Tannins are a group of compounds belonging to a larger class of substances known as polyphenols, which are a type of antioxidant.
Tannins are found in various plant tissues, including leaves, seeds, bark, wood, and fruit.
They play several key roles in plant physiology, such as protection against predation and contributing to plant growth.
There are two main types of tannins: hydrolyzable tannins and condensed tannins.
Hydrolyzable tannins can be broken down into simpler substances by the action of water and certain enzymes.
They are usually complex structures made up of sugar molecules linked to other components such as gallic acid or ellagic acid.
Condensed tannins, also known as proanthocyanidins, are polymers of flavonoid units, and they do not readily hydrolyze.
From a nutritional and health perspective, tannins are often discussed in terms of their antioxidant properties, which can help
to neutralize harmful free radicals in the body. However, because they can inhibit the absorption of certain nutrients in the
digestive system, they are also considered anti-nutritional factors in some contexts.
In the context of food and beverage, tannins contribute to flavor complexity, color, and the aging process of wine. They also
play a role in traditional processes such as the tanning of leather, where they bind to proteins in animal hides and make
them resistant to water and microbial damage.
Some points regarding tannins in herbal leaf extracts are provided below:
Plant Types
- Herbs like witch hazel, sage, rosemary, and yarrow are known for their high tannin contents.
Astringency - Tannins in herbal leaf extracts are responsible for the
astringent properties of many of these herbs. Astringency is the drying, tightening, and sometimes puckering sensation
that you experience when you consume certain foods or drinks. For example, it's the tannins that give black tea, red wine, and certain fruits like
unripe apples or persimmons their characteristic mouthfeel.
Hydrolyzable Tannins - These are found in some herbs like witch hazel
(Hamamelis virginiana). Two types of phenolic acids commonly found in hydrolyzable tannins are gallic acid and ellagic acid.
Some points regarding tannins in bark are provided below:
Role
- Tannins play essential roles in the tree's defenses against pests and diseases, and they contribute to the tree's growth and repair.
Hydrolysable Tannins - These tannins can be hydrolyzed into simpler phenolic
compounds, such as gallic acid or ellagic acid, and a sugar molecule. They are found in the bark of many tree species, including oak,
chestnut, and myrobalan.
Condensed Tannins - Also known as proanthocyanidins,
these tannins are polymers of flavonoid units and are not readily hydrolysed. They are found in high quantities in the bark of some trees,
like pine and spruce.
Industry Applications - Bark tannins are widely used in industry. For instance, the
bark of oak trees is a major source of tannins used in the tanning of leather. During the tanning process, the tannins bind to the
collagen proteins in the animal hides, making them resistant to decomposition and conferring durability.
Health Applications - Bark tannins have antioxidant properties and potential
antimicrobial, antiviral, and anticancer effects.
Phlorotannins are the main tannins in brown seaweed, being unique to this biomass type. The content of these compounds can vary
significantly depending on the seaweed species, the stage of growth, and environmental factors such as sunlight, temperature,
and nutrient availability. Some of the the different types of phlorotannins
seen in brown seaweed are described below:
Phlorethols
- These are phlorotannins where the phloroglucinol units are connected by ether linkages. An example of a phlorethol found in brown
seaweeds like Fucus vesiculosus (bladderwrack) is tetraphlorethol A.
Fuhalols and Fucols - Fuhalols are similar to phlorethols but have additional
hydroxyl groups. Fucols, on the other hand, consist of phloroglucinol units linked through aryl-aryl bonds. An example of a fucol
is trihydroxyfucol, which has been found in species like Ascophyllum nodosum (knotted wrack).
Eckols - These phlorotannins contain a dibenzodioxin linkage.
An example is eckol, which has been identified in Ecklonia cava, a type of brown seaweed common in Korea and Japan.
Carpotannins - These are a group of phlorotannins with a unique structure,
where the phloroglucinol units are linked through both aryl-aryl and ether bonds.
An example of this type is carpogel, found in Carpomitra costata.
Fucophlorethols - These are complex phlorotannins where fucol and phlorethol
units are connected through ether linkages.
The extraction process, including the solvents and methods used, can influence the concentration and types of tannins present in the final extract.
It is often the case that a balance needs to be found between fully-extracting all tannins while also ensuring that the compounds that are
obtained are of a high quality and not degraded.
At Celignis we have extensive experience in the design and optimisation of extraction protocols for a wide variety of chemical constituents from
many different biomass types. If needed we can also work on processes to separate and purify the target compounds.
Click here to read more about Celignis's Bioprocess Development Services for the extraction of
chemicals from biomass.
Celignis is a Partner in 3 Successful Proposals for EU Funding
We are pleased to announce that three of the proposals involving Celignis, submitted to the CBE-JU programme for funding collaborative biomass research in Europe, were successful. These projects will provide an additional funding of €1.5m to Celignis and build on our achievements in other CBE and EU projects. In particular, the projects are all at enhanced TRLs (6/7) and will use our existing Celignis Bioprocess infrastructure and will also fund further development of our bioprocessing capacities and the Bioprocess Development Services we offer our clients.
Details on the funded projects are provided below:
BIONEER - This project was funded under CBE-JU topic IA-06 and focuses on the TRL 6/7 production of biobased platform chemicals. Celignis's activities in the project focus on scaling up the work undertaken in our ongoing
Celignis to Exhibit and Present at Major Biochar Event
The 2024 North American Biochar Conference will take place in Sacramento, California, on Feb 12-15
On Feb 12-15 we'll be exhibiting at the 2024 North American Biochar Conference, taking place at the SAFE Credit Union Convention Centre in Sacramento, California.
We're looking forward to interacting with the 1000+ expected attendees, outlining our extensive range of analytical and application testing services for biochar.
Celignis CIO Lalitha Gottumukkala will also be a member of the expert panel focused on developing improved laboratory methods for biochar characterisation.
This Networking Event Will Involve Discussions on Collaborations for Proposals to the 2024 CBE-JU Topics
The Circular Bioeconomy Europe Joint Undertaking (CBE-JU) is an organisation that funds biomass research in Europe at various Technology Readiness Levels (TRLs). Since 2016 Celignis has been an active participant in a number of projects funded by the CBE-JU.
The Biobased Industries Consortium (BIC) is the steering committee that helps to steer the focus of research for the CBE-JU programme. In 2023 Celignis joined the BIC as a Full Industry Member and participated in several proposals submitted for different research topics in the CBE-JU's 2023 Work Programme.
We're Hiring - Business Administration & Client Relationship Manager
This position will involve working closely with senior management, fostering existing and new client relationships.
Situated in Limerick, Ireland, Celignis currently operates at two centres, Celignis Analytical and Celignis Bioprocess, actively engaging in a variety of private and public bioeconomy projects. As we continue to expand, we're looking to strengthen our team of 14 with a Business Administration and Client Relationship Manager who can bring a blend of enthusiasm and expertise.
This position will involve working closely with senior management, fostering existing and new client relationships, and ensuring successful delivery of our services, playing a key role in our ongoing growth and success.
Celignis to Sponsor and Present at Major Biochar Event
The event takes place on May 3rd at Carrick-on-Shannon
We are pleased to announce that, on May 3rd, Celignis will be presenting and exhibiting at the National Biochar and Carbon Products Conference 2023, which is taking place in Carrick-on-Shannon in County Leitrm, Ireland.
This conference is being organised under the auspices of the Interreg Northwest Europe-funded THREE C Project, entitled 'Creating and sustaining Charcoal value chains to promote a Circular Carbon economy in NWE Europe'.
The conference will highlight both Irish stakeholders who are currently working in the biochar and carbon products sector, but also partners from the THREE C project (covering Netherlands, Luxembourg, Germany, Belgium, France and Wales, as well as Ireland) who have interesting stories and products to share.
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