Tannin hydrolyzable

The hydrolysis products of the hydrolyzable tannins are not dissimilar to some of the novel oxygen scavengers developed to replace hydrazine. Oxygen reaction rates and application rates are also similar. The oxygen reaction time for tannin blends varies with pH levels and temperature but at 45 °C (113 °F) is on the order of 75% complete within 5 seconds and 90% complete within 10 seconds. 

The sodium carboxylates resulting from hydrolyzable tannins are similar to the gluconates and sarcosinates commonly employed as... 

In contrast to novel oxygen scavengers, tannins have been available for a century or more. The hydrolyzable tannin component of quebracho and other tannins under alkaline BW conditions produce a number of oxygen scavengers, primarily as sodium salts. These include ... 

BUTLER L G (1992) Antmutritional effects of condensed and hydrolyzable tannins. Basic Life Sci. 59 693-8. 

Trihydroxybenzene carboxylic acid esters with a sugar are characteristic of hydrolyzable tannins .37 These, too, may be present in coffee... 

Food and plant phenolics are commonly detected using DAD detectors (Tan and others 2008). Photodiode array detection allows collection of the entire UV spectrum during the elution of a chromatographic peak, which makes it possible to identify a phenolic compound by its spectra. Simple phenols, phenolic acids, flavanones, benzophenones, isoflavones, and flavan-3-ols have maximum absorbance at 280 nm, hydroxycinnamic acids at 320 nm, flavonols, flavones, and dihydroflavonols at 365 nm, and anthocyanins at 520 nm (Ibern-G6mez and others 2002 Merken Hand Beecher 2000). Hydrolyzable tannins show a characteristic shoulder at 300 nm, suitable for identifying them (Arapitsas and others 2007). For stilbenes, maximum absorbance of trans-forms are at 306 nm and at 285 nm for cA-forms (Lamuela-Raventos and others 1995). 

The most widely used method is based on the reaction between potassium iodate and hydrolyzable tannins (Hartzfeld and others 2002). This method provides a good estimate for gallotannins but underestimates the content of ellagitannins. 

Other analytical assays proposed for the quantification of hydrolyzable tannins in plant materials include the rhodanine assay for the estimation of gallotannins (Berardini and others 2004) and sodium nitrate for the quantitative determination of ellagic acid (Wilson and Flagerman 1990). 

Hydrolyzable tannins Ellagitannins Pomegranate juice Strawberry Blueberry Raspberry Blackberry Longan seed... 

Arapitsas P, Menichetti S, Vincieri FF and Romani A. 2007. Hydrolyzable tannins with the hexahydrox-ydiphenoyl unit and the m-depsidic link HPLC-DAD-MS identification and model synthesis. J Agric Food Chem 55(l) 48-55. 

Hartzfeld PW, Forkner R, Hunter MD and Hagerman AE. 2002. Determination of hydrolyzable tannins (gal-lotannins and ellagitannins) after reaction with potassium iodate. J Agric Food Chem 50(7) 1785—1790. 

There are two categories of tannins condensed and hydrolyzable tannins. The polymerization of flavonoid molecules produces condensed tannins, which are commonly found in woody plants (Fig. 3.9). Hydrolyzable tannins are also polymers, but they are a more heterogeneous mixture of phenolic acids (especially gallic acid) and simple sugars. Though widely distributed, their highest concentration is in the bark and galls of oaks. 

Polyphenols are significant constituents in the IDF of the samples analyzed, accounting for 1.4% to 4.7% (average, 2.5%). PPs are therefore an important constituent of DF in fruits and vegetables they are mainly condensed tannins (proanthocyanidins) and hydrolyzable tannins. 

It is estimated that the mean total intake of polyphenols in the Spanish diet ranges from 2,590 to 3,016 mg/person/day including polyphenols soluble in aqueous-organic solvents, plus insoluble condensed and hydrolyzable tannins. Fruits and vegetables provide a daily intake of 700-1,000 mg of polyphenols/person/diet a major fraction of this (600 mg/person/day) is associated with DF (Saura-Calixto and others 2007). 

In the adsorption of some metal ion by tannin adsorbents [16], tannins are widely distributed in nature and have multiple adjacent phenolic hydroxyl groups and exhibit specific chelation ability toward metal ions [17]. According to the chemical stractures of tannins, they can usually be classified into hydrolyzable tannins, condensed tannins and complex tannins. Hydrolyzed tannins yield galhc acid or ellagic acid when hydrolyzed by acid, base or some enzymes [18]. Turkish sumac tannin (hydrolyzable tannin) is illustrated in Fig. 28.1 whose basic stracture is of flavan-3-ols. 

Complex phenolics Coumarins, phenolic quinones, lignins, flavonoids, stilbenes, hydrolyzable tannins, condensed (or catechin) tannins, phenolic lipids... 

FIGURE 11.4 Hydrolyzable tannin. In the structure shown, five gallic acid units surround a sugar (hexose). 

The flavonoid quercetin suppresses growth somewhat in prairie voles, M. ochrogaster, while tannic acid, a hydrolyzable tannin, has an even stronger effect (Lindroth and Batzli, 1984). Quercetin is toxic, but does not bind with protein and, therefore, does not affect protein digestibility. Tannic acid has some effect on protein digestibility but is also toxic. 

In some cases, browsing does not appear to lead to induced defenses. Two species of northern European birch (B. pendula and B. pubescens) do not seem to respond to moose browsing with increased chemical defenses (Danell et ah, 1985). After experimental defoliation, the Emory oak of southwestern North America, Quercus emoryi, produces in its regrown leaves 2.5 times as much hydrolyzable tannins than in mature leaves, but lower amounts of condensed tannins. Refoliated branches suffered more, not less herbivory. New leaves have more protein, more water, and are tender. These properties may override any effects of induced chemical defenses, at least for the current growing season (Eaeth, 1992), but the induced compounds may still protect a plant later on, especially in winter. 

Marks, D. L., Swain, T., Goldstein, S., Richard, A., and Leighton, M. (1988). Chemical correlates of rhesus monkey food choice the influence of hydrolyzable tannins. Jottmfll of Chemical Ecology 14,213-235. 

CT = Condensed Tannin, GA = gallic acid ( a conponent molecule of TA), HT = Hydrolyzable Tannin, TA = Tannic Acid, TP = Total Phenolics. 

Very little information exists on the phenolic protein-conplexing resins, except for that on creosote bush and sane arctic plants. In contrast to condensed tannins and hydrolyzable tannins, these are typically ether-soluble compounds this may allow their entry into the body across cell membranes, and thios give them the potential for action outside the gut lumen. Reports for animals consuming seaweed indicate that astringent protein-precipitating substances (presumably phlorotannins), are potentially important in marine plant-herbivore interactions. 

As documented in a review article (9), no experimental data was available to support hypothetical mechanisms for the biosynthesis of hydrolyzable tannins until recently. Enzymatic studies have now changed this unsatisfactory situation, at least as far as the formation of pentagalloylglucose is concerned. Future work will provide insight into those other challenges discussed in this contribution and that still require clarification. 

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