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Astringency

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Ann C Noble – 1st expert on this subject based on the ideXlab platform

  • Astringency and Bitterness of Flavonoid Phenols
    , 2009
    Co-Authors: Ann C Noble

    Abstract:

    In beverages and fruits the lingering tactile sensation of Astringency,\nas well as the persistent taste of bitterness, are primarily elicited by\nflavonoid phenols. Chemically, relative Astringency of a compound is\ndefined by its effectiveness in precipitating protein. As the degree of\npolymerization of tannin increases, bitterness decreases, while\nAstringency increases. The astringent flavanol polymers or condensed\ntannins have a strong affinity for binding with proline rich proteins,\nsuch as those found in saliva. Sensorially Astringency is a drying or\nrough mouthfeel thought to result from decreased oral lubrication,\nfollowing binding of salivary proteins by tannins. This may explain the\nincrease in intensity of Astringency over several sips or wine or tea.\nAlso consistent with this hypothesis, subjects with low salivary flow\nrates perceive Astringency more intensely than high-flow individuals.

  • Bitterness and Astringency of grape and wine polyphenols
    Australian Journal of Grape and Wine Research, 2001
    Co-Authors: Franck Brossaud, Veronique Cheynier, Ann C Noble

    Abstract:

    Extracts containing anthocyanins (ACN), and skin tannins (SKIN) and seed tannins (SEED) were prepared from Vitis vinifera cv. Cabernet Franc grapes grown in the Loire Valley, and characterised. Phenolic fractions from Cabernet Franc wines made from three Loire Valley locations were also isolated and characterised. Bitterness and Astringency of ACN, SEED and SKIN as well as the wine extracts were evaluated by time intensity procedures in citric acid solution and in a base white wine. SEED and SKIN were equally astringent when tasted at the same concentration in spite of differences in tannin composition. The lower molecular weight (MW) of SEED was equal in Astringency to larger MW SKIN which had a lower percentage of galloylation. The SEED fraction was slightly more bitter than the SKIN fraction in the citric acid solution, although no difference could be detected between samples in base white wine. Astringency of ACN alone was much lower than either SKIN or SEED. Addition of ACN to either tannin fraction produced very small sensory effects in citric acid. In wine, addition of ACN to either SEED or SKIN increased Astringency significantly over either fraction alone, but had no effect on bitterness. The wine fractions differed only in Astringency, which was correlated with tannin units as determined by thiolysis.

  • effect of viscosity temperature and ph on Astringency in cranberry juice
    Food Quality and Preference, 1999
    Co-Authors: H Peleg, Ann C Noble

    Abstract:

    Abstract This study explored the interactive effects of temperature, pH, viscosity and quinic acid in modifying Astringency of cranberry juice. A panel of 17 trained judges rated Astringency of nine samples, in duplicate, at 10 and 20 s after ingestion. Astringency intensity at both times showed the same trends, although the ratings were lower at 20 s. Addition of 1.5 g/l quinic acid lowered the pH to 2.59 and failed to produce a difference in Astringency from the base juice (pH 2.65) at 5°C and 25°C. Astringency of juice adjusted to pH 3 was significantly lower than either the base or quinic acid juices at both temperatures. Decreasing temperature caused an increase of about 2 cp in viscosity and lowered the perceived Astringency at all pH levels. Increasing the viscosity by 1.5 cp using CMC (carboxymethylcellulose, medium viscosity, Sigma Chemical) lowered the perceived Astringency for all pHs but the effect was only significant at 25°C. Thus, without varying the concentration of astringent compounds, Astringency intensity could be significantly modified by altering viscosity or pH. ©

Kunsong Chen – 2nd expert on this subject based on the ideXlab platform

  • dknac7 a novel high co2 hypoxia induced nac transcription factor regulates persimmon fruit de Astringency
    PLOS ONE, 2018
    Co-Authors: Xinyue Shen, Miaomiao Wang, Donald Grierson, Wajeeha Jamil, Kunsong Chen

    Abstract:

    Artificial high-CO2 atmosphere (AHCA, 95% CO2 and 1% O2) has been widely applied as a postharvest de-Astringency treatment for persimmon fruit. AHCA increases expression of transcription factors, including ethylene response factors (DkERF), that target de-Astringency genes. Here, the promoter of DkERF9, a previously characterized AHCA-inducible and de-Astringency regulator, was utilized to screen a cDNA library by yeast one hybrid assay. A novel NAC transcription factor, named DkNAC7, was identified. Dual-luciferase assay indicated that DkNAC7 could not only trans-activate the promoter of DkERF9, but also activated the previously identified deAstringency-related gene DkPDC2. Real-time PCR analysis showed that DkNAC7 was up-regulated by AHCA treatment, in concert with the removal of Astringency from persimmon fruit and subcellular localization showed DkNAC7 was located in the nucleus. Thus, these results indicate that DkNAC7 is a putative transcriptional activator involved in regulating persimmon fruit deAstringency by trans-activition on both DkERF9 and DkPDC2, which encodes pyruvate decarboxylase.

  • involvement of dktga1 transcription factor in anaerobic response leading to persimmon fruit postharvest de Astringency
    PLOS ONE, 2016
    Co-Authors: Miaomiao Wang, Ziyuan Gong, Fang Fang, Xian Li, Donald Grierson, Kunsong Chen

    Abstract:

    Persimmon fruit are unique in accumulating proanthocyanidins (tannins) during development, which cause Astringency in mature fruit. In ‘Mopanshi’ persimmon, Astringency can be removed by treatment with 95% CO2, which increases the concentrations of ethanol and acetaldehyde by glycolysis, and precipitates the soluble tannin. A TGA transcription factor, DkTGA1, belonging to the bZIP super family, was isolated from an RNA-seq database and real-time quantitative PCR indicated that DkTGA1 was up-regulated by CO2 treatment, in concert with the removal of Astringency from persimmon fruit. Dual-luciferase assay revealed that DkTGA1 had a small (less than 2-fold), but significant effect on the promoters of de-Astringency-related genes DkADH1, DkPDC2 and DkPDC3, which encode enzymes catalyzing formation of acetaldehyde and ethanol. A combination of DkTGA1 and a second transcription factor, DkERF9, shown previously to be related to de-Astringency, showed additive effects on the activation of the DkPDC2 promoter. Yeast one-hybrid assay showed that DkERF9, but not DkTGA1, could bind to the DkPDC2 promoter. Thus, although DkTGA1 expression is positively associated with persimmon fruit de-Astringency, trans-activation analyses with DkPDC2 indicates it is likely to act by binding indirectly DkPDC2 promoter, might with helps of DkERF9.

  • isolation and expression of nac genes during persimmon fruit postharvest Astringency removal
    International Journal of Molecular Sciences, 2015
    Co-Authors: Miaomiao Wang, Fang Fang, Donald Grierson, Hongxun Wang, Kunsong Chen

    Abstract:

    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.

Donald Grierson – 3rd expert on this subject based on the ideXlab platform

  • dknac7 a novel high co2 hypoxia induced nac transcription factor regulates persimmon fruit de Astringency
    PLOS ONE, 2018
    Co-Authors: Xinyue Shen, Miaomiao Wang, Donald Grierson, Wajeeha Jamil, Kunsong Chen

    Abstract:

    Artificial high-CO2 atmosphere (AHCA, 95% CO2 and 1% O2) has been widely applied as a postharvest de-Astringency treatment for persimmon fruit. AHCA increases expression of transcription factors, including ethylene response factors (DkERF), that target de-Astringency genes. Here, the promoter of DkERF9, a previously characterized AHCA-inducible and de-Astringency regulator, was utilized to screen a cDNA library by yeast one hybrid assay. A novel NAC transcription factor, named DkNAC7, was identified. Dual-luciferase assay indicated that DkNAC7 could not only trans-activate the promoter of DkERF9, but also activated the previously identified deAstringency-related gene DkPDC2. Real-time PCR analysis showed that DkNAC7 was up-regulated by AHCA treatment, in concert with the removal of Astringency from persimmon fruit and subcellular localization showed DkNAC7 was located in the nucleus. Thus, these results indicate that DkNAC7 is a putative transcriptional activator involved in regulating persimmon fruit deAstringency by trans-activition on both DkERF9 and DkPDC2, which encodes pyruvate decarboxylase.

  • involvement of dktga1 transcription factor in anaerobic response leading to persimmon fruit postharvest de Astringency
    PLOS ONE, 2016
    Co-Authors: Miaomiao Wang, Ziyuan Gong, Fang Fang, Xian Li, Donald Grierson, Kunsong Chen

    Abstract:

    Persimmon fruit are unique in accumulating proanthocyanidins (tannins) during development, which cause Astringency in mature fruit. In ‘Mopanshi’ persimmon, Astringency can be removed by treatment with 95% CO2, which increases the concentrations of ethanol and acetaldehyde by glycolysis, and precipitates the soluble tannin. A TGA transcription factor, DkTGA1, belonging to the bZIP super family, was isolated from an RNA-seq database and real-time quantitative PCR indicated that DkTGA1 was up-regulated by CO2 treatment, in concert with the removal of Astringency from persimmon fruit. Dual-luciferase assay revealed that DkTGA1 had a small (less than 2-fold), but significant effect on the promoters of de-Astringency-related genes DkADH1, DkPDC2 and DkPDC3, which encode enzymes catalyzing formation of acetaldehyde and ethanol. A combination of DkTGA1 and a second transcription factor, DkERF9, shown previously to be related to de-Astringency, showed additive effects on the activation of the DkPDC2 promoter. Yeast one-hybrid assay showed that DkERF9, but not DkTGA1, could bind to the DkPDC2 promoter. Thus, although DkTGA1 expression is positively associated with persimmon fruit de-Astringency, trans-activation analyses with DkPDC2 indicates it is likely to act by binding indirectly DkPDC2 promoter, might with helps of DkERF9.

  • isolation and expression of nac genes during persimmon fruit postharvest Astringency removal
    International Journal of Molecular Sciences, 2015
    Co-Authors: Miaomiao Wang, Fang Fang, Donald Grierson, Hongxun Wang, Kunsong Chen

    Abstract:

    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.