 Limassol, Cyprus.
This work explores the potential for the development of a hybrid fermentation–enzymatic process for the production of ethyl lactate from dairy waste. Cheese whey was used in Kluyveromyces marxianus and Lactobacillus bulgaricus batch cultures to produce ethanol and lactic acid respectively. Subsequently, the fermentation products were transferred into an organic phase through liquid–liquid extraction and ethyl lactate was formed in an esterification reaction catalyzed by lipases. The production of ethanol and lactic acid achieved under different conditions was 23 g L−1 and 29 g L−1, respectively. Furthermore, the efficiency of various organic solvents for the esterification reaction was evaluated and toluene was chosen for application in the process. The effect of water content was determined aiming to maximize the product yield and 40 mg ml−1 was the optimal enzyme concentration. The bioprocess achieved maximum conversion of 33% constituting a valuable alternative to the application of energy demanding chemically derived methods.