Ethanol production from sugar beet molasses by S. cerevisiae entrapped in an alginate-maize stem ground tissue matrix

A new alginate-maize stem ground tissue matrix was developed as a Saccharomyces cerevisiae carrier for ethanol fermentation from sugar beet molasses. There were several fermentation procedures in the present study: using free cells and alginate-entrapped cells with and without maize stem ground tissue supplementation (F; F+C; AB; AB+C), and using a new combined alginate-maize stem ground tissue carrier (ABC). It was found that addition of maize stem ground tissue meal (C), with honeycomb configuration, provided high surface areas for cell attachment and biofilm growth, and also increased alginate matrix porosity, enabling better mass transfer characteristic, better physical strength and stability of beads. The highest values of process parameters were obtained in the case of new carrier (ABC): the ethanol concentration of 60.36 g/l, percentage of the theoretical ethanol yield of 96.56%, ethanol yield of 0.493 g/g and the volumetric ethanol productivity of 2.51 g/lh. The medium supplementation with maize stem ground tissue significantly decreased acetaldehyde and acetic acid content, did not affect fusel alcohol and ethylacetate content of the distillate.