Structure and chemical composition of bast fibers isolated from developing hemp stem

Microscopic and chemical changes of hemp bast fibers were studied during the maturation from vegetative to grain maturity stages at both apical and basal regions of the stems. The content of protein was the main factor related to fiber maturation, whereas increased proportions of mannose and glucose and decreasing levels of galactose were also highly significant. Enhanced glucose deposition in apical fibers could be related to the gradual thickening of the fibers, whereas in basal regions the thickness of the fibers nearly reached the maximum at vegetative stages. In contrast, the extent of lignification remained close to 3-4% during plant growth. Hemp fiber lignins were rich in guaiacyl units and would be rather condensed in nature. In addition, the proportion of p-hydroxyphenyl units displayed a constant decline during maturation. A progressive chemical fractionation of hemp fibers provided further insights to the occurrence and nature of noncellulosic polysaccharides. Notably, these data pointed out that maturation is accompanied by a significant increase in water- and alkali-soluble components containing glucose- and mannose-related polymers and a decrease in arabinose and galactose components disrupted by diluted hydrochloric acid. Taken together, chemical features of the noncellulosic components suggest that the architecture of hemp fibers differs slightly from that of the more widely studied flax fibers.     

Chemical and spectroscopic analysis of lignin in isolated flax fibers

The chemistry of pure flax fibers, free of contaminating nonfiber components, has not been determined. Fibers from the center sections of the stem of seed and fiber flax (Linum usitatissium L.), which had been retted after soaking in water and removal of the epidermis by hand, underwent chemical and spectroscopic analysis. Wet chemical analysis showed only trace indications of aromatics and no long chain fatty acids or alcohols in fibers. Pyrolysis mass spectroscopy (PyMS) and pyrolysis gas chromatography mass spectrometry (PyGCMS) showed only trace amounts of aromatic constituents that could be attributed to the presence of lignin. Mid-infrared (Mid-IR) and Raman spectroscopy of these fibers showed no aromatic compounds present. This study suggests that earlier work reporting the presence of lignin ranging from 1 to 4% may be the result of residual shive or epidermis/cuticle material remaining after the retting process which may be responsible for the favorable properties desired by the composites industry.     

Chemical composition and structural features of the macromolecular components of plantation Acacia mangium wood

The wood of Acacia mangium, a prominent fast-growing plantation species used in the pulp-and-paper industry and, so far, poorly investigated for its chemical structure, was submitted to a detailed characterization of its main macromolecular components. Lignin (28% wood weight) isolated by mild acidolysis and characterized by permanganate oxidation, 1H and 13C NMR, and GPC, showed a very low content of syringylpropane-derived units (S:G:H of 48:49:3), a high degree of condensation, a low content of beta-O-4 ( approximately 0.40-0.43 per C6) structures, and a Mw of 2230. Glucuronoxylan (14% wood weight) isolated by alkaline (KOH) or by dimethyl sulfoxide extraction was characterized by methylation analysis, 1H NMR, and GPC. About 10% of the xylopyranose (Xylp) units constituting the linear backbone were substituted at O-2 with 4-O-methylglucuronic acid residues. Almost half of the Xylp units (45%) were O-2 (18%), O-3 (24%) or O-2,3 (3%) acetylated. X-ray diffraction analysis of cellulose (46% wood weight), isolated according to the Kürschner-Hoffer method, showed a degree of crystallinity of 67.6%.     

Distribution of cadmium-binding components in flax (Linum usitatissimum L.) seed

The distribution of cadmium- (Cd-) binding components in flaxseed (cultivar NorMan) containing 0.526 ppm (ng/mg) Cd was investigated. Proteins extracted from dehulled, defatted flaxseed were fractionated by anion-exchange and size-exclusion chromatography. The contents of Cd and other metals, UV/visible spectral characteristics, and amino acid compositions of these fractions were analyzed. Over 66% of the eluted Cd was recovered by 0.1 M NaCl elution from DEAE-Sephacel, in a thiol-rich fraction representing only 7% of the extracted proteins. Sephadex G50 size-exclusion chromatography of this 0.1 M NaCl fraction concentrated most of the Cd in a low-molecular-weight peak eluting at V(t). About 72% of the extracted flaxseed proteins eluted from DEAE-Sephacel at 0.25 M NaCl and contained only 25% of the eluted Cd. Because the major Cd-binding fraction is a minor constituent of flaxseed, these results indicate the potential to isolate flaxseed's major storage protein with a low Cd content.     

Chemical characterization of lignin and lipid fractions in kenaf bast fibers used for manufacturing high-quality papers

The chemical composition of lignin and lipids of bast fibers from kenaf (Hibiscus cannabinus) used for high-quality paper pulp production was studied. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) of fibers showed a lignin with a high syringyl/guaiacyl ratio (5.4) and minor amounts of p-hydroxyphenyl units. Simultaneously, sinapyl and coniferyl acetates were also identified, indicating that this lignin is partially acetylated. p-Hydroxycinnamic acids were found in only trace amounts. The main lipids identified by GC/MS of extracts from kenaf fibers were series of long-chain n-fatty acids, waxes, n-alkanes, and n-fatty alcohols. Free and esterified sterols and triterpenols, steroid hydrocarbons, and steroid and triterpenoid ketones, as well as steryl glycosides, were also found. Finally, the fate of the main constituents of kenaf fibers in alkaline pulping was also investigated.     

Chemical characterization of lignin and lipid fractions in industrial hemp bast fibers used for manufacturing high-quality paper pulps

The chemical composition of lignin and lipids of bast fibers from industrial hemp (Cannabis sativa) used for high-quality paper pulp production was studied. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) of fibers showed a lignin with a p-hydroxyphenyl:guaiacyl:syringyl unit (H:G:S) molar proportion of 13:53:34 (S/G ratio of 0.64). p-Hydroxycinnamic acids, namely, p-coumaric and ferulic acids, were found in only trace amounts. Among the lipids, the main compounds identified by GC/MS of the hemp fibers extracts were series of n-alkanes, free and esterified sterols and triterpenols, waxes, and long-chain n-fatty acids. Other compounds such as n-aldehydes, n-fatty alcohols, steroid hydrocarbons, and steroid and triterpenoid ketones as well as steryl glycosides were also found.     

Chemical composition of acid precipitation in Central Texas

Studies were undertaken to determine factors affecting composition of acidic precipitation formation in the Austin area of Central Texas. The study was initiated to determine background levels of acid and alkalinity producing constitutents in an area with elevated natural dust levels from nearby limestone rock formations. Results showed normal rainfall pH values of 6.5 to 6.6 in the area, with extreme variations from 5.8 to 7.3. Significant Ca levels of 1 to 4 mg 1^?1 were observed from probably natural origin which appeared to have a buffering effect on acidity. Significant sulfate and nitrate ion concentrations occurred during the early stages of rainfall where rainfall pH was dependent on calcium-sulfate ratio.     

Engineering flax plants to increase their antioxidant capacity and improve oil composition and stability

The composition of polyunsaturated fatty acids in the tissues is very important to human health and strongly depends on dietary intake. Since flax seeds are the richest source of polyunsaturated acids, their consumption might be beneficial for human health. Unfortunately, they are highly susceptible to auto-oxidation, which generates toxic derivatives. The main goal of this study was the generation of genetically modified flax plants with increased antioxidant potential and stable and healthy oil production. Since among phenylpropanoid compounds those belonging to the flavonoid route have the lowest antioxidant capacity, the approach was to inhibit this route of the pathway, which might result in accumulation of other compounds more effective in antioxidation. The suppression of the chalcone synthase gene resulted in hydrolyzable tannin accumulation and thus increased antioxidant status of seeds of the transgenic plant. This was due to the partial redirecting of substrates for flavonoid biosynthesis to the other routes of the phenylpropanoid pathway. Consequently, transgenic plants produced more (20-45%) polyunsaturated fatty acids than the control and mainly α-linolenic acid. Thus, increasing the antioxidant potential of flax plants has benefits in terms of the yield of suitable oil for human dietary consumption.     

Chemical composition of selected edible nut seeds

Commercially important edible nut seeds were analyzed for chemical composition and moisture sorption. Moisture (1.47-9.51%), protein (7.50-21.56%), lipid (42.88-66.71%), ash (1.16-3.28%), total soluble sugars (0.55-3.96%), tannins (0.01-0.88%), and phytate (0.15-0.35%) contents varied considerably. Regardless of the seed type, lipids were mainly composed of mono- and polyunsaturated fatty acids (>75% of the total lipids). Fatty acid composition analysis indicated that oleic acid (C18:1) was the main constituent of monounsaturated lipids in all seed samples. With the exception of macadamia, linoleic acid (C18:2) was the major polyunsaturated fatty acid. In the case of walnuts, in addition to linoleic acid (59.79%) linolenic acid (C18:3) also significantly contributed toward the total polyunsaturated lipids. Amino acid composition analyses indicated lysine (Brazil nut, cashew nut, hazelnut, pine nut, and walnut), sulfur amino acids methionine and cysteine (almond), tryptophan (macadamia, pecan), and threonine (peanut) to be the first limiting amino acid as compared to human (2-5 year old) amino acid requirements. The amino acid composition of the seeds was characterized by the dominance of hydrophobic (range = 37.16-44.54%) and acidic (27.95-33.17%) amino acids followed by basic (16.16-21.17%) and hydrophilic (8.48-11.74%) amino acids. Trypsin inhibitory activity, hemagglutinating activity, and proteolytic activity were not detected in the nut seed samples analyzed. Sorption isotherms (Aw range = 0.08-0.97) indicated a narrow range for monolayer water content (11-29 mg/g of dry matter). No visible mold growth was evident on any of the samples stored at Aw < 0.53 and 25 degrees C for 6 months.     

Hydrolysis influence on phytochemical composition, antioxidant activity, plasma concentration, and tissue distribution of hydroethanolic Ilex paraguariensis extract components

The infusion of aerial parts of Ilex paraguariensis is widely consumed. Its antioxidant activity suggests an important role of this plant in the treatment/prevention of oxidative stress related diseases. Plant extract active compounds are frequently found in esterified form that may be poorly absorbed. Hydrolysis of the extract is a possible approach to increase its bioavailability. The aim of this study was to perform a phytochemical analysis and evaluate in rats the plasma concentration and tissue distribution of antioxidant compounds in the hydroethanolic extract of Ilex paraguariensis, before and after enzymatic hydrolysis. Both extracts presented high antioxidant activity and phenolic content. Rats given single or repeated doses of the hydrolyzed extract showed increased plasma antioxidant activity and higher plasma levels of caffeic acid. However, no changes of endogenous antioxidants were observed. In conclusion, hydrolysis of the extract of Ilex paraguariensis is a strategy to improve its bioavailability and in vivo antioxidant activity.     

Chemical composition and flavor of ecuadorian cocoa liquor

The contribution of the chemical composition to the flavor of cocoa liquor from an Ecuadorian selfed population of clone EET 95 was investigated. Polyphenols, purine alkaloids, organic acids, and sugars were quantified, and the key sensory characteristics of cocoa were scored by a trained panel. Despite the short bean fermentation (2 days) commonly used for Arriba cocoa, acetic acid content was closely correlated to liquor pH, demonstrating its essential role in cocoa liquor acidification. Polyphenols were positively correlated to astringency, bitterness, and the green note and negatively correlated to the fruity character. Alkaloid and polyphenol levels fluctuated significantly within the selfed progeny and tended to be lower than those of the heterozygous clone EET 95 (inbreeding effect). These results support the idea that polyphenols might be essential to the overall perception of cocoa liquor characteristics and indicate that the composition and the sensory quality of cocoa liquor are the result of both a genotypic contribution and the conditions of fermentation and roasting.     

Chemical composition and biological activities of Arachis species

Arachis hypogaea , known as the peanut, is native to South America. Peanut contains several active components including flavonoids, phenolic acids, phytosterols, alkaloids, and stilbenes. Some therapeutic effects have been reported for peanut seed extracts, such as antioxidative, antibacterial, antifungal, and anti-inflammatory activities. This paper aims to give an overview of the chemical composition, focusing on secondary metabolites, and of the biological activity of A. hypogaea, to stimulate new studies about species of the Arachis genus.     

Chemical composition of distillers grains, a review

In recent years, increasing demand for ethanol as a fuel additive and decreasing dependency on fossil fuels have resulted in a dramatic increase in the amount of grains used for ethanol production. Dry-grind is the major process, resulting in distillers dried grains with solubles (DDGS) as a major coproduct. Like fuel ethanol, DDGS has quickly become a global commodity. However, high compositional variation has been the main problem hindering its use as a feed ingredient. This review provides updated information on the chemical composition of distillers grains in terms of nutrient levels, changes during dry-grind processing, and causes for large variation. The occurrence in grain feedstock and the fate of mycotoxins during processing are also covered. During processing, starch is converted to glucose and then to ethanol and carbon dioxide. Most other components are relatively unchanged but concentrated in DDGS about 3-fold over the original feedstock. Mycotoxins, if present in the original feedstock, are also concentrated. Higher fold of increases in S, Na, and Ca are mostly due to exogenous addition during processing, whereas unusual changes in inorganic phosphorus (P) and phytate P indicate phytate hydrolysis by yeast phytase. Fermentation causes major changes, but other processing steps are also responsible. The causes for varying DDGS composition are multiple, including differences in feedstock species and composition, process methods and parameters, the amount of condensed solubles added to distiller wet grains, the effect of fermentation yeast, and analytical methodology. Most of them can be attributed to the complexity of the dry-grind process itself. It is hoped that information provided in this review will improve the understanding of the dry-grind process and aid in the development of strategies to control the compositional variation in DDGS.     

Quantitation of the lignan secoisolariciresinol diglucoside in baked goods containing flax seed or flax meal

Samples of commercially prepared white, whole wheat, flax, and multigrain breads were analyzed by a rapid RP-HPLC method for the presence of the lignan secoisolariciresinol diglucoside (SDG). SDG was detected only in products containing flax, with concentrations ranging from 0.06 to 1.98 microM/g of DW (19-602 microM/loaf). Full-fat flax meal, powdered aqueous alcohol extracts of flax seed, and SDG were added to a white bread mix and baked into loaves in a domestic bread maker. Quantitative recovery of SDG from the test breads was observed when SDG was added; however, when flax meal or aqueous alcohol extracts were added, only 73-75% of the theoretical yield of SDG was recovered. SDG was also detected in commercially prepared flax cookies, bagels, and muffins with concentrations ranging from 0.26 to 2.93 microM/g of DW. The extent of grinding of the flax seed was also shown to have a significant effect on the recovery of SDG from both flax meal breads and baked goods, with extraction of SDG from finely ground samples greater than that from course material.     

Chemical composition of shallot (Allium ascalonicum Hort.)

An extensive phytochemical analysis of the polar extracts from bulbs of shallot, Allium ascalonicum Hort., led to the isolation of two new furostanol saponins, named ascalonicoside A1/A2 (1a/1b) and ascalonicoside B (4), respectively, along with compounds 2a and 2b, most likely extraction artifacts. On the basis of 2D NMR and mass spectrometry data, the structures of the novel compounds were elucidated as furost-5(6)-en-3beta,22alpha-diol 1beta-O-beta-D-galactopyranosyl 26-O-[alpha-L-rhamnopyranosyl-(1-->2)-O-beta-D-glucopyranoside] (1a), its epimer at position 22 (1b), and furost-5(6),20(22)-dien-3beta-ol 1beta-O-beta-D-galactopyranosyl 26-O-[alpha-L-rhamnopyranosyl-(1-->2)-O-beta-D-glucopyranoside] (4). This is the first report of furostanol saponins in A. ascalonicum. High concentrations of quercetin, isorhamnetin, and their glycosides were also isolated and described.     

Chemical composition controls residue decomposition in soils differing in initial pH

Laboratory incubation studies were conducted to determine the dynamics of low-molecular-weight aliphatic carboxylic acids and their anions (LACAs) and respiration in three soils incorporated with five types of plant residues differing in chemical composition. Concentrations of total and individual LACAs in soils decreased sharply with initial 3 days after addition of plant residues, and varied with types of plant residue and soil. Irrespective of soil types, the amount of total extractable LACAs was highest in the soils treated with chickpea, followed by lucerne and high-N wheat straw, and lowest with low-N wheat straw. Lancelin soil [initial pH(CaCl₂) 5.06] contained higher concentration of extractable LACAs compared with Bodallin (pH 4.54) and Wodjil soil (pH 3.87). Soil respiration rate was rapidly increased by the addition of plant residues, and reached the peak by Day 3. Respiration rate was the greatest in Lancelin soil and the smallest in Wodjil soil. The amounts of CO₂ respired over 7 days were equivalent to 6-25% of the added C for Wodjil soil, 6-39% for Bodallin soil and 6-47% for Lancelin soil, depending on type of plant residue. Those amounts over 105 days increased further. Irrespective of plant residue and soil type, the cumulative respiration correlated positively with concentrations of N, excess cations and soluble C in plant residues and initial soil pH, and negatively with C:N of plant residues. The results suggest that chemical composition of plant residues plays an important role at the initial stage of residue decomposition.