Pectin

Rolin, Claus; Vries, Joop de

doi:10.1007/978-94-009-0755-3_10

Cited by 52 publications

(49 citation statements)

References 66 publications

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“…Algumas revisões têm sido publicadas descrevendo estrutura, processamento e aplicações de pectinas (KERTESZ, 1951;PILNIK, 1990;MAY, 1990;ROLIN;DE VRIES, 1990;PEREZ;MAZEAU;PENHOAT, 2000;RIDLEY;O'NEILL;MOHNEN, 2001) e mais recentemente Willats, Knox e Mikkelsen (2006) ressaltaram recentes avanços na estrutura discutindo as conseqüências para produção e aplicações. A pectina é descrita como uma família de oligossacarídeos e polissacarídeos com algumas estruturas comuns mas bastante diversas no que diz respeito a estrutura fina.…”

Section: Introductionunclassified

Influência da concentração de ácidos no processo de extração e na qualidade de pectina de bagaço de maçã

et al. 2006

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ResumoNo processamento do suco concentrado de maçã, o bagaço residual da primeira extração é reidratado e prensado novamente a fim de aumentar o rendimento, tornando-se então a matéria-prima para a obtenção industrial de pectina. Neste trabalho os objetivos compreenderam estabelecer os protocolos de beneficiamento do bagaço e de uso de ácidos minerais e orgânicos no rendimento gravimétrico, usando o grau de esterificação, medido por técnicas espectrofotométricas e titulométricas como referencial de qualidade. A farinha de bagaço de maçã, com umidade de 12% apresentava 33,4% de açúcares redutores, e 40% de fibra alimentar e 10-15% de pectina, em base seca, com coloração própria. Os parâmetros do processo de extração das substâncias pécticas, 97ºC/10 minutos e proporção soluto: solvente 1:40 permitiram estabelecer a eficiência de cada ácido na concentração de 1 a 750 mMol/L na solubilização da protopectina. Foram diferenciados dois tipos de comportamentos dos agentes ácidos: [1] liberação de pectina em baixas concentrações e destruição em elevados teores e [2] rendimento gravimétrico crescente, atingindo valores superiores aos possíveis, indicando uma agregação de grupamentos orgânicos na estrutura. O HNO 3 foi considerado o mais indicado para a extração de pectina, em concentração máxima de 100 mMol/L. Palavras-chave: Resíduos agroindustriais, substâncias pécticas, extração, rendimento, qualidade AbstractIn concentrated apple juice processing units the pomace is washed with tap water in order to increase the yield so that the industrial by-product contains no more soluble pectin but only insoluble protopectin. In this article the main objectives were to establish a procedure to prepare the apple pomace as raw material and to extract pectin with several kinds and concentration of mineral and organic acids considering its degree of esterification, determined by titrimetric and spectroscopic techniques, as quality references. Dried apple pomace, with 12% moisture, showed 33.4% reducing sugars and 40% dietary fiber in dry

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Section: Introductionunclassified

Influência da concentração de ácidos no processo de extração e na qualidade de pectina de bagaço de maçã

et al. 2006

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“…Pectic enzymes, in particular those from Aspergillus species, are industrially important in the processing of agricultural products (Rombouts and Pilnik, 1980). Besides the application of crude enzyme preparations in these processes, there is a growing demand for specific technical enzyme preparations for the modification of pectins (Rolin and de Vries, 1990). The study of the kinetic properties of exopolygalacturonase, the cloning of the encoding gene ( p p x ) and overexpression of the enzyme make a contribution in this direction.…”

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confidence: 99%

Primary Structure and Characterization of an Exopolygalacturonase from Aspergillus Tubingensis

Kester

Someren

Muller

et al. 1996

European Journal of Biochemistry

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From the culture fluid of the hyphal fungus Aspergillus tubingensis, an exopolygalacturonase with a molecular mass of 78 kDa, an isoelectric point in the pH-range 3.7-4.4 and a pH optimum of 4.2 was purified. The enzyme has been characterized as an exopolygalacturonase [poly( 1,4-a-~-ga~acturonide)galacturonohydrolasel that cleaves monomer units from the non-reducing end of the substrate molecule.K,,, and V,,,, for polygalacturonic acid hydrolysis were 3.2 mg mlV' and 3.1 mg ml-' and 255 U mg I and 262U mg-' for the wild-type and recombinant enzymes, respectively. The kinetic data of exopolygalacturonase on oligogalacturonates of different degree of polymerization (2-7) were interpreted in terms of a subsite model to obtain more insight into catalysis and substrate binding. On oligogalacturonates of different degrees of polymerization (2 -7), the Michaelis constant (K,,,) decreased with increasing chain length (n). The V,;,, value increased with chain length up to n = 4, then reached a plateau value. The enzyme was competitively inhibited by galacturonic acid ( K , = 0.3 mM) as well as by reduced digalacturonate (K, = 0.4 mM).The exopolygalacturonase gene (pgax) was cloned by reverse genetics and shows only 13 % overall amino acid sequence identity with A. niger endopolygalacturonases. The exopolygalacturonase is most related to plant polygalacturonases. Only four small stretches of amino acids are conserved between all known endogalacturonases and exopolygalacturonases. Expression of the pgaX gene is inducible with galacturonic acid and is subject to catabolite repression. A fusion between the promoter of the A. niger glycolytic gene encoding pyruvate kinase and the pguX-coding region was used to achieve high level production of exopol ygalacturonase under conditions where no endopolygalacturonases were produced.

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“…Neutral sugars such as galactose, glucose, rhamnose, arabinose, and xylose (usually in weights of about 5-10% of the amounts of α-D-galacturonic acid) are often present in pectin preparations, either as side-chains to the galacturonic main chain or, more likely, as a part of contaminating polysaccharides (glucans and xyloglucans). These sugars can act as dehydrating agents and, thereby, support pectin adhesion (Rolin & De Vries 1990, Turquois et al 1999.…”

Section: Mechanically-enzymatically Decomposed Potato-pulp In Productmentioning

confidence: 99%

Wood production, wood technology, and biotechnological impacts

Kües¹

2007

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Pectin

Cited by 52 publications

References 66 publications

Influência da concentração de ácidos no processo de extração e na qualidade de pectina de bagaço de maçã

Influência da concentração de ácidos no processo de extração e na qualidade de pectina de bagaço de maçã

Primary Structure and Characterization of an Exopolygalacturonase from Aspergillus Tubingensis

Wood production, wood technology, and biotechnological impacts

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