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Determination of the activity of acidic phytate-degrading enzymes in cereal seeds.

Five different methods were compared to elucidate the total activity of the acidic phytate-degrading enzymes present in the seeds of rye, wheat, and barley. Phytate-degrading activity was studied at pH 5.0 by quantifying the liberated phosphate. Rye showed the highest acid phytate-degrading activity among the cereals studied. Using an aqueous extract, only 30-50% of the activity was found (rye, 3443 mU g(-1) of grain; wheat, 1026 mU g(-1) of grain; barley, 1032 mU g(-1) of grain) compared to that found by the direct incubation of the dry-milled cereal grains in a buffered phytate-containing solution (rye, 6752 mU g(-1) of grain; wheat, 2931 mU g(-1) of grain; barley, 2093 mU g(-1) of grain). Extending the extraction time resulted in an increase in extractable phytate-degrading activity by, at maximum, 10-15%. Extraction of phytate-degrading activity is strongly enhanced in the presence of Triton X-100 and the protease inhibitor phenylmethylsulfonyl fluoride (rye, 6536 mU g(-1) of grain; wheat, 2873 mU g(-1) of grain; barley, 2023 mU g(-1) of grain), suggesting at least a partial association with membrane structures and a degradation by proteolytic activity during extraction. In addition, it was shown that determining phytate-degrading activity by quantification of the liberated inorganic phosphate is more robust and precise than determining phytate-degrading activity by quantification of the residual phytate.

6-Phytase↗

Enzymatic solubilization of arabinoxylans from isolated rye pentosans and rye flour by different endo-xylanases and other hydrolyzing enzymes. Effect of a fungal caccase on the flour extracts oxidative gelation.

Water-extractable (WEP) and water-unextractable (WUP) pentosans were isolated from a rye flour. The effect of a commercial enzyme preparation, Grindamyl S 100 (GS100), containing pentosanase activities, was investigated on WEP, WUP, a mix of WEP and WUP, and the rye flour, with the aim to monitor the solubilization and depolymerization of high molecular weight arabinoxylans and the effect on the viscosity of the reaction medium. The effects of other hydrolyzing enzymes were also tested. Three xylanases were used: xylanase 1 (Xyl-1) from Aspergillus niger, the main activity present in GS100; xylanase 2 (Xyl-2) from Talaromyces emersonii; and xylanase 3 (Xyl-3) from Bacillus subtilis. Xyl-3 was used in combination with Xyl-1, (1,4)-beta-D-arabinoxylan arabinofuranohydrolase, endo-beta-D-glucanase, or ferulate esterase from A. niger, but no synergism was observed. GS100 and xylanases increased the arabinoxylan solubilization, Xyl-3 and Xyl-1 being those that presented the best yields of extraction without extensive depolymerization of water-extractable arabinoxylans. Both xylanases were affected by an inhibitor in rye flour. Flour treated with hot ethanol was used to study the oxidative gelation of flour extracts treated with xylanases, in the presence of laccase from Pycnoporus cinnabarinus. Two doses of xylanases were tested (0.5 and 2.5 units). Only the flour extracts treated with 0.5 unit of Xyl-1 thickened.

Carboxylic Ester Hydrolases↗

Steryl phenolic acid esters in cereals and their milling fractions.

The steryl ferulate contents of rye and wheat grains and their milling fractions were analyzed using a reversed-phase high-performance liquid chromatographic (HPLC) method. HPLC-mass spectrometry was used for identification. In addition, steryl ferulates of some selected milling byproducts were determined. The total steryl ferulate contents of rye and wheat grains were 6.0 and 6.3 mg/100 g, respectively. Uneven distribution of steryl ferulates in the grains led to considerable differences in the milling products; their steryl ferulate contents ranged from trace amounts in flours with low ash content to 20 and 34 mg/100 g in rye and wheat brans, respectively. Campestanyl ferulate and sitostanyl ferulate were the main components, followed by campesteryl ferulate and sitosteryl ferulate, whereas sitosterol was the main component in total sterols. Among the other samples, a byproduct of rice milling (pearling dust) was the best source of steryl ferulates, its total steryl ferulate content being 119 mg/100 g, whereas no measurable amounts of steryl ferulates were measured in oat bran or pearling dust of barley. The results indicated that rye and wheat and especially their bran fractions are comparable to corn as steryl ferulate sources.

Chromatography, High Pressure Liquid↗

TAXI type endoxylanase inhibitors in different cereals.

An affinity-based purification procedure with the immobilized family 11 Bacillus subtilis endoxylanase XynA allowed us to obtain high yields of highly pure endoxylanase inhibitor fractions from rye, barley, and durum wheat. In contrast, no inhibitors interacting with the B. subtilis endoxylanase affinity column are present in corn, buckwheat, rice, and oats. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis and inhibitor specificity showed that the isolated inhibitors belonged to the TAXI endoxylanase inhibitor family, thus providing a view on the diversity of this cereal inhibitor family. The isolated inhibitors are basic proteins of ca. 40 kDa, occurring in two molecular forms, with pI values of ca. 8.5 (durum wheat) and ca. 9.0 (rye, barley). They are, in general, strong inhibitors of family 11 endoxylanases but not of family 10 endoxylanases. Because cereal endogenous endoxylanases belong to the latter family, this probably indicates that they do not influence cereal metabolic processes. For the first time, endoxylanase inhibitors, similar to TAXI I and TAXI II from wheat, were isolated from durum wheat and characterized. For each cereal, high-resolution cation exchange chromatography revealed the presence of multiple isoinhibitors, each of which occurs in two molecular forms. However, in durum wheat and barley, a single isoform is predominantly present.

Bacillus subtilis↗

Structural features of arabinoxylans extracted with water at different temperatures from two rye flours of diverse breadmaking quality.

The water extractable (WE) arabinoxylans from two rye flours differing in baking quality were studied following sequential extraction with water at 4, 40, and 100 degrees C. Ammonium sulfate fractionation of the resulting WE fractions and subsequent analysis revealed substantial differences in the structure of the isolated materials. Furthermore, it allowed us to identify the factors contributing to arabinoxylan water extractability. Our results provide compelling evidence for the existence of separate polymers in rye WE arabinoxylans with different substitution degrees, ranging from quantitatively dominating, lowly substituted populations (arabinose to xylose ratio, Ara/Xyl approximately 0.5) to comparatively less abundant, highly substituted analogues (Ara/Xyl approximately 1.3). Generally, arabinoxylan water extractability was governed by the relative proportion of lowly and highly branched structures. A gradually increasing proportion of highly substituted populations was observed from cold to hot WE fractions. This was associated with the lower proportion of monosubstituted xylopyranosyl residues in the backbone, the higher proportion of disubstituted xylopyranosyl residues, and the higher level of substitution with feruloyl residues. Notable differences in the ratio of phenolic compounds to arabinose residues were observed between corresponding polymers isolated from rye flours of high and low baking quality, whereas the differences in their molecular weights were much less pronounced.

Arabinose↗

Sterol ferulates, sterols, and 5-alk(en)ylresorcinols from wheat, rye, and corn bran oils and their inhibitory effects on Epstein-Barr virus activation.

Sterol ferulate, free sterol, and 5-alk(en)ylresorcinol constituents of wheat, rye, and corn bran oils were studied. Among the sterol ferulates, one novel compound, 24-methylenecholestanol ferulate (7), along with six known compounds, namely, 24-methylcholestanol ferulate (1), 24-methylcholesterol ferulate (2), 2-methyllathosterol ferulate (3), stigmastanol ferulate (4), sitosterol ferulate (5), and schottenol ferulate (6), were isolated and characterized. Five known free sterols, namely, 24-methylcholesterol (8), stigmastanol (9), sitosterol (10), schottenol (11), and stigmasterol (12), were isolated and identified. 5-Alk(en)ylresorcinols were found in wheat and rye bran oils but not in corn bran oil. Of these, one new compound, 5-n-(2'-oxo-14'-Z-heneicosenyl) resorcinol (19), and seven known compounds, namely, 5-n-heptadecyl- (13), 5-n-nonadecyl- (14), 5-n-heneicosyl- (15), 5-n-tricosyl- (16), 5-n-pentacosyl- (17), 5-n-(14'-Z-nonadecenyl)- (18), and 5-n-(2'-oxoheneicosyl)resorcinols (20), were isolated and characterized. These compounds were evaluated with respect to their inhibitory effects on the induction of Epstein-Barr virus early antigen (EBV-EA) by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells, which is known to be a primary screening test for antitumor promoters. Four compounds, 1, 2, 4, and 11, showed potent inhibitory effects on EBV-EA induction.

Coumaric Acids↗

Heterogeneity in the fine structure of alkali-extractable arabinoxylans isolated from two rye flours with high and low breadmaking quality and their coexistence with other cell wall components.

The alkali extractable (AE) arabinoxylans from two rye flours differing in baking quality were studied following sequential extraction of water-unextractable and starch-free rye flour residue with saturated barium hydroxide solution, water and 1 M sodium hydroxide solution (Ba, BaH, and Na, respectively), and further fractionation of isolated fractions by ammonium sulfate precipitation. (1)H NMR and sugar analyses of AE subfractions provided evidence for the presence of lowly branched arabinoxylans (average arabinose-to-xylose ratio, Ara/Xyl approximately 0.5), containing mainly un- and monosubstituted xylopyranosyl residues (Xylp) in the chain. The proportion of this subfraction decreased from 50% in the Ba fraction to 35 and 17% in the Na and BaH fractions, respectively. Other subfractions, rich in both mono- and disubstituted Xylp, represented arabinoxylan populations with intermediate (Ara/Xyl approximately 0.8) and high substitution degree (Ara/Xyl approximately 1.1). The Ba and Na fractions contained phenolic compounds, whereas they were absent in the BaH fraction. The higher ratio of such phenolic compounds to arabinose (PhC/Ara) found in AE arabinoxylans from rye flour of inferior baking quality was one of the most pronounced differences between arabinoxylan populations from rye flours with high and low baking quality. The arabinoxylans from rye flour of high baking quality present in Ba and Na fractions had slightly higher apparent molecular weights (MWs) when compared to those from rye flour with low baking quality. The arabinoxylans present in the BaH fractions, characterized by the highest MWs, had similar MWs.

Barium Compounds↗

Chemical basis for the antifeedant activity of natural hydroxamic acids and related compounds.

Natural hydroxamic acids and related compounds derived from the 1,4-benzoxazin-3-one structure show antifeedant activity against the aphid Rhopalosiphum padi. This antifeeding activity is based on the electrophilic character of the hydroxamic acid function, the opening of the hemiacetal function and the lipophilic character of the molecule. In addition, the antifeedant activity of the aqueous extracts of different tissues of Acanthus mollis (Acanthaceae) was determined. The activity observed is attributed to the presence of 2,4-dihydroxy-1,4-benzoxazin-3-one in the extracts.

Acanthaceae↗

Alkylresorcinols in cereals and cereal products.

The alkylresorcinol (AR) content of 8 commonly consumed cereals, 125 Triticum cultivars, milling fractions of wheat and rye, bread, and other cereal products was analyzed. ARs were found in wheat (489-1429 microgram/g), rye (720-761 microgram/g), triticale (439-647 microgram/g), and barley (42-51 microgram/g), but not in rice, oats, maize, sorghum, or millet. One durum wheat variety was found to have an exceptionally low level of ARs (54 microgram/g) compared to other durum wheat varieties (589-751 microgram/g) and Triticumspecies analyzed. The AR content of milling fractions closely followed the ash content and could be used as a marker of the presence of bran in flour. Using hot 1-propanol extraction, all ARs could be extracted from bread, contrary to previous studies which suggested that ARs were destroyed during baking. Cereal products varied greatly in AR content, with those containing wheat bran or whole rye having the highest content.

Alkylation↗

Inhibitory effect of natural phenolic lipids upon NAD-dependent dehydrogenases and on triglyceride accumulation in 3T3-L1 cells in culture.

Alkylresorcinols are phenolic lipids present at levels of 0.03-0.15% in wheat and rye grains and almost 10 times higher in respective bran products. Despite numerous studies on the influence of dietary fibers on the regulation of energy metabolism, this issue still remains controversial. The objective of our current studies was to investigate whether 5-n-alk(en)ylresorcinols, natural phenolic components of high fiber human diets, may be considered as natural regulators of excessive fat accumulation. Our studies revealed that 5-n-alk(en)ylresorcinols isolated from wheat and rye bran inhibit glycerol-3-phosphate dehydrogenase, the key enzyme in triglyceride synthesis in adipocytes, specifically and effectively. Further in vitro studies showed that these compounds also prevent triglyceride accumulation in 3T3-L1 cells. The most effective compound in both systems was 5-n-heneicosylresorcinol. The results indicate that the potential to prevent triglyceride accumulation increases with the hydrophobicity of the phenolic inhibitor.

3T3-L1 Cells↗

Enzymatic solubilization of arabinoxylans from native, extruded, and high-shear-treated rye bran by different endo-xylanases and other hydrolyzing enzymes.

The overall objective of this research was to find a new way to valorize rye bran, by producing a gellifier from the enzymatic solubilization of arabinoxylans (AX). The effects of three pure endo-xylanases from Aspergillus niger (Xyl-1), Talaromyces emersonii (Xyl-2), and Bacillus subtilis (Xyl-3) and of Grindamyl S100 (GS100), a commercial enzyme preparation containing a Xyl-1 type endo-xylanase, were tested on rye bran to study the solubilization of water-unextractable arabinoxylans (WUAX). Eight different extrusion-treated rye brans were also used as substrates to find the best physical treatment to facilitate enzymatic arabinoxylan (AX) solubilization. Arabinoxylans were better solubilized from the bran extruded at high temperature using Xyl-3. This enzyme was then tested in combination with pure (1,4)-beta-d-arabinoxylan arabinofuranohydrolase (AXH) and endo-beta-d-glucanase or ferulic acid esterase (FAE), from A. niger. Only beta-glucanase in combination with Xyl-3 improved the AX extraction, but it did not have a marked effect on the viscosity of the extracts. Xyl-3 was then tested on a high-shear-treated rye bran, and results were compared to those obtained with the high-temperature-extruded rye bran. The high-shear treatment did not improve the bran AX enzymatic solubilization. The combination of FAE with Xyl-1 or Xyl-3 did not improve the AX extraction from untreated and high-shear-treated rye bran. Finally, to study the gelation capacity of the enzymatically solubilized AX, the effect of the hydrogen peroxide/horseradish peroxidase (H(2)O(2)/POD) was tested on the Xyl-3 high-temperature-extruded bran extracts. Solubilized AX did not gel in the presence of the oxidizing system.

Dietary Fiber↗

Levels of organochlorine pesticides in soils and rye plant tissues in a field study.

The organochlorine pesticides are lipophilic and persistent and tend to accumulate in soils and growing plants. The contamination of growing plants occurs by adhesion of volatile substances from the air to the plant surface and by the migration of contaminants through xylem in inner ascendant transport. Persistent organochlorine pesticides (HCB, alpha,gamma-HCH, pp'DDE, op'DDT, pp'DDT) levels were determined in soils and rye plants. The aims of the study were the monitoring of organochlorine pesticide concentrations and the comparison of these levels among soil, rye straw, and rye grains. Fifty soil samples and 50 rye plant (50 straw and 50 grains) samples were taken. The GLC-ECD chromatographic results indicated the following contamination levels distributed among soil, straw, and grains: HCB (0.7-1.2-0.7 microg.kg(-1)), alpha-HCH (0.6-3.4-1.2 microg.kg(-1)), gamma-HCH (1.8-27.3-4.4 microg.kg(-1)), Sigma-HCH (2.5-30.7-5.6 microg.kg(-1)), pp'DDE (1.0-7.8-5.5 microg.kg(-1)), op'DDT (16.1-20.4-17.0 microg.kg(-1)), pp'DDT (38.0-41.7-49.6 microg.kg(-1)), and Sigma-DDT (54.2-63.2-72.1 microg.kg(-1)). The study verified the presence of organochlorine pesticides in the Mexican agricultural environment and their migration from soil to the growing rye plants. However, DDT has been banned since 1999 for sanitary reasons, and Lindane is applied only in some cases as a seed dresser. The determined organochlorine pesticide levels in rye plants are low, at residual levels that are below Codex Alimentarius Commission maximum residue limits.

DDT↗

Antioxidant activity of steryl ferulate extracts from rye and wheat bran.

Antioxidant activity of steryl ferulates from other sources than rice have not yet been studied much, despite the fact that rice steryl ferulates (gamma-oryzanol) have been shown to possess good antioxidant activity. In this study, steryl ferulate extracts from wheat or rye bran were studied for their capability to inhibit hydroperoxide formation in bulk methyl linoleate and methyl linoleate emulsion. Further, their activity to scavenge DPPH radicals was analyzed. The activities were compared to synthetic steryl ferulates, rice steryl ferulates, ferulic acid, and alpha-tocopherol. Nonrice cereal extracts of steryl ferulates exhibited good antioxidant activity, especially in the bulk lipid system. The radical scavenging activity was similar to that of nonesterified ferulic acid, indicating that the ferulic acid moiety is responsible for the antioxidant properties. This study illustrates a new aspect to the health-promoting properties of rye and wheat.

Antioxidants↗

Polyphenol-rich phloem enhances the resistance of total serum lipids to oxidation in men.

In humans, polyphenol supplementation studies have resulted in inconsistent findings in lipid peroxidation. Our aim was to investigate the effects of a 4-week consumption of polyphenol-rich phloem on serum lipids and lipid peroxidation in the hydrophilic fraction of serum and on isolated lipoproteins. We conducted a randomized double-blind supplementation study consisting of 75 nonsmoking hypercholesterolemic men. Participants consumed 70 g daily of either rye bread (placebo) or phloem-fortified rye bread containing 31 mg (low polyphenol, LP) or 62 mg (high polyphenol, HP) of catechins. The ex vivo susceptibility of total serum lipids and VLDL and LDL to oxidation after copper induction was measured as a lag time to the maximal oxidation rate at the baseline and after the supplementation. In the HP group, an increase in the oxidation resistance of total serum lipids was observed (11.4%), while no effect was seen in the LP group (-0.8%) or in the placebo group (-1.0%) (p = 0.007). No differences were observed in the oxidation resistance of VLDL and LDL between the study groups. The phloem also increased in vitro oxidation resistance of serum lipids and radical scavenging activity (DPPH.) in a dose-dependent manner. Our results suggest that polyphenols may inhibit lipid peroxidation in the hydrophilic fraction of serum.

Adult↗

Measurement of acrylamide and its precursors in potato, wheat, and rye model systems.

The relationship between acrylamide and its precursors, namely, free asparagine and reducing sugars, was studied in cakes made from potato flake, wholemeal wheat, and wholemeal rye, cooked at 180 degrees C, from 5 to 60 min. Between 5 and 20 min, major losses of asparagine, water, and total reducing sugars were accompanied by large increases in acrylamide, which maximized in all three products between 25 and 30 min, followed by a slow linear reduction. Acrylamide formation did not occur to a large degree until the moisture contents of the cakes fell below 5%. Linear relationships were observed for acrylamide formation with the residual levels of asparagine and reducing sugars for all three food materials.

Acrylamide↗

Alkylresorcinols as markers of whole grain wheat and rye in cereal products.

The alkylresorcinol (AR) content of Swedish wheat grain samples, as well as of cereal ingredients and cereal foods containing wheat and rye, was determined. The average total AR content in Swedish wheat was 412 microg/g (ranging between 227 and 639 microg/g), which is lower than that in Swedish rye analyzed in a previous study. The relative composition of AR homologues was consistent for wheat samples and differed markedly from that of rye. Notably, the ratio of the homologues C17:0/C21:0 was approximately 0.1 in wheat and approximately 1.0 in rye, indicating that it can be used to distinguish between those two cereals. The AR content in cereal foods commonly consumed in Sweden varied widely, from nondetectable levels in white wheat flour and products not containing the outer parts of wheat and/or rye to >900 microg/g in some whole grain rye products. AR content in cereal foods was calculated from their recipes using average AR values for the cereal ingredients determined in this study. As there was a good correlation between calculated and analyzed AR levels in cereal foods (R2 = 0.91), it is possible to estimate the proportion of whole grain wheat and/or rye in a given cereal product on the basis of AR content and C17:0/C21:0 ratio. ARs appear to be good markers of whole grain wheat and rye in foods, and their analysis may be an objective way to identify foods rich in whole grain wheat and/or rye or brans thereof.

Biomarkers↗

Factors influencing acrylamide content and color in rye crisp bread.

An industrial baking procedure for yeast-leavened whole-grain rye crisp bread was adapted to local laboratory conditions to study the effect of time and temperature of baking and the addition of fructose, asparagine, and oat-bran concentrate on the acrylamide content and color of the bread. Baking time and temperature affected acrylamide content that increased from 10 to 30 mug/kg of bread at the combination of a long time and high temperature, with a significant interaction between the two factors (p < 0.008). Added asparagine had a significant effect (p < 0.001) on the formation of acrylamide, but fructose did not. There was a correlation between acrylamide content and color of the milled bread in the time-temperature experiment, but this correlation was not observed in the experiment with added precursors. Added oat-bran concentrate with high content of mixed-linkage beta-glucan did not influence the acrylamide content in the breads.

Acrylamide↗

Identification of dehydro-ferulic acid-tyrosine in rye and wheat: evidence for a covalent cross-link between arabinoxylans and proteins.

To monitor chemical reactions between ferulate and proteins during breadmaking, 8-(14)C-(E)-ferulic acid-(d-galactopyranose-6'-yl)ester was synthesized as a radiotracer and added to wheat and rye flour prior to breadmaking. Breads were lyophilized, extracted by means of a modified Osborne fractionation, and the radioactivity of the fractions was determined by scintillation analysis. The major portion of the radioactivity remained in the water-soluble fraction. However, a significant enrichment of the tracer was also detected in the prolamin and glutelin fractions in comparison to the control experiment. Separation of the prolamin fraction by RP-HPLC and scintillation measurement of the fractions gave evidence for a chemical modification of the tracer. To determine the structure of the reaction product, the prolamin fractions were completely hydrolyzed to free amino acids by means of an enzyme cocktail, and the digests were studied by LC-MS. In one fraction, a newly formed compound was detected. Comparison of its chromatographic and mass spectrometric behavior with a synthetic reference compound gave evidence that the newly identified compound was a dehydroferulic acid-tyrosine cross-link. It is likely that this cross-link represented a covalent linkage between arabinoxylans and cereal proteins. The newly identified cross-link was also identified in wheat and rye flour doughs, which had been prepared without addition of the ferulate tracer. The relative concentration of the dehydroferulic acid-tyrosine cross-link increased during wheat dough preparation.

Bread↗