Vegetable Tannins Used in the Manufacture of Historic Leathers

Falcão, Lina; Araújo, Maria Eduarda

doi:10.3390/molecules23051081

Cited by 122 publications

(93 citation statements)

References 47 publications

(69 reference statements)

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“…Hydrolysable tannins are based on monosaccharide ring (glucose) forming gallotannins (gallic acid core) or ellagitannins (ellagic acid core). Condensed tannins are based on flavonoids [7,8].…”

Section: Introductionmentioning

confidence: 99%

Model study of the leather degradation by oxidation and hydrolysis

et al. 2019

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Many objects of culture heritage, comprised of leather, need to receive the right treatment to be restored and to elongate their lifespan. Determination of the degradation degree and even better the type of the degradation is a crucial knowledge for the way of subsequent conservation, exhibition and long-term storage. Collagen based materials are very sensitive to the deterioration and undergo, mainly hydrolysis and oxidation. Namely acid hydrolysis and photooxidation are the most often causes of the disintegration of leather. Contrary to the leather investigation, a few studies dedicated to parchment described some typical features of hydrolysis, oxidation and gelatinization observed applying Attenuated Total Reflection Fourier-Transform Infrared spectroscopy (ATR-FTIR) which is widely used in collagen degradation type research. Except of the collagen secondary structure, followed by IR spectroscopy, we determined the shrinkage temperature of the collagen substrate by Micro Hot Table method (MHT) to reach the degradation level. In this paper, artificially degraded leather samples as a theoretical representative of cultural heritage objects were examined. We discuss the use of both techniques (IR and MHT) as potential methods for fast assessment of oxidation and hydrolysis of vegetable tanned leathers and degradation level. New samples of leather tanned by various vegetable tannins were artificially degraded under controlled conditions. We simulated the photooxidation by means of the Xenon arc lamp exposure, oxidation using the soaking in hydrogen peroxide, acid hydrolysis by the soaking in hydrochloric acid and alkaline hydrolysis using the soaking in natrium hydroxide. ATR-FTIR spectra of reference and tested samples were compared. Oxidation causes increase of the distance between amide I (A I ) and amide II (A II ) wavenumbers (Δν) above 100 cm −1 and the intensity ratio between A I and A II bands (A I /A II ) above 1.6. The A I / A II ratio depends on the type of hydrolysis. The increase above 1.8 proves acid hydrolysis while the decrease under 1 demonstrate alkaline hydrolysis. MHT results are not so obvious. Generally, mainly the hydrolysis causes the decrease of the temperatures. We have found out that knowledge of the whole shrinkage interval is important and provides more appropriate information about the leather disintegration.

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Section: Introductionmentioning

confidence: 99%

Model study of the leather degradation by oxidation and hydrolysis

et al. 2019

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“…Several studies have been published in the last decade reporting the application of FTIR technique to analyse tannins in historical leather. [11,[31][32][33][34] Among them, 13 C solid-state NMR spectroscopy has proven its usefulness in characterising tanning fingerprinting in vegetable tanned leather. [23] The advantage of solid-state NMR over the widely used FTIR spectroscopy lies in the fact that the signals of collagen and aromatic molecules of tannins do not overlap in the 13 C CP-MAS spectrum.…”

Section: Leathermentioning

confidence: 99%

“…[10] The main sources of condensed tannins used for leather tanning occur in woody constituents of plants such as mimosa, birch, Norway spruce, larch, Aleppo pine and quebracho. [11] Hydrolysable tannins are basically constituted of gallic acid, the basic monomer of gallotannins, or hexahydroxydiphenic acid and its dilactone (ellagic acid), the constituent units of ellagitannins, and are commonly arranged around a central molecule of glucose (basic structure of tannic acid). [10] The hydrolysable tannins mostly occur in wood (chestnut) and woody parts of plants (galls of oak, leaves of sumac, fruits of myrabolans, acorn cups of valonea oak and leaves of myrtle).…”

Section: Introductionmentioning

confidence: 99%

“…[10] The hydrolysable tannins mostly occur in wood (chestnut) and woody parts of plants (galls of oak, leaves of sumac, fruits of myrabolans, acorn cups of valonea oak and leaves of myrtle). [11] In this study, the characterisation of newly manufactured collagen-based materials as parchment, vegetable tanned leather, hide powder and gelatin, as well as of a number of historical and archaeological leathers was performed by solid-state nuclear magnetic resonance (NMR) spectroscopy. Although NMR has already gained a great deal of importance in the study of heritage materials, [12,13] only a few studies have been conducted to characterise historical and archaeological parchment and leather.…”

Section: Introductionmentioning

confidence: 99%

“…In fact, the application of FTIR spectroscopy to characterise vegetable tannins is widely documented, [10,[26][27][28][29][30] and several researchers have also exploited its use in characterising also historical vegetable tanned leather. [11,[31][32][33][34] In addition, micro-DSC analysis provides quantitative results on the bulk material and unambiguously describes the deterioration state of historical leather identifying the key steps of deterioration process (i.e., thermal destabilisation of chemically modified and unmodified collagen, de-tanning, gelatinisation and irreversible denaturation). [35][36][37] The obtained results show that solid-state NMR spectroscopy is perfectly suitable for characterising the collagen-tannin complex in historical and archaeological vegetable tanned leathers.…”

Section: Introductionmentioning

confidence: 99%

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¹³C solid‐state NMR complemented by ATR‐FTIR and micro‐DSC to study modern collagen‐based material and historical leather

Proietti

Tullio

Carsote³

et al. 2020

Magnetic Reson in Chemistry

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Ancient vegetable tanned leathers and parchments are very complex materials in which both different manufacturing and deterioration processes make their study and chemical characterisation difficult. In this research, solid‐state nuclear magnetic resonance (NMR) spectroscopy was applied to identify different tannin families (condensed and hydrolysable) in historical leather objects such as bookbindings, wall upholsters, footwear and accessories, and military apparel. Furthermore, leather deterioration with special focus on collagen gelatinisation was investigated. A comparison with Fourier transform infrared (FTIR) spectroscopy and micro‐differential scanning calorimetry (micro‐DSC) was also performed to support the 13C CP‐MAS NMR findings and to point out the advantages and limitations of solid‐state NMR in analysing historical and archaeological leathers. A wide database of NMR and FTIR spectra of commercial tannins compounds was also collected in order to characterise historical and archaeological leathers.

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Degradation and release of tannic acid from an injectable tissue regeneration bead matrix in vivo

et al. 2021

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The development of multifunctional biomaterials as both tissue regeneration and drug delivery devices is currently a major focus in biomedical research. Tannic Acid (TA), a naturally occurring plant polyphenol, displays unique medicinal abilities as an antioxidant, an antibiotic, and as an anticancer agent. TA has applications in biomaterials acting as a crosslinker in polymer hydrogels improving thermal stability and mechanical properties. We have developed injectable cell seeded collagen beads crosslinked with TA for breast reconstruction and anticancer activity following lumpectomy. This study determined the longevity of the bead implants by establishing a degradation time line and TA release profile in vivo. Beads crosslinked with 0.1% TA and 1% TA were compared to observe the differences in TA concentration on degradation and release. We found collagen/TA beads degrade at similar rates in vivo, yet are resistant to complete degradation after 16 weeks. TA is released over time in vivo through diffusion and cellular activity. Changes in mechanical properties in collagen/TA beads before implantation to after 8 weeks in vivo also indicate loss of TA over a longer period of time. Elastic moduli decreased uniformly in both 0.1% and 1% TA beads. This study establishes that collagen/TA materials can act as a drug delivery system, rapidly releasing TA within the first week following implantation. However, the beads retain TA long term allowing them to resist degradation and remain in situ acting as a cell scaffold and tissue filler. This confirms its potential use as an anticancer and minimally invasive breast reconstructive device following lumpectomy.

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Vegetable Tannins Used in the Manufacture of Historic Leathers

Cited by 122 publications

References 47 publications

Model study of the leather degradation by oxidation and hydrolysis

Model study of the leather degradation by oxidation and hydrolysis

¹³C solid‐state NMR complemented by ATR‐FTIR and micro‐DSC to study modern collagen‐based material and historical leather

Degradation and release of tannic acid from an injectable tissue regeneration bead matrix in vivo

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Vegetable Tannins Used in the Manufacture of Historic Leathers

Cited by 122 publications

References 47 publications

Model study of the leather degradation by oxidation and hydrolysis

Model study of the leather degradation by oxidation and hydrolysis

13C solid‐state NMR complemented by ATR‐FTIR and micro‐DSC to study modern collagen‐based material and historical leather

Degradation and release of tannic acid from an injectable tissue regeneration bead matrix in vivo

Contact Info

Product

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¹³C solid‐state NMR complemented by ATR‐FTIR and micro‐DSC to study modern collagen‐based material and historical leather