Quebracho produces
tannins that can be extracted in
quebracho sawmills from the heartwood of both red (
Schinopsis lorentzii) and white quebracho (
Aspidosperma quebracho-blanco). Logs are inserted into
planers to produce chips that are used to produce the quebracho extract by boiling them in vats. It is used for fine leather tanning and imparts a red-brown color. Ordinary or warm soluble quebracho (also known as insoluble Quebracho) is the natural extract obtained directly from the quebracho wood. This type of extract is rich in condensed tannins of natural high molecular weight (
phlobaphenes), which are not easily soluble. Its use is therefore limited to addition of small amounts during the process of tanning leather intended for shoe soles in hot liquids (temperature above 35 °C) to improve the yield and the water-proofness of the leather. The cold soluble extracts are obtained by subjecting the ordinary extract to a
sulphiting process which transforms the phlobaphenes into completely soluble tannins. The cold soluble quebracho extracts are the most universally known and used types. The chemical structure of these extracts can be described as polymers of
epicatechin. The main properties of these extracts are: a very rapid penetration, a high tannin content and a relatively low percentage of non-tannins. The rather low acid and medium salt content characterise them as mild tanning extracts (low astringency). Quebracho tannins give an important added value to the quality of leathers, such as vacchetta, belts and garments, making them more compact and tear resistant with a pleasant touch. The sulphited quebracho extract may be carcinogenous in mice. Other recent studies show that quebracho tannins present a strong anti-mutagenic activity. The heartwood contains from 20 to 30 percent tannin and 3 or 4 percent water-soluble nontannin. It is said to not ferment.
Fustin (predominantly (-)-Fustin 66%), (-)-7:3':4'-trihydroxyflavan-3:4-diol ((-)-
leuco-fisetinidin), (+)-
catechin, gallic acid,
fisetin and
2-benzyl-2-hydroxycoumaran-3-ones have been isolated from the heartwoods of
Schinopsis balansae,
Schinopsis quebrachocolorado and from commercial quebracho extract. Quebracho tannin is rich in
profisetinidins and
prorobinetidins. The expected masses found in mass spectrometry in negative mode in quebracho tannin are 289, 561, 833, 951, 1105, 1377, 1393, 1651 and 1667. In Quebracho , the sugars and the
lignins are thought to be covalently linked to the condensed tannins. Quebracho tannin is also sold as an
enological tannin. The quebracho tannins structure is very similar to that of grape tannins, making them a desirable alternative to consider comparatively because they are much less expensive to produce than grape tannins.
Myo-inositol and
arabitol are detected in tannins from quebracho. Researches are being made to develop an eco-friendly anti-
biofouling paint from quebracho tannin. The
tannic acid, in the form of alkalized salts, was extensively used as a
deflocculant in
drilling muds in 1940s-1950s, until it was replaced with
lignosulfonates. Its red color gave the mixture the name
red mud. Quebracho tannin acts as flocculant agent to remove surfactant as
sodium dodecylbenzenesulfonate in water treatment. For its polyphenolic structure, quebracho tannin is widely studied for
particle boards,
plywood and
fiber board gluing. The Argentine companies
Unitán and
Silvateam are the main leaders in quebracho tannins production. ==Quebracho exploitation==