Sample records for galacturonic acid
from WorldWideScience.org

Sample records 1 - 5 shown.



1

Extração de pectina de goiaba desidratada/ Extraction of pectin from dehydrated guava

Munhoz, Cláudia Leite; Sanjinez-Argandoña, Eliana Janet; Soares-Júnior, Manoel Soares
2010-03-01

Resumo em português Goiabas (Psidium guajava L.) cultivar Pedro Sato foram utilizadas para extração de pectina. Os frutos separados polpa e polpa com casca foram secos em estufa com circulação de ar. Amostras secas foram caracterizadas física e quimicamente. O planejamento composto central rotacional com quatro pontos axiais e três repetições no ponto central foi utilizado para determinar o rendimento de extração de pectina das farinhas de polpa e de polpa com casca de goiaba. A ex (mais) tração foi realizada em 4 g de farinha para 200 mL de solução de ácido cítrico em diferentes concentrações e em diferentes tempos de extração, a temperatura de 97 ºC. As pectinas obtidas nas melhores condições de extração foram caracterizadas. A extração de pectina com ácido cítrico e precipitação alcoólica forneceu rendimentos acima de 11% para a farinha de polpa e de polpa com casca de goiaba. As melhores condições de extração foram: concentração de ácido cítrico de 5 g.100 g-1 e tempo de extração de 60 minutos. As pectinas obtidas apresentaram-se de baixa esterificação e com teor de ácido galacturônico próximo ao padrão comercial (65%). Resumo em inglês Pedro Sato cultivar guavas (Psidium guajava L.) were used for extraction of pectin. The fruits were divided into pulp and pulp with peel, and dried in a stove with air circulation. Dry samples were characterized physically and chemically. The planning consisted of central axial rotation with four points, and three replicates in the central point were used to determine the extraction yield of pectin flour from the guava pulp and pulp with peel. The extraction was performed (mais) in 4 g of flour to 200 mL of solution of citric acid at different concentrations and at different times of extraction, at a temperature of 97 ºC. The pectins obtained in optimum conditions for extraction were characterized. The extraction of pectin with citric acid and alcohol precipitation provided yield above 11% for the guava flour, with pulp and pulp with peel. The best conditions for the extraction were: concentration of citric acid 5 g.100 g-1 and extraction time of 60 minutes. Pectins obtained demonstrated low esterification and with a level of galacturonic acid close to the commercial standard (65%).

Scientific Electronic Library Online (Portuguese)

2

Comportamento reológico de sistemas pécticos de polpas de frutas vermelhas/ Rheological behavior of pectic systems of red fruit pulps

Haminiuk, Charles Windson Isidoro; Sierakowski, Maria-Rita; Izidoro, Dayane Rosalyn; Maciel, Giselle Maria; Scheer, Agnes de Paula; Masson, Maria Lucia
2009-03-01

Resumo em português Neste trabalho, o comportamento reológico de sistemas pécticos formulados com as pectinas extraídas das polpas de morango, amora-preta e framboesa foi investigado através de testes reológicos oscilatórios. Adicionalmente, as propriedades químicas dessas pectinas foram estudadas. Os sistemas pécticos das polpas de frutas vermelhas apresentaram um caráter de gel forte de acordo com os testes reológicos, sendo o gel de morango caracterizado como o mais forte. Os te (mais) stes reológicos foram confirmados pelo experimento de Cox-Merz, grau de esterificação e peso molecular médio. O ácido galacturônico está diretamente relacionado com a formação da rede de pectina. Além disso, a diferença entre a força dos três géis pécticos pode ser atribuída aos valores do grau de esterificação e peso molecular médio desses biopolímeros. As pectinas extraídas das frutas vermelhas estudadas neste trabalho podem ser classificadas como pectinas de alta metoxilação, apresentado o grau de esterificação maior que 50%. Os três géis pécticos apresentaram uma boa estabilidade ao aumento da temperatura e ao tempo de cisalhamento oscilatório constante. Resumo em inglês In this work, the rheological behavior of pectic systems formulated with pectins extracted from strawberry, blackberry, and raspberry pulps was investigated by means of oscillatory rheological tests. In addition, the chemical properties of these pectins were studied. The pectic systems from those red fruit pulps showed a strong gel character according to the rheological tests showing that the strawberry pectin presented the strongest gel character, which was confirmed by (mais) the Cox-Merz experiment, degree of esterification, and average molecular weight data. The galacturonic acid is directly related to the formation of the pectin network. Besides, the difference between the strength of the three pectic gels can be attributed to the esterification degree values and the average molecular weight of these biopolymers. The pectins extracted from the red fruits studied in this work can be classified as high methoxy pectins with a degree of esterification higher than 50%. The pectic gels exhibit good stability with an increase in temperature and in the shear-oscillatory constant time.

Scientific Electronic Library Online (Portuguese)

3

Isolamento e seleção de microrganismos pectinolíticos a partir de resíduos provenientes de agroindústrias para produção de aromas frutais/ Screening of fruit flavors producing pectinolitic microorganisms isolated from agroindustrial residues

Uenojo, Mariana; Pastore, Glaucia Maria
2006-09-01

Resumo em português As pectinases são enzimas produzidas naturalmente por plantas, fungos, leveduras e bactérias. Estes microrganismos podem ser inoculados em meios contendo resíduos agroindustriais utilizados como fonte de carbono para a produção de compostos de maior valor agregado, como enzimas, etanol, proteínas, aminoácidos e compostos de aroma. Vários microrganismos foram isolados e selecionados quanto à produção de enzimas pectinolíticas pelo método da placa, através de (mais) zonas claras de degradação de pectina ao redor da colônia. De 104 linhagens testadas, 18 foram selecionadas para fermentarem em meio líquido, contendo pectina para a determinação de atividade de poligalacturonase (PG) e de pectina liase (PMGL), e em meio frutose/extrato de levedura para produção de aromas. As linhagens 2, 9, 20, 39, 70, 74 e 99 apresentaram unidades de atividade de PG superiores a 80 µmol de ácido galacturônico/mL/min, as linhagens 17, 18, 31, 37, 73, 74 e 125 apresentaram unidades de atividade de PMGL superiores a 1000 etamol de produtos insaturados/mL/min e as linhagens 13, 70, 73, 74, 125 e 144 apresentaram os melhores descritores e as maiores intensidades de aromas percebidos por um painel não treinado de provadores. Resumo em inglês Pectinases are enzymes used in food industries, produced by plants, fungi, yeasts and bacteria. These microorganisms can be inoculated in a medium containing agro-industrial residues from processing agricultural products, used as a carbon source to produce value-added products such as enzymes, ethanol, proteins, amino acids and flavor compounds. Several microorganisms were isolated and selected due to their capacity to produce pectinolytic enzymes in clear halos around co (mais) lonies by plate assay. From 104 strains, 18 were inoculated in a medium containing pectin as a carbon source and the pectinolytic activities of polygalacturonase (PG) and pectin lyase (PMGL) were determined. Strains 2, 9, 20, 39, 70, 74, and 99 showed activity units of PG higher than 80 µmol galacturonic acid/mL/minute. Strains 17, 18, 31, 37, 73, 74 and 125 showed activity units of PMGL higher than 1000 etamol unsaturated products/mL/minute. Strains 13, 70, 73, 74, 125 and 144 showed good signs of flavor noticed in the fructose and yeast extract medium and the most intense flavor according to a non-trained board of tasters.

Scientific Electronic Library Online (Portuguese)

4

Pectinases: aplicações industriais e perspectivas/ Pectinolytic enzymes: industrial applications and future perspectives

Uenojo, Mariana; Pastore, Glaucia Maria
2007-04-01

Resumo em inglês Pectic substances are structural heteropolysaccharides that occur in the middle lamellae and primary cell walls of higher plants. They are composed of partially methyl-esterified galacturonic acid residues linked by alpha-1, 4-glycosidic bonds. Pectinolytic enzymes are complex enzymes that degrade pectic polymers and there are several classes of enzymes, which include pectin esterases, pectin and pectate lyases and polygalacturonases. Plants, filamentous fungi, bacteria a (mais) nd yeasts are able to produce pectinases. In the industrial world, pectinases are used in fruit juice clarification, in the production of wine, in the extraction of olive oil, fiber degumming and fermentation of tea, coffee and cocoa.

Scientific Electronic Library Online (Portuguese)

5

Composição química da casca de ramí em diversas fases do seu desenvolvimento

Medina, J. C.; Jensen, G. O.; Neri, J. P.
1942-01-01

Resumo em inglês A study was made of the chemical composition of samples of the ribbons taken from the rami stalks at successive stages of growth with the object of determining the percentage oí lignin, cellulose, pectin, pentosans and of some substances not belonging to the cell wall. After an initial decrease, the percentage of ash increased as the plant grew and matured. The maximum (17,5%) was reached when the plant was 105 days old. The percentage of cellulose increased regularly an (mais) d reached a maximum (38,2%) when the plant was 75 days old. Subsequently there was a decrease as the plant grew older. After an initial increase, the percentage of lignin decreased somewhat and again increased as the plant matured. The maximum (14,5%), however, was observed when the plant was 45 days old. The percentage of pectin (galacturonic acid) was maximum (22,9%) in the first stage, afterwards showed a nearly regular decrease as the plant developed, but in the last two stages (105 and 120 days) there was a small increase. The percentage of pentosans (calculated of the furfurol phloroglucide yielded by pentosans only, with the Tollens'Tables), as well as the percentage of reducing sugars increased regulaily as the plant grew older. The maximum was 5,2 and 3,8 percent respectively. The percentage of hot-water extractive after a decrease in the earlier stages of the plant growth increased and reached a maximum (24,2%) in the penultimate stage of its development. The percentage of ethanol-benzene extractive from a maximum (8,3%) decreased regularly as the plant developed, but in the last stages of its development it increased somewhat. The percentage of crude protein (N x 6,25) irom a maximum (15,2%) in the first stage showed a regular decrease, but in the last two stages of the plant development there was an increase.

Scientific Electronic Library Online (Portuguese)