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Ethanol produced by alcoholic fermentation from renewable sources, referred to as bioethanol, is widely used as an environmentally friendly and renewable energy source, as well as a chemical in various industries such as the medical, food and feed, pharmaceutical and chemical industries. This paper investigates the bioethanol production from sugar beet thick juice by immobilized Saccharomyces cerevisiae cells in calcium alginate beads and in a new matrix in the form of combined alginate-maize stem ground tissue beads. Higher values of fermentation parameters were obtained by yeast immobilized in new calcium alginatemaize stem ground tissue beads in comparison to calcium-alginate beads. A maximum ethanol concentration of 97.2 g/l, an ethanol yield per utilized sugar of 0.494 g/g, a percentage of the theoretical ethanol yield of 96.6 %, and a volumetric ethanol productivity of 2.03 g/lh were obtained at the end of batch alcoholic fermentation of the medium based on sugar beet thick juice with an initial sugar concentration of 200 g/l.

In this paper yields of bioethanol from seven samples of bread were compared. Samples of bread were produced and prepared in a laboratory by mixing wheat and buckwheat flour in amounts of 0, 20, 40, 50, 60, 80 and 100%. At first, the analysis of all seven samples of bread was done (dry matter, starch content and pH value of bread sample suspensions). Then the waste bread suspensions were hydrolyzed by applying commercial hydrolytic enzymes, Termamyl® SC and SAN Extra® L. The fermentation process was carried out with dry instant yeast, Saccharomyces cerevisiae, after which distillation of all fermented suspensions was performed. The ethanol contents in the distillates of all seven samples were determined. The highest yield of bioethanol was detected in the bread sample made of pure wheat flour. The ethanol yield gradually decreased with increasing content of buckwheat flour in bread. These results could be useful when considering the possibility of utilization of waste bread from different sources as a feedstock for bioe­thanol production.

Natural adhesion of Saccharomyces cerevisiae onto sugar beet pulp (SBP) is a very simple and cheap immobilization method for retaining high cells density in the ethanol fermentation system. In the present study, yeast cells were immobilized by adhesion onto SBP suspended in the synthetic culture media under different conditions such as: glucose concentration (100, 120 and 150 g/l), inoculum concentration (5, 10 and 15 g/l dry mass) and temperature (25, 30, 35 and 40°C). In order to estimate the optimal immobilization conditions the yeast cells retention (R), after each immobilization experiment was analyzed. The highest R value of 0.486 g dry mass yeast /g dry mass SBP was obtained at 30°C, glucose concentration of 150 g/l, and inoculum concentration of 15 g/l. The yeast immobilized under these conditions was used for ethanol fermentation of sugar beet molasses containing 150.2 g/l of reducing sugar. Efficient ethanol fermentation (ethanol concentration of 70.57 g/l, fermentation efficiency 93.98%) of sugar beet molasses was achieved using S. cerevisiae immobilized by natural adhesion on SBP. [Projekat Ministarstva nauke Republike Srbije, br. TR-31002]

The present work highlights the advances of integrated starch and bioethanol production as an attractive industrial solution for complex wheat exploitation to value-added products focusing on increased profitability. Bioethanol is conventionally produced by dry-milling wheat grain and fermenting sugars obtained by the hydrolysis of starch, while unused nonfermentable kernel compounds remain in stillage as effluents. On the other hand, the wet-milling of wheat flour enables complex wheat processing for the simultaneous production of starch, gluten, and fiber. The intermediates of industrial wheat starch production are A-starch milk, containing mainly large starch granules (diameter > 10 μm), and B-starch milk, containing mainly small starch granules (diameter < 10 μm). The present study investigates different starch hydrolysis procedures using commercial amylase for bioethanol production from A-starch and B-starch milk by batch fermentation using distillers’ yeast Saccharomyces cerevisiae Thermosacc®. Cold hydrolysis with simultaneous liquefaction and saccharification at 65 °C, a pH of 4.5, and a duration of 60 min was the most efficient and energy-saving pretreatment reaching a high conversion rate of starch to ethanol of 93% for both of the investigated substrates. A process design and cost model of bioethanol production from A-starch and B-starch milk was developed using the SuperPro Designer® v.11 (Intelligen Inc., Scotch Plains, NJ, USA) software. [ABSTRACT FROM AUTHOR]

Abstract: The potential of sugar beet pulp (SBP) and dried sugar beet pulp (DSBP) as economically cheap and renewable supports for immobilization of Saccharomyces cerevisiae cells was investigated. The hydrated supports showed similar cells retention capacities of 0.178±0.038g/g and 0.182±0.041g/g for SBP and DSBP, respectively. The DSBP-immobilized biocatalyst was used for repeated ethanol fermentation, because DSBP is more stable material. Yeast cells immobilization was confirmed by the scanning electron microscopy (SEM). Repeated batch ethanol fermentation of thick juice by yeast immobilized on hydrated DSBP was successfully carried out for at least seven successive cycles without any significant decrease in ethanol production, while in the case of molasses, after the third batch, significant decrease was observed. A maximum ethanol concentration of 52.26±2.0g/l and ethanol yield of 0.446±0.017g/g was achieved in the seventh fermentation batch of thick juice (initial sugar of 120g/l) with almost complete utilization of sugar (97.52±0.15%). The sugar beet thick juice was found to be more convenient industrial substrate for repeated batch ethanol fermentation than molasses and can be used without any nutrient supplementation. The production of bioethanol from sugar beet thick juice and molasses using DSBP-immobilized cell system enables one more opportunity for achieving the zero-waste goal, through a rational use of intermediate and by-products of sugar beet processing. [Copyright &y& Elsevier]

Abstract: The potential of by-products and intermediate products of sugar beet processing as raw materials for bioethanol production in Vojvodina region has a big scope in view of the demand of ethanol as an alternative for fossil fuels. Also, from ecological point of view, use of agricultural waste as carriers for cells immobilization is justifiable. The biocatalyst prepared by immobilization of Saccharomyces cerevisiae on maize stem ground tissue was used for batch fermentation of sugar beet molasses and thick juice under normal and very high gravity (VHG) conditions. Cell immobilization was observed by electron microscopy. The carrier was effective for cell immobilization and provided strength and stability to the yeast cell mass and functioned as a fortification against toxins and inhibitors, enabling efficient ethanol fermentation, particularly in VHG conditions. Three different initial glucose concentrations were tested: 100, 150 and 300g/l. The maximum ethanol concentration of 83.20g/l for molasses and 132.39g/l for thick juice were achieved in VHG fermentation by immobilized cells, whereas the free yeast cells were unsuccessful in the same media. Taking into consideration significant process parameters sugar beet thick juice was found to be economically favorable, compared to molasses, particularly in the VHG fermentation process. [Copyright &y& Elsevier]