Extraction of a novel tanning agent from indigenous plant bark and its application in leather processing

The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects.In this work,an attempt has been made to extract vegetable tannins from Xylocarpus granatum bark using different solvents(e.g.,water,methanol,ethanol,and chloroform)and compare with conventional vegetable tanning agents such as mimosa and quebracho.The highest extraction efficiency was observed 31.22%by methanol.The presence of tannin content and polyphenolic compounds,e.g.(-)epicatechin(503 mg/100 g dry extract),catechin hydrate(218 mg/100 g dry extract),catechol(29 mg/100 g dry extract)were ensured by UV-Vis,FT-IR spectroscopy and HPLC.Again,condensed tannins,moisture content,and pH of the methanol extracted tannin were found 47.80%,5.82%,and 3.97 respectively.The leather tanned by Xylocarpus granatum tannin showed a shrinkage temperature of 86.34±1.52℃.Other properties such as tensile strength,tear strength,grain cracking load,and distention at grain cracking were comparable to conventional vegetable-tanned leather.The cross-sectional morphology of the tanned leathers was also characterized by scanning electron microscopy(SEM)which revealed a compact structure of the leather fibers.In light of the findings from the study,X.granatum bark tannin could be a well alternative to chromium and a new source of vegetable tannin for the leather industry.

Tanning capacityof Tessmannia burttii extracts:thepotentialeco-friendlytanning agents fortheleatherindustry

In the present study,the tannins from stem and root barks of Tessmannia burttii Harms(Caesalpiniaceae),a plant species abundantly growing in Tanzania and other parts of Africa,were investigated for their suitability in hides tanning.Tannin powder was extracted at selected temperatures(30,50 and 80°C)and the influence of each temperature on the crosslinking capacity was evaluated.The interaction mechanism between hide powder collagen and the tannins was studied by Differential Scanning Calorimetry(DSC),trinitrobenzensulfonic(TNBS)acid assay and amino acid hydrolysis methods.Extraction temperatures showed low influence on crosslinking capacity of the tannins.However,extract obtained at 50°C exhibited best performance in terms of gap size between T onset and T peak.The stem bark extract yield was higher than that from the root bark,but both were within the recommended ranges.The tannin content(61%)of T.burttii stem bark extract was above recommended value(10%),whereas its total phenolic content and total flavonoic content were found to be above that of commercial Acacia mearnsii tannin.The study of cross-linking parameters as a function of pH showed cross-linking to occur via a covalent mechanism at the basic amino groups.However,the bonds were not resistant to acid hydrolysis.The observed interaction mechanism indicated that tannins from stem and root barks of T.burttii belong to the condensed tannin,similar to A.mearnsii(black wattle),a commercial tannin source that was used in this study as a reference.Findings from this study depict that T.burttii extracts are auspicious eco-friendly alternative source of vegetable tannins to overcome the use of chromium salts in the leather industry.

Extraction of a novel tanning agent from indigenous plant bark and its application in leather processing

The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects. In this work, an attempt has been made to extract veg-etable tannins from Xylocarpus granatum bark using different solvents (e.g., water, methanol, ethanol, and chloroform) and compare with conventional vegetable tanning agents such as mimosa and quebracho. The highest extraction efficiency was observed 31.22% by methanol. The presence of tannin content and polyphenolic compounds, e.g. (-)epicatechin (503 mg/100 g dry extract), catechin hydrate (218 mg/100 g dry extract), catechol (29 mg/100 g dry extract) were ensured by UV-Vis, FT-IR spectroscopy and HPLC. Again, condensed tannins, moisture content, and pH of the methanol extracted tannin were found 47.80%, 5.82%, and 3.97 respectively. The leather tanned by Xylocar-pus granatum tannin showed a shrinkage temperature of 86.34 ± 1.52 °C. Other properties such as tensile strength, tear strength, grain cracking load, and distention at grain cracking were comparable to conventional vegetable- tanned leather. The cross-sectional morphology of the tanned leathers was also characterized by scanning electron microscopy (SEM) which revealed a compact structure of the leather fibers. In light of the findings from the study, X. granatum bark tannin could be a well alternative to chromium and a new source of vegetable tannin for the leather industry.

Tannin characterization and sourcing in historical leathers through FTIR spectroscopy and PCA analysis

This study aimed to identify and classify the type of plants used for tanning historical leathers using cost-effective Fourier transform infrared(FTIR)spectroscopy.The investigation was carried out on five plants(oak bark,sumac,valonia,tara,and gallnut)and four historical leather samples from book bindings dating back to the Qajar period.Tannin extraction from both plants and leathers was performed using acetone-water solvent,and the samples were then subjected to FTIR spectroscopy.Pre-processing of the spectra included baseline correction,smoothing,and normalization.Principal component analysis(PCA)was used to identify the source of tannins based on FTIR results.FTIR was found to provide a good separation of condensed tannins from hydrolysable ones.However,PCA analysis allowed for the separation and identification of the type of plant used for tannin extraction.The examination of historical leather samples revealed that the primary classification based on the type of tannin is possible,but accurate identification faces challenges due to structural changes and degradation over time.