共查询到20条相似文献，搜索用时 667 毫秒
1.
Rachel R. Schendel Ann‐Katrin Puchbauer Natalie Britscho Mirko Bunzel 《Cereal Chemistry》2016,93(5):493-501
Arabinoxylan structures vary based on the degree and pattern of substitution of the β‐(1→4)‐linked d ‐xylopyranose backbone with α‐l ‐arabinofuranose units, acetyl groups, uronic acids, and feruloylated side chains. Substitution differences affect arabinoxylans’ physicochemical and physiological characteristics. Wheat bran arabinoxylans were hydrolyzed with GH10 and GH11 endo‐1,4‐β‐xylanases, and feruloylated oligosaccharides were isolated and purified (Amberlite XAD‐2 isolation, Sephadex LH‐20 gel permeation chromatography, and preparative reversed‐phase HPLC). The pure, isolated compounds were structurally characterized via liquid chromatography–electrospray ionization–mass spectrometry and one‐dimensional and two‐dimensional NMR analyses. In addition to the well‐known products of endo‐xylanase hydrolysis (xylotriose and xylobiose O–3‐substituted with a 5‐O‐trans‐feruloyl‐α‐arabinofuranosyl unit on the middle and nonreducing xylose residue, respectively), novel structural features, including O–2‐monosubstitution of xylose adjacent to a xylose carrying feruloylated arabinose, were observed. Additionally, a simultaneously acetylated and feruloylated oligosaccharide has been isolated and tentatively characterized. Oligosaccharides esterified with caffeic acid were also isolated, but these were proven to result, at least in part, as artifacts of the enzymatic hydrolysis. 相似文献
2.
A modified digestion method was used to hydrolyze large amounts of quinoa meal to study polysaccharide‐bound phenolic acids. Besides the well‐characterized oligosaccharide O‐(2‐O‐trans‐feruloyl‐α‐l ‐arabinofuranosyl)‐(1→5)‐l ‐arabinofuranose, O‐(2‐O‐trans‐coumaroyl‐α‐l ‐arabinofuranosyl)‐(1→5)‐l ‐arabinofuranose was isolated from the hydrolysate and identified by LC‐MS, GC‐MS, and NMR experiments. This study demonstrates for the first time that p‐coumaric acid can be linked to pectic side chains of dicotyledonous plants. 相似文献
3.
Valerie Van Craeyveld Emmie Dornez Ulla Holopainen Emilia Selinheimo Kaisa Poutanen Jan A. Delcour Christophe M. Courtin 《Cereal Chemistry》2010,87(4):283-291
Wheat bran‐derived arabinoxylan‐oligosaccharides (AXOS) recently have been shown to potentially exert prebiotic effects. In this study, 15 bran samples obtained by milling different wheat cultivars were treated with xylanases from Hypocrea jecorina (XHJ), Aspergillus aculeatus (XAA), and Pseudoalteromonas haloplanktis (XPH) to assess the effect of bran source and xylanase properties on the AXOS yield and structure. The total arabinoxylan (AX) extraction yield was higher with XHJ (8.2–10.7%) and XAA (8.2–10.8%) than with XPH (6.9–9.5%). Irrespective of the enzyme, a significant negative correlation was observed between extraction yield and arabinose to xylose (A/X) ratio of bran AX (r = –0.7), but not between yield and bran AX level. The A/X ratio of the extracted material was 0.27–0.34 for all bran samples and all enzymes, which combined with yield data and microscopic analysis, indicated primary hydrolysis of aleurone and nucellar epidermis AX. The average degree of polymerization (avDP) of the extracted AX was very low for all enzymes (2–3), owing to the release of high levels of monomeric arabinose and xylose. The release of these monosaccharides could be ascribed to 1) the activity of wheat bran‐associated enzymes (arabinofuranosidases and xylosidases); 2) the hydrolytic properties of the xylanases themselves; and 3) the presence of xylosidases as contaminations in enzyme preparation, in that order of importance. Heat treatment of bran before xylanase treatment significantly decreased the levels of monomeric arabinose and xylose in the extract, without affecting the extraction yield, resulting in a higher avDP of 3–7, thus yielding true AXOS. Overall, for AXOS production, wheat cultivars with a low bran A/X ratio of the AX are preferable as starting materials, and inactivation of bran‐associated enzymes before incubation is desirable. The XHJ xylanase was the best enzyme for wheat bran‐derived AXOS production. 相似文献
4.
Peter Biely Jeffrey A. Ahlgren Timothy D. Leathers Richard V. Greene Michael A. Cotta 《Cereal Chemistry》2003,80(2):144-147
Soluble protein extracts of germinating maize seedlings exhibited a limited ability to hydrolyze purified xylans, and specific assays were unable to confirm the presence of endo‐β‐1,4‐xylanase activity. However, extracts contained a variety of aryl‐glycosidase activities, including β‐glucosidase, β‐xylosidase, and α‐l ‐arabinofuranosidase. These activities peaked in three‐ to four‐day seedlings and were particularly concentrated in shoot and root tissues. Maximal levels of β‐glucosidase were two orders of magnitude greater than those of β‐xylosidase or α‐l ‐arabinofuranosidase. Isoelectric focusing gels revealed multiple forms of these enzymes. The principal β‐glucosidase and α‐l ‐arabinofuranosidase protein species were clustered at pI 4.8–4.9 and pI 5.8–6.0, respectively. β‐Xylosidase activity appeared to be associated with both of these enzymes, and no evidence was obtained for a distinct β‐xylosidase. 相似文献
5.
Maize starches of the endosperm mutants waxy (wx), dull:waxy (duwx), and amylose‐extender:dull:waxy (aeduwx) from inbred line Ia453 lack amylose. However, in addition to high molecular weight (HMW) amylopectin, the duwx and aeduwx starches contained 40 and 80%, respectively, intermediate branched material of low molecular weight (LMW). As gelatinized, the amylopectin of the wx starch was easily hydrolyzed into small dextrins by the α‐amylase of B. amyloliquefaciens, but components of duwx and aeduwx possessed partial resistance to amylolytic attack. Residual material of intermediate size obtained by a 4‐hr α‐amylolysis could not be separated from LMW dextrins by fractional precipitation in methanol. It is suggested that this material possessed a more regularly branched structure, in which the d ‐glucosyl chain segments were too short to allow α‐amylase action. The granular starches of duwx and aeduwx genotypes were initially considerably more resistant than the wx sample to α‐amylase attack. This was possibly due to an altered structure in the amylopectin component or the high content of intermediate material in the former granules. 相似文献
6.
Riana J. B. Heinemann Zhimin Xu J. Samuel Godber Ursula M. Lanfer‐Marquez 《Cereal Chemistry》2008,85(2):243-247
Whole rice contains several fat‐soluble phytochemicals such as tocopherols, tocotrienols, and γ‐oryzanol which have been reported to possess beneficial health properties. This study was conducted to determine whether brown rice belonging to indica and japonica subspecies were distinguishable from each other regarding the concentration of these compounds by analyzing 32 genotypes. The fat‐soluble compounds were analyzed by normal‐phase HPLC in a single run. The variability of the compounds analyzed was high, but the mean content of γ‐oryzanol across all samples was significantly higher (P < 0.01) in japonica (246.3 mg/kg) than in indica rice (190.1 mg/kg). Similar differences were found for total vitamin E contents which were 24.2 mg/kg in japonica and 17.1 mg/kg in indica rice, respectively. In japonica rice, α‐tocopherol, α‐tocotrienol, and γ‐tocotrienol were the most abundant homologs, while in indica rice the most abundant were γ‐tocotrienol, α‐tocopherol, and α‐tocotrienol. A significant Pearson coefficient (0.80, P < 0.001) between α‐tocopherol and α‐tocotrienol levels was found, independent of the subspecies. Both compounds were positively correlated to total tocols and γ‐oryzanol contents. Although more studies are needed to evaluate the interference of growing rice in different environments and multiple years, the present study provided information on natural variations of the vitamin E isomers and the γ‐oryzanol contents in different rice genotypes. 相似文献
7.
β‐Glucan can be solubilized from barley by warm water, with increasing solubilization as the temperature is increased. Substantially less glucan is extracted if the barley is dehusked using sulfuric acid, particularly if the dehusked barley is denatured. This indicates that enzymes capable of solubilizing glucan are present in barley. Various purified enzymes promote the solubilization of glucan from denatured and dehusked barley. Apart from endo‐β‐(1→3)(1→4)‐glucanase, these enzymes include endo‐xylanases, arabinofuranosidase, xyloacetylesterase, and feruloyl esterase. Ferulic acid and, probably, acetyl groups are esterlinked to arabinoxylan, not β‐glucan, in the cell walls of barley starchy endosperm, so the ability of the esterases, xylanases, and arabinofuranosidase to solubilize glucan indicates the pentosan component of the cell wall can restrict the extraction of glucan. 相似文献
8.
Gary A. Hareland 《Cereal Chemistry》2003,80(2):232-237
Preharvest sprouted wheat is often characterized by the falling number (FN) test. FN decreases in preharvest sprouted wheat as enzymatic degradation of the starchy endosperm increases. Wheat with FN values <250–275 is often discounted at the time of sale. The intent of this investigation was to evaluate the effects of debranning or pearling on the flour quality traits of five samples of wheat rated as low, med‐low, medium, med‐high, and sound that exhibited a range in FN values of 62–425 sec. Replicates of each sample were pearled for 30, 60, and 120 sec to remove portions of the outer bran layers before milling. FN was highly correlated with α‐amylase activity (r > ‐0.97) in the med‐low, medium, and med‐high FN sample sets as pearling time increased. FN increased in the medlow, medium, and med‐high FN samples by 128, 123, and 80%, respectively, after 120 sec of pearling. Pearling had no effect on flour FN of the low FN sample but α‐amylase activity was significantly decreased. Pearling had little or no effect on FN and α‐amylase activity of the sound sample. FN was moderately to strongly correlated with Rapid Visco Analyser (RVA), alveograph, and farinograph properties, and poorly correlated with protein content, flour yield, and bread loaf volume. In subsequent breadmaking studies, bread loaf volume, and crumb characteristics of flour from pearled wheat were not significantly different from loaf volume and crumb characteristics of flour from the corresponding nonpearled wheat. 相似文献
9.
The effect of food additives reduction on quality attributes in steamed‐and‐fried instant noodles was investigated. Three additives, l ‐ascorbic acid, l ‐cysteine, and sodium bisulfite, were evaluated for their effect on deoxynivalenol (DON) reduction and sensory acceptability of instant noodles. After screening the different concentrations of three food additives, the maximum reduction of DON was optimized for the following concentration ranges: l ‐ascorbic acid, 0–100 μg/g; l ‐cysteine, 0–300 μg/g; and sodium bisulfite, 0–200 μg/g. The experimental results were fitted to a second‐order polynomial model, which gave a coefficient of determination (R2) of 0.987. The results indicated that the overall optimal condition resulting in the maximum DON reduction in instant noodles was obtained at the following combined level: sodium bisulfite, 167 μg/g; l ‐cysteine, 254 μg/g; and l ‐ascorbic acid, 23 μg/g. The sensory evaluation of noodles with the optimal condition of additives showed that the overall acceptability was in the range of “like slightly” and was not significantly (P > 0.05) different from the control sample. The optimized protocol produced a mixture that can reduce DON in instant noodles up to 67%. Modifying the processing of instant noodles by using additives may be useful to reduce the risk of DON exposure via instant noodles. 相似文献
10.
Maria Liakopoulou‐Kyriakides Athanasios Karakatsanis Michael Stamatoudis Stavros Psomas 《Cereal Chemistry》2001,78(5):603-607
Four α‐amylases and two glucoamylases from various sources, in eight combinations, were used to study the synergistic hydrolysis of crude corn starch at various temperatures. At 40 and 50°C, the combinations containing Rhizopus mold glucoamylase enhanced hydrolysis of corn starch compared wth that obtained with the combinations from Aspergillus niger. At 60°C, Rhizopus mold combinations gave low reaction yields as the enzyme was inactivated. The differences observed between α‐amylases are smaller, with the exception of Bacillus licheniformis α‐amylase, which presented more than twice the productivity of the other α‐amylases, at all temperatures. In terms of substrate conversion at 5 hr of hydrolysis, the combination of B. licheniformis α‐amylase with Rhizopus mold glucoamylase at 50°C presents 76% substrate conversion, whereas, with all the other combinations, starch conversion was 13–73%. HPLC analysis of the reaction products obtained at 50°C showed that the main product of corn starch hydrolysis was glucose at 85–100%. Further experiments showed that A. niger glucoamylase and B. licheniformis α‐amylase were the only enzymes that retained their initial activity after incubation at the temperatures studied. 相似文献
11.
Tina Immerstrand Bjrn Bergensthl Christian Trgrdh Margareta Nyman Steve Cui Rickard
ste 《Cereal Chemistry》2009,86(6):601-608
Effects of various enzymes and extraction conditions on yield and molecular weight of β‐glucans extracted from two batches of commercial oat bran produced in Sweden are reported. Hot‐water extraction with a thermostable α‐amylase resulted in an extraction yield of ≈76% of the β‐glucans, while the high peak molecular weight was maintained (1.6 × 106). A subsequent protein hydrolysis significantly reduced the peak molecular weight of β‐glucans (by pancreatin to 908 × 103 and by papain to 56 × 103). These results suggest that the protein hydrolyzing enzymes may not be pure enough for purifying β‐glucans. The isolation scheme consisted of removal of lipids with ethanol extraction, enzymatic digestion of starch with α‐amylase, enzymatic digestion of protein using protease, centrifugation to remove insoluble material, removal of low molecular weight components using dialysis, precipitation of β‐glucans with ethanol, and air‐drying. 相似文献
12.
Tomoko Maeda Tetsu Hashimoto Masashi Minoda Shin‐ichiro Tamagawa Naofumi Morita 《Cereal Chemistry》2003,80(6):722-727
Thermostable mutant α‐amylases (21B, M111, and M77) with various degrees of thermostability were purified from Bacillus amyloliquefaciens F and used as improvers for breadmaking. Test baking with the mutant enzymes was conducted using the long fermentation sponge‐dough method. Addition of an appropriate amount of mutant α‐amylases to the ingredients distinctly increased the specific volume of the bread and improved the softness of breadcrumb as compared with the addition of Novamyl (NM), an exo‐type α‐amylase. M77 was the most effective in retarding the staleness of breadcrumb. The softness of breadcrumb during storage, however, was not correlated with the thermostability. All mutant α‐amylases weakened the mixing property of the dough, whereas they strengthened the property of fermented dough. Especially, M77 and NM had different effects on the dough properties, but their bread qualities were similar to each other. The strong tolerance of M77 dough to the long baking process might be due to the production of hydrolyzed starches, oligosaccharides in the range of maltopentaose to maltohexaose, as compared with NM. Therefore, in the light of present findings, these mutant α‐amylases are possible substitutes for NM as bread improvers. 相似文献
13.
Mark A. Newell Hyun Jung Kim Franco G. Asoro Adrienne Moran Lauter Pamela J. White M. Paul Scott Jean‐Luc Jannink 《Cereal Chemistry》2014,91(2):183-188
Oats (Avena sativa L.) have received significant attention for their positive and consistent health benefits when consumed as a whole grain food, attributed in part to mixed‐linkage (1‐3,1‐4)‐β‐d ‐glucan (referred to as β‐glucan). Unfortunately, the standard enzymatic method of measurement for oat β‐glucan is costly and does not provide the high‐throughput capability needed for plant breeding in which thousands of samples are measured over a short period of time. The objective of this research was to test a microenzymatic approach for high‐throughput phenotyping of oat β‐glucan. Fifty North American elite lines were chosen to span the range of possible values encountered in elite oats. Pearson and Spearman correlations (r) ranged from 0.81 to 0.86 between the two methods. Although the microenzymatic method did contain bias compared with the results for the standard streamlined method, this bias did not substantially decrease its ability to determine β‐glucan content. In addition to a substantial decrease in cost, the microenzymatic approach took as little as 6% of the time compared with the streamlined method. Therefore, the microenzymatic method for β‐glucan evaluation is an alternative method that can enhance high‐throughput phenotyping in oat breeding programs. 相似文献
14.
Gabriela R. Lemos Mendes Chiara Leal Alves Paola Lopes Cavalheiro Cristiana Costa Bretanha Fernanda Arnhold Pagnussatt Eliana Badiale‐Furlong 《Cereal Chemistry》2015,92(6):611-616
Fusarium verticillioides is one of the most important pathogens in maize and is a producer of fumonisin B1 (FB1). Although reports of its presence in wheat are scarce, the susceptibility of this cereal to fungus of the same genus motivates interest in investigating compounds present in the grain with inhibitory activity against this species. The aim of this study was to extract α‐amylase inhibitors from wheat and apply them in vitro to evaluate its effect on the development and expression of toxigenic potential of F. verticillioides. The α‐amylase inhibitors, both crude (P0) and purified (P1), were applied to in vitro culture containing a pathogen mycelium disc. Mycelial growth of the pathogen, glucosamine content, α‐amylase activity, and production of FB1 were investigated. All protein extracts of wheat showed the ability to inhibit pathogen growth, especially the extract P0 from cultivar Quartzo, which resulted in a reduction of glucosamine content (66%) and α‐amylase activity (84%). Furthermore, the protein inhibitors showed antifumonisin effect, reducing by 33 and 47% the mycotoxin production when applied as P0 and P1, respectively. These results suggest that α‐amylase inhibitor contributed to resistance against pathogen attack, acting in a diversified manner for each fungal species. 相似文献
15.
Native and processed high‐amylose maize starch (HAMS) is an important source of resistant starch (RS). The objectives of this work were to use an in vitro procedure to estimate the RS content of native granules from a series of ae‐containing HAMS genotypes, and to examine the nature of the α‐amylase resistant starch (ARS). By the method of Englyst et al (1992), RS for ae V, ae VII, ae su2, and ae du were estimated to be 66.0, 69.5, 69.5, and 40.6%, respectively. By transmission electron microscopy, most of the residual granules from ae V, ae VII, and ae su2 showed little evidence of digestion. Partially digested granules had a radial digestion pattern in the interior and an enzyme‐resistant layer near the surface. Size and chain‐length profile of constituents of ARS were similar to those of the native HAMS (unlike type 3 RS), consistent with complete hydrolysis in susceptible granule regions. Between crossed polarizers, many iodine‐stained native and residual HAMS granules had blue centers and pink exteriors, which may be due to a difference in orientation of the amylose‐iodine complexes in the exterior. Four granule color types were observed for ae du, differing in enzyme resistance. The high‐enzyme resistance of native HAMS granules may result from altered granule organization, which appears to vary among and within granules from ae‐containing genotypes. 相似文献
16.
Various carbohydrate‐active esterases are detected in extracts of malted barley when analyzed by polyacrylamide gel electophoresis. The slowest migrating and most heat‐resistant of these are relatively cationic acetylxylan esterases. Two such activities, one with a high affinity for esterase substrates including acetylated xylan, and one with a low affinity, are indicated. These enzymes did not hydrolyze methyl ferulate. A relatively heat‐labile anionic feruloyl esterase has also been purified. It has some, albeit low, ability to act on acetylated xylan. The feruloyl esterase effects extensive release of ferulate from endosperm cell walls isolated from barley, whereas the acetylxylan esterases are only capable of very limited release of acetate. 相似文献
17.
Jakob D. Kammeraad Michael J. Giroux Andrew C. Hogg John M. Martin 《Cereal Chemistry》2016,93(2):201-208
Wheat (Triticum aestivum) end‐product quality is impacted by grain hardness, which is determined by the Hardness locus consisting of the Puroindoline a and Puroindoline b genes, Pina and Pinb, respectively. Hard wheats commonly contain just one of two Pin mutations. We previously demonstrated the creation and preliminary hardness testing of 46 Pin missense alleles. In this study we examine the degree that individual Pin missense alleles confer unique milling and bread quality traits. Three Pina (PINA‐R103K, ‐G47S, and ‐P35S) and four Pinb (PINB‐D34N, ‐T38I, ‐G46D, and ‐E51K) missense alleles were chosen because they impart variable grain hardness levels, with one allele conferring soft seed texture, three conferring intermediate hardness (single‐kernel characterization system [SKCS] hardness approximately 50), and three conferring hard grain texture (SKCS hardness greater than 60). All but two of the alleles (PINA‐R103K and PINA‐G47S) resulted in higher total flour yield when compared with wild‐type controls. All hard and intermediate hardness alleles had decreased break flour yield, but intermediate hardness allele PINA‐P35S had higher break flour yield than common hard allele Pinb‐D1b. Intermediate and hard alleles resulted in increased abundance of larger and reduced levels of smaller flour particles. None of the missense alleles differed from their controls for loaf volume. The seven selected Pin alleles imparted defined levels of grain hardness and milling properties not previously available that may prove useful in wheat improvement. 相似文献
18.
A new procedure was developed for the isolation of highly purified water‐extractable arabinoxylan (WE‐AX) from hull‐less barley flour. It included inactivation of endogenous enzymes, removal of proteins with silica gel, and removing β‐glucans, arabinogalactan‐peptides, and starch fragments by enzyme or solvent precipitation steps. WE‐AX recovered by this isolation procedure represented, on average, 47% of all WE‐AX present in hull‐less barley flour. Purified WE‐AX from flour of different hull‐less European barley cultivars contained 84.9–91.8% AX and showed small structural differences. The apparent peak molecular weight of the purified WE‐AX was 730,000–250,000, and the arabinose‐to‐xylose ratio was 0.55–0.63. Proton nuclear magnetic resonance spectroscopy showed that the levels of un‐, O‐2 mono‐, O‐3 mono‐, and O‐2,O‐3 disubstituted xylose residues were 59.1–64.7%, 8.2–10.0%, 5.7–10.6%, and 17.6– 23.1%, respectively, and the ratio of di‐ to monosubstituted xylose was 0.90–1.54. Both O‐3 mono‐ and disubstituted xylose residues occurred isolated or next to disubstituted xylose residues in the WE‐AX chain. 相似文献
19.
The main nonstarch polysaccharide of rye is arabinoxylan (AX), but rye contains significant levels of (1→3)(1→4)‐β‐d ‐glucan, which unlike oat and barley β‐glucan, is not readily extracted by water, possibly because of entrapment within a matrix of AX cross‐linked by phenolics. This study continues objectives to improve understanding of factors controlling the physicochemical behavior of the cereal β‐glucans. Rye β‐glucan was extracted by 1.0N NaOH and increasing concentrations of ammonium sulfate were used to separate the β‐glucan from AX and prepare a series of eight narrow molecular weight (MW) distribution fractions. Composition and structural characteristics of the isolated β‐glucan and the eight fractions were determined. High‐performance size‐exclusion chromatography (HPSEC) with both specific calcofluor binding and a triple detection (light scattering, viscometry, and refractive index) system was used for MW determination. Lichenase digestion followed by high‐performance anion exchange chromatography of released oligosaccharides, was used for structural evaluation. The overall structure of all fractions was similar to that of barley β‐glucan. 相似文献
20.
A mouse lymphatic endothelial cell (SVEC4‐10) in vitro model was developed and found to be effective in the study of antioxidant activity of γ‐oryzanol in rice bran. The critical and vital parameters in developing these cell models included the emulsion preparation of hydrophobic compounds, the consistent management of cell culture, and the selection of cell viability detection methods compatible with the cell lines and the test substances. The SVEC4‐10 cell line had a fast metabolism and consequently could be used to determine antioxidant activity of a test substance in a relatively rapid manner. Results showed that γ‐oryzanol, ferulic acid, and α‐tocopherol could interact with cells such that oxidative damage induced by tert‐butyl hydroperoxide on cellular mitochondrial activity lessened, and in some situations, γ‐oryzanol was a more effective antioxidant than α‐tocopherol. The results also suggested different antioxidant mechanisms among γ‐oryzanol, ferulic acid, and α‐tocopherol. The three major components of γ‐oryzanol generally had higher antioxidant activity than γ‐oryzanol, with 24‐methylene cycloartanyl ferulate relatively more effective. Synergistic antioxidant activity among γ‐oryzanol, ferulic acid, and α‐tocopherol was also found. 相似文献