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1.
The total plant sterol, steryl ferulate and steryl glycoside contents in wheat and rye milling fractions show that there are significant differences in both sterol content and composition between various milling fractions collected from a commercial mill. Total sterols were analysed by gas chromatography after acid and alkaline hydrolyses. The steryl conjugates were first extracted with acetone, fractionated on solid phase extraction (SPE) cartridges and then analysed individually (steryl glycosides by gas chromatography and steryl ferulates by reverse phase-high performance liquid chromatography with UV detection. Differences in sterol contents of the wheat samples were greater than in the rye samples. The highest total sterol content was found in wheat germ, but surprisingly high sterol contents, that were comparable to bran, were found in some flour fractions. Contents of steryl ferulates were high in the bran fractions contributing up to 17% of total sterols. The variation in the content of steryl glycosides in the samples was lower and contributed less than 10% of total sterols. These results show that much of the bioactive components may be lost when certain flour fractions produced in common flour milling procedures are discarded. However, some of these fractions with significantly high sterol contents could possibly be introduced into milling products used in breadmaking and the food industry without greatly compromising consumer acceptability.  相似文献   

2.
So far, data on absorption and metabolism of steryl ferulates from edible sources is scarce. Therefore, the impact of enzyme-aided baking and in vitro digestion was examined in this study. Wheat flours and wheat breads were subjected to a static in vitro digestion model and changes in the contents of steryl ferulates and free sterols (possible hydrolysis products of steryl ferulates) were monitored. Baking degraded steryl ferulates at a similar rate in all types of breads (43–47%) compared to the corresponding flours, while baking induced changes in free sterols showed no clear pattern. In vitro digestion provoked five folds lower content of steryl ferulates in flours than in breads and it also resulted in significant free sterol accumulation. Interestingly, bioaccessibility (0.01–0.25%) was not influenced by the cereal matrix. The four steryl ferulate species, which were detected in wheat, showed similar hydrolysis rates during digestion. As baking had a significant impact on the steryl ferulate content of wheat, we suggest that both raw and processed sources should be considered further in vitro, animal or human trials, when studying the metabolic fate of steryl ferulates.  相似文献   

3.
Wheat bran is a composite material made of several layers, such as pericarp, testa and aleurone. It could be fractionated into purified fractions, which might either be used as food ingredients, or serve as a starting material for extraction of bioactive compounds. The aim of this work was to evaluate the potential of using electrostatic separation as a way to obtain purified fractions from wheat bran. Ultrafine-ground bran obtained either by cryogenic grinding or by grinding at ambient temperature was used as starting material. The ultrafine bran was then charged by tribo-electrification and introduced in a chamber containing two high voltage electrodes, where bran particles were separated depending on their acquired charge, allowing positively and negatively charged fractions to be collected separately. The particle size distribution, microstructure and biochemical composition of the obtained fractions were studied. The charge of the particles was influenced by their biochemical composition: particles rich in highly branched and cross-linked arabinoxylans (pericarp) were separated from particles rich in β-glucan, ferulic acid and para-coumaric acid (aleurone cell walls). The testa and the intracellular compounds from aleurone were not highly charged, neither positively nor negatively. The most positively charged fraction represented 34% of the initial bran, and contained 62% of the ferulic acid present in the initial bran. The yield of the separation process was good (5.4% loss), and could be further increased.  相似文献   

4.
Wheat bran tissue fractionation using biochemical markers   总被引：1，自引：0，他引：1  
Phenolic acid analysis of hand-isolated outer grain layers and endosperm led to the identification of markers of pericarp and aleurone layers, respectively. A new dehydrotrimer of ferulic acid (DHT) was found to be concentrated in the outer pericarp of wheat bran whereas p-coumaric (p-CA) acid was mainly in the aleurone layer. Phytates were also used as a marker of aleurone layer and starch as a marker of starchy endosperm. Biochemical markers constitute an original method for determining the histological composition of any technological bran fractions. A pin milling process was applied to coarse bran produced by a conventional milling process. Three different fractions (B1, B2 and B3) were obtained by sieving the bran products and then the smallest bran particle fraction (B3) was air-classified to obtain two particle size fractions (B3a and B3b with a D50 of 83 and 7 μm, respectively). The biochemical composition of these fractions was used to calculate the distribution of tissues according to the sieving process. The dissociation behavior of individual bran tissues upon mechanical fractionation was investigated in relation to particle size and discussed according to their mechanical properties.  相似文献   

5.
To produce safe and healthy whole wheat food products, various grain or bran dry fractionation processes have been developed recently. In order to control the quality of the products and to adapt these processes, it is important to be able to monitor the grain tissue proportions in the different milling fractions produced. Accordingly, a quantitative method based on biochemical markers has been developed for the assessment of grain tissue proportions in grain fractions. Grain tissues that were quantified were the outer pericarp, an intermediate layer (including the outer pericarp, the testa and the hyaline layer), the aleurone cell walls, the aleurone cell contents, the endosperm and the germ, for two grain cultivars (Tiger and Crousty). Grain tissues were dissected by hand and analysed. Biochemical markers chosen were ferulic acid trimer, alkylresorcinols, para-coumaric acid, phytic acid, starch and wheat germ agglutinin, for outer pericarp, intermediate layer, aleurone cell walls, aleurone cell contents, endosperm and germ respectively. The results of tissue quantification by hand dissection and by calculation were compared and the sensitivity of the method was regarded as good (mean relative errors of 4% and 8% for Crousty and Tiger outer layers respectively). The impact of the analytical variability (maximum 13% relative error on coarse bran) was also regarded as acceptable. Wheat germ agglutinin seems to be a promising marker of wheat germ: even if the quantification method was not able to quantify the germ proportions in milling fractions, it was able to classify these fractions according to their germ content. The efficiency of this method was tested, by assessing the grain tissue proportions of fractions exhibiting very different compositions such as flour, bran and aleurone-rich fractions obtained from three different grain or bran dry fractionation processes (conventional milling, debranning process, production of aleurone-rich fractions from coarse bran). By calculation of the composition of the different products generated, it was possible to study the distribution of the different tissues among fractions resulting from the different fractionation processes. This quantitative method is thus a useful tool for the monitoring and improvement of processes, and allows the effects of these processes to be understood and their adaption to reach the objectives.  相似文献   

6.
Einkorn wheat bulgur is a traditional food deeply rooted in some areas of Turkey, since ages. The objective of this study was to evaluate the impact of simulated traditional bulgur preparation on einkorn wheat bioactive compound content.A local einkorn wheat grain sample from Turkey was boiled for 2, 3 and 4 h, then dried in a thermo-ventilated oven. Tocols, carotenoids, phytosterols and phenolics, determined as free (FPC) and bound (BPC) phenolic compounds, were analysed in hulled (spikelets) and dehulled (kernels) bulgur samples, to highlight also glumes’ contribute to their content and evolution.Kernel carotenoid and tocol content significantly decreased following bulgur preparation, to an extent of 42–58% and 15–30%, respectively. Phytosterols slightly decreased in cooked (12–19%), with respect to raw kernels. Phenolics showed different patterns, highlighting glumes’ contribute: kernel FPC increased (+87%) after 4 h of boiling, whereas no significant variations were observed for BPC. A drastic decrease of total and BPC (20.5–28.0%), was observed in spikelets following bulgur preparation. Ferulic and p-coumaric acid resulted the most abundant phenolic acids, respectively, in kernels and spikelets.Decreases in tocol, carotenoids and phytosterol contents were observed whereas an increase of kernel FPC content was calculated after cooking.  相似文献   

7.
Ozone treatment (10 g/kg) of common wheat grains with a new patented process, Oxygreen®, used before milling was found to significantly reduce (by 10–20%) the required energy at breaking stage whatever the grain hardness and without changes in the flour yield. Detailed study of each of the milling steps undertaken on a hard type cultivar showed that both the breaking and the reduction energy were decreased. Reduction of the coarse bran yield was also observed concomitantly with an increase in the yield of white shorts. Biochemical characterization of the milling fractions pointed out changes in technological flour properties as starch damage reduction, aleurone content enrichment and increase of insoluble glutenin polymers. Measurement of wheat grain tissue mechanical properties showed that ozone treatment leads to reduction of the aleurone layer extensibility and affects the local endosperm resistance to rupture. These data as well as the direct effect of ozone oxidation on biochemical compounds could explain the observed changes in milling energy, bran and shorts yield and flour composition.  相似文献   

8.
Ultra-fine grinding increases the antioxidant capacity of wheat bran   总被引：1，自引：0，他引：1  
In order to study the influence of wheat bran particle size on its antioxidant capacity, the wheat bran was ground under normal and cryogenic conditions with variable intensity to produce ten fractions with different physical structures. The high energy grinding increased 3-fold the specific surface of the bran fractions and also the proportion of particles smaller than 50 μm assimilated to the proportion of disrupted aleurone cells. All the ground bran fractions presented similar total ferulic acid concentration and chemical form (free, conjugated, linked). A positive effect of the grinding on the antioxidant capacity of the bran fractions was noticed. The antioxidant capacity increased from 30 to 45 mmol TEAC/kg when the specific surface increased from 0.09 to 0.26–0.30 m2/g. The antioxidant capacity of the bran fractions was linearly correlated with the specific surface, with the D50 values and with the proportion of particles smaller than 50 μm. In in vitro gastric conditions, the finely ground bran inhibited the accumulation of conjugated dienes more efficiently than coarse bran. In conclusion, the bran structure affects its antioxidant capacity. This effect remained in gastric conditions showing that grinding can be used to produce wheat bran fractions with higher nutritional value.  相似文献   

9.
Asparagine is known to accumulate in wheat grain under conditions of sulphur deficiency, leading to increased levels of acrylamide formation during processing. Analyses of milling fractions and of the outer layers of the grain prepared by hand dissection showed that the highest levels of asparagine were present in the bran fractions and in particular the aleurone layer, when grain were grown with sufficient sulphur supply. However, even mild S deficiency resulted in disproportional increases in the asparagine contents of white flour fractions, implying that optimisation of yield in a conventional milling system is not an appropriate strategy for processing grain from sulphur-deficient crops.  相似文献   

10.
Wholegrain consumption is associated with several health benefits, in contrast to the consumption of refined grains. This can partly be related to the antioxidant compounds in the outer parts of the grain kernel. The bioaccessibility of these antioxidant compounds from the wholegrain matrix during gastrointestinal digestion is crucial for their absorption and bioavailability. In the current study, the bioaccessible compounds from aleurone, bran and flour were obtained from a dynamic in vitro model of the upper gastrointestinal tract. They were collected at 1 h time intervals to assess their antioxidant capacity (TEAC assay) and also their anti-inflammatory effect (TNF-α reduction in U937 macrophages stimulated with LPS). The bioaccessible compounds from aleurone had the highest antioxidant capacity and provided a prolonged anti-inflammatory effect, shown by the TNF-α reduction of a relatively late time-interval (3–4 h after start of digestion). The contribution of ferulic acid to those effects was minor due to its low bioaccessibility. Aleurone seems a promising wheat fraction for cereal products with a healthy added value.  相似文献   

11.
The fatty acid composition, Acid Value, and the content and composition of tocopherols, tocotrienols, carotenoids, phytosterols, and steryl ferulates were determined in corn germ oil and four post-fermentation corn oils from the ethanol dry grind process. The oxidative stability index at 110 °C was determined for the five oils, and four oils were compared for their stability during storage at 40 °C as determined by peroxide value and hexanal content. The fatty acid composition of all five oils was typical for corn oil. The Acid Value (and percentage of free fatty acids) was highest (28.3 mg KOH/g oil) in corn oil extracted centrifugally from a conventional dry grind ethanol processing facility and for oil extracted, using hexane, from distillers dried grains with solubles (DDGS) from a raw starch ethanol processing facility (20.8 mg KOH/g oil). Acid Value was lowest in two oils extracted centrifugally from thin stillage in a raw starch ethanol facility (5.7 and 6.9 mg KOH/g oil). Tocopherols were highest in corn germ oil (∼1400 μg/g), but tocotrienols, phytosterols, steryl ferulates, and carotenoids were higher in all of the post-fermentation corn oils. Hexane extracted oil from DDGS was the most oxidatively stable as evaluated by OSI and storage test at 40 °C, followed by centrifugally extracted thin stillage oil from the raw starch ethanol process, and centrifugally extracted thin stillage oil from the conventional dry grind ethanol process. Corn germ oil was the least oxidatively stable. When stored at room temperature, the peroxide value of centrifugally extracted thin stillage oil from the raw starch ethanol process did not significantly increase until after six weeks of storage, and was less than 2.0 mequiv. peroxide/kg oil after three months of storage. These results indicate that post-fermentation corn oils have higher content of valuable functional lipids than corn germ oil. Some of these functional lipids have antioxidant activity which increases the oxidative stability of the post-fermentation oils.  相似文献   

12.
The contents and the compositions of free sterols/stanols, steryl/stanyl fatty acid esters and steryl/stanyl phenolic acid esters were determined in 25 corn cultivars grown at the same location and in the same year. The lipid extracts obtained from the flours of whole kernels were subjected to solid-phase extraction for the isolation and separation of the sterol classes, followed by capillary gas chromatography. The study provides for the first time information on the variability of individual steryl/stanyl fatty acid esters in corn cultivars. The analysis revealed pronounced differences in total contents of each sterol class. The levels of free sterols/stanols ranged from 298 to 433 μg/g dry matter flour, those of steryl/stanyl fatty acid esters from 430 to 1187 μg/g and those of steryl/stanyl phenolic acid esters from 46 to 240 μg/g. Free sterols/stanols were mainly composed of sitosterol and campesterol; up to 11% were made up of stanols. Steryl/stanyl esters of C18-fatty acids were dominating, with sitosteryl linoleate as the most abundant ester (44.7–53.5% of total fatty acid esters). Among the three investigated sterol classes, the distribution patterns of steryl/stanyl phenolic acid esters showed the greatest variability between the cultivars, even though trans-sitostanyl ferulate was the dominating ester in all samples.  相似文献   

13.
The objectives of this work were to 1) determine the physical structure of untreated wheat bran and the differences in physical structure between its dissected layers; 2) evaluate how bran hydration affected bran crystallinity and polymer order; and 3) determine how enzymatic treatment of wheat bran affected its physical structure. For the first time, X-ray diffraction (XRD), small angle X-ray scattering (SAXS), solid-state 13C cross-polarization magic-angle spinning nuclear magnetic resonance (13C CP/MAS NMR), and polarized light microscopy with a waveplate were used to study the physical structure of wheat bran and its dissected layers. The XRD and solid-state 13C CP/MAS NMR both confirmed the presence of crystalline cellulose in untreated bran, enzymatically treated bran, and dissected bran layers. The outer pericarp had the highest crystallinity of the dissected bran layers and showed negative birefringence. The aleurone layer was low in cellulose content and completely amorphous, yet the cell walls in the aleurone layer showed strong positive birefringence. The treatment of destarched and deproteinated bran with the Updegraff reagent removed amorphous material, leaving its crystalline cellulose structure intact. Hydration of the outer pericarp increased its crystallinity index and CP/MAS NMR resonance intensity, which indicated a possible increase in polymer order. The SAXS also confirmed that cell wall polymers, possibly aggregated cellulose microfibrils, increased in order as a result of hydration.  相似文献   

14.
The dehydrodiferulic acid content of different common and durum wheat grains and milling fractions was determined by an HPLC procedure. The 8-O-4′, 5–8′ benzofuran, 5–8′ and 5-5′ dehydrodimers were identified in all samples studied and occurred in decreasing relative amounts, respectively. Durum wheats were twice as concentrated in dimers as common wheats. An important genetic variation for dehydrodiferulic acid content was shown within durum wheat grains, whereas the agronomic conditions had no effect. There was 10 to 20 times more dehydrodiferulic acids in external layers (aleurone, bran) than in the starchy endosperm of durum wheat grains. The content and composition in dimers of the inner endosperm did not vary according to genotypes and cultivation conditions. The ratio of dehydrodimers to monomers of ferulic acid which represented an index of dimerisation, was 1·6 times higher in the external layers of the grain than in the endosperm. No relation was found, however, between the degree of ferulic acid dimerisation and the milling behaviour of durum wheat grains.  相似文献   

15.
The antioxidant potential of milling fractions from breadwheat and durum   总被引：1，自引：0，他引：1  
The effect of primary processing, namely milling, on the phenolic content and antioxidant capacity of two wheat cultivars, namely Canada Western Amber Durum (Triticum turgidum L. var. durum) and Canada Western Red Spring (Triticum aestivum L.) was studied. The milling products: bran, flour, shorts and feed flour fractions were examined. In addition, semolina was an end-product of durum wheat milling. Antioxidant activity of wheat phenoliocs was evaluated using oxygen radical absorbance capacity, inhibition of photochemiluminescence, the Rancimat method, and inhibition of oxidation of low-density lipoprotein cholesterol and deoxyribonucleic acid. The phenolic composition of wheat extracts was determined using high performance liquid chromatography. Bran showed the highest antioxidant activity whereas the endosperm possessed the lowest in both cultivars examined. The phenolic compounds are concentrated in the outermost layers namely the bran. The consumption of wheat with bran in the form of whole grain may provide beneficial health effects.  相似文献   

16.
Bran (branml) obtained by roller milling of soft (Scipion) and hard (Baroudeur) wheat cultivars was further ball-milled for increasing times and the observed particle size distribution expressed as a dispersion index. Bran (branhi) and aleurone layers were also hand-isolated from the same grains and the pattern of size reduction during ball-milling were compared with branml. Branml and branhi were found to fracture more rapidly than isolated aleurone layers due to the presence of the highly friable pericarp and the possible mechanical constraints due to tissues surrounding the aleurone layer. Previously identified markers of the aleurone layer cell contents (phytates) and cell walls (p-coumaric acid) were used to determine their water extractabilities from ball-milled samples and the state and degree of dissociation of the aleurone layer, either as an isolated tissue or within branml and branhi. The results suggest that ball-milling rapidly induces fractures in walls of cells in the aleurone layer. The partial opening of the cells in the aleurone layer allowed extraction of most (≈70%) of the water-extractable phytates, even though their mean particle size was much larger than the dimensions of the cells. A further increase in extractability of phytates was observed when the particle size was reduced below the aleurone cell dimensions. Although much less soluble, p-coumaric acid followed a similar trend to phytates. The different behaviour of branml and branhi was consistent with a weakening effect of the tissues in the former, probably due to the previous milling process. The bran and aleurone layers from both wheat varieties exhibited a similar behaviour.  相似文献   

17.
Wheat bran is good for human health due to the abundance of dietary fiber. However, it also contains much phytate which has been well documented as an anti-nutritional factor. This study is the first to explore the effectiveness of reducing phytate content in wheat bran by directly removing the aleurone cell content utilizing different roller mills (smooth roller, coarse smooth roller and teeth roller) and different clean-up methods (brushing and ultrasonic washing). Through analysis of phytate content in wheat bran obtained from different mill systems, the best raw material was found to be obtained from the 5B system. By investigating various roller types and clean-up methods, the optimal technique was found to use a teeth roller mill combined with ultrasonic washing, which could reduce the phytate content by the greatest amount: the reduction of phytate content achieved 62.98% (from 26.80 mg/g to 9.92 mg/g) in wheat bran. The optical microscope observation indicated that ultrasonic washing could wash the aleurone cell content out from broken aleurone cells which were destroyed by the teeth roller mill.  相似文献   

18.
Hand dissection of mature grains from two common wheats (Triticum aestivum L., cv. Caphorn and cv. Crousty) were performed to quantitatively assess their tissue composition and to obtain homogeneous samples of embryonic axis, scutellum, starchy endosperm, aleurone layer, hyaline layer, outer pericarp and a composite layer made up of testa+hyaline layer+inner pericarp. Polymeric neutral sugar and phenolic acid contents of the samples were determined and used to identify specific composition patterns in each tissue irrespective of the cultivar. The scutellum and embryonic axis showed the lowest amount of carbohydrates with similar relative amounts of arabinose and xylose (Ara+Xyl), but the scutellum differed from the embryonic axis in its high phenolic acid, in particular ferulate dehydrodimer, content. The peripheral layers of the grains were mainly composed of cell wall polysaccharides, chiefly arabinoxylans but with differing structures. The hyaline layer was mostly composed of arabinoxylan with extremely low Ara/Xyl ratio (0.1), with high amounts of ferulic acid monomers and hence very weakly crosslinked. The aleurone layer differed from the outer pericarp by its much lower Ara/Xyl ratio and lower amounts of ferulic acid dimers and trimers. High proportions of ether-linked phenolic acids (released by alkali at 170 °C) were detected specifically in the seed coat and tissues in the crease region. The possible application of biochemical markers found in the various tissues to monitor wheat grain fractionation processes is discussed.  相似文献   

19.
In this study 7 bran fractions were produced by grinding coarse durum wheat bran followed by sieving to achieve median particle size ranges between 115 and 1497 μm. These bran fractions were incorporated into pasta at 1, 5, 10 and 20% and the phytochemical and technological properties evaluated. Higher incorporation of bran, especially at 20%, reduced pasta quality, but a reduced impact was seen at the same degree of incorporation using finer bran. Bran increased antioxidants (by up to 65%), ferulic acid (up to 400%) and phytosterols (up to 130%) in pasta, parameters which were insensitive to bran particle size above 10% incorporation except for ferulic acid, which was higher in particles between 248 and 1497 μm. It is recommended to use finer fractions if bran is added to pasta at 20% and higher, since they provide a better quality pasta while still delivering enhancements in phytochemical content above regular semolina pasta.  相似文献   

20.
This study evaluated the effects of cultivar and region on the composition of alkylresorcinols (ARs) of 24 wheat bran samples from 6 cultivars grown in four locations (Bath, Nairn, Palmerstone and Ridgetown) in Ontario (ON), Canada, using gas chromatography/mass spectrometry (GC/MS). Total phenolic content (TPC) of wheat bran extracts was determined by the Folin–Ciocalteau method and the antioxidant activity of wheat bran extracts was measured by 2, 2-Dipheny-1-picryhydrazyl radical (DPPH) scavenging activity and oxygen radical absorbance capacity (ORAC). The highest ARs content (μg/g) was found in cultivars Emmit (1522), Harvard (1305), Warthog (1170), and Superior (853), grown in Ridgetown. The relative saturated and unsaturated ARs (%) were 89 and 11, respectively. Total ARs content, their composition, TPC and antioxidant activity of wheat bran extracts were significantly (P < 0.05) affected by location and cultivar and their interaction. TPC, %DPPHdis, and ORAC values for different wheat bran sample extracts ranged from 3 to 58 (mg FAE/g), 5 to 68 (%), and 6 to 94 (μmol TE/g), respectively. Our work provides a detailed examination of region and cultivar effects on potential of ARs in wheat bran and the results can be used for screening and breeding purposes.  相似文献   

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