Low Molecular Weight Phenolic Compounds Research Articles

Bioremediation and toxicity reduction in pulp and paper mill effluent by newly isolated ligninolytic Paenibacillus sp.

The present study deals with the bioremediation of potentially hazardous pulp and paper mill effluent by a laccase producing Paenibacillus sp. strain LD-1 (JX499920) isolated from contaminated soil sample by lignin enrichment method. The bacterium effectively reduced pollution parameters (colour 68%, lignin 54%, phenol 86%, BOD 83% and COD 78%) after 144h of treatment at 34±1°C and 120rpm. GC–MS analysis of control and treated samples showed that concentration of most of the low molecular weight phenolic compounds like 2-methoxyphenol, 2,6-dimethoxy phenol, 2-methoxy-4-ethyl-phenol, 3-allyl-6-methoxyphenol, ethanone 1-(-4-hydroxy-3,5-dimethoxyphenyl), benzoic acid, 2-methoxy-4-(1-propenyl) phenol and 4-methoxycinnamic acid present in control untreated effluent were reduced after bacterial treatment. The toxicity assessments were carried out with treated and untreated effluent by studying the growth and germination of seeds of mung bean (Vigna radiata L.). The mung bean bioassay confirmed the detoxification of effluent after bacterial treatment.

Occurrence of low molecular weight phenolics in Vitis vinifera red grape cultivars and their winemaking by-products from São Paulo (Brazil)

The content of low molecular weight phenolic compounds present in winemaking by-products (skins from grape marc and wine lees) of red wine made from the Vitis vinifera grape cultivars Cabernet Sauvignon and Cabernet Franc in the state of São Paulo (Brazil) has been examined. The study was extended to two consecutive years and showed that winemaking by-products still contained high concentrations of interesting functional and bioactive phenolic compounds. In addition to original grape phenolics, the winemaking by-products contained new phenolics originated by the action of enzymatic (yeast mediated) and chemical reactions during winemaking, including formation of anthocyanin-derived pigments and hydrolysis products from flavonol glycosides and tartaric esters of hydroxycinnamic acids. A total of 19 anthocyanins, 9 pyranoanthocyanins, 18 flavonols, 7 hydroxycinnamic acid derivatives, and 3 resveratrol-based stilbenes were identified. Wine lees have been revealed as an interesting source of flavonol aglycones and pyranoanthocyanins. The best sample preparation technique prior to the extraction of phenolic compounds, with regard to the maintenance of phenolic compound profiles and concentrations, was freeze-drying. However, in the case of lees, spray-drying showed to be also effective in the preservation of phenolic compounds and is a less expensive technique. Oven-drying at 50°C should be avoided if there is interest in using winemaking by-products for further purposes, since phenolic compound concentrations were strongly reduced by thermal degradation.

Assessment of advanced oxidative processes based on heterogeneous catalysis as a detoxification method of rice straw hemicellulose hydrolysate and their effect on ethanol production by Pichia stipitis

In the present work, detoxification treatments based on advanced oxidative processes (AOPs) aiming to improve the ethanol production by Pichia stipitis were evaluated. The experimental design was carried out according to a Taguchi L8 orthogonal array in order to evaluate the influences of pH, catalyst type (ZnO or TiO2), UV radiation (UVA or UVC), and oxidant agent (O2 or O3) on aromatic compounds concentration and fermentation performed. The results showed that treatment conditions which most contribute to reducing the toxicity of the hydrolysate in relation to ethanol production were pH 8.0 and the use of O3 as an oxidizing agent. Within the region evaluated, there was no difference between the use of TiO2 or ZnO and or UVA or UVC radiation. The heterogeneous AOPs were able to remove above 49 % of the furan, above 39 % of the total phenolic compounds, and 100 % of the low molecular weight phenolic compounds, without affecting the sugar concentrations in the hydrolysate. Furthermore, heterogeneous processes have provided relevant increases on sugars consumption (148 %) and maximum ethanol concentration (154 %) as compared with untreated hydrolysate. In addition, the AOPs treatment showed advantages such as it does not generate waste, does not degrade hydrolysate sugars, and does not lead to loss of hydrolysate volume due to the treatment. Based on the results, it can be concluded that AOPs are promising processes for application in hydrolysate treatment to reduce toxicity and consequently improve the fermentability of lignocellulosic hydrolysates.

Catalytic hydrothermal upgradation of wheat husk

Catalytic hydrothermal upgradation of wheat husk was performed at 280°C for 15 min in the presence of alkaline catalysts (KOH and K2CO3). The effect of alkaline catalysts on the yield of bio-oil products and composition of bio-oils obtained were discussed. Total bio-oil yield (31%) comprising of bio-oil1 (ether fraction) and bio-oil2 (acetone fraction) was maximum with K2CO3 solution. Powder XRD (X-ray diffraction) analysis of wheat husk as well as bio-residue samples show that the peaks due to cellulose, hemicellulose and lignin become weak in bio-residue samples which suggest that these components have undergone hydrolytic cleavage/decomposition. The FTIR spectra of bio-oils indicate that the lignin in the wheat husk samples was decomposed to low molecular weight phenolic compounds. (1)H Nuclear Magnetic Resonance (NMR) spectrum of bio-oil1 shows more than 50% of the protons resonate in the up field region from 0.5 ppm to 3.0 ppm.

Phenolic composition of skins from four Carmenet grape varieties (Vitis vinifera L.) during ripening

Phenolic composition of skins from Vitis vinifera L. cv Carménère (CA), Merlot (M), Cabernet Franc (CF) and Cabernet Sauvignon (CS) grapes during ripening was evaluated by HPLC-DAD and spectrophotometric analysis. At the time of harvest maturity, CS skins showed the highest contents of monomeric, oligomeric and polymeric flavan-3-ols with respect to other varieties. Likewise, the L∗, C∗ and a∗ CIElab parameters showed no statistical differences between the four varieties but the H∗ and b∗ CIElab parameters exhibited clear differences between the M and CS skins. Alike, the sum of glucoside and cumarilglucoside anthocyanins in CA identified by HPLC-DAD was higher than in CF and CS in some sampling date. Additionally, significant differences in the content of low molecular weight phenolic compounds quantified by HPLC-DAD were observed. Comparatively, the CS skins displayed higher mDP, %EG and aMW values than the rest of the cultivars on the last sampling date. Overall, we conclude that CA, M, CF and CS grape skins present marked differences in phenolic composition during ripening.

Treatment of rice straw hemicellulosic hydrolysates with advanced oxidative processes: a new and promising detoxification method to improve the bioconversion process

BackgroundThe use of lignocellulosic constituents in biotechnological processes requires a selective separation of the main fractions (cellulose, hemicellulose and lignin). During diluted acid hydrolysis for hemicellulose extraction, several toxic compounds are formed by the degradation of sugars and lignin, which have ability to inhibit microbial metabolism. Thus, the use of a detoxification step represents an important aspect to be considered for the improvement of fermentation processes from hydrolysates. In this paper, we evaluated the application of Advanced Oxidative Processes (AOPs) for the detoxification of rice straw hemicellulosic hydrolysate with the goal of improving ethanol bioproduction by Pichia stipitis yeast. Aiming to reduce the toxicity of the hemicellulosic hydrolysate, different treatment conditions were analyzed. The treatments were carried out according to a Taguchi L16 orthogonal array to evaluate the influence of Fe+2, H2O2, UV, O3 and pH on the concentration of aromatic compounds and the fermentative process.ResultsThe results showed that the AOPs were able to remove aromatic compounds (furan and phenolic compounds derived from lignin) without affecting the sugar concentration in the hydrolysate. Ozonation in alkaline medium (pH 8) in the presence of H2O2 (treatment A3) or UV radiation (treatment A5) were the most effective for hydrolysate detoxification and had a positive effect on increasing the yeast fermentability of rice straw hemicellulose hydrolysate. Under these conditions, the higher removal of total phenols (above 40%), low molecular weight phenolic compounds (above 95%) and furans (above 52%) were observed. In addition, the ethanol volumetric productivity by P. stipitis was increased in approximately twice in relation the untreated hydrolysate.ConclusionThese results demonstrate that AOPs are a promising methods to reduce toxicity and improve the fermentability of lignocellulosic hydrolysates.

Enzymatic synthesis of antibody-human serum albumin conjugate for targeted drug delivery using tyrosinase from Agaricus bisporus

Highly specific targeted drug delivery devices can be obtained with antibody-human serum albumin (mAb-HSA) conjugates. However, their conventional production involves several reaction steps including chemical modification and activation of both proteins followed by cross-linking often involving toxic chemicals. Here, we describe the enzymatic synthesis of mAb-HSA conjugates for targeted drug delivery devices using tyrosinase from Agaricus bisporus under mild reaction conditions (pH 6.8, 25 °C). Reaction conditions were optimized by using fluorescence labeled HSA to facilitate SDS-PAGE analysis with fluorescence scanning. Enzymatic cross-linking in the presence of natural low molecular weight phenolic compounds (e.g. caffeic acid) resulted in reaction products in the molecular weight range of ∼216 kDa, corresponding to mAb-HSA conjugates. The composition of the conjugates was confirmed with tryptic digestion followed by LC-MS/MS analysis of the resulting peptide fragments. Successful binding of mAb-HSA conjugates (in contrast to free HSA) to MHC II molecules, located on antigen-presenting cells, was demonstrated by both ELISA and flow cytometry analysis.

Organosolv Black Liquor Hydrolysis to Obtain Low Molecular Weight Phenolic Compounds

In this work, olive tree pruning was used as raw material to delignify it employing organosolv treatment. Obtained liquor was hydrolyzed at a high pressure reactor at 300 oC for 40 min to depolymerize lignin it contains. Thus, lignin from the liquor was depolymerize avoiding the precipitation step. Different experiments were carried modifying organosolv black liquor. Products resulted after treatment were characterized by two techniques: Gas chromatography/Mass spectroscopy (GC/MS) and high performance size exclusion chromatography (HPSEC). Obtained oil after hydrolysis reaction of the organosolv black liquor had high concentration in guaiacol and syringol.

Enhancing bioavailability of nutrients in whole grain products

There is little doubt that consumption of whole cereals and other grains confers benefits to consumers, and a number of studies support the notion that health and wellness outcomes correlate positively with levels of whole grains in the diet. Although there are a number of strong assessments of the effects of whole grains on health, the biochemical evidence supporting many whole grain “benefits” is often indirect, circumstantial, or poorly defined, at best, although an enormous number of studies have added greatly to our understanding of grain composition and structure. It is obvious from these analyses that we are now much better equipped to define the physiological effects (and benefits) of whole grains, providing that we attempt to integrate appropriate epidemiological, genetic, and biochemical assessments. The soluble fibre components of cereals have received considerable attention over the past 20 years, in part due to their impact on serum cholesterol in human subjects, and in part because of their potential impact on mammalian immune systems. In addition to extensively documented results relating to beneficial effects of cereal fibre-enriched products, there remains a substantial array of additional grain components that are poorly characterized. Many of these are attracting increased attention, including many different antioxidants and immune stimulators, but it is becoming obvious that we have only superficial information regarding their availability as nutrients, their fate during processing, and their physiological impact(s) in common processed whole grain foods. Some of these grain components, including vitamins, minerals, and several low molecular weight phenolic compounds are particular emphasised with regard their nutritional availability when included in whole grain manufactured products.

Pre-bottling use of dehydrated waste grape skins to improve colour, phenolic and aroma composition of red wines

Different dehydrated waste grape skins from the juice industry were added into aged and young red wines as an innovative way of compensating for colour loss before bottling. After addition of grape skins, colour intensity of wines increased a mean 11% and a maximum of 31% with predominance of the red component. Total polyphenols mean increase was 10% with a maximum value of 20%. Analysis of low molecular weight phenolic compounds by HPLC–DAD showed a significant (p<0.05) content increase of the bioactive compounds gallic acid, (+)-catechin, (−)-epicatechin, and (E)-resveratrol. Anthocyanins content also increased at an average of 50mg/l. The volatile profile of wines analysed by SBSE–GC–MS was only moderately influenced by the treatments. Mixtures of dehydrated waste grape skins were useful to improve the colour and polyphenol profile of red wines, considering them a useful tool for correcting colour loss before bottling.

Waste grape skins thermal dehydration: potential release of colour, phenolic and aroma compounds into wine

Exploitation of grape waste material is scarce. One of the main issues to deal with is its high moisture content, as it causes spoilage and degradation of valuable compounds. In order to assess this limitation, four different Vitis vinifera waste grape skins from the juice industry were dehydrated at 60, 90 and 100°C. Characterisation of dehydrated waste grape skins (DWGS) was firstly done in wine model solution to evaluate the release of colour, phenolic and volatile compounds. Colour of DWGS-60°C solutions was similar to the control one (freeze-drying) in terms of red and yellow components regardless of the variety. Samples of Garnacha Tintorera, Bobal and AMIX dehydrated at 60°C showed the highest content of low molecular weight phenolic compounds. Bobal DWGS-60°C released the highest concentration of volatiles. An assay by direct addition of Bobal DWGS-60°C into a white wine demonstrated the potential of these residues for producing rosé wines.

LC‐DAD/ESI‐MS/MS study of phenolic compounds in ash (Fraxinus excelsior L. and F. americana L.) heartwood. Effect of toasting intensity at cooperage

The phenolic composition of heartwood extracts from Fraxinus excelsior L. and F. americana L., both before and after toasting in cooperage, was studied using LC-DAD/ESI-MS/MS. Low-molecular weight (LMW) phenolic compounds, secoiridoids, phenylethanoid glycosides, dilignols and oligolignols compounds were detected, and 48 were identified, or tentatively characterized, on the basis of their retention time, UV/Vis and MS spectra, and MS fragmentation patterns. Some LMW phenolic compounds like protocatechuic acid and aldehyde, hydroxytyrosol and tyrosol, were unlike to those for oak wood, while ellagic and gallic acid were not found. The toasting of wood resulted in a progressive increase in lignin degradation products with regard to toasting intensity. The levels of some of these compounds in medium-toasted ash woods were much higher than those normally detected in toasted oak, highlighting vanillin levels, thus a more pronounced vanilla character can be expected when using toasted ash wood in the aging wines. Moreover, in seasoned wood, we found a great variety of phenolic compounds which had not been found in oak wood, especially oleuropein, ligstroside and olivil, along with verbascoside and isoverbascoside in F. excelsior, and oleoside in F. americana. Toasting mainly provoked their degradation, thus in medium-toasted wood, only four of them were detected. This resulted in a minor differentiation between toasted ash and oak woods. The absence of tannins in ash wood, which are very important in oak wood, is another peculiar characteristic that should be taken into account when considering its use in cooperage.

The phenylalanine ammonia lyase (PAL) gene family shows a gymnosperm-specific lineage

BackgroundPhenylalanine ammonia lyase (PAL) is a key enzyme of the phenylpropanoid pathway that catalyzes the deamination of phenylalanine to trans-cinnamic acid, a precursor for the lignin and flavonoid biosynthetic pathways. To date, PAL genes have been less extensively studied in gymnosperms than in angiosperms. Our interest in PAL genes stems from their potential role in the defense responses of Pinus taeda, especially with respect to lignification and production of low molecular weight phenolic compounds under various biotic and abiotic stimuli. In contrast to all angiosperms for which reference genome sequences are available, P. taeda has previously been characterized as having only a single PAL gene. Our objective was to re-evaluate this finding, assess the evolutionary history of PAL genes across major angiosperm and gymnosperm lineages, and characterize PAL gene expression patterns in Pinus taeda.MethodsWe compiled a large set of PAL genes from the largest transcript dataset available for P. taeda and other conifers. The transcript assemblies for P. taeda were validated through sequencing of PCR products amplified using gene-specific primers based on the putative PAL gene assemblies. Verified PAL gene sequences were aligned and a gene tree was estimated. The resulting gene tree was reconciled with a known species tree and the time points for gene duplication events were inferred relative to the divergence of major plant lineages.ResultsIn contrast to angiosperms, gymnosperms have retained a diverse set of PAL genes distributed among three major clades that arose from gene duplication events predating the divergence of these two seed plant lineages. Whereas multiple PAL genes have been identified in sequenced angiosperm genomes, all characterized angiosperm PAL genes form a single clade in the gene PAL tree, suggesting they are derived from a single gene in an ancestral angiosperm genome. The five distinct PAL genes detected and verified in P. taeda were derived from a combination of duplication events predating and postdating the divergence of angiosperms and gymnosperms.ConclusionsGymnosperms have a more phylogenetically diverse set of PAL genes than angiosperms. This inference has contrasting implications for the evolution of PAL gene function in gymnosperms and angiosperms.

Multivariate statistical approaches for wine classification based on low molecular weight phenolic compounds

Background and Aims: Phenolic compounds influence colour, flavour and astringency of wines. Technology and grape variety are the main factor affecting the phenolic content of wines. Different multivariate statistical approaches were used to investigate the relationships between the profile of phenolic compounds and grape variety and also the impact of malolactic fermentation (MLF). Methods and Results: A reversed phase liquid chromatography/diode array detection method was used for the analysis of major non-flavonoid phenolic compounds in wines from Trincadeira, Aragonez, Cabernet Sauvignon, Alfrocheiro, Casteão and Touriga Nacional varieties before and after MLF. The impact of MLF and grape variety on phenolic profile was evaluated by principal component analysis (PCA), variation partitioning analysis (VPA) and artificial neural network (ANN). PCA explained 86.5% of the total variance among samples. ANN showed a significant clustering of samples according to grape variety and confirmed that MLF has a minor effect on wine phenolic profile. VPA enabled more information to be extracted from the data by identifying explanatory variables responsible for variability among samples. Conclusions: Compared with PCA and ANN, VPA provides more information concerning the variability on the sample system. Also, grape varieties have a more effective impact on wine low molecular weight phenolic compounds than MLF. Significance of the Study: Each one of the three multivariate statistical approaches showed ways of analysing large chemistry experimental datasets. VPA is a step forward in data analysis, providing more solid and complete assessment of sample system variability, not possible by PCA and ANN.

A Rapid Two-Step Bioremediation of the Anthraquinone Dye, Reactive Blue 4 by a Marine-Derived Fungus

A rapid two-step technique for bioremediation of the anthraquinone dye, the Reactive Blue 4 (RB4) by a marine-derived fungus is reported here. In the first step, 1,000 mg l−1 of this dye treated with partially purified laccase of this fungus resulted in 61 % color removal and twofold decrease in chemical oxygen demand by 12 h. The metabolites formed during the enzymatic degradation were characterized by mass spectrometry, ultra performance liquid chromatography, and UV/visible spectroscopy. These analyses confirmed changes in the aromatic character of the parent dye and formation of low molecular weight phenolic compounds as the final products of the enzymatic degradation. Based on these results, the probable degradation products of RB4 were 2-formylbenzoic acid, 1,2,4,5-tetrahydroxy-3-benzoic acid, 2,3,4-trihydroxybenzenesulfonic acid, and 1,2,3,4-pentahydroxybenzene. In the second step, the enzyme-transformed dye solution subjected to sorption on the powdered fungal biomass resulted in a further reduction in color up to 93 % within 10 min. Sorption of the degraded dye was confirmed by the changes in the pattern of Fourier transform infrared spectroscopy spectrum. The two-step treatment resulted in a decrease of 29 % in total carbon accompanied by twofold decrease in toxicity. This is the first report on decolorization, detoxification, and mineralization of RB4 by laccase from a marine-derived fungus.

Characterization and Quantitation of Low and High Molecular Weight Phenolic Compounds in Apple Seeds

The phenolic constituents of seeds of 12 different apple cultivars were fractionated by sequential extraction with aqueous acetone (30:70, v/v) and ethyl acetate after hexane extraction of the lipids. Low molecular weight phenolic compounds were individually quantitated by RP-HPLC-DAD. The contents of extractable and nonextractable procyanidins were determined by applying RP-HPLC following thiolysis and n-butanol/HCl hydrolysis, respectively. As expected, the results revealed marked differences of the ethyl acetate extracts, aqueous acetone extracts, and insoluble residues with regard to contents and mean degrees of polymerization of procyanidins. Total phenolic contents in the defatted apple seed residues ranged between 18.4 and 99.8 mg/g. Phloridzin was the most abundant phenolic compound, representing 79-92% of monomeric polyphenols. Yields of phenolic compounds significantly differed among the cultivars under study, with seeds of cider apples generally being richer in phloridzin and catechins than seeds of dessert apple cultivars. This is the first study presenting comprehensive data on the contents of phenolic compounds in apple seeds comprising extractable and nonextractable procyanidins. Furthermore, the present work points out a strategy for the sustainable and complete exploitation of apple seeds as valuable agro-industrial byproducts, in particular as a rich source of phloridzin and antioxidant flavanols.

Effect of the aging on lees and other alternative techniques on the low molecular weight phenols of Tempranillo red wine aged in oak barrels

The effect of different alternative techniques to the traditional aging on lees on the low molecular weight phenolic compounds of red wines was study as well as their evolution during the aging in oak wood barrels for six months. The study was carried out with Tempranillo red grapes from two consecutive vintages. The techniques assayed were the traditional aging on lees with or without the addition of exogenous β-glucanase enzymes, the use of yeast derivative preparations also with or without the addition of exogenous β-glucanase enzymes, the micro-oxygenation applied together with the aging on lees, and the use of non-toasted oak wood chips.Hydroxycinnamic acids were the compounds most affected by these treatments, mainly in the wines treated with chips and commercial yeast derivative products, which showed higher concentrations of the free acids, compounds that play an important role in wine stabilization color since they can act as anthocyanin copigments.The differences found between the assayed treatments were more important in the 2007 vintage than in the 2008. However, a more significant effect of micro-oxygenation in the 2008 vintage was observed, which could be related to the fact that in this vintage the treatment was longer. In the 2008 vintage, the differences between treatments decreased along the aging in barrel. This vintage effect could be associated to the differences in the phenolic concentration of the initial wines. In this sense more research should be done to corroborate this fact.

In vitro anti‐platelet effects of simple plant‐derived phenolic compounds are only found at high, non‐physiological concentrations

Bioactive polyphenols from fruits, vegetables, and beverages have anti-platelet effects and may thus affect the development of cardiovascular disease. We screened the effects of 26 low molecular weight phenolic compounds on two in vitro measures of human platelet function. After platelets had been incubated with one of 26 low molecular weight phenolic compounds in vitro, collagen-induced human platelet aggregation and in vitro TRAP-induced P-selectin expression (as marker of platelet activation) were assessed. Incubation of platelet-rich plasma from healthy volunteers with 100 μmol/L hippuric acid, pyrogallol, catechol, or resorcinol significantly inhibited collagen-induced platelet aggregation (all p<0.05; n≥15). Incubation of whole blood with concentrations of 100 μmol/L salicylic acid, p-coumaric acid, caffeic acid, ferulic acid, 4-hydroxyphenylpropionyl glycine, 5-methoxysalicylic acid, and catechol significantly inhibited TRAP-induced surface P-selectin expression (all p<0.05; n=10). Incubation with lower concentrations of phenolics affected neither platelet aggregation nor activation. As concentrations of 100 μmol/L are unlikely to be reached in the circulation, it is doubtful whether consumption of dietary phenolics in nutritionally attainable amounts plays a major role in inhibition of platelet activation and aggregation in humans.

ROS production and antioxidative system activity in embryonic axes of Quercus robur seeds under different desiccation rate conditions

The seeds of pedunculate oak (Quercus robur L.) were subjected to slow (S) and rapid (R) desiccation at desiccation rates of 0.16 and 0.39% H2O per hour, respectively. Till ca. 40% water content (WC) the germination capacity of seeds in the S and R variants was high (ca. 100%). Between 40 and 28% WC, germination capacity declined to 20 and 50% in S and R variants, respectively. The decrease in seed viability was accompanied by a significant increase of electrolyte leakage from embryonic axes (28% for S and 15% for R variants). In the embryonic axes of seeds subjected to slow desiccation, malondialdehyde (MDA) and free fatty acid (FFA) contents were significantly higher than those in R variants, indicating greater membrane damage due to lipid peroxidation. The production of ROS (H2O2 and O2·−) was significantly higher in S than in R variants. The low molecular weight antioxidants α-tocopherol, ascorbic acid (ASA), and phenolic compounds indicated different reactions in response to desiccation stress. ASA levels decreased during desiccation to a similar degree in both the S and R variants. A significant decrease of total phenols was observed in R variant, which coincided with a significant increase of guaiacol peroxidase (POX) activity. α-Tocopherol content was significantly higher in the embryonic axes of seeds subjected to rapid drying. The activities of the enzymatic scavengers APX and GR had similar runs and were slightly higher in R variant. The activities of POX and SOD were significantly higher in the embryonic axes of seeds subjected to rapid drying. These results show that rapid dehydration of Q. robur seeds leads to the greater mobilization of antioxidant system in embryonic axes, particularly increased levels of α-tocopherol and POX and SOD activities, in the first stages of water loss. This mobilization has a greater impact on maintenance of higher viability of seeds after drying to lower level of WC.

Effect of Toasting Intensity at Cooperage on Phenolic Compounds in Acacia (Robinia pseudoacacia) Heartwood

The phenolic composition of heartwood from Robinia pseudoacacia, commonly known as false acacia, before and after toasting in cooperage was studied by HPLC-DAD and HPLC-DAD/ESI-MS/MS. A total of 41 flavonoid and nonflavonoid compounds were identified, some tentatively, and quantified. Seasoned acacia wood showed high concentrations of flavonoid and low levels of nonflavonoid compounds, the main compounds being the dihydroflavonols dihydrorobinetin, fustin, tetrahydroxy, and trihydroxymethoxy dihydroflavonol, the flavonol robinetin, the flavanones robtin and butin, and a leucorobinetinidin, none of which are found in oak wood. The low molecular weight (LMW) phenolic compounds present also differed from those found in oak, since compounds with a β-resorcylic structure, gallic related compounds, protocatechuic aldehyde, and some hydroxycinnamic compounds are included, but only a little gallic and ellagic acid. Toasting changed the chromatographic profiles of extracts spectacularly. Thus, the toasted acacia wood contributed flavonoids and condensed tannins (prorobinetin type) in inverse proportion to toasting intensity, while LMW phenolic compounds were directly proportional to toasting intensity, except for gallic and ellagic acid and related compounds. Even though toasting reduced differences between oak and acacia, particular characteristics of this wood must be taken into account when considering its use in cooperage: the presence of flavonoids and compounds with β-resorcylic structure and the absence of hydrolyzable tannins.