Tannins

Anuraga Jayanegara

Department of Nutrition and Feed Technology

Outline

A. IntroductionB. StructureC. InteractionD. Analytical methodsE. Biological effectsF. Treatments/processing methods

Department of Nutrition and Feed Technology

A. Introduction

Plant secondary compounds- Do not function in primary metabolism such as biosynthesis,

biodegradation and other energy conversions of intermediary metabolism

- Do have diverse biological activities ranging from toxicity to hormonal mimicry

- May play a role in protecting plants from herbivory and disease- Examples: alkaloids, terpenes, phenolics

Tannins, definitionWater-soluble phenolic compounds that have ability to precipitate proteins

Department of Nutrition and Feed Technology

ClassificationCondensed tannin (CT, proanthocyanidins): oligomers of two or more flavan-3-ols such as catechin, epicatechin, or gallocatechin.Hydrolysable tannin (HT): consisting of a central core of carbohydrate to which phenolic carboxylic acids are bound by ester linkage.

Department of Nutrition and Feed Technology

Department of Nutrition and Feed Technology

Why plants produce phenolics?

A strategy adopted by plants to deter attack by microorganisms,

insects and higher animals.

Factors affecting tannin levels:

- Nutrient stress (N, P, K, S deficiencies)

- High light intensity

- High temperature

- Severe drought

- Tissue damage

Increase tannin

levels

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Condensed tannin (CT)

Hydrolysable tannin (HT)

B. Structure

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Diversity of tannin structures

Source: Mueller-Harvey (2006)

J. Sci. Food Agric. 86, 2010-2037.

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Multiple hydroxyl groups: enable phenolics to form complexes

with proteins, polysachharides and minerals.

Tannin-protein complex:

1. Hydrogen bonds: free phenolic hydroxyl groups

2. Hydrophobic bonds: aromatic ring structures

3. Covalent bonds: polymerization reactions due to heating,

exposure to UV radiation and the action of polyphenol

oxidase

C. Interaction

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Illustration of protein precipitation by tannins

Marangon et al. (2010)Analytica Chimica Acta 660, 110-118

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D. Analytical methods

- Categorized into: (1) chemical methods, (2) protein precipitation methods, (3) gravimetric assays, (4) tannin bioassay, (5) Others.

- Chemical assays: - Total phenols and total tannins: Folin-Ciocalteu (oxidation-reduction),

ferric chloride (metal-complexing property of phenolics)- Condensed tannins: vanilin assay, butanol-HCl assay- Hydrolysable tannins: rhodanine method, HPLC

- Protein precipitation assays: ninhydrin assay, BSA method, radial diffusion assay

- Gravimetric methods: ytterbium acetate, PVPP- Tannin bioassay: in vitro gas production + PEG (e.g. Jayanegara &

Sofyan, 2008)

More detailed methods ....

Department of Nutrition and Feed Technology

E. Biological effects

Negative effects:- Decreasing nutrient utilization, in particular protein utilization- Decreasing feed intake- Toxicity and death of animals

Positive effects:- Prevention of bloat- Protection of protein from rumen degradation- Mitigating methane emission- Modulation of PUFA biohydrogenation in the rumen- Controling of gastro-intestinal nematode parasites

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Decreasing nutrient utilization

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Toxicity problems

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Prevention of bloat

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Protection of protein from rumen degradation

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Mitigating methane emission

Source: Morgavi et al. (2010)

Animal 4, 1024-1036

• Global warming

• Loss of energy

Department of Nutrition and Feed Technology

Evidences:- Jayanegara et al. (2009), Animal Feed Science and Technology 150, 230-

237- Jayanegara et al. (2009), Media Peternakan 32, 120-129- Jayanegara et al. (2010), Sustainable Improvement of Animal Production

and Health (Odongo, N.E., Garcia, M., Viljoen, G.J. (Eds.)), FAO, Rome, pp. 151-157

- Jayanegara et al. (2011), Animal Feed Science and Technology 163, 231-243

- Jayanegara et al. (2012), Journal of Animal Physiology and Animal Nutrition 96, 365-375

- Jayanegara et al. (online first), British Journal of Nutrition

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Source: Bhatta et al. (2009)

J. Dairy Sci. 92, 5512-5522 Phenolics and microbial population

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Protozoa colonized by

methanogens

Ruminal methanogens attached to protozoal

species interspecies H transfer

Protozoa-associated methanogens contribute

up to 37% of total rumen methane emissions

Removal of protozoa from the rumen

(defaunation) may ↓ CH4 emission

Department of Nutrition and Feed Technology

Source: Chilliard et al. (2007)

Eur. J. Lipid Sci. Technol. 109, 828-855

α-Linolenic acid

Linoleic acid

Rumenic acid

Vaccenic acid

Stearic acid

• Reduce the risk of

cardiovascular disease

• Lowering plasma

cholesterol level

• Prevent cancer

proliferation

• Decrease atherosclerosis

• Improve immune system

Modulation of PUFA biohydrogenation

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Source: Khiaosa-ard et al. (2009)

J. Dairy Sci. 92, 177-188

CH: grass-clover hay (control)

TF: dried sainfoin (7.9% CT)

TH: CH + A. mearnsii extract (7.9% CT)

SH: CH + Y. schidigera extract (1.1% saponins)

Condensed tannins (CT)

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Influence of tannins on biohydrogenating bacteria

Source: Vasta et al. (2010)

Appl. Environ. Microbiol. 76, 2549-2555

Containing 6.4% tannins

from quebracho powder

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Inhibition of phenolics on lipase activity

Source: Van Ranst et al. (2011)

Animal 5, 512-521

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Other evidences:- Jayanegara et al. (2011), Animal Production Science 51, 1127-1136- Jayanegara et al. (2012), Livestock Science 147, 104-112- Palupi et al. (online first), Journal of the Science of Food and Agriculture

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F. Treatment methods

- Wood ash: a good source of alkali; 10% solution of oak wood ash decreased the content of TP, CT and protein precipitation capacity by 66, 80 and 75% in oak leaves, respectively.

- Urea-ammoniation: 4% urea in fresh leaves. - Drying: but not effective.- Chemicals: extraction with organic solvents (30% acetone, 50%

methanol, 40% ethanol) removed ca 70% tannins from oak leaves.- Solid-state fermentation: biodegradation of tannins using white-rot

fungi.- Addition of tannin-binding polymers: PEG (polyethylene glycol)

incorporation, PVPP.

Department of Nutrition and Feed Technology

Department of Nutrition and Feed Technology

Department of Nutrition and Feed Technology

Thank you for your attention!