Continuous fermentations were performed in an external-recycle, biofilm reactor using glucose and CO2 as carbon substrates. The nitrogen source for the auxotrophic Actinobacillus succinogenes was a combination of yeast extract (YE) and corn steep liquor (CSL), and sometimes only YE or CSL was used. In this study, the succinic acid productivity of A. succinogenes decreased by 67% as the amount of YE in the complex nitrogen source mixture decreased from 16 g·L-1 to 0 g·L-1. Succinic acid production increased as the CSL concentration in the nitrogen source increased, and the mass ratio of succinic acid to acetic acid exceeded the theoretical maximum limit of 3,93 g·g-1 when only CSL was used as the nitrogen source. The mass ratio of formic acid to acetic acid was consistently within the theoretical yield limitations (0,77 g·g−1) and decreased as the CSL concentration in the nitrogen source increased. The highest SA concentration in this study was 22,57 g·L-1 when only YE was used as the nitrogen source in the growth medium, and the highest SA productivity obtained in this study was 1,58 g·L-1·h-1 when a combination of YE and CSL was used as a nitrogen source. The highest mass ratio of SA to AA achieved was 8,3 g·g-1 when CSL was the sole nitrogen source. The mass ratio of FA to AA was consistently less than 0,77 g·g-1, approaching 0 g·g-1, as the CSL concentration in the nitrogen source increased. / Dissertation (MSc)--University of Pretoria, 2016. / National Research Foundation (NRF) / Chemical Engineering / MSc / Unrestricted

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2017-08-21T17:48:06Z No. of bitstreams: 1 Cristiane Tomas 2016.pdf: 3290049 bytes, checksum: 1f383e6c83c3ca0a2b8d59aa65426c21 (MD5) / Made available in DSpace on 2017-08-21T17:48:06Z (GMT). No. of bitstreams: 1 Cristiane Tomas 2016.pdf: 3290049 bytes, checksum: 1f383e6c83c3ca0a2b8d59aa65426c21 (MD5) Previous issue date: 2016-08-29 / The search for renewable energy sources is a concern of the new generations in face of possible fossil fuel scarcity and climate change caused by greenhouse gas emissions. When compared with diesel derived from petroleum, the biodiesel can reduce 78% carbon dioxide emissions, considering plants reabsorption; also, it can reduce by 90% emissions of smoke and virtu ally eliminates sulfur oxide. The purpose of this research was to investigate the cultivation of microalgae Scenedesmus acuminatus in the substrate composed by corn steep liquor for biodiesel production purposes. Initially a preliminary test was carried out to verify the viability of growing the microalgae in the effluent; further, a central composite design was carried to study the influence of the effluent and inoculum concentration on the cell density biomass, production of biomass, chemical oxygen demand (COD) and maximum growth rate (μmax) of microalgae culture. Statistical analysis indicated that the percentage of inoculum and effluent had na influence on the cell density, COD and maximum specific growth rate and that the optimal cultivation conditions would be achieved with the use of 53.5 % of efluente and 5.2% of inoculum. The proposed model was validated through cultivation under the proposed conditions, achieving 0.30 g/L of dry biomass on the seventh day. The cultivation, together with the coagulation procedure, was efficient for the removal of organic matter, verified through the COD and pH reduction, reaching the appropriate level according the standard required by current legislation. HARA & RADIN (1978) was more efficient for extraction at 45ºC: achieved a yield of 44,50 ± 2,12 mg / L total lipids. The extraction temperature had influence on the yield of lipids: the procedure performed at 45 ° C was able to extract more lipids in both methods. / A busca por fontes renováveis de energia é uma preocupação das novas gerações em face da possível escassez dos combustíveis fósseis e das alterações climáticas causadas pelas emissões dos gases do efeito estufa. Comparado ao óleo diesel derivado de petróleo, o biodiesel pode reduzir em 78% as emissões de gás carbônico, considerando-se a reabsorção pelas plantas; também reduz em 90% as emissões de fumaça e praticamente elimina as emissões de óxido de enxofre. O objetivo desta pesquisa foi investigar o cultivo de microalgas Scenedesmus acuminatus em substrato composto por água de maceração do milho para fins de produção de biodiesel. Inicialmente realizou-se um teste preliminar para verificar a viabilidade de crescimento dessa microalga no efluente; posteriormente foi realizado um delineamento composto central rotacional para estudar a influência da concentração de efluente no meio e percentual inicial de células (inóculo) sobre a densidade celular, acúmulo de biomassa, DQO e velocidade máxima de crescimento (μmax) do cultivo. A análise estatística indicou que os percentuais de inóculo e efluente tiveram influência sobre a densidade celular, DQO e velocidade máxima específica de crescimento e que as condições ótimas do cultivo seriam alcançadas com a utilização de 53,5% de efluente e 5,2% de inóculo. O modelo proposto foi validado através de um cultivo nas condições propostas, cujo rendimento em biomassa seca foi de 0,30g/L ao sétimo dia. O cultivo, aliado ao procedimento de coagulação, foi eficiente para remoção de matéria orgânica do meio de cultura, observada através da redução dos valores de DQO e pH, que atingiram nível adequado ao padrão exigido pela legislação vigente. A metodologia HARA & RADIN (1978) foi a mais eficiente foi mais eficiente para extração de lipídeos totais à temperatura de 45ºC: obteve um rendimento de 44,50 ± 2,12 mg/L. A temperatura de extração teve influência sobre o rendimento em lipídeos: o procedimento realizado a 45°C foi capaz de extrair maior quantidade de lipídeos para ambos os métodos.

Orientador: Ranulfo Monte Alegre / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-18T15:45:23Z (GMT). No. of bitstreams: 1 Coelho_RenatoSano_M.pdf: 1626359 bytes, checksum: 9f1206c0b5868e3fac4cf8ccec536403 (MD5) Previous issue date: 2011 / Resumo: O interesse a respeito do ácido kójico tem crescido fortemente nos últimos anos desde a descoberta de suas propriedades de inibição de tirosinase, que permitem seu uso no tratamento de hiperpigmentação dermatológica, inibição de escurecimento enzimático de frutas e vegetais, produção de antiinflamatórios e analgésicos, produção de polímeros, dentre outras aplicações. Dado o potencial econômico do ácido kójico, são necessários processos mais eficazes para sua síntese reduzindo custos de produção e tornando-o mais atrativo à aplicação industrial. Este trabalho visou estudar o processo de produção fermentativa do ácido kójico, determinando parâmetros que auxiliarão no desenvolvimento de tecnologias competitivas de produção. Além disso, propõe a utilização de matérias-primas de baixo custo e grande disponibilidade no mercado brasileiro como glicerol e água de maceração de milho. A espécie selecionada para o estudo foi Aspergillus flavus NRRL 626, que apresentou maior velocidade de crescimento, esporulação e produção de ácido kójico. As melhores fontes de carbono foram a glicose e o glicerol e as melhores fontes de nitrogênio foram o extrato de levedura e a água de maceração de milho. A otimização por planejamentos experimentais utilizando glicose como fonte de carbono e água de maceração de milho como fonte de nitrogênio possibilitou produtividade de até 0,12 g ¿ L-1 ¿ h-1 e concentração final de 48 g ¿ L-1 após 22 dias. A otimização de meio de cultivo com glicerol como fonte de carbono e água de maceração de milho apresentou produtividade de 0,13 g ¿ L-1 ¿ h-1 e concentração final de 48 g ¿ L-1 após 20 dias de fermentação. O glicerol bruto da produção de biodiesel causou forte inibição da produção de ácido kójico e forma obtidos até 18 g ¿ L-1 após 22 dias de fermentação. Ensaios em fermentador de bancada apresentaram problemas de formação de espuma devido às características do meio de cultura e de aderência da biomassa às paredes do fermentador. Os processos de cristalização com anti-solvente e clarificação com carvão ativado mostraram-se adequados à recuperação e purificação do ácido kójico / Abstract: There has been a growing interest on kojic acid since the discovery of its tyrosinase inhibiton properties, which make it useful for many different applications like dermal hyperpigmentation treatment, inhibition of fruits and vegetables enzymatic browning, antiinflamatory and analgesic drugs production, polymer productions, among others. The economical potential of kojic acid motivates researchers to develop more efficient and economical ways of producing it and therefore increase its commercial attractiveness. The present work focused on the study of the kojic acid fermentative production process in order to determine parameters that could help the development of more competitive production technologies. It also proposes the use of low cost raw materials with large availability in Brazil, since as glycerol and corn steep liquor. The selected species for the study was the Aspergillus flavus NRRL 626, which showed the highest growth rate, sporulation and kojic acid production. The selection of substrates pointed that glucose e glycerol were the best carbon sources and yeast extract and corn steep liquor were the best nitrogen sources for kojic acid production. Culture medium optimized through experimental designs with glucose as carbon source and corn steep liquor as nitrogen source allowed a productivity of 0,12 g kojic acid ¿ L-1 ¿ h-1 and a final concentration of 48 g ¿ L-1 after 22 days. The optimized medium containing glycerol as carbon source obtained maximum productivity of 0,13 g ¿ L-1 ¿ h-1 and 48 g kojic acid ¿ L-1 after 20 days of fermentation. Crude glycerol from biodiesel strongly inhibited koijc acid production and its use as carbon source reached the maximum concentration of 18 g kojic acid ¿ L-1 after 22 days of fermentation. Cultivation in a 5 L batch fermentor using glycerol and corn steep liquor showed excessive foam formation e wall adherence. Anti-solvent crystallization and active carbon clarification were successful techniques for recovery and purification of kojic acid produced / Mestrado / Engenharia de Alimentos / Mestre em Engenharia de Alimentos

Continuous fermentations were performed in a novel external-recycle, biofilm reactor using D-glucose and CO2 as carbon substrates. Corn steep liquor (CSL) and yeast extract (YE) served as nitrogen sources. In anaerobic fermentations using medium containing CSL and YE, succinic acid (SA) yields were found to be an increasing function of glucose consumption. The ratio of SA to the major by-product, acetic acid (YAASA), increased from 2.4 g g-1 at a glucose consumption of 15 g L-1, to 5.7 g g-1 at a glucose consumption of 46 g L-1. For medium containing no CSL, YAASA remained near 1.97 g g-1, exceeding this for cases where biofilm grown on CSL-containing medium was present. The ratio of formic acid to acetic acid (YAAFA), for CSL-containing medium, decreased from an equimolar value (0.77 g g-1) at a glucose consumption of 10 g L-1 to zero at 46 g L-1 glucose consumed. In contrast, YAAFA for YE-only medium remained at 0.77 g g-1. Therefore, pyruvate was metabolised solely by pyruvate-formate lyase when no CSL was present. The highest SA yield obtained on glucose, SA titre and SA productivity were 0.91 g g-1, 48.5 g L-1 and 9.4 g L-1 h-1, respectively, all for medium containing CSL. Medium that included CSL significantly outperformed medium that excluded CSL, achieving 64%, 21% and 203% greater SA titres, yields on glucose and productivities respectively. Metabolic flux analyses based on the established C3 and C4 metabolic pathways of Actinobacillus succinogenes revealed that the increase in YAASA, for CSL-containing fermentations, could not be attributed to the decrease in formate and biomass formation, and that an additional source of reducing power was present. The fraction of reducing power (NADH) unaccounted for increased with glucose consumption, suggesting that the maintenance or non-growth metabolism encountered at higher SA titres differs from the growth metabolism. It is postulated that the additional reducing power originates from an active pentose phosphate pathway in non-growing cells or from an undetected component(s) in the fermentation medium. No major metabolic flux variations were found in fermentations that excluded CSL. / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Chemical Engineering / unrestricted

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nas últimas três décadas, a busca por combustíveis alternativos e renováveis teve maior evidência no cenário mundial, devido as crescentes preocupações ambientais e com a perspectiva de esgotamento de fontes energéticas de origem fóssil. A produção de biomassa de micro-organismos tem sido sugerida como adequada para a conversão em energia. Este trabalho teve como objetivo avaliar o potencial biotecnológico de amostras de Aspergillus spp. isolados da Caatinga através da seleção entre dez amostras do gênero, sendo Aspergillus niger (3) A. flavus (3), e A. parasiticus (4). Foram realizadas extrações dos lipídeos totais e a amostra com melhor percentual realizou-se a cinética de crescimento, caracterização dos ácidos graxos e atividade antioxidante da amostra selecionada. As amostras foram cultivadas em meio sintético Czapek líquido, e em meio alternativo (milhocina e melaço de cana-de- açúcar), utilizando o planejamento fatorial completo 23. Os lipídeos totais foram extraídos utilizando combinação binária de clorofórmio e metanol. Foram obtidas quantidades de lipídeos totais acima de 20% em ambos meios de cultura, caracterizando o gênero Aspergillus como oleaginoso. Os resultados indicaram que o Aspergillus parasiticus UCP 1182, obteve uma produção de 2,03 g/L de biomassa e uma produção de 44,2% de lipídeos totais em Meio Czapek, enquanto na produção em meio alternativo (melaço de cana-de açúcar e Milhocina) obteve no ensaio (8) 2,83g de biomassa em 48,9% de lipídeos totais. O perfil dos ácidos graxos cultivado em meio Czapek indicou a presença de ácido graxos linolêico (36,54%) e oleico (33,95%). E no meio alternativo o composto favoreceu a produção do acido graxo linolênico (28,66%) e ácido linolêico (40%). Na atividade oxidante do A. parasiticus calculada em regressão linear, obteve o EC50 de 4,06774 μg/mL do extrato lipídico. Assim, os resultados obtidos com Aspergillus parasiticus UCP 1182, sugerem como fonte de lipídeos importantes para seu emprego em processos biotecnológico, como aplicação em biocombustíveis e fármacos. / In the last three decades, the search for alternative and renewable fuels had greater evidence on the world stage, due to growing environmental concerns and the prospect of depletion of fossil energy sources. The biomass of microorganisms has been suggested as suitable for conversion to energy. This study aimed to assess the biotechnological potential of Aspergillus spp. isolated from Caatinga through the selection of ten genre samples, Aspergillus niger (3), A. flavus (3), and A. parasiticus (4). Of total lipid extractions were performed and the sample with better percentage held the growth kinetics, characterization of fatty acids and antioxidant activity of selected sample. Samples were grown in synthetic medium Czapek liquid, and reciprocating means (molasses and corn steep liquor sugarcane), using the complete factorial design 23. The total lipids were extracted using binary combination of chloroform and methanol. Total lipid amounts were obtained over 20% in both culture media, featuring the genus Aspergillus as oleaginous. The results indicated that the Aspergillus parasiticus CPU 1132, an output obtained from 2.03 g / L of biomass production and a 44.2% total lipids in Medium Czapek while in alternative production medium (sugar cane molasses and corn steep liquor) obtained in the trial (8) 2,83g biomass to 48.9% of total lipids. The fatty acid profile grown in Czapek medium indicated the presence of acid g [[ raxos linoleic (36.54%) and oleic (33.95%). And alternative way to favor the production of the compound linolenic acid (28.66%) and linoleic acid (40%). In oxidant activity of Aspergillus parasiticus, calculated in linear regression, got the EC50 4.06774 mg / mL of lipid extract. This the results obtained from Aspergillus parasiticus CPU 1182, suggest important as a source of lipids for its use in biotechnological processes such as application and biofuels drugs.

Orientador: Ranulfo Monte Alegre / Dissertação (mestrado) - Universidade Estsadual de Cam,pinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-18T17:54:10Z (GMT). No. of bitstreams: 1 AlcazarAlay_SylviaCarolina_M.pdf: 2176104 bytes, checksum: 32f8cdfe0b86e00e15edc533c76b33cb (MD5) Previous issue date: 2011 / Resumo: O interesse pela produção de ácido láctico tem crescido fortemente nos últimos anos desde a descoberta das propriedades de seus polímeros, os que apresentam caraterísticas de biodegradabilidade e biocompatibilidade; e sua aplicação como solvente ¿verde¿ ou ambientalmente saudável para os processos de misturas de solventes na indústria química. Dado o potencial econômico do ácido láctico, são necessários processos mais eficazes para sua síntese e redução dos custos de produção. Este trabalho visou aperfeiçoar o processo de produção fermentativa do ácido láctico, determinando formulações do meio de cultura que auxiliarão no desenvolvimento de tecnologias competitivas de produção. Além disso, esse trabalho propõe a utilização de matérias-primas de baixo custo e grande disponibilidade no mercado brasileiro como por exemplo melaço de cana e água de maceração de milho. A espécie selecionada para o estudo foi Lactobacillus delbrueckii, duas linhagens foram estudadas, selecionando-se a que apresentou maior velocidade de crescimento e produção de ácido láctico no meio de cultura padrão. O estudo de otimização da produção de ácido láctico foi realizado utilizando a estratégia de planejamentos experimentais. O uso de melaço de cana e água de maceração de milho como fonte de carbono e nitrogênio, em concentração de 240 gL-1 e 14 gL-1 respectivamente, possibilitou produtividade de até 57,17 gL-1 após 96 horas, com eficiência de 82% (gramas de ácido láctico produzido / grama de substrato utilizado) / Abstract: The interest in lactic acid has grown strongly in the last years since the discovery of its properties of application in production of biodegradable and biocompatible polylactate polymers and their application as "green solvent¿ or ¿safety solvent¿ to processes of mixtures of solvents in the chemical industry. Considering the commercial potential of lactic acid, more efficient processes are needed for its synthesis, reducing costs of production and turning its industrial application more atractive, as its cost still prevents it from being used in some areas. This work aimed at improving the process of fermentative lactic acid production, determining formulations that will help develop competitive technologies of production. Furthermore, the use of low cost raw materials, easily available on the brazilian market, such as sugarcane molasses and corn steep liquor is proposed. The species selected for the study was Lactobacillus delbrueckii, two strains were studied, Lactobacillus delbrueckii spp. bulgaricus, shown the greatest growth speed and lactic acid production in the standard culture medium. The optimization study of lactic acid production was performed using the strategy of experimental design, using sugarcane molasses as a carbon source and corn steep liquor as a nitrogen source allowed a productivity of up to 57,17 gL-1 after 96 hours, with 82% lactic acid yield efficiency (g lactic acid produced / g substrate utilized) using an initial concentration of 240 gL-1 and 14 gL-1 of sugarcane molasses and corn steep liquor respectively / Mestrado / Engenharia de Alimentos / Mestre em Engenharia de Alimentos

Submitted by (lucia.rodrigues@ufrpe.br) on 2016-06-10T13:37:13Z No. of bitstreams: 1 Mitaliene de Deus Soares Silva.pdf: 621798 bytes, checksum: 8452afc474da55a7e9d20fa3b33c6aff (MD5) / Made available in DSpace on 2016-06-10T13:37:13Z (GMT). No. of bitstreams: 1 Mitaliene de Deus Soares Silva.pdf: 621798 bytes, checksum: 8452afc474da55a7e9d20fa3b33c6aff (MD5) Previous issue date: 2013-02-25 / Biosurfactant production was the selection factor between 20 yeasts isolated from bee pollen of Melipona seminigra merrilae of the lower Amazonas - AM. The production of biosurfactant by yeast 9II using waste as a source of carbon and nitrogen was optimized using statistical design Plackett-Burman. The metabolic liquid cell-free presented surface tension 28,30 mN/m, yield of 5,09 g/L of crude biosurfactant. The growth kinetics and production of the biosurfactant with the best production condition studied demonstrated a correlation between the growth of yeast with the biosurfactant production. The liquid metabolic presented emulsification of 100% for virgin engine oils and residual oil engine. The biosurfactant was stable before a pH range (2-12), temperature (4-120 °C) and NaCl concentrations (2-12%, w/v) and no toxicity compared to Lactuca sativa L., Brassica oleracea L. and Coriandrum sativum L. seeds and Artemia salina shrimp. / A produção de biossurfactante foi o fator de seleção entre 20 leveduras isoladas do pólen apícola de Melipona seminigra merrilae da região do baixo Amazonas - AM. A produção do biossurfactante pela levedura 9II usando resíduo como fonte de carbono e nitrogênio foi otimizada usando planejamento estatístico Plackett-Burman. O líquido metabólico livre de células apresentou tensão superficial de 28,30 mN/m e rendimento de 5,09 g/L de biossurfactante bruto. A cinética de crescimento e de produção do biossurfactante com a melhor condição de produção estudada, demonstraram que há correlação entre o crescimento da levedura com a produção de biossurfactante. O líquido metabólico apresentou emulsificação de 100% para os óleos de motor virgem e óleo residual de motor. O biossurfactante mostrou-se estável frente à diferentes pHs (2-12), temperaturas (4-120 °C) e concentrações de NaCl (2-12%, p/v) e não apresentou toxicidade frente a sementes de Lactuca sativa L., Brassica oleracea L. e Coriandrum sativum L. e ao microcrustáceo Artemia salina.

Made available in DSpace on 2017-06-01T18:20:45Z (GMT). No. of bitstreams: 1 nairane_silva_rosa_leao.pdf: 1864571 bytes, checksum: 1bf2d31634a6610929236b3a53702bac (MD5) Previous issue date: 2015-05-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the last three decades, the search for alternative and renewable fuels had greater evidence on the world stage, due to growing environmental concerns and the prospect of depletion of fossil energy sources. The biomass of microorganisms has been suggested as suitable for conversion to energy. This study aimed to assess the biotechnological potential of Aspergillus spp. isolated from Caatinga through the selection of ten genre samples, Aspergillus niger (3), A. flavus (3), and A. parasiticus (4). Of total lipid extractions were performed and the sample with better percentage held the growth kinetics, characterization of fatty acids and antioxidant activity of selected sample. Samples were grown in synthetic medium Czapek liquid, and reciprocating means (molasses and corn steep liquor sugarcane), using the complete factorial design 23. The total lipids were extracted using binary combination of chloroform and methanol. Total lipid amounts were obtained over 20% in both culture media, featuring the genus Aspergillus as oleaginous. The results indicated that the Aspergillus parasiticus CPU 1132, an output obtained from 2.03 g / L of biomass production and a 44.2% total lipids in Medium Czapek while in alternative production medium (sugar cane molasses and corn steep liquor) obtained in the trial (8) 2,83g biomass to 48.9% of total lipids. The fatty acid profile grown in Czapek medium indicated the presence of acid g [[ raxos linoleic (36.54%) and oleic (33.95%). And alternative way to favor the production of the compound linolenic acid (28.66%) and linoleic acid (40%). In oxidant activity of Aspergillus parasiticus, calculated in linear regression, got the EC50 4.06774 mg / mL of lipid extract. This the results obtained from Aspergillus parasiticus CPU 1182, suggest important as a source of lipids for its use in biotechnological processes such as application and biofuels drugs. / Nas últimas três décadas, a busca por combustíveis alternativos e renováveis teve maior evidência no cenário mundial, devido as crescentes preocupações ambientais e com a perspectiva de esgotamento de fontes energéticas de origem fóssil. A produção de biomassa de micro-organismos tem sido sugerida como adequada para a conversão em energia. Este trabalho teve como objetivo avaliar o potencial biotecnológico de amostras de Aspergillus spp. isolados da Caatinga através da seleção entre dez amostras do gênero, sendo Aspergillus niger (3) A. flavus (3), e A. parasiticus (4). Foram realizadas extrações dos lipídeos totais e a amostra com melhor percentual realizou-se a cinética de crescimento, caracterização dos ácidos graxos e atividade antioxidante da amostra selecionada. As amostras foram cultivadas em meio sintético Czapek líquido, e em meio alternativo (milhocina e melaço de cana-de- açúcar), utilizando o planejamento fatorial completo 23. Os lipídeos totais foram extraídos utilizando combinação binária de clorofórmio e metanol. Foram obtidas quantidades de lipídeos totais acima de 20% em ambos meios de cultura, caracterizando o gênero Aspergillus como oleaginoso. Os resultados indicaram que o Aspergillus parasiticus UCP 1182, obteve uma produção de 2,03 g/L de biomassa e uma produção de 44,2% de lipídeos totais em Meio Czapek, enquanto na produção em meio alternativo (melaço de cana-de açúcar e Milhocina) obteve no ensaio (8) 2,83g de biomassa em 48,9% de lipídeos totais. O perfil dos ácidos graxos cultivado em meio Czapek indicou a presença de ácido graxos linolêico (36,54%) e oleico (33,95%). E no meio alternativo o composto favoreceu a produção do acido graxo linolênico (28,66%) e ácido linolêico (40%). Na atividade oxidante do A. parasiticus calculada em regressão linear, obteve o EC50 de 4,06774 μg/mL do extrato lipídico. Assim, os resultados obtidos com Aspergillus parasiticus UCP 1182, sugerem como fonte de lipídeos importantes para seu emprego em processos biotecnológico, como aplicação em biocombustíveis e fármacos.

Thesis (PhD (Chemical Engineering))--Cape Peninsula University of Technology, 2020 / The use of bioproducts in different commercial sectors such as medicine, agriculture, cosmetics, food, and chemical industries motivates the need for easy production and recovery techniques of bioproducts at laboratory and pilot scale. This study aims at the production and recovery of some selected bioproducts using supercritical fluid extraction techniques. Three products are chosen as case studies: these are ethanol, acetoin, and vanillin, since the ease of separation is influenced by the concentration of the product in the broth, these compounds were selected based on their concentration in the fermentation broth, according to literature sources. A standard method was developed in a spectrophotometer for quantifying the targeted product in the broth, while the product recovery studies was carried out using a supercritical fluid extraction pilot plant. Saccharomyces and Bacillus species were chosen for the bioproduction of the selected bioproducts. Experimental design and statistical analysis of results were carried out using response surface methodology (RSM) and artificial neural network (ANN). Studies on each of the selected bioproducts are as justified in the paragraphs below. Bioethanol production has recently become an increasing trend in research, with a focus on increasing its economic viability. Hence, the need to develop a low-cost fermentation medium with minimum redundant nutritional supplements, thereby minimizing the costs associated with nutritional supplements whereby inoculum preparation becomes necessary for ethanol production. Corn steep liquor (CSL) in glucose fermentation by Saccharomyces Type 1 (ST1) strain and Anchor Instant Yeast (AIY), which are low-cost media, are used as replacements for yeast extract (YE). The fermentation process parameters were optimized using artificial neural networks (ANN) and the response surface methodology (RSM). The study shows that for CSL, a maximum average ethanol concentration of 41.92 and 45.16 g/L representing 82% and 88% of the theoretical yield were obtained after 36 h of fermentation in a shake flask for ST1 and AIY respectively. For YE, ethanol concentration equivalent to 86% and 88% of theoretical yield were obtained with ST1 and AIY respectively after 48 h. Although, ANN predicted the responses of ethanol yield better than RSM, optimum conditions for ethanol production were better predicted by RSM. The consumers’ preference for ‘naturally’ produced aromas drives the development of bioproduction of acetoin from glucose with a view to optimize its production. The results revealed that by using a cheap nitrogen source, corn steep liquor, the yield of acetoin was similar to those of yeast and beef extracts. Furthermore, it was shown that by using Box-Behnken design, the optimum parameters such as glucose concentration, corn steep liquor, and inoculum size to maximize the concentration of acetoin produced were 78.40 g/L, 15.00% w/v and 2.70% v/v respectively. The validated concentration of acetoin produced in a triplicate analysis, 10.7 g/L, was 0.06% less than the predicted value. Increasing awareness of consumers of healthy, eco-friendly flavors and fragrances motivates the bioproduction of vanillin. The interactive effects of three variables on vanillin yield were evaluated by response surface methodology (RSM) with Box-Behnken design (BBD) model. The results showed the optimum conditions for the biotransformation of ferulic acid into vanillin can be achieved with maximum overall desirability (D) of 1.0 and a significant (p<0.05) quadratic model with regression coefficient (R2) of 0.995. Corn steep liquor, initial ferulic acid concentration and pH significantly influence the concentration of vanillin in the broth. The results in triplicate experiments confirmed vanillin yield of 386 mg/L after validation, which was in agreement with the prediction of the model. The maximum vanillin yield of 384.40 mg/L was predicted when corn steep liquor, ferulic acid concentration and pH were 7.72 g/L, 2.33 g/L, and 9.34 respectively. Fermentation system in a bioreactor has been proven to be an efficient system for the study of controlled fermentation variables when compared to a shake flask study. The influence of agitation, aeration, time and pH were analysed by Taguchi orthogonal array design for the upscale of acetoin in a bioreactor. The optimized parameters in 1.3L of fermentation vessel were as follows: 300 rpm agitation, 1.5 slpm aeration; 2 days’ fermentation time and 6.5 pH value. Agitation with above 70% was the most contributing factor and other variables were less than 30% in the percentage analysis of variance of each fermentation variables in the batch study of acetoin. A fourfold gain in acetoin titre (42.30 g/L) was obtained with the same substrate concentration in a lab-scale bioreactor on scaling up when compared with the shake flask batch study. The validated acetoin concentration of 41.72 g/L was obtained after a triplicate experiment to confirm the possibility of reproducing acetoin using the optimized conditions. Many separation techniques have been proven to recover value-added products from fermentation broth with a preference for several methods above other and new techniques that are emerging. Supercritical fluids separation using CO2 is one such technique. The feasibility of acetoin concentration and recovery was studied in supercritical CO2 pilot plant with pressure ranges of 100 to 300 bar, CO2 feed rate of 5 to 15 kg/h, at a process temperature of 37 and 80 °C in simulated and fermentation broth, respectively. The validated conditions for the fractionation of acetoin by supercritical fluid extraction (SFE) were determined as follows: extraction pressure, 300 bar; CO2 feed rate, 15 kg/h; extraction temperature 37 °C; and fractionation time of 30 minutes. At these operating conditions, the percentage recovery of acetoin with respect to the feed solution at the raffinate for the simulated and actual ermentation broth was 77.8% (0.20 g/L) and 77% (0.15 g/L) respectively. A two-fold extract increase was obtained after 30 minutes of fractionation. The study provides the technical feasibility and the base case data which are critical to the development and design of processes for production and recovery of acetoin. The lesson gleaned from this study may be extended to develop processes for the production and recovery of other bioproducts (ethanol and vanillin).

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Consumer Science: Food and Nutrition in the Faculty of Applied Sciences at the Cape Peninsula University of Technology 2012 / The chronic diseases of lifestyle, tuberculosis and Human immunodeficiency virus/Acquired immunodeficiency syndrome have a high prevalence in South Africa. These diseases are characterised by oxidative stress and a chronic inflammatory state that contribute to both the development and the acceleration of these diseases. Research into the phytochemical plant food components suggest that these substances could possibly play a vital role in the prevention of such disease. Corn steep liquor (CSL) is a waste product with an exceptionally high polyphenol content and total antioxidant capacity (TAC). This led to the suggestion that it could be utilised in the development of food products with functional food characteristics. Stock cubes, due to the widespread use among consumers of different socio-economic backgrounds, were identified as vehicle for the delivery of the CSL with its phytochemical content. This lead to the development of a stock cube utilising CSL as a source of phytochemical polyphenolic antioxidants with the micronutrients zinc, selenium and copper as added support to immunonutrition, along with iron due to the wide spread prevalence of iron deficiency in the South African population. The acceptability of the developed stock cube was tested by preparing savoury rice and pea soup and having blue collar (n = 50) and white collar (n = 49) participants rate the acceptability on a 9-point hedonic scale, ranging from “dislike extremely” to “like extremely”. The savoury rice received a 41% “like very much” rating followed by a 24% “like moderately” rating. The pea soup was rated even more positively as it received a 42% “like very much” rating and a 29% “like extremely” rating. In addition, among the blue collar participants, significant (p < 0.05 for each) findings occurred with a greater liking of the sample dishes prepared with the developed stock cube by participants of the ethnic Black grouping, with Xhosa as home language and being married, as well as those participants who habitually prepare the meals in the household. A significant (p < 0.05) finding with the white collar participants was a greater liking of the sample dishes prepared with the developed stock cube among those participants who would be willing to make use of a stock cube with health benefits. The developed stock cube was also subjected to six months accelerated shelf-life stability testing, reflecting twelve months real time storage. The parameters measured were microbial growth, oxidative rancidity, antioxidant status and organoleptic changes. All microbial growths tested remained within the acceptable specification ranges. Oxidative rancidity, measured as the peroxide value, was detected analytically at the fifth and sixth samplings, but was not detectable organoleptically. The antioxidant status, measured as the TAC and the total polyphenol content, remained relatively stable during the testing period. Though no noticeable organoleptic changes were observed during the stability testing, there was a darkening of the colour by the second sampling. The results of the acceptance testing, as well as the shelf-life stability testing, support the conclusions that the study objectives of developing a stock cube with functional food characteristics and it being received positively by consumers were achieved. Keywords: stock cubes; corn steep liquor; phytochemicals; consumer acceptance; new product development