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Remoção de adstringência de caqui: um enfoque bioquímico, fisiológico e tecnológico; Removal of astringency in persimmon fruits: a biochemical, physiological and technological view

EDAGI, Fernando Kazuhiro; KLUGE, Ricardo Alfredo
Fonte: Universidade Federal de Santa Maria Publicador: Universidade Federal de Santa Maria
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.979878%
Apenas na Ásia, centro de origem do caqui (Diospyros kaki L.), existem mais de 2000 cultivares diferentes, das quais, a maioria é adstringente. Diante de tamanha variabilidade, existem diferentes métodos de remoção de adstringência, de tal forma que cada um deve ser adaptado a cada cultivar e local de produção. Tais métodos de destanização objetivam promover um acúmulo de acetaldeído na polpa dos frutos, o qual provoca a polimerização das moléculas de taninos solúveis, responsáveis pela adstringência, transformando-os num composto com consistência de gel, insolúvel e, assim, não adstringente. Entre os métodos mais utilizados estão: aplicação de vapor de álcool etílico, que ativa a enzima álcool dehidrogenase com subseqüente acúmulo de acetaldeído, e a promoção da anaerobiose, que induz a transformação do piruvato em acetaldeído em uma reação catalisada pela enzima piruvato descarboxilase. Neste trabalho de revisão, visa à discussão dos principais fatores a serem observados no processo de remoção da adstringência de caquis, como o método a ser utilizado, a temperatura de destanização, o tempo de exposição ao tratamento e o ponto de maturação dos frutos, entre outros.; In Asia, the center of origin of persimmon (Diospyros kaki L.)...

Destanização e armazenamento refrigerado de caqui 'Rama Forte' em função da época de colheita; Remove astringency and cold storage of Rama Forte persimmon according to harvest time

Vitti, Daniela Cristina Clemente
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 03/09/2009 Português
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O caqui Rama Forte representa, aproximadamente 60% da produção brasileira. No entanto, é uma cultivar que ainda apresenta problemas de comercialização e conservação pós-colheita. Os frutos desta cultivar pertencem ao grupo de polinização variável, o que significa dizer que, na ausência de sementes, os frutos preservam a adstringência mesmo quando maduros, necessitando, portanto, de um processo artificial para a remoção da adstringência. Dentro deste contexto, o objetivo do trabalho foi determinar os melhores tratamentos utilizando o etanol e o CO2 como agentes destanizadores dos frutos colhidos no início, meados e final da safra. Caquis Rama Forte foram colhidos em pomar comercial, em três épocas distintas nas safras de 2005/2006 e 2006/2007. A safra 2005/2006 visou determinar os melhores tratamentos utilizando-se 70% e 80% de CO2 por 12 e 18 horas e etanol, por 6 e 12 horas. Na safra 2006/2007 os melhores tratamentos obtidos na safra anterior foram repetidos e, adiconalmente, os frutos foram mantidos sob refrigeração por 30, 60 e 90 dias. Ao saírem da condição refrigerada, os frutos permaneceram em condições de comercialização simulada por até 16 dias. Os resultados foram submetidos à análise de erro do desvio padrão. As diferenças entre dois tratamentos maior que a soma de dois desvios padrões foram consideradas significativas. Os frutos de meados e final de safra apresentam-se em um estádio de maturação mais avançado...

Métodos combinados para destanização e conservação pós-colheita de caquis 'Giombo'; Combined methods for astringency removal and postharvest storage of Giombo persimmon

Terra, Felipe de Angelis Monteiro
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/10/2010 Português
Relevância na Pesquisa
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O presente trabalho teve como objetivo verificar a possibilidade de combinação de diferentes técnicas de pós-colheita em caquis cv. Giombo destanizados com álcool etílico, visando o aumento da conservação pós-colheita desses frutos através da manutenção da firmeza de polpa durante o armazenamento. Para tanto, aplicou-se o armazenamento refrigerado, associado à aplicação de 1-metilciclopropeno e destanização através de vapores de álcool etílico. No primeiro experimento os frutos foram acondicionados em câmaras de destanização, sendo submetidos à dosagem fixa de álcool etílico (3,50 mL Kg-1) durante 12 horas e a aplicação de uma dosagem fixa de 1000 nL L-1 de 1-metilciclopropeno (1-MCP) também durante 12 horas, sendo que a diferenciação entre os tratamentos foi obtida de acordo com o momento da destanização, da aplicação de 1-MCP e da combinação entre eles. Todos os frutos foram armazenados durante 30 dias sob refrigeração a 5 ± 1°C e 90 ± 5% UR e, posteriormente, em temperatura ambiente (25°C e 90 ± 5% UR) durante 15 dias. No segundo experimento, os frutos de caqui foram acondicionados em câmaras de destanização e submetidos aos mesmos processos do primeiro experimento. Os tratamentos foram obtidos através da combinação entre o momento da destanização e aplicação do 1-MCP e após serem submetidos aos tratamentos...

Técnicas de remoção da adstringência e refrigeração de caqui 'Giombo'; Techniques for astringency removal and cold storage of 'Giombo' persimmon

Monteiro, Mariana Ferraz
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 19/08/2011 Português
Relevância na Pesquisa
28.035405%
O presente trabalho teve como objetivo a determinação das melhores condições para a remoção da adstringência de caqui Giombo, com relação à temperatura, concentrações e tempos de exposição ao etanol, além de uso da atmosfera modificada em embalagens plásticas. As melhores combinações foram utilizadas para remoção de adstringência sucedida de armazenamento refrigerado com o objetivo de prolongar o período de oferta dos frutos e a manutenção da qualidade. Para isso, foram realizados 4 experimentos. No primeiro, foram avaliados doses e tempos de exposição ao etanol, sendo os frutos expostos a 1,75mL kg-1 por 12 ou 24hs; e 3,50mL kg-1 por 12 e 24hs antes de serem armazenados a 1ºC por 20 dias. No segundo experimento, foram avaliadas temperaturas de armazenamento, sendo elas 5ºC, 10ºC e 15ºC, para remoção da adstringência utilizando-se a melhor concentração e tempo de exposição ao etanol do experimento anterior (1,75mL kg-1 por 12hs). O terceiro experimento consistiu na utilização da atmosfera modificada na remoção da adstringência. Os frutos foram selados a vácuo em diferentes filmes plásticos: polietileno de baixa densidade (PEBD), polipropileno (PP) e polinylon (PN), todos com 20µm de espessura...

Caracterização do fruto de cambuci (Campomanesia phaea O. Berg.) e efeito da destanização sobre o potencial funcional in vitro; Characterization of the cambuci fruit (Campomanesia phaea O. Berg.) and deastringency effect on the in vitro functional potential

Sanches, Maria Cecilia Rocha
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/06/2013 Português
Relevância na Pesquisa
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A espécie Campomanesia phaea (O. Berg.) Landrum é popularmente conhecida como "cambuci". É uma das diversas espécies brasileiras de Myrtaceae com fruto comestível e ocorre nos estados de Minas Gerais e São Paulo, principalmente na Serra do Mar. Os frutos possuem intenso aroma agradável e são importantes fontes de compostos fenólicos. Apesar do excelente sabor e aroma do cambuci, a alta adstringência dos frutos, devido ao elevado conteúdo de taninos, reduz a sua aceitabilidade e aplicabilidade na indústria alimentícia. Uma maneira eficaz para remoção da adstringência é submeter o fruto a um processo de destanização, tal como atualmente utilizado para o caqui. O objetivo deste trabalho foi avaliar a variabilidade dos frutos provenientes de uma mesma região e de diferentes regiões, caracterizar frutos em diferentes estádios de maturação, avaliar a eficiência de tratamentos de destanização e determinar o efeito da destanização sobre o potencial funcional, através da determinação do teor e perfil de compostos fenólicos, capacidade antioxidante in vitro e inibição das enzimas do metabolismo de carboidratos. Os tratamentos testados foram: câmaras de etileno, câmara de etanol, ambiente anóxico, etanol no cálice e imersão em etanol. Os resultados mostram que frutos de uma mesma localidade apresentam variações no tamanho e na acidez. Frutos de diferentes regiões apresentaram variação significativa nos teores de fenólicos totais...

Estudos anatômicos e fisiológicos de frutos de caquizeiro (Diospyros kaki L.) quanto ao acúmulo de taninos e aos processos de destanização; Anatomical and physiological studies of persimmon fruits (Diospyros kaki L.) on the tannin accumulation and deastringency processes

Tessmer, Magda Andréia
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/04/2014 Português
Relevância na Pesquisa
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O presente trabalho visou analisar comparativamente as alterações fisiológicas e estruturais de caquis adstringentes (PVA) e não adstringentes (PCNA) desde o início do desenvolvimento até a maturação avançada. Além disso, na pós-colheita, foram realizados tratamentos de destanização e testadas diferentes condições de armazenamento para "Giombo". Este trabalho está sendo apresentado em seis capítulos, sendo que os últimos cinco capítulos referem-se aos experimentos realizados entre 2010 a 2013. No capítulo 2 é apresentado o desenvolvimento de caquis "Giombo" (PVA) e "Fuyu"(PCNA). Foi possível observar que a diferenciação das células taníferas e o processo de acúmulo de taninos no vacúolo não variou entre as cultivares, porém houve diferença significativa em relação à densidade de células taníferas e aos teores de taninos solúveis. O capítulo 3 apresenta o estudo comparativo de sete estádios de maturação de caquis "Giombo" e "Rojo Brillante"(PVA) e "Fuyu" e "Hana Fuyu" (PCNA). A redução da firmeza do mesocarpo de caquis de ambos os grupos está relacionada ao avanço da maturação e não à perda natural da adstringência. A capacidade antioxidante e o teor de sólidos solúveis em caquis dos dois grupos indicam que pode haver relação com a perda natural da adstringência...

Influence of condensed tannins from Brazilian semi-arid legumes on ruminal degradability, microbial colonization and ruminal enzymatic activity in Saanen goats

Guimaraes-Beelen, P. M.; Berchielli, T. T.; Beelen, R.; Medeiros, A. N.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 35-44
Português
Relevância na Pesquisa
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The present study aimed at determining the influence of condensed tannins present in the Brazilian legume species Mimosa hostilis, Mimosa caesalpinifolia and Bauhinia cheilantha on ruminal degradability, microbial colonization and enzymatic activity. Polyethylene glycol (PEG) was used to reduce the astringency and concentration of soluble condensed tannins. Four ruminally-cannulated Saanen goats (60 +/- 8 kg BW) were fed, in two experimental periods, with a hay diet based on the studied legumes treated or non-treated with PEG. Voluntary intake, microbial colonization, DM, CP, NDF, and ruminal degradability of PEG treated and non-treated forage leaves, as well as pH, ammonia and 1,4 P-endoglucanase activity of the rumen content were evaluated. Astringency and soluble tannin concentration of the studied legumes were reduced by approximately 70% and 50%, respectively, with PEG treatment. Average DM intake was higher for the treated diet (16.76 g DM/kg BW/day against 13.06 g DM/kg BW/day). Percentile values for degradation parameters and for potential and effective degradabilities of DM, CP and NDF were also affected by the tannins, but at different intensities. Electron microscopic observations of ruminally-incubated legume leaves showed a more effective microbial colonization of PEG-treated leaves for all legume species. A decrease in pH and an increase in ammonia concentration and in endoglucanase activity in the ruminal content was also observed for PEG-treated diets at all sampling periods. Condensed tannins of the studied legume species have influenced the adhesion conditions...

Effects of isoflavones on beany flavor and astringency of soymilk and cooked whole soybean grains

Carrão-Panizzi,Mercedes Concórdia; Beléia,Adelaide Del Pino; Prudêncio-Ferreira,Sandra Helena; Oliveira,Maria Cristina Neves; Kitamura,Keisuke
Fonte: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira Publicador: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/1999 Português
Relevância na Pesquisa
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Flavor is the main limiting factor affecting soybean acceptability in the Occidental countries. The purpose of this study was to determine the effetcs of isoflavones on soybean flavor. Differences in beany flavor and astringency of soymilk and cooked whole soybean grains, prepared with cultivars IAS 5 and BR-36 (136 and 54 mg of total isoflavones /100 g of sample, respectively) with pre-soaking and pre-heating of grains, were sensorially analised, by an unstructured category scale of ascending intensity. Differences in isoflavone contents for both soybean cultivars were maintained in the two products, despite the pre-treatments in the processing. Pre-soaking of grains intensified beany flavor in the soymilk, reducing the perception of astringency, which is caused by the aglucones that were developed in reduced amounts.The whole soybeans grains cooked under pressure (1.5 kgf/cm² at 127°C) presented reduced levels of isoflavones malonyl-glucosides. Due to thermal instability, these compounds were converted to conjugated glucosides, genistin and daidzin. In the cooked whole soybean grains, no aglucones were formed and consequently it was not possible to detect differences in astringency. Results suggest that pre-heating of grains promote better flavor in soybean products.

Ethylene-responsive transcription factors interact with promoters of ADH and PDC involved in persimmon (Diospyros kaki) fruit de-astringency

Min, Ting; Yin, Xue-ren; Shi, Yan-na; Luo, Zheng-rong; Yao, Yun-cong; Grierson, Donald; Ferguson, Ian B.; Chen, Kun-song
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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The persimmon fruit is a particularly good model for studying fruit response to hypoxia, in particular, the hypoxia-response ERF (HRE) genes. An anaerobic environment reduces fruit astringency by converting soluble condensed tannins (SCTs) into an insoluble form. Although the physiology of de-astringency has been widely studied, its molecular control is poorly understood. Both CO2 and ethylene treatments efficiently removed the astringency from ‘Mopan’ persimmon fruit, as indicated by a decrease in SCTs. Acetaldehyde, the putative agent for causing de-astringency, accumulated during these treatments, as did activities of the key enzymes of acetaldehyde synthesis, alcohol dehydrogenase (ADH), and pyruvate decarboxylase (PDC). Eight DkADH and DkPDC genes were isolated, and three candidates for a role in de-astringency, DkADH1, DkPDC1, and DkPDC2, were characterized by transcriptional analysis in different tissues. The significance of these specific isoforms was confirmed by principal component analysis. Transient expression in leaf tissue showed that DkPDC2 decreased SCTs. Interactions of six hypoxia-responsive ERF genes and target promoters were tested in transient assays. The results indicated that two hypoxia-responsive ERF genes...

Isolation and Expression of NAC Genes during Persimmon Fruit Postharvest Astringency Removal

Min, Ting; Wang, Miao-Miao; Wang, Hongxun; Liu, Xiaofen; Fang, Fang; Grierson, Donald; Yin, Xue-Ren; Chen, Kun-Song
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 15/01/2015 Português
Relevância na Pesquisa
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NAC genes have been characterized in numerous plants, where they are involved in responses to biotic and abiotic stress, including low oxygen stress. High concentration of CO2 is one of the most effective treatments to remove astringency of persimmon fruit owing to the action of the accumulated anoxia metabolite acetaldehyde. In model plants, NAC genes have been identified as being responsive to low oxygen. However, the possible relationship between NAC transcription factors and persimmon astringency removal remains unexplored. In the present research, treatment with a high concentration of CO2 (95%) effectively removed astringency of “Mopan” persimmon fruit by causing decreases in soluble tannin. Acetaldehyde content increased in response to CO2 treatment concomitantly with astringency removal. Using RNA-seq and Rapid amplification of cDNA ends (RACE), six DkNAC genes were isolated and studied. Transcriptional analysis indicated DkNAC genes responded differentially to CO2 treatment; DkNAC1, DkNAC3, DkNAC5 and DkNAC6 were transiently up-regulated, DkNAC2 was abundantly expressed 3 days after treatment, while the DkNAC4 was suppressed during astringency removal. It is proposed that DkNAC1/3/5/6 could be important candidates as regulators of persimmon astringency removal and the roles of other member are also discussed.

Effects of isoflavones on beany flavor and astringency os soymilk and cooked whole soybean grains.

CARRAO-PANIZZI, M.C.; BELEIA, A.D.P.; PRUDENCIO-FERREIRA, S.H.; OLIVEIRA, M.C.N.; KITAMURA, K.
Fonte: Pesquisa Agropecuaria Brasileira, Brasilia, v.34, n.6, p.1045-52, jun. 1999. Publicador: Pesquisa Agropecuaria Brasileira, Brasilia, v.34, n.6, p.1045-52, jun. 1999.
Tipo: Artigo em periódico indexado (ALICE)
Português
Relevância na Pesquisa
27.685166%
Flavor is the main limiting factor affecting soybean acceptability in the Occidental countries. The purpose of this study was to determine the effects of isoflavones on soybean flavor. Differences in beany flavor and astringency of soymilk and cooked whole soybean grains, prepared with cultivar IAS 5 and BR-36 (136 and 54 mg of total isoflovones/100 g of sample, respectively) with pre-soaking and pre-heading of grains, were sensorially analised, by an unstructured category scale of ascending intensity. Differences in isoflavone content for both soybean cultivars were maintained in the two products, despite the pre-treatments in the processing. Pre-soaking of grains intensified beany flavor in the soymilk, reducing the perception of astringency, which is caused by the aglucones that were developed in reduced amounts. The whole soybean grains cooked under pressure (1.5 kgf/cm2 at 127 Graus C.) presented reduced levels of isoflavones malonyl-glucosides. Due to thermal instability, these compounds were converted to conjugated glucosides, genistin and daidzin. In the cooked whole soybean grains, no aglucones were formed and consequently it was not possible to detect differences in astringency. Results suggest that pre-heating of grains promote better flavor in soybean products.; 1999

Effects of isoflavones on beany flavor and astringency os soymilk and cooked whole soybean grains.

CARRÃO-PANIZZI, M. C.; BELÉIA, A. D. P.; PRUDÊNCIO-FERREIRA, S. H.; OLIVEIRA, M. C. N.; KITAMURA, K.
Fonte: Pesquisa Agropecuária Brasileira, Brasília, v. 34, n. 6, p. 1045-1052, jun. 1999. Publicador: Pesquisa Agropecuária Brasileira, Brasília, v. 34, n. 6, p. 1045-1052, jun. 1999.
Tipo: Artigo em periódico indexado (ALICE)
Português
Relevância na Pesquisa
27.685166%
Flavor is the main limiting factor affecting soybean acceptability in the Occidental countries. The purpose of this study was to determine the effetcs of isoflavones on soybean flavor. Differences in beany flavor and astringency of soymilk and cooked whole soybean grains, prepared with cultivars IAS 5 and BR-36 (136 and 54 mg of total isoflavones /100 g of sample, respectively) with pre-soaking and pre-heating of grains, were sensorially analyzed, by an unstructured category scale of ascending intensity. Differences in isoflavone contents for both soybean cultivars were maintained in the two products, despite the pre-treatments in the processing. Pre-soaking of grains intensified beany flavor in the soymilk, reducing the perception of astringency, which is caused by the aglucones that were developed in reduced amounts.The whole soybeans grains cooked under pressure (1.5 kgf/cm2 at 127°C) presented reduced levels of isoflavones malonyl-glucosides. Due to thermal instability, these compounds were converted to conjugated glucosides, genistin and daidzin. In the cooked whole soybean grains, no aglucones were formed and consequently it was not possible to detect differences in astringency. Results suggest that pre-heating of grains promote better flavor in soybean products.; 1999

Remoção da adstringência de caquis 'Giombo' com subdosagens de etanol; Astringency removal of 'Giombo' persimmon with ethanol sub-doses

EDAGI, Fernando Kazuhiro; CHIOU, Diego Garcia; TERRA, Felipe de Angelis Monteiro; SESTARI, Ivan; KLUGE, Ricardo Alfredo
Fonte: Universidade Federal de Santa Maria Publicador: Universidade Federal de Santa Maria
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.49337%
O objetivo do trabalho foi avaliar a eficácia da aplicação de subdosagens de etanol na remoção da adstringência de caqui 'Giombo'. Além disso, foi avaliada a influência da temperatura e do tempo de exposição ao etanol no processo de destanização dos frutos. Assim, foram testadas diferentes doses de etanol (1,75; 3,5 e 7mL kg-1 ou 0,3 e 0,6mL L-1 de câmara-1), tempos de exposição (6, 12, 24 e 36h) e temperaturas de aplicação dos tratamentos e de armazenamento após a aplicação (5, 20 e 24°C). A exposição dos frutos à concentração de 1,75mL de etanol, durante 12 horas, foi suficiente para destanizar completamente os frutos. Após a aplicação dos tratamentos, os frutos levaram quatro dias para estarem aptos ao consumo. A refrigeração de caquis 'Giombo', após o tratamento com etanol, não influenciou o posterior processo de polimerização dos taninos solúveis.; The objective of this research was to evaluate ethanol sub-doses efficacy on the astringency removal of 'Giombo'. Additionally, it was evaluated the influence of temperature and ethanol exposure time on fruit deastringency. Thus, experiments were carried out with different exposition times (6, 12, 24 and 36h) and ethyl alcohol concentrations (1.75; 3.5 e 7mL kg-1 or 0.3 and 0.6mL L-1 of chamber). Fruit exposition to ethanol concentration of 1.75mL during 12 h was sufficient to remove completely the persimmon fruit astringency. After the treatment application...

SPR based Studies for Pentagalloyl Glucose Binding to α-Amylase

Guerreiro, J. Rafaela L.; Sutherland, Duncan S.; Freitas, Victor De; Sales, M. Goreti F.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
Relevância na Pesquisa
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Astringency is an organoleptic property resulting mostly from the interaction of salivary proteins with dietary polyphenols. It is of great importance to consumers but being typically measured by sensorial panels it turns out subjective and expensive. The main goal of the present work is to develop a sensory system to estimate astringency relying on protein/polyphenol interactions. For this purpose, a model protein was immobilized on a sensory gold surface and its subsequent interaction with polyphenols was measured by Surface Plasma Resonance (SPR). α-amylase and pentagalloyl glucose (PGG) were selected as model protein and polyphenol, respectively. To ensure specific binding between these, various surface chemistries were tested. Carboxylic terminated thiol decreased the binding ability of PGG and allowed covalent attachment of α-amylase to the surface. The pH 5 was the optimal condition for α-amylase immobilization on the surface. Further studies focus on Localized SPR sensor and application to wine samples, providing objectivity when compared to a trained panel.

TANNIN-PROTEIN INTERACTION IS MORE CLOSELY ASSOCIATED TO ASTRINGENCY THAN TANNIN-PROTEIN COMPLEX PRECIPITATION

Peña Neira, Alvaro; López Solís, Remigio; Obreque Slier, Elías
Fonte: ACS Paragon Plus Environment Publicador: ACS Paragon Plus Environment
Tipo: Artículo de revista
Português
Relevância na Pesquisa
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For Review. Confidential The relative abilities of two enological tannins to interact with a single gelatin were compared with their relative abilities to elicit astringency. A trained sensory panel assessed astringency whereas the interaction between tannins and gelatin was estimated by observing the ability of tannins both to interfere with gelatin diffusion on a cellulose membrane and to form tanningelatin precipitates. HPLC chromatography and spectroscopic analysis showed that one of the tannins was hydrolysable tannin while the other one was a proanthocyanidin. The majority of the sensory panelists recognized the hydrolysable tannin as far more astringent than the proanthocyanidin. Finally we showed that the more astringent tannin interfered markedly with gelatin diffusion on the cellulose membrane but it failed to produce tannin-gelatin precipitation whereas the proanthocyanidin tannin both interfered with gelatin diffusion and was a powerful gelatin-precipitant. Thus, this study supports the hypothesis that astringency correlates better with gelatin-tannin interaction than gelatin-tannin precipitation.

Enhancement of Both Salivary Protein-Enological Tannin Interactions and Astringency Perception by Ethanol

López Solís, Remigio; Peña Neira, Alvaro; Obreque Slier, Elías
Fonte: Universidade do Chile Publicador: Universidade do Chile
Tipo: Artículo de revista
Português
Relevância na Pesquisa
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Red wine astringency has been associated with interactions of tannins with salivary proteins. Tannins are active protein precipitants. Not much evidence exists demonstrating contribution of other wine components to astringency. We aimed to investigate an eventual role of ethanol both in astringency and salivary protein-enological tannin interactions. A trained sensory panel scored perceived astringency. Salivary protein-tannin interactions were assessed by observing both tannin-dependent changes in salivary protein diffusion on cellulose membranes and tannin-induced salivary protein precipitation. Proanthocyanidins and gallotannins in aqueous and hydroalcoholic solutions were assayed. A biphasic mode of diffusion on cellulose membranes displayed by salivary proteins was unaffected after dilution with water or enological concentrations of ethanol. At those concentrations ethanol was not astringent. In aqueous solution, tannins provoked both restriction of salivary protein diffusion, protein precipitation, and astringency. Those effects were exacerbated by 13% ethanol. In summary, enological concentrations of ethanol exacerbate astringency and salivary protein-tannin interactions.; This study was partially supported by grants Fondecyt-Chile 1080559...

Precipitation of low molecular weight phenolic compounds of grape seeds cv. Carmenere (Vitis vinifera L.) by whole saliva

Peña Neira, Alvaro; López Solís, Remigio; Obreque Slier, Elías
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artículo de revista
Português
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Artículo de publicación ISI; Low molecular weight phenolic compounds (LMWP) contribute to astringency and bitterness, two important sensory attributes. This work aimed to study the interactions between human saliva and a group of LMWP from a grape seed extract, namely, monomers, dimers and trimers of flavan-3-ol plus gallic acid. LMWP in the sediment that was produced by mixing whole saliva with the grape seed extract were identified by high-performance liquid chromatography analysis (HPLC-DAD). Two assays to produce LMWP-salivary protein sediments were carried out. An indirect assay consisted of in vitro mixing aliquots of saliva with a constant volume of the grape seed extract followed by centrifugation and sediment analysis. In a direct assay, aliquots of the grape seed extract were mixed in-mouth with saliva, returned to a vessel and centrifuged. In each assay, polyphenol composition of the sediments varied according to the tannin/saliva vol/vol ratio although in both cases monomeric LMWP were the most abundant polyphenol components of the sediments. The study also suggested the need for a strict control of the in vitro experimental conditions used to mimic the in vivo conditions in which tannin-protein interactions do occur and produce astringency perception.; Fondecyt-Chile 1080559 Corfo-Innova Tecnovid 05CTE02-04 DI- Universidad de Chile Mult-05/35-2

Interactions of enological tannins with the protein fraction of saliva and astringency perception are affected by pH

Peña Neira, Alvaro; López Solís, Remigio; Obreque Slier, Elías
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo de revista
Português
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Artículo de publicación ISI; The effects of pH on both tannin-induced astringency and tanninesalivary protein interactions were investigated. A trained sensory panel evaluated astringency perception. Tanninesalivary protein interactions were assessed in vitro by examining the effects of either a condensed enological tannin or an hydrolyzable enological tannin on two physicochemical properties of the protein fraction of saliva, namely, its mode of diffusion on cellulose membranes and its precipitation. Comparative assays mimicking the degree of dilution experienced by saliva during a tasting assay were performed at pH 3.5 and pH 7.0. Results indicated that both enological tannins were perceived as clearly more astringent at pH 3.5 compared with pH 7.0. In addition, the effects of tannins on protein diffusion and protein precipitation were markedly exacerbated at pH 3.5.; This study was partially supported by grants DI- Universidad de Chile Mult-05/35-2 and Fondecyt-Chile 1110832.

Comparison of analytical methods for measuring proanthocyanidins in wines and their relationship with perceived astringency

López Solís, Remigio; Jara Campos, Carla; Canals, Joan M.; Narváez Bastías, Jaime; Peña Neira, Álvaro; Cáceres Mella, Alejandro
Fonte: International Journal of Food Science and Technology, Institute of Food Science and Technology Publicador: International Journal of Food Science and Technology, Institute of Food Science and Technology
Tipo: Artículo de revista
Português
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37.90893%
Artículo de publicación ISI; The concentration of proanthocyanidins from twenty red wines from cv. Cabernet Sauvignon, five ros e wines from cv. Cabernet Sauvignon and five white wines from cv. Sauvignon Blanc was quantified using four analytical methodologies, and their relationship with the perceived astringency was investigated. Proanthocyanidin concentrations were determined by a methylcellulose precipitation assay, a protein precipitation assay and two colourimetric methods (Bate-Smith and vanillin assay). The four methodologies showed high repeatability but differed widely in proanthocyanidin concentrations. The methylcellulose and protein precipitation assays could not quantify proanthocyanidins in ros e and white wines. The protein precipitation assay gave the lowest concentration of proanthocyanidins in all of the red wines. The methylcellulose precipitation assay (r = 0.7725; r2 = 0.59) and the protein precipitation assay (r = 0.6828; r2 = 0.47) showed a strong correlation with the perceived astringency compared with the colourimetric methods. The strong correlation of the methylcellulose precipitation method with the perceived astringency could be a useful tool to estimate red wine astringency.

Colloidal stability of tannins: astringency, wine tasting and beyond

Zanchi, D.; Poulain, C.; Konarev, P.; Tribet, C.; Svergun, D. I.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 07/10/2008 Português
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Tannin-tannin and tannin-protein interactions in water-ethanol solvent mixtures are studied in the context of red wine tasting. While tannin self-aggregation is relevant for visual aspect of wine tasting (limpidity and related colloidal phenomena), tannin affinities for salivary proline-rich proteins is fundamental for a wide spectrum of organoleptic properties related to astringency. Tannin-tannin interactions are analyzed in water-ethanol wine-like solvents and the precipitation map is constructed for a typical grape tannin. The interaction between tannins and human salivary proline-rich proteins (PRP) are investigated in the framework of the shell model for micellization, known for describing tannin-induced aggregation of beta-casein. Tannin-assisted micellization and compaction of proteins observed by SAXS are described quantitatively and discussed in the case of astringency.