Made available in DSpace on 2014-12-17T15:01:51Z (GMT). No. of bitstreams: 1
MariaVPR_TESE_1-170.pdf: 4608142 bytes, checksum: 9ed83cbe76a127f48714302cd74c674a (MD5)
Previous issue date: 2010-11-22 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Recently, global demand for ethanol fuel has expanded very rapidly, and this should further
increase in the near future, almost all ethanol fuel is produced by fermentation of sucrose or
glucose in Brazil and produced by corn in the USA, but these raw materials will not be
enough to satisfy international demand. The aim of this work was studied the ethanol
production from cashew apple juice. A commercial strain of Saccharomyces cerevisiae was
used for the production of ethanol by fermentation of cashew apple juice. Growth kinetics and
ethanol productivity were calculated for batch fermentation with different initial sugar
(glucose + fructose) concentration (from 24.4 to 103.1 g.L-1). Maximal ethanol, cell and
glycerol concentrations (44.4 g.L-1, 17.17 g.L-1, 6.4 g.L-1, respectively) were obtained when
103.1 g.L-1 of initial sugar concentration were used, respectively. Ethanol yield (YP/S) was
calculated as 0.49 g (g glucose + fructose)-1. Pretreatment of cashew apple bagasse (CAB)
with dilute sulfuric acid was investigated and evaluated some factors such as sulfuric acid
concentration, solid concentration and time of pretreatment at 121?C. The maximum glucose
yield (162.9 mg/gCAB) was obtained by the hydrolysis with H2SO4 0.6 mol.L-1 at 121?C for 15
min. Hydrolysate, containing 16 ? 2.0 g.L-1 of glucose, was used as fermentation medium for
ethanol production by S. cerevisiae and obtained a ethanol concentration of 10.0 g.L-1 after 4
with a yield and productivity of 0.48 g (g glucose)-1 and 1.43 g.L-1.h-1, respectively. The
enzymatic hydrolysis of cashew apple bagasse treated with diluted acid (CAB-H) and alkali
(CAB-OH) was studied and to evaluate its fermentation to ethanol using S. cerevisiae.
Glucose conversion of 82 ? 2 mg per g CAB-H and 730 ? 20 mg per g CAB-OH was
obtained when was used 2% (w/v) of solid and loading enzymatic of 30 FPU/g bagasse at 45
?C. Ethanol concentration and productivity was achieved of 20.0 ? 0.2 g.L-1 and 3.33 g.L-1.h-1,
respectively when using CAB-OH hydrolyzate (initial glucose concentration of 52.4 g.L-1).
For CAB-H hydrolyzate (initial glucose concentration of 17.4 g.L-1), ethanol concentration
and productivity was 8.2 ? 0.1 g.L-1 and 2.7 g.L-1.h-1, respectively. Hydrolyzates fermentation
resulted in an ethanol yield of 0.38 g/g glucose and 0.47 g/g glucose, with pretreated CABOH
and CAB-H, respectively. The potential of cashew apple bagasse as a source of sugars for
ethanol production by Kluyveromyces marxianus CE025 was evaluated too in this work. First,
the yeast CE025 was preliminary cultivated in a synthetic medium containing glucose and
xylose. Results showed that it was able to produce ethanol and xylitol at pH 4.5. Next, cashew
apple bagasse hydrolysate (CABH) was prepared by a diluted sulfuric acid pre-treatment. The
fermentation of CABH was conducted at pH 4.5 in a batch-reactor, and only ethanol was
produced by K. marxianus CE025. The influence of the temperature in the kinetic parameters
was evaluated and best results of ethanol production (12.36 ? 0.06 g.L-1) was achieved at 30
?C, which is also the optimum temperature for the formation of biomass and the ethanol with
a volumetric production rate of 0.25 ? 0.01 g.L-1.h-1 and an ethanol yield of 0.42 ? 0.01 g/g
glucose. The results of this study point out the potential of the cashew apple bagasse
hydrolysate as a new source of sugars to produce ethanol by S. cerevisiae and K. marxianus
CE025. With these results, conclude that the use of cashew apple juice and cashew apple
bagasse as substrate for ethanol production will bring economic benefits to the process,
because it is a low cost substrate and also solve a disposal problem, adding value to the chain
and cashew nut production / Recentemente, a demanda mundial por etanol combust?vel tem se expandido de
forma muito r?pida, sendo quase todo etanol combust?vel ? produzido por fermenta??o de
sacarose no Brasil ou glicose de milho nos Estados Unidos, por?m, estas mat?rias-primas n?o
ser?o suficientes para satisfazer a demanda internacional. Neste contexto, o objetivo deste
trabalho foi avaliar a produ??o de bioetanol a partir do ped?nculo de caju. Para tal fim,
inicialmente, estudou-se a produ??o de etanol utilizando o suco de caju como fonte de
carbono, avaliando a influ?ncia da concentra??o inicial de substrato por Saccharomyces
cerevisiae. Nessa etapa, os melhores resultados foram utilizando uma concentra??o inicial de
a??car de 87,71 g.L-1 obtendo a concentra??o m?xima de etanol de 42,8 ? 3 g.L-1 com uma
produtividade de 9,71 g.L-1.h-1 e rendimento de etanol de 0,49 g etanol/g glicose + frutose.
Posteriormente, estudou-se a produ??o de etanol utilizando como material lignocelul?sico o
baga?o de caju (CAB) que continha 20,9% celulose, 16,3% hemicelulose e 33,6% lignina +
cinzas. Inicialmente estudou-se o pr?-tratamento do CAB com ?cido sulf?rico dilu?do
avaliando-se diferentes par?metros, obtendo as maiores concentra??es dos a??cares glicose
(22,8 ? 1,5 g.L-1) e xilarabin (arabinose + xilose plus, 29,2 ? 2,4 g.L-1), na fra??o l?quida
(CAB-H), no pr?-tratamento conduzido em autoclave a 121?C por 15 min usando H2SO4 0,6
mol.L-1 e 30% m/v de CAB, com rendimentos de glicose, xilarabin e a??cares totais de 75,99
? 5,0, 97,17 ? 8,1 e 173,16 ? 13,0 mg.(g de baga?o)-1, respectivamente. A convers?o obtida
nesse pr?-tratamento com base na percentagem de celulose e hemicelulose do CAB foi 322,1
? 20,1 mg glicose.(g celulose)-1 e 514,1 ? 43,1 mg xilarabin.(g hemicelulose)-1. Na
fermenta??o do hidrolisado CAB-H por S. cerevisiae obteve-se 10 g.L-1 de etanol ap?s 4
horas de cultivo, com rendimento de 0,48 g.(g glicose)-1 e produtividade de 2,62 g.L-1h-1.
Ap?s, estudou-se a hidr?lise enzim?tica do CAB ap?s pr?-tratamento com H2SO4 dilu?do
(CAB-H) e alcalino (CAB-OH) e a fermenta??o dos hidrolisados por S. cerevisiae para
produzir etanol. Uma convers?o de glicose de 82 ? 2 mg.(gCAB-H)-1 e 730 ? 20 mg.(gCAB-OH)-1
foi obtida utilizando 2% (m/v) de s?lidos e carga enzim?tica de 30 FPU.(g baga?o)-1 a 45?C.
Na fermenta??o conduzida com o hidrolisado obtido da hidr?lise enzim?tica do CAB-OH,
obteve-se uma concentra??o de etanol, produtividade e rendimento de 20,0 ? 0,2 g.L-1, 3,33
g.L-1.h-1 e 0,38 g.(g de glicose)-1, respectivamente. Para o hidrolisado da hidr?lise do CAB-H,
a concentra??o de etanol foi 8,2 ? 0,1 g.L-1 com 2,7 g.L-1.h-1 de produtividade e rendimento
de 0,47 g.(g glicose)-1 em 3 h de ensaio. O potencial do baga?o de caju como fonte de
a??cares para a produ??o de etanol por Kluyveromyces marxianus CE025 tamb?m foi
avaliado e verificou-se a influ?ncia da temperatura nos par?metros cin?ticos, sendo os ensaios
conduzidos em batelada a pH 4,5, utilizado o hidrolisado (CAB-H) como fonte de carbono.
Os melhores resultados para a produ??o de etanol foram a 30?C, coincidindo com a
temperatura ?tima de crescimento, resultando em 12,36 ? 0,06 g.L-1 de etanol, com uma taxa
volum?trica de produ??o de 0,26 ? 0,01 g.L-1.h-1 e rendimento de 0,42 ? 0,01 g.(g de glicose)-
1. Os resultados apresentados demonstram o potencial do ped?nculo de caju (suco e baga?o)
como nova fonte de carbono para produzir etanol por S. cerevisiae e K. marxianus CE025
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/15906 |
| Date | 22 November 2010 |
| Creators | Rocha, Maria Valderez Ponte |
| Contributors | CPF:10847022404, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4788057U7, Santos, Everaldo Silvino dos, CPF:87510383404, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4799564Y2, Pagnoncelli, Maria Giovana Binder, CPF:02714319971, http://lattes.cnpq.br/1360308643397232, Melo, V?nia Maria Maciel, CPF:11269545353, http://lattes.cnpq.br/1572504650930605, Gouveia, Ester Ribeiro, CPF:65930606404, http://lattes.cnpq.br/6291196494488690, Goncalves, Luciana Rocha Barros, Macedo, Gorete Ribeiro de |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Engenharia Qu?mica, UFRN, BR, Pesquisa e Desenvolvimento de Tecnologias Regionais |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
Page generated in 0.0026 seconds