Tannins content, determination

Abstract In this study, a new natural adsorbent (sumae leaves) for removing Cu (II) ion from the aqueous solutions has been investigated. Leaves of sumae were obtained from Siirt, Tmkey. The tannins were extraeted with acetone water (70 30, v/v) mixture from the leaves of sumac. For the total tannin determination Folin-Ciocalteu method was used and tannin content was found 27%. In batch experiments, pH profile, adsorption time, adsorbent/hquid ratio, initial concentration of metal ions, adsorbent amoimt, particle size of adsorbent and temperature were performed to determine binding properties of adsorbent for the Cu(II) ions. The concentrations of the metal ions in solutions before and after adsorption were measured with an atomic absorption spectrophotometer. 

In this work, sumac leaves will use to remove Cu + ions in aqueous solutions. Firstly the tarmins will extract from leaves and determine tannin contents. Then, binding properties of leaves for the Cu " ions will be investigated. 

Leaves of Sumac were used for removal of ions in aqueous solution. Tannins were extracted from the leaves of sumac by extracting with 70% (v/v) acetone-water solution. For the total tarmin determination Folin-Ciocalteu method was used and tannin content was found 27%. Various adsorption parameters for the effective removal of Cu + ions by using sumac leaves as an adsorbent from aqueous solutions were studied and optimized. 

Price ML, Butler LG (1977) Rapid visual estimation and spectrophotometric determination of tannin content of sorghum grain. J Agric Food Chem 25 1268-1273... 

In the fining of juices with a low tannin content, the silica sol is added before the gelatin, but in the case of juices with a high tannin content the gelatin is added first (in powder form) and then silica gel (30%), with about 5-7 times as much silica sol as gelatin being used. The amount of silica sol used is determined by the amount of gelatin used. 

Analysis of vegetable tannins is used to determine the tannin content in the extract solution from the raw or spent materials. The tannin analysis method set up by the American Leather Chemists Association (ALCA, 1954a) is based on the absorption of materials from the extract by hide protein. It is not based on chemical analysis of a true tannin molecule. 

For synthesized Gelatin (G)/Tannin (T) resins, gelatin powder was purchased from tilker Food Company-Istanbul, Turkey. Flydrolyzable tannins were obtained from the sumac leaves which were collected from Siirt, Turkey. The raw leaves were dried at room temperature in dark and then ground 500 pm particle sizes. For the total tannin determination Folin-Ciocalteu method was used and tannin content found 27%. Tannins are extracted from sumac leaves with 1 1 (v/v) acetone/water solution [15]. Tannic acid (TA) powder, which was extracted from sumac leaves (30 g) was dissolved in distilled waster at 95-98°C, then solution cooled at room temperature and 37% formaldehyde solution added to the solution. G powder was dissolved distilled water at 95-98°C and then added to the TA/formaldehyde solution. Concentrated hydrochloric acid was added to the mixture and heated 95-98°C for 12 h with a reflux condenser. G/TA resin was washed distilled water, dried at 110°C. Dried resin was crushed into small particles, <500 pm [16]. 

Various methods of analysis are available for the determination of tannin content. These methods can generally be grouped into two broad classes ... 

Brugirard and Tavernier (1952) used the property of true tannins of flocculating a solution of 1% gelatine in 10% sodium chloride for their tannin determination in cider. They determined the total tannoids (T) by the Neubauer-Loewenthal procedure, then precipitated the true tannin in a buffered solution with 2.0% cinchonine sulfate, and determined the non-tannin polyphenols (< ) in the centrifugate. T — V thus equals the true tannins. Since the tannin content decreases with time, Fessler (1947) noted that the age of the sample should be stated along with the tannin results. Rentschler and Hauser (1950) precipitated the catechin tannins in a hot acid solution with formaldehyde, filtered, washed with alcohol and ether, dried and weighed. The anthocyanin pigments were reported not to interfere. 

Maxson, E.D., Clark, L.E., Rooney, L.W., and Johnson, J.W., 1972, Factors affecting the tannin content of sorghum grain as determined by two methods of tannin analysis. Crop Sci.,... 

Price, M.L. and Butler, L.G., Rapid visual estimation and spectrophotometric determination of tannin content of sorghum grain, J. Agric. Food Chem., 25, 1268, 1277, 1977. Folin, O. and Ciocalteu, V., On tyrosine and tryptophan determinations in proteins, J. Biol. Chem., 27, 627, 1927. 

Petit-Dominguez, M.D., Garcia-Gimenez, R., and Rucandio, M. I. (2003). Chemical characterization of Iberian amphorae and tannin determination as indicative of amphora contents. Mikrochimica Acta 141 63-68. 

A calibration graph 3-15 ppm TA concentration range was constructed and the content of tannins in sumac leaves was determined by the Folin-Ciocalteu method. 

Singleton and Esau (I) reviewed the methods for phenol analysis of wine. They pointed out that study would be greatly advanced if one could determine the total content of phenolic substances and express it in such a way that analysis of subclasses of phenols could be related to the original total and a balance sheet could be obtained. One could then say, for example, this wine has a total phenolic content of 1200 mg/liter calculated as gallic acid, and of that total, cinnamic acid derivatives account for 200 mg/liter, anthocyanins for 300 mg/liter, other small flavonoids for 200 mg/liter, and condensed tannins complete the total with 500 mg/liter of gallic acid equivalent. To accomplish this, the total phenol analysis not only must meet ordinary criteria of reproducibility and precision, but it also must be based on chemical relationships such that fractions determined separately can be converted to units of the total. Of course when clearcut fractionation can be accomplished by... 

The ash of true leather tanned with tannin consists essentially of calcium carbonate with traces of iron and of phosphates. Coloured leathers may contain metals from the mordants used (tin, copper, iron, chromium, aluminium) tin may also be introduced as stannous chloride used for bleaching. Small quantities of silicates (talc, kaolin) may be employed in the treatment of the leather. Finally, other mineral matters (barium, magnesium and lead salts and sodium chloride) may have been added as filling to increase the weight. Complete quantitative analysis of the ash is rarely necessary, but determination of its calcium content is sometimes required, this being made by the ordinary methods. 

From this result and those of the determinations of sections 1-4, the percentage of combined tannin is obtained by subtracting from 100, the sum of the percentages of moisture (taken as 18 if the other components are referred to the substance with normal moisture content), ash, fat, soluble organic substances and hide substance determined as above. 

The contents of the ampule are diluted in water to a final volume of 50 mL. A 1-mL sample is then taken for the assay. To this sample 1.5 mL 0.667% (w/v) rhodanine in methanol is added. After exactly 5 min. 1 mL 0.5N KOH is added. After 2.5 min. water is added to a final volume of 25 mL. The absorbance is read at 520 nm after a 5-10 min. incubation. A standard curve is made by reaction of gallic acid in 0.2N sulfuric acid with the rhodanine solution. Hagerman and Butler (1989) argued that this assay is more suitable than the potassium iodate assay for the determination of hydrolysable tannins, although it has to be kept in mind that the rhodanine assay is sensitive to any gallic acid ester, including those in non-tannin compounds. 

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