Phenolic glucosides in bread containing flaxseed

Three phenolic glucosides, secoisolariciresinol diglucoside, p-coumaric acid glucoside and ferulic acid glucoside, were analyzed in commercial breads containing flaxseed. The total phenolic glucoside content ranged from 15 to 157 mg/100 g dry bread. Secoisolariciresinol diglucoside was the dominating phenolic glucoside with an average relative content of 62%, followed by p-coumaric acid glucoside (20%) and ferulic acid glucoside (18%). Strong positive correlations between the phenolic glucosides were found, indicating no major effect of raw material or bread-making process on the relative content of the phenolic glucosides in flaxseed.     

Investigation of the ester- and ether-linked phenolic constituents of cell wall types of normal and brown midrib pearl millet using chemical isolation,microspectrophotometry and 13C NMR spectroscopy

The cell walls of rind, parenchyma and vascular bundle fractions of pearl millet (Pennisetum glaucum (L) R Br) were isolated from two brown midrib mutants and their normal (N) near-isogeneic line. The walls were sequentially treated with 1 M NaOH at 25°C for 20 h to determine ester-linked phenolic acids and then with 4 M NaOH at 170°C for 2 h to determine ether-linked phenolic constituents. The untreated walls and their residues resulting from each treatment were analyzed by microspectrophotometry and ¹³C NMR spectroscopy. The amount of ester-linked p-coumaric acid was determined by chemical analysis and found to be two to six times higher in the N line with no difference among lines in ferulic acid content. Ether-linked ferulic acid was about 30% higher in the rind in the N line and ether-linked p-coumaric acid was only slightly higher with the greatest difference found in the rind tissue. Microspectrophotometry of the untreated tissues showed absorption maxima at 232–238 nm. 288–292 nm and 312–324 nm. Treatment with 1 M NaOH generally reduced or eliminated the 312–324 nm absorption, with 4 M NaOH removing the remainder of the 288–292 nm absorption. ¹³C NMR confirmed these reductions of aromatic functionalities by alkali treatments. The combination of techniques provides excellent correlation of two types of spectral data with chemical identification and quantitation and establishes that bmr mutants have less ester-linked p-coumaric acid and less ether-linked ferulic acid, thus providing a better understanding of the factors contributing to biodegradability.     

Phenolic profiles of Andean purple corn (Zea mays L.)

Qualitative and quantitative high performance liquid chromatography with diode array detection (HPLC-DAD) was performed to characterize the presence of phenolic compounds in Andean purple corn. Phenolic compounds were analyzed by separating them in two main fractions: a water fraction (WF) and an ethyl acetate fraction (EAF). The WF rich in anthocyanins revealed the presence of cyanidin-3-glucoside, pelargonidin-3-glucoside and peonidin-3-glucoside. The respective acylated anthocyanin glucoside forms of these compounds were also detected following alkaline hydrolysis. The EAF was composed of phenolic acids such as p-coumaric, vanillic acid, protocatechuic acid, flavonoids such quercetin derivatives and a hesperitin derivative. Alkaline and acid hydrolysis of the EAF revealed the presence of p-coumaric and ferulic acid as main components in four bound hydroxycinnamic acid forms present in the ethyl acetate fraction.     

Phenolic constituents of cell wall types of normal and brown midrib mutants of pearl millet (Pennisetum glaucum (L) R Br) in relation to wall biodegradability

The cell walls of parenchyma, rind and vascular bundle fractions of pearl millet (Pennisetum glaucum (L) R Br) were isolated from two brown midrib mutants (bmr) 5753 and 5778 and from their normal (N) near-isogenic line. The cell wall content of parenchyma was lower than that of vascular bundle which, in turn, was lower than that of rind. The amounts of ferulic and p-coumaric acids released by NaOH treatment of the cell walls were in the ranges 3-7 mg g^?1 and 2-26 mg g^?1, respectively. Parenchyma cell walls of the N line had the highest content of p-coumaric acid (26 mg g^?1). This content of p-coumaric acid in the N line contrasts with that of bmr 5753 parenchyma (2 mg acid g^?1 walls) and bmr 5778 (7 mg acid g^?1 walls). The concentration of p-coumaric acid was highest in parenchyma cell walls that had been found to be the least digested. Parenchyma, rind and vascular bundle cells walls of the N line had much higher ratios of p-coumaric acid to ferulic acid than the mutants; rind and vascular bundle walls were less digestible than parenchyma. Small amounts of truxillic acid dimers were released by NaOH from the parenchyma walls of bmr 5778. Treatment of parenchyma, rind and vascular bundle cells walls with purified ‘driselase’ (containing xylanases and cellulases) released p-coumaroyl and feruloyl trisaccharides. Between 25 and 53% of the ferulic acid that was released by the NaOH treatment could be accounted for as feruloyl trisaccharide, but only 1-19% of the p-coumaric acid was accounted for as p-coumaroyl trisaccharide.     

Distribution of insoluble bound phenolic acids in barley grain

Insoluble bound phenolic acids were analysed by g.l.c. and by h.p.l.c. in eight abraded fractions of barley grain. Vanillic, p-coumaric, ferulic and diferulic acids were identified in all the fractions. Ferulic and p-coumaric acids were quantitatively the most important. The outer layers, comprising husks, pericarp, testa and aleurone cells, contained the highest concentrations of total phenolic acids (0.6–0.9%) while their concentrations were considerably lower in the endosperm layers (0.1% or less). Calculated on the basis of the cell wall content in the fractions, the highest concentration of ferulic acid was found in fractions enriched with aleurone cells while the highest concentration of p-coumaric acid was found in fractions containing high levels of husks.     

HPLC-DAD-ESI/MS identification of anthocyanins in Dioscorea trifida L. yam tubers (purple sachapapa)

The coloured tubers of purple sachapapa (Dioscorea trifida L.), a common crop in the subtropical and tropical regions, were analysed to characterise their anthocyanin composition. High-performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-ESI/MS) allowed the detection of 12 anthocyanin pigments. The compounds identified were derived from peonidin (Pn), cyanidin (Cy), and pelargonidin (Pg) aglycones, most of them showing the same substitution pattern, anthocyanin 3-acylglucoside-5-glucoside, where the acyl residue consisted of a hydroxycinnamic acid (i.e., ferulic or p-coumaric acid). The main anthocyanin found was peonidin 3-O-p-coumaroylglucoside-5-O-glucoside.     

Color enhancing effect of carboxylic acids on anthocyanins

The color enhancing effect of aromatic and aliphatic carboxylic acids on anthocyanin-glucosides was investigated in this work. The color of black rice anthocyanin-rich fraction was successfully improved after the addition of aromatic acids (p-coumaric acid, ferulic acid, and sinapic acid), aliphatic acid (lipoic acid) and tannic acid (as a complex acid). The addition of carboxylic acids showed an enhancing and stabilizing effect on the color of black rice juice during storage, which was observed through changes in CIELAB and spectrophotometric parameters. Sinapic, ferulic, and p-coumaric acids enhanced the color of black rice juice the most, with the highest efficiency for the dimethoxylated cinnamic acid derivate (sinapic acid). New anthocyanin-derived pigments were first isolated through silica gel TLC and identified using Maldi-Mass spectrometry at m/z values of 613, 659, 673, and 639, respectively, for vinylpyranoanthocyanins formed after adding coumaric, ferulic, sinapic, and lipoic acids. Based on these experimental results, the addition of carboxylic acids in an anthocyanin-rich fraction can be used as an efficient tool for their color enhancement and stability.     

Pyrolysis-mass spectrometry of the phenolic constituents of plant cell walls

Cell walls of plant parts of maize, barley, Italian ryegrass, wheat bran, lucerne and red clover were subjected to low voltage pyrolysis-mass spectrometry. The ion intensity at m/z 120, which is characteristic of p-coumaric acid, was significantly correlated (r=0.99) with the p-coumaric acid content of the walls; the ion intensity at m/z 150, characteristic of ferulic acid, was present in the spectra of the graminaceous walls. Factor analysis of the pyrolysis-mass spectra indicated that some, at least, of the p-coumaric and ferulic acid constituents of the walls are bound to pentosans, and suggested that not all the aromatic constituents of the walls are bound to polysaccharides.     

Phenolic acids in the jute plant (corchorus capsularis)

The bark and the stem of unretted jute plant (Corchorus capsularis) were found to contain various free, glycosidic and ester-linked phenolic acids. From an 80% aqueous ethanol extract, p-coumaric, ferulic, caffeic, vanillic and p-hydroxybenzoic acids were identified and quantified. p-Coumaric acid, the major component, and β-sitosterol were isolated and characterised.     

Sugars, organic acid and phenolic compounds of Ziziphus mauritiana Fruit

This study was conducted to identify soluble sugars, non-volatile acids and phenolic compounds in Ziziphus mauritiana fruit. Soluble sugars in Ziziphus mauritiana fruit were qualitatively determined by TLC. The sugars identified to be present in Ziziphus mauritiana were galactose, fructose and glucose. TLC was also used for qualitative analysis of phenolic compounds; five spots of phenolic compounds were observed. Only two of the observed spots were identified using the R_f values of the standards that were available. The two phenolic compounds identified by TLC were caffeic acid and p-coumaric acid. Phenolic compounds were also quantified using HPLC. Twelve peaks of phenolic compounds were detected. Among these, p-hydroxybenzoic acid, caffeic, ferulic acid and p-coumaric acid were the most abundant with concentrations of 365.94, 30.76, 19.64 and 19.28 mg/kg dry mass respectively, whereas vanillic acid was the least abundant with a concentration of 2.52 mg/kg. The organic acids were qualitatively analysed by PC and citric acid, malonic acid and malic acid were identified in the Ziziphus mauritiana fruit.     

Grape phenolics: The anthocyanins of Vitis vinifera,variety shiraz

The pigments of the Shiraz variety of Vitis vinifera grown in the Barossa Valley of South Australia have been identified as the 3-monoglucosides of delphinidin, petunidin, malvidin and peonidin, together with a number of acylated derivatives of these anthocyanins. involving both p-coumaric and caffeic acids. The principal acyl derivatives are two different p-coumaroyl and one caffeoyl derivative of malvidin 3-glucoside, and a p-coumaroyl derivative of peonidin 3-glucoside. Corresponding derivatives of the two other 3-glucosides are present in small amounts. The point of attachment of the acyl substituent in the main group of p-coumaroyl derivatives has been shown to be on the glucose moiety. The major pigment component is malvidin 3-glucoside which in the various forms present is responsible for approximately 70% of the total colour. Crystalline samples of several of the components have been isolated and their extinction values determined.     

Degradation of cell walls of forages by sequential treatment with sodium hydroxide and a commercial cellulase preparation

Cell walls of barley straw (whole sample and stem), Italian ryegrass (shoot) and lucerne (mature stem) were treated sequentially with NaOH followed by a commercial ‘cellulase’ preparation and, in other experiments, with the cellulase followed by the alkali. The phenolic compounds released by NaOH were determined and related to increases in the degradability of the walls as measured with cellulase. Two sequential treatments of the cell walls of barley straw increased degradability from 11% on treatment with cellulase alone to 87%, compared with increases from 72 to 99% and from 19 to 54% for the ryegrass and lucerne walls respectively. The first alkali treatment released ferulic and p-coumaric acids from the walls of barley and ryegrass together with other u.v. absorbing compounds, whereas the compounds released by the second alkali treatment did not include these two acids. The treatment with alkali did not release either ferulic acid or p-coumaric acid from the walls of lucerne and the amounts of other u.v. absorbing compounds that were released were much smaller.     

Anthocyanin Pigments of Royal Okanogan Huckleberry Juice

Juice processed from Royal Okanogan Huckleberries had an intense purple color, (CIE L*a*b*= L*, 22.66, a*, ?0.06, b*, ?0.46) and high anthocyanin pigment content, (>5 g/L). The anthocyanins were separated by HPLC and characterized from retention times and UV-visible spectra of purified pigments and their hydrolysis products. The major pigment (>70%) was petunidin 3-(p-coumaroyl-rutinoside)-5-glucoside. Eleven additional anthocyanins were identified as petunidin, delphinidin, and malvidin with the same glycosidic substitution pattern as the major pigment, and varying degrees of acylation with p-coumaric, ferulic, and caffeic acids. It was concluded from comparative pigment analyses and berry morphology that Royal Okanogan Huckleberries had identical characteristics to the Garden Huckleberry, Solanaceae melanocerasum (renamed S. scabrum).     

Effect of aqueous ammonia and other alkalis on the in-vitro digestibility of barley straw

The in-vitro digestibility of the organic matter of unground barley straw was increased by approximately 14 units by treatment with aqueous ammonia for 1 week at 20°C. Longer treatment times of 4 and 13 weeks had little or no additional effect on digestibility. Treatment with sodium hydroxide or tetramethylammonium hydroxide increased digestibility by up to 22 units. The content of cell walls of the straw after treatment with any of the alkalis was lower than that of untreated straw and the degradability of the walls from alkali-treated straw was more than 85% greater than that of the walls from untreated straw. Alkali treatment of straw caused loss of p-coumaric, ferulic and diferulic acids from the cell walls, the loss being greater with the stronger alkalis. The loss of ferulic was greater than that of p-coumaric acid.     

Metabolism of food phenolic acids by Lactobacillus plantarum CECT 748

Phenolic acids account for almost one third of the dietary phenols and are associated with organoleptic, nutritional and antioxidant properties of foods. This study was undertaken to assess the ability of Lactobacillus plantarum CECT 748^T to metabolize 19 food phenolic acids. Among the hydroxycinnamic acids studied, only p-coumaric, caffeic, ferulic and m-coumaric acids were metabolized by L. plantarum. Cultures of L. plantarum produced ethyl and vinyl derivatives from p-coumaric and caffeic acids, 4-vinyl guaiacol from ferulic acid, and 3-(3-hydroxyphenyl) propionic acid from m-coumaric acid. Among the hydroxybenzoic acids analysed, gallic acid and protocatechuic acid were decarboxylated to pyrogallol and catechol, respectively. Inducible enzymes seem to be involved, at least in m-coumaric and ferulic acid metabolism, since cell-free extracts from cultures grown in the absence of these phenolic acids were unable to metabolize them. Further work is needed for the identification of the enzymes involved, since the knowledge of the metabolism of phenolic compounds is an important issue for the food industry.     

Changes of Phenolic Acids During Aging of Organic Wines

Grapes (Vitis vinifera L. origin var: Carignane, Cabernet Sauvignon, Merlot, Grenache, Columbard, and Semillon) were cultivated and processed according to accepted organic agriculture and organic wine techniques. Aged wines (5 years) were evaluated for changes of their phenolic acids. The highest reduction of gallic acid concentrations were determined in Cabernet Sauvignon (24.36 mg/L) and Carignane (16.00 mg/L) wines. The quantities of p-hydroxybenzoic acid decreased mostly in Carignane (22.47 mg/L) and Columbard (20.84 mg/L) wines. The decreases of syringic acid were dominant in Cabernet Sauvignon (2.34 mg/L) and Carignane (1.69 mg/L) wines. In the case of ferulic acid, the highest reduction was determined in Cabernet Sauvignon (3.97 mg/L) wines. The decreases of p-coumaric acid contents were the same and mostly in Merlot (1.06 mg/L) and Grenache (1.035 mg/L) wines. The principal component analyses results demonstrated the relations among aged wines produced from different grape varieties and their phenolic acids. The distribution of data was accumulated into two groups. The first group included total phenols, gallic acid, p-hydroxybenzoic acid, syringic acid, p-coumaric acid, and Merlot/Carignane/Grenache wines. The second one included ferulic acid and Cabernet Sauvignon wine.     

In Vivo Release of 14C-Labelled Phenolic Groups from Intact Dietary Spinach Cell Walls During Passage Through the Rat Intestine

Feruloyl and p-coumaroyl groups in spinach cell walls (CW) were labelled using [¹⁴C]cinnamic acid and fed to rats. In the caecum and colon, ferulic acid (FA) and p-coumaric acid (PCA) were released from the CW. Few feruloyl or coumaroyl groups remained in the CW to be excreted in faeces, and thus the presence of simple phenol–sugar esters provided little protection of the polysaccharides to enzymic attack. Some oxidatively coupled phenols were also released but a portion remained in the CW. The oxidatively coupled phenols accumulated in the gut whereas the FA and PCA were absorbed by the rat. Thus enzyme-resistant fragments, containing oxidatively coupled phenols (and possibly sugar residues), may survive microbial attack by rat intestinal bacteria.     

Anthocyanin Pigments of Sweet Potatoes–Ipomoea batatas

The anthocyanin pigments of red sweet potato roots (Impomoea batatas) were isolated, purified and identified by HPLC and conventional paper chromatographic, spectral and chemical methods. Two major pigments and two minor pigments were present in fresh tissue slices extracted with boiling 1% HAc methanol. Tissues extracted cold yielded 11 or more pigments probably from degradation of the two major pigments. One major pigment was identified as peonidin-3-diglucoside-5-glucoside with three molecules of ferulic acid and one molecule of caffeic acid. The other major pigment was peonidin-3-diglucoside-5-glucoside with two molecules of ferulic acid and one caffeic acid.     

Phenolic constituents of mesophyll and non-mesophyll cell walls from leaf laminae of Lolium perenne

trans-Ferulic acid was the main phenolic constituent released when walls of mesophyll and non-mesophyll cells from leaf laminae of Lolium perenne L. were treated with sodium hydroxide. cis-Ferulic, trans and cis-p-coumaric, p-hydroxybenzoic and diferulic acids were also present. Mesophyll and non-mesophyll cell walls contained similar amounts of ferulic acid (approximately 6 mg g^?1 cell wall), but mesophyll walls contained only small amounts of p-coumaric acid (0.4 mg g^?1 cell wall) compared with those of non-mesophyll (3 mg g^?1 cell wall).     

Tiller Development Influences Seasonal Change in Cell Wall Digestibility of Big Bluestem(Andropogon gerardii)

The productivity of cool-season forage grasses declines during mid-summer in the southern corn belt of the USA. Warm-season grasses are productive during this time, but their digestibility decreases from spring to summer. The objective of this study was to investigate cell wall factors contributing to the decline in in vitro dry matter digestibility (IVDMD) of big bluestem ( Andropogon gerardii Vitman) leaf blades from late spring (May) to mid-summer (July) under three harvest regimens. Under frequent defoliation, decrease in cell wall digestibility accounted for much of the change in IVDMD. Among cell wall constituents, only xylose and alkali-labile phenolic acids increased significantly from spring to summer. Change in p -coumaric acid content and the ratio of p -coumaric acid to ferulic acid were both negatively correlated with the decrease in cell wall digestibility. While glucose and uronic acid digestibility decreased from spring to summer, xylose was consistently the least digestible of the cell wall monomers. In warm-season grasses grown under constant environments, tiller development causes an increase in leaf structural tissue, and the data suggest that the seasonal decline in leaf blade cell wall digestibility was partially due to tiller development.