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Thermal inactivation of polyphenoloxidase and peroxidase in green coconut (Cocos nucifera) water

MURASAKI-ALIBERTI, Nathalia da C.; SILVA, Rodrigo M. S. da; GUT, Jorge A. W.; TADINI, Carmen C.
Fonte: WILEY-BLACKWELL PUBLISHING, INC Publicador: WILEY-BLACKWELL PUBLISHING, INC
Tipo: Artigo de Revista Científica
Português
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P>Coconut water is an isotonic beverage naturally obtained from the green coconut. After extracted and exposed to air, it is rapidly degraded by enzymes peroxidase (POD) and polyphenoloxidase (PPO). To study the effect of thermal processing on coconut water enzymatic activity, batch process was conducted at three different temperatures, and at eight holding times. The residual activity values suggest the presence of two isoenzymes with different thermal resistances, at least, and a two-component first-order model was considered to model the enzymatic inactivation parameters. The decimal reduction time at 86.9 degrees C (D(86.9 degrees C)) determined were 6.0 s and 11.3 min for PPO heat labile and heat resistant fractions, respectively, with average z-value = 5.6 degrees C (temperature difference required for tenfold change in D). For POD, D(86.9 degrees C) = 8.6 s (z = 3.4 degrees C) for the heat labile fraction was obtained and D(86.9 degrees C) = 26.3 min (z = 6.7 degrees C) for the heat resistant one.; FAPESP (The State of Sao Paulo Research Foundation); CAPES (Brazilian Committee for Postgraduate Courses in Higher Education)

Some Biochemical properties of polyphenoloxidase from spearmint (Mentha arvensis)

Neves, Valdir Augusto; Picchi, Douglas Gatte; Silva, Maraiza Aparecida da
Fonte: Brazilian Archives of Biology and Technology Publicador: Brazilian Archives of Biology and Technology
Tipo: Artigo de Revista Científica Formato: 1001-1010
Português
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Polifenoloxidase (PPO, EC 1.14.18.1) extraída de folhas de Mentha arvensis foi isolada por precipitação com (NH4)2SO4 e diálise extensiva. Seu pH e temperatura ótimos variaram com o substrato. A PPO apresentou atividade com vários difenóis. Valores de Km foram 0,825; 0,928 e 7,41 mM para ácido caféico, 4-metilcatecol e catecol, respectivamente. Na inativação térmica, 50% da enzima foi inativada após 60 e 15 segundos a 70 e 75ºC, respectivamente. A medida de atividade residual mostrou um efeito estabilizante de sacarose a várias temperaturas e uma energia de ativação (Ea) para inativação aumentando com a concentração de sacarose de 0 a 40% (p/p). Valores de energias de ativação de 78,13; 80,37; 82,79 and 81,00 kJ/Mol foram encontradas para 0, 15, 30 e 40% de sacarose, respectivamente. A PPO foi inibida pelos ácidos ascórbico, benzóico, cinamico, ferulico, p-cumárico, protocatéquico, além de metabisulfito de sódio, resorcinol e pirogalol. Os valores de Ki mostram que o ácido ascórbico foi o mais efetivo inibidor. O tipo de inibição foi determinado para cada inibidor.; Polyphenoloxidase (PPO; EC 1.14.18.1) extracted from Mentha arvensis leaves was isolated by (NH4)2SO4 precipitation and extensive dialysis. Its optimum pH and temperature varied with the substrate. The PPO showed activity with various diphenols. Km values were found 0.825...

Isolation and characterization of latent and active polyphenoloxidase in BRS Clara (CNPUV 154-147 x Centennial seedless) and BRS Morena (Marroo seedless x Centennial seedless) seedless table grapes

Lago-Vanzela, Ellen Silva; Pavezzi, Fabiana Carina; Martin, Natalia; Gomes, Eleni; Da Silva, Roberto
Fonte: Elsevier France-editions Scientifiques Medicales Elsevier Publicador: Elsevier France-editions Scientifiques Medicales Elsevier
Tipo: Artigo de Revista Científica Formato: 1251-1258
Português
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); The seedless grapes BRS Clara and BRS Morena, developed in Brazil, are currently growing in popularity due to their premium texture and taste. However, there are no reports on the polyphenoloxidase (PPO) from these cultivars. In this paper, active and latent PPO from BRS Clara and BRS Morena seedless grapes were extracted using the non-ionic detergents Triton-X-100 (active) and Triton-X-114 (latent), and their catecholase activities were characterized. The PPO extracted using Triton-X-110 exhibited maximum activities at pH 6.0 and at 25 degrees C. Above 30 degrees C, a gradual decline in activities was noted, with complete inactivation at 60 degrees C. The PPO from grapes extracted with Triton-X-114 was activated with 0.2% of the ionic detergent sodium dodecyl sulfate (SDS), and exhibited maximum activities at pH 5.5 and at 30 degrees C. It was stable until the temperature reached 60 degrees C. (C) 2011 Elsevier Masson SAS. All rights reserved.

Polyphenoloxidase activity in peaches after vibration

Dantas, Tiago B. H.; Ferraz, Antônio C. de O.; Honório, Sylvio L.; Lima, Giuseppina P.P.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 312-318
Português
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The vibration during transportation is one of the main causes of fruit damage. The actual methodologies used for damage evaluation in fruits seem to be subjective, since most of them are based on visual evaluation. In this study the effect of vibration, for one and two hours, on polyphenoloxidase (PPO) activity in peach pulp was investigated. The relation among PPO activity variation, postharvest time and resting time were also considered. Results showed that vibration affects PPO activity. However, it was not possible to correlate PPO activity variation and vibration.

Caracterização parcial da polifenoloxidase e avaliação de compostos fenolicos e antioxidantes em pessego (cv. Biuti); Parcial characterization of polyphenoloxidase and antioxidants and phenolic compounds evaluation in peach (cv. Biuti)

Ana Silvia Fidelis Belluzzo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/02/2008 Português
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O pêssego é uma das frutas que vêm ganhando destaque na produção nacional. Dentre as principais variedades produzidas, a biuti é uma das mais cultivadas, sendo utilizada tanto para o consumo in natura quanto para a indústria. A indústria de processamento de pêssego encontra muita dificuldade na manutenção da qualidade de seus produtos devido às alterações orgnolépticas que ocorrem durante sua vida de prateleira. A principal causa dessas alterações são as enzimas peroxidase (PDO) e polifenoloxidase (PPO), as quais catalisam reações de escurecimento enzimático, causando também mudanças indesejáveis no sabor e textura dos alimentos. O objetivo deste trabalho foi investigar as características bioquímicas da PPO de pêssego biuti, propor um tratamento térmico eficiente para a inativação da PPO e quantificar os compostos fenólicos e antioxidantes do pêssego congelado, pêssego em calda e polpa de pêssego. A PPO apresentou atividade ótima a 20°C em pH 5,5. A enzima se mostr ou estável após 30 minutos de tratamento térmico na faixa de 15 a 40°C. Na fa ixa de pH 7,0 a 8,0 a atividade ainda se manteve a níveis de 70 a 90% de atividade. A ação dos inibidores mostrou que os mais eficientes foram: ácido ascórbico...

Caracterização bioquímica da polifenoloxidase e da peroxidase de ameixa rubimel, polpa de cacau e estudo do efeito de agentes anti-escurecimento; Biochemical characterization of polyphenoloxidase and peroxidase of plum rubimel, cocoa pulp and study of the effect of agents anti-browning

Janai Cristiane Santos Nascimento Paz
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/07/2010 Português
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A reação de escurecimento enzimático ocorre em muitas frutas e vegetais quando certos compostos fenólicos são oxidados em reações catalisadas por enzimas como polifenoloxidase (PFO) (EC 1.14.18.1) ou peroxidases (POD) (EC 1.11.1.7). A ampliação das alternativas de conservação de frutas como a ameixa nacional Rubimel, cuja produção nacional tem aumentado nos últimos anos e da polpa de cacau, uma fruta de sabor exótico e muito agradável, muito consumida no Estado da Bahia, é necessária, pois possibilita a busca por mercado consumidor dos produtos derivados dessas frutas em regiões mais distantes, preservando a qualidade da fruta in natura. Este trabalho teve como objetivo caracterizar as enzimas polifenoloxidase e peroxidase presentes nas polpas de ameixa Rubimel e de cacau e estudar o efeito de alguns agentes antioxidantes na preservação da cor natural dessas polpas. O suco de ameixa Rubimel escureceu rapidamente após a extração. O extrato enzimático bruto obtido pela centrifugação da polpa de ameixa Rubimel apresentou atividade de polifenoloxidase (448U/g de polpa) e peroxidase (705U/g de polpa). Em estudo univariável (ensaio preliminar ao estudo do efeito combinado) a PFO do extrato bruto de ameixa Rubimel apresentou atividade ótima na faixa de temperatura de 30 a 35°C e pH 6...

Polyphenoloxidase activity and total phenolic content as related to browning of minimally processed ‘Jonagored’ apple

Rocha, Ada MCN; Morais, Alcina MMB
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Publicado em //2002 Português
Relevância na Pesquisa
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Phenolic content, polyphenoloxidase (PPO) activity and browning have been reported by different authors to vary in different ways, depending on cultivar, picking maturity, storage conditions, etc. Numerous authors have attempted to correlate browning results with the phenolic content and/or enzymatic activity of apples, but data published in the literature are divergent as to which of the two factors, ie the enzyme or the substrate, plays the decisive role in the overall phenomenon of enzymatic browning. The aim of this work was to follow the PPO activity and phenolic content of minimally processed apple (cv ‘Jonagored’) during cold storage and to establish a potential relationship with enzymatic browning. Increasing storage time of minimally processed apple seemed to result in an increase in PPO activity. No changes (P > 0.05) in total phenolic content were observed during storage. Colour degradation of apple cubes, as indicated by changes in colour parameters, was found to be highly correlated with PPO activity. Browning of ‘Jonagored’ apple cubes during storage was found to be moderately correlated with PPO activity. No correlation was found between the browning index and the total phenolic content.

Characterization of polyphenoloxidase (PPO) extracted from "Jonagored" apple

Rocha, A.M.C.N.; Morais, A. M. M. B.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2001 Português
Relevância na Pesquisa
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Polyphenoloxidase (PPO) was extracted from apple (cv. Jonagored) with addition of 2% PVP and 0.25% Triton X100 to the extraction buffer containing phenolic adsorbents. Experiments were performed to evaluate the affinity and specificity towards several substrates. ‘Jonagored’ apple PPO was found to have higher specificity (lower Km) towards L-dopa, 4-methylcatechol and (+) catechin than other phenols tested, but the highest activity level was obtained with p-cresol. The ratio Vmax/Km indicates that p-cresol followed by L-dopa and 4-methylcatechol are the best substrates for ‘Jonagored’ apple PPO. The enzyme activity showed two pH optima, at 5.0 and 7.5, at room temperature, with the main peak at pH 7.5 and the secondary one at pH 5.0 when catechol was the substrate.

Modelling the kinetics of thermal inactivation of apple polyphenoloxidase

Machado, M. F.; Saraiva, J.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Conferência ou Objeto de Conferência
Português
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The enzymatic browning of fruits and vegetables caused by mechanical injury during postharvest storage or processing is initiated by the catalytic action of polyphenoloxidase (PPO). A bleaching treatment prior to processing is still considered mostly effective in inhibiting the catalytic activity of PPO, and thus controlling undesirable enzymatic browning. In this work, different mathematical routines were assessed in terms of their adequacy to describe the thermal inactivation of PPO from Golden apples over a range of temperatures from 62.5 to 72.5 ºC. The classical approach to kinetic modelling of the decay activity of apple PPO, commonly reported to follow a first-order model, employs a two-step procedure, in which the model parameters are individually obtained, by each temperature studied, using non-linear or linear regressions. Thereafter, the estimated parameters are further used to calculate their temperature dependence. Alternatively, a one-step method provides a regression fit to all experimental data sets, with the temperature dependence equation being directly built in the kinetic model. This fitting technique thus, (a) avoids the estimation of intermediate parameters and, (b) substantially increases the degrees of freedom and hence the precision of parameters’ estimates. Within this issue was further explored the logarithmic transformation of the mathematical equations used on the adequacy of the model to describe experimental data. In all cases non-weighted least-squares regression procedures were used. Both the examination and criticism of the current modelling strategies were done by assessing statistical data obtained...

Altas pressões hidrostáticas na conservação de sumo de maçã 100%

Roldão, Maria Margarida Gomes
Fonte: ISA Publicador: ISA
Tipo: Dissertação de Mestrado
Publicado em //2014 Português
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Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia; The aim of this study was to assess the causes of instability in 100% apple juice treated by high hydrostatic pressure (500 MPa, 120 s, 18 °C, 0.1% ascorbic acid) and seek solutions to maintain the its original quality. Enzymatic browning of the juice and the appearance of a precipitate in the bottom of containers is due to the fact that the treatment is able to only inactivate 66% of polyphenoloxidase and 84.9% of pectinmethylesterase enzymes. The addiction of ascorbic acid was essential to maintenance the colour of juice, at 4 °C during 35 days. By varying the applied pressure (450 to 600 MPa) it was concluded that the inactivation of polyphenoloxidase was directly proportional to pressure, however an effective inactivation was not reached even at higher pressures. Futhermore, for pressures higher than 578 MPa a complete (100%) inactivation of pectinmethylesterase was achieved. Microwave treatment (T = 87 at 105 °C, ramp time = 76 to 300 s, holding time = 0 to 180 s) was completely effective (100%) in the inactivation of the pectinmethylesterase across the studied range of radiation. The microwave treatment was equally effective in the inactivation of polyphenoloxidase only for temperatures above 87 °C and ramp time above 280 seconds and/or temperature above 101°C and ramp time above 80 seconds. However...

Polyphenoloxidase activity in peaches after vibration

Dantas,Tiago B. H.; Ferraz,Antônio C. de O.; Honório,Sylvio L.; Lima,Giuseppina P. P.
Fonte: Associação Brasileira de Engenharia Agrícola Publicador: Associação Brasileira de Engenharia Agrícola
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2013 Português
Relevância na Pesquisa
37.44%
The vibration during transportation is one of the main causes of fruit damage. The actual methodologies used for damage evaluation in fruits seem to be subjective, since most of them are based on visual evaluation. In this study the effect of vibration, for one and two hours, on polyphenoloxidase (PPO) activity in peach pulp was investigated. The relation among PPO activity variation, postharvest time and resting time were also considered. Results showed that vibration affects PPO activity. However, it was not possible to correlate PPO activity variation and vibration.

Polyphenoloxidase and peroxidase in avocado pulp (Persea americana Mill.)

Vanini,Lucimara Salvat; Kwiatkowski,Angela; Clemente,Edmar
Fonte: Sociedade Brasileira de Ciência e Tecnologia de Alimentos Publicador: Sociedade Brasileira de Ciência e Tecnologia de Alimentos
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2010 Português
Relevância na Pesquisa
27.63%
The aim of the present investigation was to evaluate the enzymatic activity of polyphenoloxidase and peroxidase in avocado pulps, from the Northwest area of Paraná-Brazil, in order to compare the varieties on their enzymatic activity for both, minimum and industrial processing. Enzymatic extracts were prepared from avocado pulp of Choquete, Fortuna and Quintal varieties, in green and ripe maturation stage. Thermal treatment was applied with temperatures 60, 65, 70, 75 and 80 °C. The enzymatic activities were determined by using spectrophotometer. A decline of polyphenoloxidase activity was observed in all of the varieties when both, temperature and time increased. Total inactivation of enzymes was not observed in the largest temperature. Fortuna and Choquete variety showed the lowest polyphenoloxidase activity in the ripe stage. Soluble peroxidase showed activity in the green stage, whereas, ionically bound peroxidase activity increased with the change from green to ripe maturation stage in Choquete variety.

Effect of pH and temperature on peroxidase and polyphenoloxidase activities of litchi pericarp

Mizobutsi,Gisele Polete; Finger,Fernando Luiz; Ribeiro,Rosilene Antônio; Puschmann,Rolf; Neves,Ludmila Lafetá de Melo; Mota,Wagner Ferreira da
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2010 Português
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After harvesting litchi, the red color of the fruit pericarp is rapidly lost resulting in discoloration and browning during storage and marketing. The loss of the red color is caused by the degradation or loss of stability of anthocyanins. The action of peroxidase and polyphenoloxidase is usually related to the browning and discoloration of fruits of various species. This study aimed to evaluate the influence of pH and temperature on peroxidase and polyphenoloxidase activities, in a partially purified preparation of pericarp of the litchi cultivar Bengal. Fruits were harvested at the ripe stage and polyphenoloxidase was partially purified by sequential saturation in 80% ammonium sulfate. At concentrations of 40-50% and 60-70% ammonium sulfate the activities of polyphenoloxidase and peroxidase were, respectively, 124 times and 158 times higher than in the crude extract. The activity of peroxidase and polyphenoloxidase was maximum at pH 6.5 and 7.0, respectively, and no activity was detected at pH 2.5 and 9.5. Pre-incubation of the enzyme extract for 45 min at pH 2.5 or 9.5 completely inactivated the enzymes, with the highest degree of efficiency at pH 2.5. Peroxidase activity was highest at 70ºC and remained active for a period of 120 min at 70 and 80ºC. Peroxidase became completely inactive when maintained at 90ºC for 10 min or 1 min at 100ºC. Polyphenoloxidase activity was highest at 20ºC and remained active for a period of 120 min at 40 and 50ºC and was inactivated after 10 min at 60ºC. Due to the high temperature of inactivation of the peroxidase and polyphenoloxidase activities...

Peroxidase (POD) and polyphenoloxidase (PPO) in grape (Vitis vinifera L.)

Troiani,Estela de Pieri; Tropiani,Clariza Tomé; Clemente,Edmar
Fonte: Editora da Universidade Federal de Lavras Publicador: Editora da Universidade Federal de Lavras
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2003 Português
Relevância na Pesquisa
37.84%
The enzimatic activity of peroxidase (POD) and polyphenoloxidase (PPO) extracted from three grape cultivars (Vitis vinifera L.), cultivated in Marialva city, state of Paraná, was evaluated in this study. The enzymatic extracts were prepared starting from the Rubi, Borbon and Benitaka grape cultivars pulp and peel. The activity of the peroxidase was 53.00 units/100 g in the extract from the Rubi cultivar peel, and 327.00 units/100 g from the Benitaka cultivar, these values being superior to those observed in the same cultivars pulp extracts, which were 7.67 units/100 g and 44.00 units/100 g respectively. However, the result was opposite in the Borbon cultivar, with values of 141.11 units/100 g in the pulp and 11.50 units/100 g in the peel being found. The results of the polyphenoloxidase in the Borbon cultivar activity were 100.18 units/100 g in the pulp and 102.60 units/100 g in the peel, and in the Rubi and Benitaka cultivars were 60.40 units/100 g, 48.62 units/100 g in the pulp and 17.40 units/100 g, and 26.20 units/100 g in the peel, respectively. Protein determination was carried out in each extract, and the results found in the pulp and peel, respectively, were 0.56 and 0.64 mg/100 g for cultivar Benitaka, 1.38 and 6.45 mg/100 g for cultivar Rubi...

Some Biochemical properties of polyphenoloxidase from spearmint (Mentha arvensis)

Neves,Valdir Augusto; Picchi,Douglas Gatte; Silva,Maraiza Aparecida da
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2009 Português
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37.44%
Polyphenoloxidase (PPO; EC 1.14.18.1) extracted from Mentha arvensis leaves was isolated by (NH4)2SO4 precipitation and extensive dialysis. Its optimum pH and temperature varied with the substrate. The PPO showed activity with various diphenols. Km values were found 0.825, 0.928 and 7.41mM for caffeic acid, 4-methylcatechol and catechol, respectively. On heat-inactivation, half of the activity was lost after 60 and 15 sec at 70 and 75ºC, respectively. Measuring of residual activity showed a stabilizing effect of sucrose at various temperatures with activation energy (Ea) for inactivation increasing with sucrose concentration from 0 to 40% (w/w). Ea values of 78.13; 80.37; 82.79 and 81.00 kJ/Mol were found for 0, 15; 30 and 40% sucrose, respectively. PPO was inhibited by ascorbic, benzoic, cinnamic, ferulic, p-coumaric, protocatechuich acids, sodium metabisulfite, pyrogallol and resorcinol. The Ki values showed that ascorbic acid was the most effective inhibitor. The type inhibition was determined for each inhibitor.

Pyrophosphatase, Peroxidase and Polyphenoloxidase Activities during Leaf Development and Senescence 1

Patra, Hemanta K.; Mishra, Dinabandhu
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1979 Português
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Inorganic pyrophosphatase, peroxidase, and polyphenoloxidase activities were studied as the function of leaf insertion level in eight monocotyledonous and eight dicotyledonous species. Alkaline inorganic pyrophosphatase shows a declining activity toward the end of senescence whereas no regular drift in either peroxidase or polyphenoloxidase activities was noticed during senescence of attached leaves. In the primary leaves of rice, peroxidase and polyphenoloxidase activities were high in the senescent leaves and there exists a correlation between chlorophyll content and peroxidase activity though not with polyphenoloxidase activity. Upon detachment leaves exhibit increasing peroxidase and polyphenoloxidase activities with time. The distribution of the enzyme activities during senescence of attached leaves is suggested to be species-specific, and an increase in peroxidase and polyphenoloxidase activities cannot be taken as an indicator of leaf senescence.

Desenvolvimento de biossensor contendo polifenoloxidases de sementes de jatobá para análise ambiental; Developmento of biosensor containing polyphenoloxidase jatobá seed for environmental analysis

SANTIAGO, Patrícia de Oliveira
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Engenharia do Meio Ambiente; Engenharias Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Engenharia do Meio Ambiente; Engenharias
Tipo: Dissertação Formato: application/pdf
Português
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The polyphenoloxidase (PPO) is responsible for catalyzing the conversion of phenolic compounds to quinones in the presence of oxygen. This enzyme is widely used in biosensor production and selective evaluation of phenol content in industrial effluents. In this work a biosensor modified with enzyme extract containing polyphenoloxidase from Hymenaea stigonocarpa (jatoba) seed was developed to detect phenolic compounds. The extraction was performed using Structural Risk Minimization (SRM) factorial design with 22 more central point. The extraction conditions were optimized in 1.0% (w / v) polyvinylpyrrolidone (PVP) in 50 mmol l-1 phosphate buffer pH 7.5, time 40 min. The activity obtained was 0,97 ± 0,03 UEmg-1 proteins. The crude extract was partially purified using precipitation with ammonium sulfate 60% (w / v) and fractionated in phosphate buffer pH 7.0 in 1.0% Triton TX-100.The PPO activity resulting precipitated fraction was 2.7 times higher than in the crude extract. In 10% SDS gel were found six bands, three of which have molecular weights characteristic of PPO. The biosensor was constructed with a mixture of 60 mg of graphite powder, 30 mL of mineral oil and 10 mg of the enzymatic extract. The amperometric response was measured as the concentration of phenol...

Peroxidase (POD) and polyphenoloxidase (PPO) in grape (Vitis vinifera L.)

Fonte: Editora da Universidade Federal de Lavras Publicador: Editora da Universidade Federal de Lavras
Tipo: Artigo de Revista Científica Formato: text/html
Português
Relevância na Pesquisa
37.84%
The enzimatic activity of peroxidase (POD) and polyphenoloxidase (PPO) extracted from three grape cultivars (Vitis vinifera L.), cultivated in Marialva city, state of Paraná, was evaluated in this study. The enzymatic extracts were prepared starting from the Rubi, Borbon and Benitaka grape cultivars pulp and peel. The activity of the peroxidase was 53.00 units/100 g in the extract from the Rubi cultivar peel, and 327.00 units/100 g from the Benitaka cultivar, these values being superior to those observed in the same cultivars pulp extracts, which were 7.67 units/100 g and 44.00 units/100 g respectively. However, the result was opposite in the Borbon cultivar, with values of 141.11 units/100 g in the pulp and 11.50 units/100 g in the peel being found. The results of the polyphenoloxidase in the Borbon cultivar activity were 100.18 units/100 g in the pulp and 102.60 units/100 g in the peel, and in the Rubi and Benitaka cultivars were 60.40 units/100 g, 48.62 units/100 g in the pulp and 17.40 units/100 g, and 26.20 units/100 g in the peel, respectively. Protein determination was carried out in each extract, and the results found in the pulp and peel, respectively, were 0.56 and 0.64 mg/100 g for cultivar Benitaka, 1.38 and 6.45 mg/100 g for cultivar Rubi...

Atividade de polifenoloxidase após vibração e impacto em pêssego 'douradão'; Polyphenoloxidase activity after vibration and impact in 'Douradão' peach

Tiago Bassani Hellmeister Dantas
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 13/07/2010 Português
Relevância na Pesquisa
37.63%
Estima-se que as perdas pós-colheita de frutas e hortaliças variam de 15 a 40% em relação ao total da produção brasileira. Uma das etapas em que ocorrem tais perdas é o transporte, envolvendo o meio de transporte, condições das rodovias brasileiras e embalagens, dentre outros fatores. Dentre as principais dificuldades encontradas no acondicionamento de frutas e hortaliças, destacam-se os parâmetros do ensaio de vibração, utilizado como ferramenta no desenvolvimento de embalagens, e a forma de avaliação do desempenho físico-mecânico do conjunto produto-embalagem. Os parâmetros de vibração sugeridos em normas de ensaio como ABNT e ASTM não se aplicam à realidade de frutas e hortaliças, sendo excessivamente severos a tais produtos. Além disso, grande parte dos estudos nessa área é baseada em avaliações visuais de danos mecânicos e índices fisiológicos tradicionais, apresentando assim resultados pobres quanto ao conhecimento das reais alterações ocasionadas no produto. Assim, o presente trabalho teve por objetivo estudar as respostas bioquímicas do tecido vegetal em função de solicitações mecânicas por vibração e impacto, estabelecendo-se a seguinte hipótese: As alterações bioquímicas no tecido vegetal dependem dos níveis dos esforços vibracionais e por impacto. Amostras de pêssego 'Douradão' foram submetidas aos dois tipos de solicitação mecânica...

Efeito do pH e da temperatura nas atividades da peroxidase e polifenoloxidase do pericarpo de lichia; Effect of pH and temperature on peroxidase and polyphenoloxidase activities of litchi pericarp

Mizobutsi, Gisele Polete; Finger, Fernando Luiz; Ribeiro, Rosilene Antônio; Puschmann, Rolf; Neves, Ludmila Lafetá de Melo; Mota, Wagner Ferreira da
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/04/2010 Português
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Após a colheita do fruto, a cor vermelha do pericarpo da lichia é rapidamente perdida, o que resulta em descoloração e escurecimento durante o armazenamento e comercialização. A perda da cor vermelha é devido à degradação de antocianinas ou à perda de sua estabilidade. Usualmente, a ação da peroxidase e polifenoloxidase está relacionada ao escurecimento e à descoloração de várias frutas. Avaliou-se a influência do pH e da temperatura na atividade da peroxidase e polifenoloxidase em uma preparação purificada parcial de pericarpo de cultivar Bengal. Os frutos foram colhidos no estádio vermelho maduro. A polifenoloxidase foi parcialmente purificada por saturação seqüencial até 80% de sulfato de amônio. Na concentração de 40-50% e de 60-70% de sulfato de amônio, a atividade da polifenoloxidase e peroxidase foi 124 e 158 vezes maior vezes maior do que a encontrada no extrato cru. A peroxidase e polifenoloxidase apresentaram ótima atividade em pH 6,5 e 7,0 e nenhuma atividade foi detectada a pH 2,5 e 9,5. A pré-incubação do extrato das enzimas até 45 min a pH 2,5 ou 9,5 inativou completamente as enzimas, sendo que o maior grau de eficiência ocorreu em pH 2,5. A peroxidase apresentou maior atividade a 70ºC...