Tannin is a surprising substance, present in all plants (although some contain it in a higher percentage). Once extracted, it finds useful applications in many sectors, from leather tanning to cosmetics, from the food industry to agriculture. Let’s get to know it more and try to understand why tannin is important.
What is tannin?
Tannin is a member of the polyphenol family. Plants produce it because it helps fight the onslaught of fungi and bacteria while preserving the health of the vegetal organism. It also discourages herbivorous animals that try to eat it, as it gives the plant an unpleasant taste (the well-known ‘sour’ and ‘astringent’ mouthfeel).
Furthermore, tannins are valuable allies of our organism because, thanks to their antioxidant properties, they preserve tissues from losing elasticity and help fight cellular aging. We can therefore say that Nature has found in tannin its first and greatest partner for the protection and evolution of the plant kingdom.
How is tannin extracted?
This polyphenolic compound is extracted from certain plants, where it is present in high concentrations, through a process that requires attention, time and dedication. The vegetal material is extracted solely with hot water, without involving any solvents or chemical substances.
In fact, the tannin extraction process has remained largely unchanged over the centuries, respecting both humans and nature.
How is tannin obtained from plants?
Let’s start with the principle that not all plants contain the same amount of tannin. It is found in different concentrations in roots, rhizomes, bark, berries, fruit, leaves and flowers, and it is precisely tannin that protects plant species from attack by fungi, bacteria, parasites and mould. The plants richest in this valuable substance are the Chestnut and Quebracho.
The logs of these plants, obtained in a sustainable manner and in compliance with local forestry legislations, undergo a seasoning process, a very ancient practice that consists of leaving the wood, carefully stacked to prevent it from bending, in the air for several months. This first phase is fundamental because it facilitates subsequent processing.
Once the wood has reached the most suitable level of seasoning, the logs are shredded into small pieces called ‘chips’.
Extracting tannin: an ancient but still topical method
The next step is the actual extraction of the tannin from the wood ‘chips’, which are steeped in giant autoclaves filled with hot water above 100°C. This process and parameters may vary depending on the type of wood used to ensure optimal tannin yield.
The extraction of tannin from plants requires only the use of hot water, without the addition of other substances or chemicals… a bit like tea infusion!
The tannin is then separated from the extraction solution. This separation usually takes place by means of filtration or centrifugation processes, resulting in a more concentrated product free of impurities. Afterwards, the tannin can undergo further treatment to improve its properties and quality.
How is tannin obtained: processing steps
One of the techniques used to further purify tannin is precipitation: the aqueous tannin solution is cooled down to room temperature to allow substances that are not completely soluble and impurities to precipitate.
And just like that! This is how you get liquid tannin. Although it can be sold in this form, to make it easier to transport, store and use, it can be turned into a powder through a spray-drying process.
But where is tannin shipped to? The powdered tannin is then shipped worldwide, finding applications in various industries.
The spent wood, which no longer contains tannin, is not discarded but can be used to generate energy in biomass power plants or transformed into 100% natural stove pellets.
How is tannin used?
There are indeed numerous application areas, but one of the most well-known and ancient is vegetable tanning of leather.
Additionally, tannin finds application in the food and beverage industry, pharmaceuticals, nutraceuticals, cosmetics, as well as in sectors such as corrugated cardboard, fracking, and mineral extraction.
In the past, tannin has been used for dyeing fabrics and the preparation of inks: its historical uses are truly diverse! (mettere link come in italiano)
And here it is revealed how the super tannin manages to go from being naturally present to becoming a fundamental substance for sectors such as fashion and cosmetics: an almost superhero-like transformation!