Plant tanning materials

Plant tanning materials are phenolic compounds which dissolve in water. They have a low degree of polymerization, and they are used in the leather industry for tanning. 

The tanning materials enter the waters by the natural route as well as from wastewaters of the leather industry, and also after elution of the waste deposits from the preparation of tanning leaches and wastes of the wood-working industry. 

All the known tanning materials are polyhydroxyphenols from the viewpoint of chemical structure, with different relative molecular weights. The most important functional groups are phenolic hydroxyls. Many of these compounds provide a multicoloured spectrum of different parts of plants. 

From the chemical viewpoint the tanning materials are classified into hydrolysable and condensed substances. 

The hydrolysable ones have a structure of polyesters with two essential constituents — saccharide and phenolcarboxylic acid. Under the effect of hydrolytic agents (acids, enzymes, alkalies) they split into the original components. Thus, gallotannines provide — in addition to the sucrose component — also gallic acid, and elagitannines provide hexahydroxydiphenyl 

---

These two substances, composed of the evaporated and dried aqueous extracts of certain plants, may be included among the colouring matters and also among the tanning materials, with reference to either their composition or their uses. 

U. gambit Malaysia, Singapore, and Indonesia Aqueous extract of this plant is used as astringent and tanning material [10],... 

All the tannins readily react with proteins, forming insoluble, stable compounds when they react with collagen, the main constituent of animal skin, they form leather, a material that is resistant to hydrolysis, oxidation, and biological attack and therefore stable to weathering and resistant to decomposition. Since tannins from different plant sources have different chemical compositions, each tannin used for tanning skin produces a leather having slightly different properties and color. Tannins that have... 

Tannins are water-soluble phenolic compounds which are usually extracted from plant material by hot water. After lignins, they are the second most abundant group of plant phenolics. Their tanning property is due to their capacity to combine with proteins. However, they can also complex with other polymers such as alkaloids, cellulose, and pectins. 

Most modem brooms are made of either plant materials or synthetics. The old round broom shape gave way to the more efficient flat broom, which was invented by the Shakers in the early 1800s. The modem corn broom is made of the stems of sorghum, which is also called Guinea corn or millet. The seeds of this plant are used to make bread, or as food for livestock. The tan or yellow stems are used to make bmshes and brooms. 

Phytase (Aspergillus niger var.) Produced as an off white to brown powder or as a tan to dark brown liquid by controlled fermentation using Aspergillus niger var. Soluble in water, but practically insoluble in alcohol, in chloroform, and in ether. Major active principles (1) 3-phytase and (2) acid phosphatase. Typical applications used in the production of soy protein isolate and in the removal of phytic acid from plant materials. 

The conversion of animal hides into leather by treatment with water-soluble plant extractives has been practiced since antiquity. This process became known as tanning and obviously involved the reaction of a naturally occurring extractive, tannin, with the protein in the hide. We now know, of course, that tannins comprise a whole spectrum of chemical compounds, but generally they are polyphenolic and polymeric. Tannins have been isolated from a wide variety of raw materials, including insect galls, fruit skins, seed hulls, leaves, bark, and heartwood. Indeed, tannins are of nearly ubiquitous occurrence in higher orders... 

From among the methods mentioned above, iron has been determined with the use of Chrome Azurol S - in waters [176], Bromopyrogallol Red - in magnetic Fe-Co-Ni films [177], sulphanilic acid - in blood plasma [129] and in plants [109], Tiron - in geological materials [114], in aluminium alloys and copper [115], 2,2 -diquinoxalyl - in niobium oxide [128], PAN - in alloys and biological samples [79] and in waste waters [178], TAN - in geological samples [83], 5-Br-PADAP - in biological samples (by derivative spectrophotometry) [91] and in copper alloys [179], and morin - in copper-chromium and nickel-chromium alloys [122]. 

Tannins are widespread in nature but are quantitatively and geochemically less important than lignin. They are important in making plants less palatable to herbivores and, when extracted by steeping plant material, particularly bark and leaves, in water, they can be used for tanning leather. The structural units of tannins are polyhydroxy aromatic acids, such as gallic acid and... 

The occurrence of normal alkanes in living matter was reviewed by Lester (1979). In most cases the major alkanes contain an odd number of carbon atoms and in higher plants, the typical range is n-C15 to n-C. In oils and fats, the alkane concentration and composition is to some extent dependent on the condition of the raw material from which the oil was extracted. It was shown, for example, that their concentration in crude PKO from fresh whole kernels, was 3.7 mg/kg, while that from low quality kernels was 15.4 mg/kg (Tan and Kuntom 1994). Also, processing of the oil has been shown to reduce the total hydrocarbon concentration by more than one third (Kuksis 1964). 

---