Corn Fiber: Structure, Composition, and Response to Enzymes for Fermentable Sugars and Coproducts

Corn (Zea mays L.) fiber, which is the seed coat and residual endosperm left after grain processing, is a low-value residue that contains carbohydrates and aromatic compounds that could provide value-added coproducts. Treatment of corn fiber with NaOH and assessment by gas chromatography indicated a prevalence of ferulic acid, with about 90% ester-linked in the cell walls. p-Coumaric acid was much lower at about 10% of the amount of ferulic acid. Histochemical reactions employing acid phloroglucinol and diazotized sulfanilic acid indicated the presence of phenolic acids in cell walls of the pericarp and aleurone layer. Various protocols were tested using milled corn fiber and pretreatment with commercial ferulic acid esterases before cellulase treatment, and dry weight loss and sugars and phenolic acids released into the filtrate were evaluated. Ferulic acid esterases effectively degraded corn fiber and released substantial amounts of ferulic acid and sugars (e.g., glucose and xylose) in the incubation medium. Light microscopy showed that ferulic acid esterase substantially disrupted the aleurone layer but caused little visible damage to the lignified pericarp cell walls. Amounts of compounds released varied with protocols, and one study with various milling methods showed that esterase pretreatment followed by cellulase released about 2.8 to 4.4 and 1.5 to 2.9 times more ferulic acid and glucose, respectively, than cellulase alone. The highest levels for one lot of corn fiber with esterase pretreatment followed by cellulase were 3.9 and 218 mg/g of ferulic acid and glucose, respectively.     

Biotransformation of Rice Bran to Ferulic Acid by Pediococcal Isolates

Ferulic acid (FA) is widely used in foods, in beverages, and in various pharmaceutical industries as a precursor of vanillin. FA biotransformation can occur during the growth of lactic acid bacteria (LAB), and its conversion to other phenolic derivatives is observed by many scientists, where ferulic acid esterase (FAE) and ferulic acid decarboxylase (FDC) play significant roles. The present study aimed at screening a panel of LAB for their ability to release FA from rice bran, an agro waste material. FAE and FDC activities were analyzed for the preliminary screening of various dairy isolates. Two Pediococcus acidilactici isolates were selected for studying further the hydrolysis of FA from rice bran and its bioconversion into phenolic derivatives like 4-ethylphenol, vanillin, vanillic acid, and vanillyl alcohol. P. acidilactici M16, a probiotic isolate, has great potential for the production of FA from rice bran and could be exploited as starter culture in the food industry for the production of biovanillin.     

Corn stover fractions and bioenergy

Information is presented on structure, composition, and response to enzymes of corn stover related to barriers for bioconversion to ethanol. Aromatic compounds occurred in most tissue cell walls. Ferulic acid esterase treatment before cellulase treatment significantly improved dry weight loss and release of phenolic acids and sugars in most fractions over cellulase alone. Leaf fractions were considerably higher in dry weight loss and released sugars with esterase treatment, but stem pith cells gave up the most phenolic acids. Results help identify plant fractions more appropriate for coproducts and bioconversion and those more suitable as residues for soil erosion control.     

Lipids from <Emphasis Type="Italic">Halostachys caspica</Emphasis> and <Emphasis Type="Italic">Halocharis hispida</Emphasis>

The composition of lipids from the aerial parts of two species of halophytes from the family Chenopodiaceae, Halostachys caspica C. A. Mey. and Halocharis hispida Bge. was determined. Neutral lipids (NL, 62.1 and 54.2%, respectively) dominated the total lipids (TL) of these plants. More than a third of the NL were esters of aliphatic alcohols and phytosterols (FAE). Fatty acids 16:0, 18:1, and 18:2 dominated the acids of FAE; 16:0, 18:1, and 18:3, the phospholipids. The principal fatty acids of glycolipids were unsaturated acids (68.3 and 75.1%) with linolenic acid dominating (44.9 and 43.5%). Presented at the 7th International Symposium on the Chemistry of Natural Compounds, Tashkent, October 16–18, 2007. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 276–278, May–June, 2009.     

A biotechnological process involving filamentous fungi to produce natural crystalline vanillin from maize bran

A new process involving the filamentous fungi Aspergillus niger and Pycnoporus cinnabarinus has been designed for the release of ferulic acid by enzymic degradation of a cheap and natural agricultural byproduct (autoclaved maize bran) and its biotransformation into vanillic acid and/or vanillin with a limited number of steps. On the one hand, the potentialities of A. niger I-1472 to produce high levels of polysaccharide-degrading enzymes including feruloyl esterases and to transform ferulic acid into vanillic acid were successfully combined for the release of free ferulic acid from autoclaved maize bran. Then vanillic acid was recovered and efficiently transformed into vanillin by P. cinnabarinus MUCL 39533, since 767 mg/L of biotechnologic vanillin could be produced in the presence of cellobiose and XAD-2 resin. On the other hand, 3-d-old high-density cultures of P. cinnabarinus MUCL39533 could be fed with the autoclaved fraction of maize bran as a ferulic acid source and a. niger I-1472 culture filtrate as an extracellular enzyme source. Under these conditions, P. cinnabarinus MUCL39533 was shown to directly biotransform free ferulic acid released from the autoclaved maize bran by A. niger I-1472 enzymes into 584 mg/L of vanillin. These processes, involving physical, enzymic, and fungal treatments, permitted us to produce crystallin vanillin from autoclaved maize bran without any purification step.     

Probing occurrence of phenylpropanoids in Morinda citrifolia in relation to foliar diseases

Accumulation of phenolic compounds in cell walls of different plant organs leading to increased lignification is an early defence response of plants against biotic stress. The aim of this work was to delineate occurrence of cell wall-bound (CWB) phenolic compounds in Morinda citrifolia leaves. Alkaline hydrolysis of the cell wall material of leaf tissues yielded 4-coumaric acid (4-CA) as the major bulk of the phenolic compounds in all Morinda germplasms. Next in line was 4-hydroxybenzoic acid. Other phenolics identified were vanillic acid, 4-hydroxybenzaldehyde, vanillin and ferulic acid. Concentrations of all the CWB phenolics were highest in the germplasm CHN-5, followed by the germplasm CHN-1. Incidentally, these two Morinda germplasms recorded lowest incidence of foliar diseases. Significantly higher amounts of 4-CA in combination with other phenolics may be the reasons for lowest incidence of foliar diseases in CHN-5 and CHN-1 germplasms of M. citrifolia.     

Thermodynamics of microemulsion systems. IV. Enthalpies of solution of fatty acid cosurfactants in hydrocarbon oils

The enthalpies of solution of heptanoic, octanoic and nonanoic acids, all potential hydrocarbon-soluble cosurfactants, in octane, benzene, carbon tetrachloride and chloroform have been measured calorimetrically at 308.15K. The standard enthalpies of solution, both of the monomeric and the dimeric acids, and all thermodynamic functions of dimerization have been calculated via a set of mass-action law equations. ΔH° (soln) of the monomers is strongly endothermic in all solvents, and that of the dimeric form is either slightly endothermic or slightly exothermic. The heat effect on dissolution is essentially due to the rupture of the double hydrogen bond in the dimeric fatty acid.     

Borate cross-linked/total rhamnogalacturonan II ratio in cell walls for the biochemical diagnosis of boron deficiency in hydroponically grown pumpkin.

Boron (B) is an essential micronutrient for vascular plants. The function of B has been demonstrated to cross-link monomeric rhamnogalacturonan II (mRG-II) to form dimeric RG-II-borate (dRG-II-B), and thus to stabilize plant cell walls. The dRG-II-B to total RG-II ratio in the cell walls of pumpkin hydroponically grown under various low-B conditions was analyzed to evaluate its applicability to the diagnosis of plant B deficiency. The dRG-II-B ratio in cell walls ranged between approximately 0.9 in B-sufficient tissues and approximately 0.15 in severe B-deficient tissues, reflecting the B nutritional status of tissues. This result indicates that the degree of B shortage in plant tissues is very likely to be diagnosed by the dRG-II-B ratio in cell walls.     

What is the role of acid–acid interactions in asymmetric phosphoric acid organocatalysis? A detailed mechanistic study using interlocked and non-interlocked catalysts

Organocatalysis has revolutionized asymmetric synthesis. However, the supramolecular interactions of organocatalysts in solution are often neglected, although the formation of catalyst aggregates can have a strong impact on the catalytic reaction. For phosphoric acid based organocatalysts, we have now established that catalyst–catalyst interactions can be suppressed by using macrocyclic catalysts, which react predominantly in a monomeric fashion, while they can be favored by integration into a bifunctional catenane, which reacts mainly as phosphoric acid dimers. For acyclic phosphoric acids, we found a strongly concentration dependent behavior, involving both monomeric and dimeric catalytic pathways. Based on a detailed experimental analysis, DFT-calculations and direct NMR-based observation of the catalyst aggregates, we could demonstrate that intermolecular acid–acid interactions have a drastic influence on the reaction rate and stereoselectivity of asymmetric transfer-hydrogenation catalyzed by chiral phosphoric acids.

Supramolecular acid–acid interactions lead to competing monomeric and dimeric pathways in phosphoric acid catalysis – so that stereoselectivities depend on catalyst concentration.     

Fatty acid composition of Viscum album subspecies from Turkey

The lipophylic extracts of three Viscum album subspecies growing on different host plants in Turkey were comparatively analyzed for derived methyl esters of their fatty acids by capillary gas chromatography-mass spectrometry (GC-MS). The sample of V. album ssp. album growing on apricot trees was remarkably rich in palmitic acid (11.47%). Arachidic acid was found in only ssp. austriacum and ssp. abietis samples. The unsaturated fatty acids, mainly oleic and linoleic acids, were identified in nine lipophylic extracts obtained from V. album samples belonging to ssp. album. The amounts of linoleic and oleic acid were the highest in the sample of ssp. album growing on apricot trees (12.18 and 9.19%, respectively). Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 523–525, November–December, 2006.     

Fractionation of Corn Fiber Treated by Soaking in Aqueous Ammonia (SAA) for Isolation of Hemicellulose B and Production of C5 Sugars by Enzyme Hydrolysis

A process was developed to fractionate and isolate the hemicellulose B component of corn fiber generated by corn wet milling. The process consisted of pretreatment by soaking in aqueous ammonia followed by enzymatic cellulose hydrolysis, during which the hemicellulose B was solubilized by cleavage into xylo-oligosaccharides and subsequently recovered by precipitation with ethanol. The pretreatment step resulted in high retention of major sugars and improvement of subsequent enzymatic hydrolysis. The recovered hemicellulose B was hydrolyzed by a cocktail of enzymes that consisted of β-glucosidase, pectinase, xylanase, and ferulic acid esterase (FAE). Xylanase alone was ineffective, demonstrating yields of less than 2% of xylose and arabinose. The greatest xylose and arabinose yields, 44% and 53%, respectively, were obtained by the combination of pectinase and FAE. A mass balance accounted for 87% of the initially present glucan, 91% of the xylan, and 90% of the arabinan. The developed process offered a means for production of corn fiber gum as a value-added co-product and C5 sugars, which could be converted to other valuable co-products through fermentation in a corn wet-milling biorefinery.     

On the Molecularity of Bilirubins and their Esters and Anions in Chloroform Solution

 Bilirubins with propionic acids at C-8 and C-12 engage in intramolecular hydrogen bonding and are thought to be monomeric in solution, although the latter is unproven. In contrast, their dimethyl esters and etiobilirubin analogs (with the C-8 and C-12 propionic acids replaced by alkyl residues) favor intermolecular hydrogen bonding and are thought to be dimeric in nonpolar solvents. There is little information on the molecularity of the bilirubin dianion in solution. In this work, vapor pressure osmometry studies of chloroform solutions of bilirubins, their dimethyl esters, and etio-analogs clearly indicate that the diacids and dianions are monomeric, whereas the diesters and dialkyls are dimeric. However, the presence of a C-10 gem-dimethyl group causes the ester and the etiobilirubin to become monomeric.     

On the Molecularity of Bilirubins and their Esters and Anions in Chloroform Solution

Summary.  Bilirubins with propionic acids at C-8 and C-12 engage in intramolecular hydrogen bonding and are thought to be monomeric in solution, although the latter is unproven. In contrast, their dimethyl esters and etiobilirubin analogs (with the C-8 and C-12 propionic acids replaced by alkyl residues) favor intermolecular hydrogen bonding and are thought to be dimeric in nonpolar solvents. There is little information on the molecularity of the bilirubin dianion in solution. In this work, vapor pressure osmometry studies of chloroform solutions of bilirubins, their dimethyl esters, and etio-analogs clearly indicate that the diacids and dianions are monomeric, whereas the diesters and dialkyls are dimeric. However, the presence of a C-10 gem-dimethyl group causes the ester and the etiobilirubin to become monomeric. Received May 9, 2000. Accepted May 19, 2000     

Analysis of dimeric cyanine–nucleic acid dyes by capillary zone electrophoresis in N,N-dimethylacetamide as non-aqueous organic solvent

A method based on capillary zone electrophoresis is presented for the determination of the purity of commercial dimeric cyanine dyes (TOTO, YOYO, BOBO, all -1 and -3 species, LOLO-1, POPO-1) that are common as fluorescent probes for nucleic acid staining. These dyes are tetracharged cations, and have a strong tendency to interact with negatively charged centres, where they are rapidly adsorbed, especially from aqueous solutions. Thus anionic sites at the capillary wall must be avoided, and aqueous buffers are not suitable. The method introduced here avoids both complications, using non-aqueous N,N-dimethylacetamide as solvent, and suppressing the dissociation of silanol groups at the capillary surface due to selection of acidic separation conditions (20 mmol/l perchloric acid as background electrolyte). The present method enables the determination of the purity of all 10 dyes in less than 15 min. The selectivity of the method allows separation of at least five main and differentiating a number of unresolved minor contaminants as demonstrated in detail for TOTO-3 as an example. Quantitation (with 100% normalisation of the peak areas) of nine lots of this dye results in a purity between 33 and 87%.     

General acid catalysis in benzoic acid–Crystal Violet carbinol base reactions in toluene

Kinetics of benzoic acid–dye carbinol base reactions in an apolar aprotic solvent exhibit a complex dependence on the concentration of the acid, indicating the occurrence of general acid catalysis, the acid playing the dual role of the substrate and the catalyst. The complex kinetic behavior observed for 23 ortho‐ and meta‐substituted benzoic acids has been traced to overlapping participations of the monomer acid, hyperacidic open chain homoconjugated complex (dimeric and trimeric) acids, and nonreactive cyclic dimer and trimer acids. It has been found that although the degree of proton transfer in the transition state is 50–60% when the acid acts exclusively in the monomeric form, it gets enhanced to as high as more than 90% when the role of homoconjugated complex acids is taken into consideration. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 570–576, 2012     

Novel deoxycholic acid alkylamide-phenylurea-derived organogelators

Three monomeric and three dimeric deoxycholic acid (DCA) alkylamido-phenylurea derivatives are designed based on known gelators and are synthesized and characterized by ¹H and ¹³C NMR spectroscopy, ESI-TOF mass spectrometry, and elemental analyses. Among them, a monomeric derivative forms supramolecular gels in CHCl₃ and chlorobenzene, whereas a dimeric derivative gels THF and higher 1-alkanols containing 7-10 carbons. The morphologies of their xerogels are studied by scanning electron microscopy (SEM). No signature of macroscopic chirality of the gels is visible.     

Inclusion compound of β-cyclodextrin with binuclear <Emphasis Type="Italic">guests</Emphasis> containing residues of some pharmocologically important aromatic monocarboxylic acids

Stable monomeric and dimeric inclusion compounds of β-cyclodextrin with binuclear guests containing the residues of some pharmacologically important aromatic monocarboxylic acids were obtained.     

Proton transfer reactions of matrix-assisted laser desorption/ionization matrix monomers and dimers

The gas-phase basicities of monomeric and dimeric deprotonated ferulic and sinapic acids, common matrix-assisted laser desorption/ionization (MALDI) matrices, were determined. A new bracketing method based on structure-reactivity correlations was developed for deriving gas-phase basicities from reaction efficiencies. The matrix dimer anions were found to be significantly less basic than the monomer anions, by about 115 kJ/mol. The low basicity of the dimer anion can qualitatively be explained by resonance stabilization. The energies for proton transfer from dimers to monomers are therefore about 1.2 eV lower than for proton transfer between monomers. For the MALDI process, proton transfer reactions involving matrix dimers provide a low energy pathway for matrix and analyte ion formation.     

Comparison of phenolic content and antioxidant activity of Actaea racemosa L. and Actaea cordifolia DC

Actaea racemosa L. is used as a component of drugs or dietary supplements to alleviate the menopause symptoms. Its biological activity is associated with the presence of phenolic compounds. In our work, the analysis of isoflavones and phenolic acids – caffeic acid (CA), ferulic acid and isoferulic acid (iFA) – both free and bonded in two species of Actaea, was conducted using HPLC-PAD technique. Moreover, the antioxidant effect of extracts from different parts of the investigated plants was determined on the basis of DPPH assay. Significant variation of CA and iFA content was observed. The highest content of CA was found in A. racemosa, while Actaea cordifolia contained the highest amount of iFA. Isoflavones were not found in the investigated plants. The antioxidant activity assay showed the high free radical-scavenging ability of the extracts obtained from different parts of the plant.     

Grass lignocellulose

Grass lignocelluloses are limited in bioconversion by aromatic constituents, which include both lignins and phenolic acids esters. Histochemistry, ultraviolet absorption microspectrophotometry, and response to microorganisms and specific enzymes have been used to determine the significance of aromatics toward recalcitrance. Coniferyl lignin appears to be the most effective limitation to biodegradation, existing in xylem cells of vascular tissues; cell walls with syringyl lignin, for example, leaf sclerenchyma, are less recalcitrant. Esterified phenolic acids, i.e., ferulic and p-coumaric acids, often constitute a major chemical limitation in nonlignified cell walls to biodegradation in grasses, especially warm-season species. Methods to improve biodegradation in grasses, especially warm-season species. Methods to improve biodegradability through modification of aromatics include: plant breeding, use of lignin-degrading white-rot fungi, and addition of esterases. Plant breeding for new cultivars has been especially effective for nutritionally improved forages, for example, bermudagrasses. In laboratory studies, selective white-rot fungi that lack cellulases delignified the lignocellulosic materials and improved fermentation of residual carbohydrates. Phenolic acid esterases released p-coumaric and ferulic acids for potential coproducts, improved the available sugars for fermentation, and improved biodegradation. The separation and removal of the aromatic components for coproducts, while enhancing the availability of sugars for bioconversion, could improve the economics of bioconversion.