Self-Blowing Non-Isocyanate Polyurethane Foams Based on Hydrolysable Tannins

ABSTRACT Non-isocyanate polyurethane(NIPU)foams using a hydrolysable tannin,also vulgarly called tannic acid,namely here commercial chestnut wood tannin extract was prepared.Compression strength did not appear to depend on the foam apparent density while the formulation composition of the NIPU foams has been shown to be more determinant.These NIPU foams appeared to be self-extinguishing once the high temperature flame is removed.The ignition time gave encouraging results but for improved fire resistance the foams may need some fire-retardant addition.FTIR spectrometry showed the formation of non-isocyanate urethane linkages.Thermogravimetric analysis indicated a good thermal resistance of these foams,with thermal degradation following four phases.First in the interval 25℃–120℃ range,mainly evaporation of water occurs with a maximal loss of 10%weight.In the 150℃–450℃ temperature range foams mass loss is of almost 70%.In particular in the 125℃–275℃ range occurs the degradation of some small molecular weight substances.In the 500℃–790℃ temperature range the foams do not present any further large degradation.

A New C-glycosidic Hydrolysable Tannin from Rhodomyrtus tomentosa

Tomentosin(1), a new C-glycosidic hydrolysable tannin, isolated from the leaves of Rhodomyrtus tomentosa. Its structure determined by chemical method and (1)HNMR spectroscopic analysis.

Hydrolysable Chestnut Tannin Extract Chemical Complexity in Its Reactions for Non-Isocyanate Polyurethanes(NIPU)Foams

Non-isocyanate polyurethane(NIPU)foams from a commercial hydrolysable tannin extract,chestnut wood tannin extract,have been prepared to determine what chemical species and products are taking part in the reactions involved.This method is based on two main steps:the reaction with dimethyl carbonate and the formation of urethane bonds by further reaction of the carbonated tannin with a diamine-like hexamethylene diamine.The hydroxyl groups on the tannin polyphenols and on the carbohydrates intimately linked with it and part of a hydrolysable tannin are the groups involved in these reactions.The carbohydrate skeleton of the hydrolysable tannin is also able to participate through its hydroxyl groups to the same two reactions rendering the whole molecular complex able to react to form NIPUs.The analysis by Matrix-Assisted Laser Desorption Ionization(MALDI-TOF)mass spectrometry and 13C Nuclear Magnetic Resonance(13C NMR)to further investigate the reaction mechanisms involved revealed the unsuspected complexity of chestnut hydrolysable tannin,with different fragments reacting in different manners forming a hardened network of considerable complexity.As the morphology and performance of these types of foams changes slightly with the change in the amount of glutaraldehyde and hexamine hardeners,the best performing foam formulation previously determined was scanned by SEM and analysed chemically for the structures formed.

Effect of pulsed ultrasound assisted extraction and aqueous acetone mixture on total hydrolysable tannins from pomegranate peel

Pomegranate peels are disposed of as waste even though it is an eminent source of total hydrolysable tannins(THT)and possesses a great worth for recycling.The present study was carried out with the hypothesis that pulsed system ultrasound-assisted extraction(PSUAE)technique optimization would aid in retaining high extract yield and THT recovery yield from pomegranate peel extract(PPE)with enhanced antioxidant potential.The extraction was performed at various conditions regarding solvent concentration(30-90% of acetone),solvent-feed ratio(10-30 mL/g),extraction time(10-20 min),and ultrasound amplitude(40-80%)for maximum extract yield,THT and antioxidant activity(AA).To model and optimize the process conditions tools namely response surface methodology(RSM)and artificial neural network(ANN)were applied.For solvent concentration,solvent-feed ratio,extraction time,and amplitude the optimal conditions attained with aid of RSM and ANN were:56%,26.5 mL/g,15 min,55%,and 45%,23 mL/g,15 min,50% respectively.The extract yield and THT content determined with RSM and ANN optimized values were 51.2%,86.4 mg TAE/g,and 62%,98.1 mg TAE/g,respectively.The mean square error value displayed the minimum and R^(2) exhibited maximum value in case of ANN compared to RSM model.PSUAE significantly augmented the AA of PPE to 77.2±0.50% compared to 49.7±0.35% of conventional extraction.FTIR and HPLC analysis established that PPE produced from PSUAE contains a significant amount of THT compounds(gallic acid and tannic acid derivative).SEM elucidated that the sonication effect resulted in peel cell wall disruptions ensuing in elevated extraction of THT.Therefore,this pulsed mode of ultrasound extraction could be regarded as an easy,cost-effective,and competent technique for the extraction of preferred natural THT from pomegranate peels that possess high prospective to be applied in food and nutraceutical formulations.

Terminalic Acid, a New Tannin from the Fruit of Terminalia chebula

Terminalic acid 1, a new hydrolysable tannin, was isolated from the fruit of Terminalia chebula. Its structure was found to be 1-O-galloyl-2,4-chebuloyl-beta-D-glucopyranose by chemical method and H-1-NMR, C-13-NMR, H-1-H-1 COSY, HMQC, HMBC and FAB-MS spectral analyses.

Chestnut tannin:New use,research and bioeconomy

Chestnut tannin,extracted from the bark or wood of chestnut trees,possesses unique properties that make it valuable in various industries.It serves as a natural source of tannins,which are widely used in the production of leather,textiles,and wood preservation.As research continues to explore its potential applications,chestnut tannin remains a promising resource with diverse industrial uses.Highlighting new use,research and bioeconomy aspects,this study provides a unified perspective on chestnut tannin.New advanced applications will likely emerge shortly.

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.

Different metabolomic responses of grass carp(Ctenopharyngodon idellus)to dietary tannin and rapeseed meal

In order to study the metabolomic responses of rapeseed meal on grass carp and the role that tannin plays in those responses,grass carp were fed four diets for an eight week trial.Two were practical diets:FM diet contained 10%fishmeal without rapeseed meal,RM diet contained 50%rapeseed meal without fishmeal;the other two were semi-purified diets without(T0)or with 1.25%(T1)of supplemental hydrolysable tannin.The tannin content in the RM diet was close to that of T1.The rate of weight gain for RM was significantly lower than FM,while the feed conversion ratio in the T1 was significantly higher than T0.The muscle lipid and protein content was significantly lower and glycogen higher in the RM and T1 compared to the other treatments.The percent of muscle-saturated fatty acid(SFA)in the RM and T1 groups was significantly lower than FM and T0 groups,respectively,while the mono-unsaturated fatty acid(MUFA)in the RM group was significantly higher than FM.The hepatic activities of alanine aminotransferase and aspartate aminotransferase were lower and the hepatic glycogen and malonaldehyde were higher in the T1 and RM than the other treatments.The total serum protein,globulin,and triglycerides were significantly higher in T1 and RM;the alanine aminotransferase in the T1 was significantly higher than T0;and the aspartate aminotransferase in the RM and T0 groups were significantly higher than the other treatments.In a metabolomic assay,29 differential metabolites were identified between T0 and T1,23 metabolites were downregulated,and 6 metabolites were upregulated in T1 compared to T0.Ninety-two differential metabolites were identified between FM and RM,31 metabolites were downregulated,and 61 metabolites were upregulated in RM compared to FM.These indicated that lipid utilization and carbohydrate metabolism might be improved,while the protein metabolism was suppressed by rapeseed meal.The abnormal protein and lipid metabolism may be partly caused by tannin in the rapeseed meal,as the tannin contained within the rapeseed meal seemed to bring different effects that the tannin additive.

The anti-proliferative activity and cellular antioxidant activity of oenothein B and its content in different Eucalyptus species and region

The leaves of Eucalyptus are abundant in natural resources as a novel potential antioxidant and have broad market prospect.Four of characteristic hydrolysable tannins from Eucalyptus leaves have been demonstrated great application potential as natural antioxidants in our previous research.In this study,the bioactive activities of another hydrolysable tannin isolated and identified as oenothein B(OEB)were evaluated.Content of bioactive compound(hydrolysable tannin)from different Eucalyptus species and regions in southern China were investigated.The results showed that OEB not only exerted anti-proliferative activity against HepG2 cell,but also showed higher cellular antioxidant activity than some common antioxidants.Generally,content of characteristic hydrolysable tannins decreased in the order of OEB>tellimagrandin I(T1)>pedunculagin>gemin D>pentagalloyl glucose(PGG).E.grandis×E.urophylla GL9 and E.urophylla×E.grandis could be recommended as new natural sources to exploit hydrolysable tannins because of high content,widely plantation and strong adaptability.This study supplied first insight on introduction of high cellular antioxidant activity of OEB and selecting the species and region to exploit natural antioxidants.It will promote the increasing of economic value of Eucalyptus.

Addition of phenolic compounds to bread: antioxidant benefits and impact on food structure and sensory characteristics

The use of flours or phenolic extracts obtained from non-traditional sources or agri-food industry by-products has been a strategy used to formulate new bakery products with characteristics of a functional food.However,phenolic compounds present great structural diversity,as well as the ability to interact in a complex way with the macromolecules that constitute the bread matrix.Therefore,the addition of these flours,extracts or pure compounds produces various effects on the microstructure of bread,and several of its sensory properties.This is mainly due to interactions between phenolic compounds and gluten proteins.The objective of this review is to analyze some of the most recent published works on the addition of phenolic compounds in wheat bread to identify the type of positive and negative effects that have been observed and how they can be related to the physicochemical interactions between phenolic compounds and the macromolecules that constitute the food matrix,mainly gluten.The effect of monomeric and polymeric phenolic compounds on the strength of these interactions and on the properties of dough and bread are discussed.