Papers by Aleksandra Djukić-Vuković
Fuel, 2015
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Hemijska industrija, 2011
Page 1. 1 Pregledni rad Novi pravci i izazovi u proizvodnji mlečne kiseline na obnovljivim sirovi... more Page 1. 1 Pregledni rad Novi pravci i izazovi u proizvodnji mlečne kiseline na obnovljivim sirovinama Aleksandra J. Đukić Vuković 1 , Ljiljana V. Mojović 1 , Duanka Pejin 2 , Maja Vukainović-Sekulić1 , Marica Rakin 1, Svetlana Nikolić1 i Jelena Pejin 2 ...
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Bioresource Technology, 2013
In this study, lactic acid and biomass production on liquid distillery stillage from bioethanol p... more In this study, lactic acid and biomass production on liquid distillery stillage from bioethanol production with Lactobacillus rhamnosus ATCC 7469 was studied. The cells were immobilized onto zeolite, a microporous aluminosilicate mineral and the lactic acid production with free and immobilized cells was compared. The immobilization allowed simple cell separation from the fermentation media and their reuse in repeated batch cycles. A number of viable cells of over 10(10) CFU g(-1) of zeolite was achieved at the end of fourth fermentation cycle. A maximal process productivity of 1.69 g L(-1), maximal lactic acid concentration of 42.19 g L(-1) and average yield coefficient of 0.96 g g(-1) were achieved in repeated batch fermentation on the liquid stillage without mineral or nitrogen supplementation.
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Waste Management, 2015
Waste substrates from bioethanol and beer productions are cheap, abundant and renewable substrate... more Waste substrates from bioethanol and beer productions are cheap, abundant and renewable substrates for biorefinery production of lactic acid (LA) and variability in their chemical composition presents a challenge in their valorisation. Three types of waste substrates, wasted bread and wasted potato stillage from bioethanol production and brewers' spent grain hydrolysate from beer production were studied as substrates for the production of l(+) LA and probiotic biomass by Lactobacillus rhamnosus ATCC 7469. The correlation of the content of free alpha amino nitrogen and the production of LA was determined as a critical characteristic of the waste media for efficient LA production by L. rhamnosus on the substrates which contained equal amount of fermentable sugars. A maximal LA productivity of 1.54gL(-1)h(-1) was obtained on wasted bread stillage media, whilst maximal productivities achieved on the potato stillage and brewers' spent grain hydrolysate media were 1.28gL(-1)h(-1)and 0.48gL(-1)h(-1), respectively. A highest LA yield of 0.91gg(-1) was achieved on wasted bread stillage media, followed by the yield of 0.81gg(-1) on wasted potato stillage and 0.34gg(-1) on brewers' spent grain hydrolysate media. The kinetics of sugar consumption in the two stillage substrates were similar while the sugar conversion in brewers' spent grain hydrolysate was slower and less efficient due to significantly lower content of free alpha amino nitrogen. The lignocellulosic hydrolysate from beer production required additional supplementation with nitrogen.
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Hemijska industrija, 2015
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Chemical Engineering Transactions
Lactic acid and biomass production on distillery stillage - a by-product of bioethanol industry -... more Lactic acid and biomass production on distillery stillage - a by-product of bioethanol industry - was studied in this paper. Batch and fed-batch fermentation strategies for lactic acid production on distillery stillage were performed by Lactobacillus rhamnosus ATCC 7469. The most appropriate initial sugar concentration in the stillage was determined and different fermentation strategies were studied under selected conditions The most efficient sugar conversion in batch fermentation was attained with the initial sugar concentration of 55 g/L. Enhancement in lactic acid productivity (up to 1.80 g/Lh) and a very high number of viable cells (108 CFU/mL) were achieved in fed-batch fermentation. The high lactic acid concentration attained in fedbatch fermentation opened a new possibility for stillage processing. In addition, extensive bacterial growth achieved during fermentation of the stillage could bring additional value to the process through utilization of the spent media for animal ...
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ABSTRACT Lactic acid is a significant chemical for the food industry. Fermentative lactic acid pr... more ABSTRACT Lactic acid is a significant chemical for the food industry. Fermentative lactic acid production on wastes could significantly im-prove the economy and sustainability of the process. In this study, lactic acid production was performed by L. rhamnosus ATCC 7469 on a stillage from bioethanol production on waste bread. Under optimal conditions, in fed-batch fermentation lactic acid productivity of 1.80 g L -1 h -1 has been achieved with a cell number of above 10 9 CFU mL -1 . L. rhamnosus has shown high survival rate of over 85% in the presence of beef bile and at low pH value of MRS broth. The residuals after the fermentation were chemically analysed and their composition corresponded well with the values recommended for the feed. The digestible energy was 17452.25 kJ kg -1 , while metabolisable energy was 17360.83 kJ kg -1 . The high values of energy parameters indicated that an integrated process for lac-tic acid and feedstuff production could be a good strategy.
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Hemijska industrija, 2012
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Chemical Industry and Chemical Engineering Quarterly, 2014
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Causes, Impacts and Solutions to Global Warming, 2013
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Journal of Food Processing and Preservation, 2014
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Fuel, 2015
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Hemijska industrija, 2013
ABSTRACT Brewer's spent grain is the major by-product in beer production. It is produced ... more ABSTRACT Brewer's spent grain is the major by-product in beer production. It is produced in large quantities (20 kg per 100 L of produced beer) throughout the year at a low cost or no cost, and due to its high protein and carbohydrates content it can be used as a raw material in biotechnology. Biotechnological processes based on renewable agro-industrial by-products have ecological (zero CO2 emission, eco-friendly by-products) and economical (cheap raw materials and reduction of storage costs) advantages. The use of brewer's spent grain is still limited, being basically used as animal feed. Researchers are trying to improve the application of brewer's spent grain by finding alternative uses apart from the current general use as an animal feed. Its possible applications are in human nutrition, as a raw material in biotechnology, energy production, charcoal production, paper manufacture, as a brick component, and adsorbent. In biotechnology brewer's spent grain could be used as a substrate for cultivation of microorganisms and enzyme production, additive or yeast carrier in beer fermentation, raw material in production of lactic acid, bioethanol, biogas, phenolic acids, xylitol, and pullulan. Some possible applications for brewer's spent grain are described in this article, includeing pre-treatment conditions (different procedures for polysaccharides, hemicelluloses and cellulose hydrolysis), working microorganisms, fermentation parameters and obtained yields. The chemical composition of brewer's spent grain varies according to barley variety, harvesting time, malting and mashing conditions, and a quality and type of unmalted raw material used in beer production. Brewer's spent grain is lignocellulosic material rich in protein and fibre, which account for approximately 20 and 70% of its composition, respectively.
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Food Research International, 2014
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Hemijska industrija, 2011
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Food Research International, 2014
ABSTRACT Utilization of distillery stillage from bioethanol production for lactic acid and feed p... more ABSTRACT Utilization of distillery stillage from bioethanol production for lactic acid and feed production was studied. The lactic acid fermentation of the stillage was performed by Lactobacillus rhamnosus ATCC 7469 and maximal lactic acid concentration of 50.18 g L−1, yield of 0.90 g g−1, productivity of 1.48 g L−1 h−1 and viable cell number of 5 × 109 CFU mL−1 were achieved. Solid residues with biomass remains after lactic acid fermentation were assessed for animal consumption. The content of proteins and ash decreased in the residues after the fermentation, whilst the content of oil and nitrogen free extract was higher when compared to unfermented samples. The digestible (17480.64 kJ kg−1) and metabolisable (17389.08 kJ kg−1) energies as well as digestibility (966.95 g kg−1) of the fermentation residue were very high. The in vitro assessment of L. rhamnosus ATCC 7469 survival in simulated gastric conditions has shown high survival rate (87%). In addition, this bacterium has shown good antimicrobial activity against the most important pathogens and capability to produce exopolysaccharide on different sugars present in animal diet. After effective lactic acid fermentation, the residues could be recommended as a high quality feed for monogastric animals.
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Renewable Energy, 2015
ABSTRACT Simultaneous saccharification and acetone–ethanol–butanol (ABE) fermentation was conduct... more ABSTRACT Simultaneous saccharification and acetone–ethanol–butanol (ABE) fermentation was conducted in order to reduce the number of steps involved in the conversion of lignocellulosic biomass into butanol. Enzymatic saccharification of pretreated oil palm empty fruit bunch (OPEFB) by cellulase produced 31.58 g/l of fermentable sugar. This saccharification was conducted at conditions similar to the conditions required for ABE fermentation. The simultaneous process by Clostridium acetobutylicum ATCC 824 produced 4.45 g/l of ABE with butanol concentration of 2.75 g/l. The butanol yield of 0.11 g/g and ABE yield of 0.18 g/g were obtained from this simultaneous process as compared to the two-step process (0.10 g/g of butanol yield and 0.14 g/g of ABE yield). In addition, the simultaneous process also produced higher cumulative hydrogen (282.42 ml) than to the two-step process (222.02 ml) after 96 h of fermentation time. This study suggested that the simultaneous process has the potential to be implemented for the integrated production of butanol and hydrogen from lignocellulosic biomass.
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Renewable and Sustainable Energy Reviews, 2012
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Journal of the Science of Food and Agriculture, 2013
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Papers by Aleksandra Djukić-Vuković