Oat Fractions Research Articles

Separation behavior of sieved endosperm-enriched oat fractions via tribo-electrostatic approach

Endosperm-enriched oat fraction passed through 106-μm aperture size sieving of oat groats was further processed by dry and chemical-free tribo-electrostatic separation approach for protein enrichment. The sieved oat flour consisting of both bran and endosperm particles was fluidized in dry air to be tribo-charged in a polytetrafluoroethylene (PTFE) tube before being separated under an external electric field into protein-rich and protein-depleted fractions. The effects of airflow rate and electric field strength were assessed by conducting fifteen tribo-electrostatic separations at five different plate voltages of ±1, ±3, ±7, ±12, and ± 15 kV, as well as three different airflow rates of 7, 10, and 14 l per minute (LPM), providing laminar, transient, and turbulent conditions in the tribo-charger tube, respectively. All fractions attracted to the negatively charged plate (i.e., NCP fraction) were enriched in protein. However, the fractions absorbed on the positively charged plate (PCP fraction) or collected by gravity at the bottom of the separation chamber (i.e., CB fraction) were all depleted of proteins. Higher protein enrichments were observed for NCP fractions at laminar airflow rate, where the lowest yields and protein separation efficiencies were obtained. Increasing plate voltages slightly reduced the NCP fractions' protein content but significantly improved their yields and protein separation efficiencies. Therefore, a laminar airflow rate of 7 LPM and a high plate voltage of ±12 kV was selected as the best separation conditions for sieved oat flour. The SEM images of the NCP fraction obtained at 7 LPM and ± 12 kV showed the presence of bran and endosperm particles, while the PCP and CB fractions were depleted of bran particles. The full compositional analysis of the fractions produced at 7 LPM and ± 12 kV conditions showed the highest percentage of dietary fiber content in the PCP fraction. A negative correlation was observed between the protein content and mean particle size (D50) of the electrostatically separated fractions at the laminar and transient airflow rates. However, the protein-rich NCP fractions had the largest particle sizes at the turbulent airflow rate due to particle agglomeration and intense particle-particle interactions. An indirect offline approach was adapted to assess the charging behavior of all electrostatically separated fractions as functions of their protein content and particle sizes. All NCP fractions acquired higher charge density values than other fractions, which could be attributed to their higher protein contents. An online tribo-charge analysis method should be developed to assess the particle-particle interactions in the tribo-charger tube during electrostatic separation.

Mycotoxins in oat flakes - changes during production and occurrence on the Czech market

Raw oats are frequently contaminated by fungi producing mycotoxins, and as such, they can pose a health risk to humans regularly consuming oat products. To reveal the effect of particular processing steps on contamination levels in final oat products, two series of samples obtained from an oat flake manufacturer were analysed. Among oat fractions treated, the most significant mycotoxin decrease was demonstrated in cleaning and dehulling steps, where the observed mycotoxin reduction was in the range of 13–75% for monitored mycotoxins, enniatin B, enniatin B1, HT-2 toxin, T-2 toxin, beauvericin and tentoxin. The overall mycotoxin reduction found in final oat flakes was in the range of 65–100%. Furthermore, 20 commercially available oat flakes from the Czech market were analysed. We detected 16 mycotoxins, mainly trichothecenes and emerging enniatins with levels in the interval of 1–156 μg kg<sup>–1</sup>. With regard to the current EU legislation, two analysed oat flake products exceeded the maximum limit for ochratoxin A.

Quantitative analysis of inositol phosphate contents in oat products using an anion exchange chromatographic method

Oat has gained interest due to its high nutritional value. When utilising oat fractions rich in dietary fibre, their inositol phosphate (InsP, including phytate) content is considerably high due to the lack of active phytase in the kilned oat ingredients. The high InsP content is linked to decreased mineral absorption in the gut, but the mineral-binding ability of InsPs also results in antioxidativity and a decrease in starch hydrolysis, thus lowering glycaemic response. This study aimed to further develop an anion exchange liquid chromatographic method for quantification of different InsP forms from oat products and to study the changes in the InsP contents resulting from the differences in the ingredients or processes. The method was applicable for quantifying such InsP forms that can effectively bind minerals. The InsPs were stable at moderate temperatures and in the oat baking process, but a significant degradation occurred during the high-temperature treatments, extrusion, and bacterial fermentation.

Enhancing three phenolic fractions of oats (Avena sativa L.) and their antioxidant activities by solid-state fermentation with Monascus anka and Bacillus subtilis

This work aims to improve phenolic fractions of oats and their antioxidant activities by solid-state fermentation (SSF) combining Monascus anka with Bacillus subtilis. Results revealed that the fermentation system significantly (p < 0.05) increased the total phenolic content (TPC), which was 23-fold over that in unfermented oats. The hydrolytic enzyme activities of α-amylase, β-glucosidase, and cellulase were significantly (r > 0.75, p < 0.05) correlated to the TPC, indicated an important role in the release of phenolic in oats. The proportion of free phenolic fraction in oats was increased from 39.76% to 61.62%, while that of bound phenolic fraction decreased from 42.17% to 22.78%. Moreover, the phenolic compositions of free, conjugated and bound phenolic fractions varied with fermentation. It implied that the phenolic compounds in different forms could be converted and transformed in the SSF system. Meanwhile, the DPPH· and ABTS·+ scavenging activities of the free and conjugated phenolic fractions in oats became stronger after fermentation. It indicated that the changes of antioxidant activities of phenolic fractions might be closely related to the structural modification by microbial enzymes in the SSF system. Consequently, this study provides a prospect fermentation process for improving the phenolic release and antioxidant activities in oats.

Применение деки из полиуретана для центробежного шелушения овса

Introduction. Oat-meal mills often have a low efficiency ratio of oat grains, which may be improved by new dehulling methods. The present research proved that it is possible to reduce the amount of destroyed cores by replacing elastic steel decks with viscoelastic polyurethane ones. The research objective was to assess the feasibility of using viscoelastic material in oat dehulling.&#x0D; Study objects and methods. The study featured two size fractions of oats. The grain was harvested in the foothills of the Altai Territory in 2017. A set of comparative tests was performed to define the efficiency of two dehulling machines. One had a standard metal deck, while the other had a deck made of material of A-80-95 ShA and an elastic modulus of 2.8 MPa during the second dehulling.&#x0D; Results and discussion. The polyurethane deck remained efficient for the first fraction during the second dehulling after 400 tons, for the second fraction – after 1,500 tons. The dehulling coefficient for the polyurethane deck exceeded the results for the metal deck by 12.0% during the second dehulling of the first fraction and by 5.9% during the second peeling of the second fraction. The integrity of the core increased by 34.0% for the first fraction and by 30.0% for the second fraction, which increased the mass fraction of the finished product by 2.9%.&#x0D; Conclusion. Ppolyurethane decks proved efficient for the second dehulling of the first and second fractions. Their use improved the processing of oat grains into Hercules oat flakes by 3.1%.

Change in Quality Parameters of Hulled Oats Grain at Fractionation

The changes in the main indices for grain quality of hulled oats at fractionation for the development of the method for their regulation were studied. It was shown that the grains of various fractions of hulled oats is not equal by biochemical composition and technological qualities. Fractionation of the grain samples collected from homogeneous large batches of oats and carrying out of corresponding analyses allowed the determination of a broad range of quality indices of individual fractions and their dependence on the thickness of the caryopsis. Then, by the correct selection and installation of top and (or) bottom sieves on seed cleaning machines of secondary cleaning, one can change (increase or decrease) the basic quality indices of a batch of grain from hulled oats up to values regulated by the State Standard or standards demanded by the consumer.

Extraction of soluble β-glucan from oat and barley fractions: Process efficiency and dispersion stability

This study comprises laboratory-scale extraction of soluble β-glucan (BG) from oat (16 and 32% BG) and barley (12 and 32% BG) fractions, investigation of chemical composition and stability of dispersions prepared from water extracts and techno-economic evaluation for small industrial scale production. Oat and barley fractions were hydrolysed with an enzyme preparation and BG was extracted from hydrolysed samples by boiling water. Enzymatic hydrolysis resulted in medium molecular weight (MW = 38,500–69,400 g/mol) after 2 h incubation with 10 nkat β-glucanase activity/g bran and low MW (11,800–22,600 g/mol) after 4 h incubation with 50 nkat/g bran. MW and concentration of BG affected the stability of dispersions during storage. Barley fractions, after both 2 and 4 h hydrolysis, resulted in higher viscosities than oat fractions. MW of BG in soluble barley fractions was only slightly higher, but the difference in MW does not seem to be adequate to justify the observed viscosity differences. Barley extracts contained higher amounts of starch, however, starch did not have a distinct effect on viscosity. Techno-economic analysis for production process with feedstock design capacity of 100 kg/h showed that production costs varied from 0.06 to 0.11€/g soluble BG. Raw material and capital charge were key cost factors.

Analysis of avenanthramides in oat products and estimation of avenanthramide intake in humans

Avenanthramides are phenolic compounds found only in oats, and are of interest due to suggested bioactivities, including anti-inflammatory effects and induction of apoptosis. The objective of this work was to optimise a high performance liquid chromatography (HPLC) method for analysis of avenanthramides in food, and analyse the avenanthramide content in 45 oat fractions and products. The optimised HPLC method was based on triplicate extraction of 100 mg sample with 1 ml 80% ethanol in phosphate buffer (pH 2.8) and used gallacetophenone as an internal standard. Avenalumic acid-derived avenanthramide homologues 2fd and 2pd were also present, making up to 20% of the total avenanthramides detected in oats. The amounts of avenanthramides detected in oat products was 2–82 µg/g. It was estimated that mean avenanthramide intake among oat consumers ranges from 0.3 to 2.1 mg/day, considerably lower than the amount used in studies that have investigated biological effects of avenanthramides in humans.

Hypocholesterolemic and Prebiotic Effects of a Whole-Grain Oat-Based Granola Breakfast Cereal in a Cardio-Metabolic "At Risk" Population.

Meta-analyses of randomized controlled trials (RTC) have confirmed the hypocholesterolaemic effect of oats and oat based fibers. However, the mechanisms by which oats or oat fractions lower cholesterol is not totally clear. Recognizing the important role of the gut microbiome in metabolism and metabolic disease risk, we examined the impact of whole grain oat Granola (WGO) on the human gut microbiota and cardio-metabolic risk factors using a randomized crossover dietary intervention in at risk individuals (ClinicalTrials.gov Identifier: NCT01925365). We randomized 32 individuals at risk of developing cardio-metabolic disease by virtue of mild hypercholesterolaemia or glucose intolerance, into two groups consuming either 45 g of WGO or non-whole grain (NWG) breakfast cereals daily for two 6-week intervention periods separated by a 4-week wash out period in a randomized, controlled, crossover, double-blinded design. Confirming the cholesterol lowering effect of WGO, we observed a significant time by treatment interaction, for total cholesterol (TC) (P = 0.0001) and LDL-cholesterol (LDL-C) (P = 0.02) compared to NWG. A significant time by treatment interaction was also observed for the relative abundance of fecal bifidobacteria (P = 0.0001), lactobacilli (P = 0.001) and total bacterial count (P = 0.008), which were all elevated after consumption of WGO. Daily consumption of WGO resulted in a prebiotic effect on the human gut microbiota composition and significant reductions in TC and LDL-C concentrations. Prebiotic modulation of the human gut microbiota may thus constitute a previously unrecognized mechanism contributing to the hypocholesterolaemic effects of whole grain oat Granola.

Identification and molecular characterization of oat peptides implicated on coeliac immune response

BackgroundOats provide important nutritional and pharmacological properties, although their safety in coeliac patients remains controversial. Previous studies have confirmed that the reactivity of the anti-33-mer monoclonal antibody with different oat varieties is proportional to the immune responses in terms of T-cell proliferation. Although the impact of these varieties on the adaptive response has been studied, the role of the dendritic cells (DC) is still poorly understood. The aim of this study is to characterize different oat fractions and to study their effect on DC from coeliac patients.Methods and resultsProtein fractions were isolated from oat grains and analyzed by SDS–PAGE. Several proteins were characterized in the prolamin fraction using immunological and proteomic tools, and by Nano-LC-MS/MS. These proteins, analogous to α- and γ-gliadin-like, showed reactive sequences to anti-33-mer antibody suggesting their immunogenic potential. That was further confirmed as some of the newly identified oat peptides had a differential stimulatory capacity on circulating DC from coeliac patients compared with healthy controls.ConclusionsThis is the first time, to our knowledge, where newly identified oat peptides have been shown to elicit a differential stimulatory capacity on circulating DC obtained from coeliac patients, potentially identifying immunogenic properties of these oat peptides.

Processamento hidrotérmico em escala industrial sobre parâmetros de qualidade em frações de aveia

A aveia destaca-se dentre os cereais por seu teor e qualidade proteica, alta porcentagem de lipídios distribuídos por todo o grão e predominância de ácidos graxos insaturados, além de possuir altos teores de fibra alimentar, minerais e antioxidantes, responsáveis pelos efeitos benéficos à saúde humana. Devido aos seus constituintes, a aveia apresenta forte tendência à rancidez e, por esse motivo, faz-se necessária a inativação enzimática das cariopses. Na indústria, a inativação normalmente é realizada pelo tratamento hidrotérmico. Objetivou-se, com este trabalho, estudar os efeitos do processamento hidrotérmico em escala industrial sobre parâmetros de composição química, atividade enzimática, β-glicanas e compostos fenólicos solúveis totais nas frações de aveia farinha, farelo e integral. O processamento industrial da aveia foi realizado em batelada com temperatura e pressão constantes e tempo de retenção na coluna de 37min e 110min. O experimento foi conduzido em delineamento inteiramente casualizado, sendo os resultados submetidos à análise de variância e as médias comparadas pelo teste Tukey a 5% de significância. Os constituintes químicos das frações farinha, farelo e integral foram pouco afetados nos tempos de retenção estudados. O tempo de retenção de 37min se mostra mais adequado por ser suficiente para inativar as enzimas lipase e peroxidase e preservar os compostos fenólicos solúveis totais em todas as frações de aveia estudadas.

Optimizing the Bioactive Potential of Oat Bran by Processing

Oats have attracted consumer, research, and commercial interest due to the health benefits associated with their consumption. β-Glucans are major dietary constituents in oats that have been linked to reduced serum cholesterol concentrations in humans, and foods containing oats are allowed to carry a health claim related to the ability of the soluble fiber in oats to reduce the risk of heart disease. However, to receive the recommended amount of β-glucans (3 g/day) from whole oat groats may require consumption of large quantities of oat products. Thus, the production of oat fractions enriched with higher levels of β-glucans is desirable. The most common commercially available oat product with an increased concentration of β-glucans is oat bran. In addition to higher concentrations of β-glucan, other physical and physicochemical properties of oat bran preparations should be considered as part of their production to achieve the optimal and expected health benefits from consumption of such products. Conventio...

Folate in oats and its milling fractions

Total folate content in oat varieties from three harvesting years (2006–2008), and in oats milling fractions, was determined using microbiological assay. Furthermore, folate vitamer distribution in milling fractions were examined with the UPLC method, which was taken in use and validated. The total folate content of the cultivars varied moderately within each year. The average content in the 2008 samples was 685ng/gdm. The UPLC method proved fast and sensitive for determining seven folate monoglutamates in cereal samples. Folate content in fractions, which are normally discarded, such as flour from oat cutting and flaking, were 1.5- to 2.5-fold higher than in native grain. The main folate vitamers found in the oat fractions were 5-CH3-H4folate, 5-HCO-H4folate, and 5,10-CH+-H4folate. The UPLC results more closely matched the microbiological results compared to those that are usually achieved with HPLC methods. This study illustrates that oats and, especially, by-products of milling are good sources of folate.

Dietary oats and modulation of atherogenic pathways

Consumption of oats has long been known to lower plasma total and low-density lipoprotein (LDL) cholesterol levels, an effect usually attributed to the soluble fibers β-glucans. On the basis of this cholesterol-lowering effect, oats are ascribed cardiovascular health-promoting properties. However, besides cholesterol levels, effects of oats on parameters relating to atherosclerosis development have not been extensively investigated. Since oxidation of lipoproteins and inflammation are characteristics of atherosclerosis in addition to lipid accumulation in the vessel wall, micronutrients in oats (phytochemicals) with antioxidative and anti-inflammatory properties may contribute to an atheroprotective action. Here, we summarize evidence on antiatherogenic properties of oats obtained from in vitro assays, animal experiments, and human studies. Possible effects involving anti-inflammatory and antioxidative actions, as well as preservation of endothelial function, are considered in addition to those related to reduction of plasma cholesterol. Since results of in vitro assays with isolated oat components are difficult to compare with effects of whole oats in humans and experimental animals, more observational studies with isolated oat components or fractions of oats are warranted. Also, there is a lack of epidemiological studies focusing on effects of oat intake on the cardiovascular disease panorama.

Viscosity of beta-glucan in oat products

Oats contain 3-5% of mixed linked beta-glucan, or (1-3), (1-4) â-D-glucan, referred to hereafter as beta-glucan. Oat beta-glucan is a viscous, and soluble dietary fibre component. Soluble and viscous dietary fibres, including the beta-glucan present in oats are associated with two major health promoting effects, i.e. the attenuation of postprandial plasma glucose and insulin levels and the control of cholesterol. Increased viscosity in the intestine delays absorption of glucose and suppresses absorption of cholesterol and reabsorption of bile acids. In spite of its apparent key role physiologically the viscosity of beta-glucan has been discussed relatively little in terms of analytical procedures. In clinical studies performed with oats, the viscosity of beta-glucan has been properly documented in only a few cases. Viscosity of beta-glucan in foods and in the food digest depends on solubility, concentration and molecular weight. A food manufacturer aiming at health-promoting products must pay attention not only to sufficient concentration of beta-glucan (dose) in the raw material, but also to the processing methods that will ensure sufficient solubility of beta-glucan and minimize enzymatic or mechanical breakdown of the beta-glucan molecule. We have been working both with different food processes utilising oat fractions high in beta-glucan and with the development of a method for viscosity determination of the soluble beta-glucan fibre. This review discusses some of the aspects related to the development with a method that could predict the behaviour of beta-glucan in oat processing with respect to its anticipated physiological functions.;

Evaluation of the fermentability of oat fractions obtained by debranning using lactic acid bacteria

The overall kinetics of the fermentation of four oat fractions obtained by debranning using three potentially probiotic lactic acid bacteria were investigated. The main objective was to study the suitability of these fractions as fermentation media for the growth and the metabolic production of bacteria isolated from human intestine. The cell growth, lactic acid production and substrate uptakes of the three lactobacilli was monitored for 30 h. An unstructured mathematical model was used to describe and fit the experimental data. In the medium from fraction B (1-3% pearlings or beta-glucan-rich fraction) all strains reached the highest cell populations, maximum growth rates and maximum lactic acid productions. This could be because of the high levels of total fibre and beta-glucan of this fraction. Limited growth and lactic acid formation was found in medium A (0-1% pearlings or bran-rich fraction). Medium B (1-3% pearling fraction) is the most suitable for fermentation and produces considerably higher probiotic cell concentrations. Debranning technology could be used to separate fractions from cereal grains for the production of functional formulations with higher probiotic levels than the ones that were obtained with the whole grain.

Enzymatic digestion and in vitro fermentation of oat fractions by human lactobacillus strains

Oats have received considerable interest for their high content of soluble and insoluble fibre and for their high fermentability with probiotic lactic acid bacteria. However, these fibres are not uniformly distributed within the oat kernel. Oat fractions were obtained by debranning technology and the pearlings generated were hydrolysed in vitro using gastric and pancreatic enzymes of human origin. The indigestible part was separated using dialysis and the soluble and insoluble fibre was obtained by precipitation with ethanol. The suspensions were later fermented by lactic acid bacteria of human origin to evaluate the prebiotic potential of the oat fractions and flours in vitro. Of the three probiotic strains tested, Lactobacillus plantarum showed in all media a higher maximum growth. The 1–3% pearling oat sample has higher fermentation ability and the indigestible components of this fraction showed the highest growth of lactobacilli.

Nutritive value of different varieties and morphological fractions of oats harvested at the soft dough stage

AbstractChemical composition and in vitro organic matter digestibility (IVOMD) were measured in whole forage and morphological fractions of 20 varieties of oats (Avena sativa) harvested at the soft dough stage. Among the varieties, crude protein (CP) varied from 48 to 76 g kg−1 dry matter (DM), neutral detergent fibre (NDF) from 586 to 683 g kg−1 DM, acid detergent fibre (ADF) from 370 to 482 g kg−1 DM and lignin from 54 to 83 g kg−1 DM. The IVOMD of the whole forage ranged from 43 to 62%. Among the morphological fractions, leaf blades had the highest CP content and IVOMD, whereas the fibre constituents (NDF, ADF and lignin) were highest in the stems. The results revealed considerable variation in chemical composition and IVOMD among the oat varieties and morphological fractions. This implies that there are opportunities for improving forage production and quality from oats through appropriate exploitation of varietal differences. However, manipulation of management practices (such as choice of harvesting stage, use of mixed cropping with compatible legumes and fertiliser application) may still be needed for further improvement. Copyright © 2008 John Wiley &amp; Sons, Ltd

Fermentation kinetics of the carbohydrate fraction of fresh forage, silage and hay of Avena sativa

SummaryThe aim of the present paper was to study the fermentation characteristics and kinetics of the carbohydrate fractions of fresh, ensiled and hay of oats (Avena sativa) using the Cornell Net Carbohydrate and Protein System (CNCPS) and the in vitro gas production technique (GPT). The whole forage and its NDF and EIR (ethanol insoluble residue) fractions were incubated in order to estimate the fermentation kinetics of carbohydrate fractions (A, B1 and B2) with the curve subtraction method. The carbohydrates fermentation kinetics estimated with the GPT agree with the three CNCPS carbohydrate fractions and explain some modification due to forage preservation methods. For all forages, the fermentation rate of the three CNCPS carbohydrate fractions showed the same ranking A &gt; B1 &gt; B2. Fermentation rate value (RM: 0.163, 0.057, 0.032 h-1 A, B1, B2 fraction for fresh oats; 0.106, 0.032, 0.016 h-1 for A, B1, B2 fractions of ensiled oats; 0.165, 0.051, 0.022 h-1 A, B1, B2 fraction for oats hay) could be used as kd in the CNCPS.

Protein fractions of oats and possibilities of oat utilisation for patients with coeliac disease

The applicability was evaluated of 16 different oats species and varieties of different provenance in the coeliac diet in view of the composition of the protein complex and immunological testing during two-year experiments (2001 and 2002). Determination was carried out of total nitrogen content (average of evaluated oats collection in 2001 was 2.21%, in 2002 2.78%), protein nitrogen content (average 2001 1.94%, 2002 2.28%), and crude protein (N&amp;nbsp;&amp;times;&amp;nbsp;6.25) content (average 2001 13.80%, 2002 17.37%). The proportions of different protein fractions play a decisive role for the aims of this study because, based on the existing knowledge, coeliacally active protein components are present particularly in the prolamin fraction. The percentage of prolamins (determined by discontinual fractionation after Osborne) in the author&amp;rsquo;s evaluated collection of oats species and varieties under the conditions of Central Bohemia reached on average 17.68% of the total protein in 2001, and 15.36% in 2002. The average percentage of albumins and globulins of the total protein reached 36.97% in 2001 and 41.04% in 2002, the average percentage of glutelins of the total proteins was 37.61% in 2001 and 34.10% in 2002, and residual was on average 7.55% in 2001 and 8.70% in 2002, respectively, of the total protein. Electrophoretic analysis of reserve (gluten) proteins (SDS-PAGE ISTA) showed in the oats collection evaluated the percentage of LMW + prolamins in the range 56&amp;ndash;77% of the total reserve proteins in 2001, and 52&amp;ndash;73% in 2002. The results of A-PAGE electrophoretic analysis of prolamin proteins confirmed the presence of &amp;alpha;-prolamins, that ranged in the total content of prolamins from 50 to 88% in 2001, and from 77 to 100% in 2002, while &amp;beta;- + &amp;gamma;-prolamins ranged in 2001 from 11 to 49%, and in 2002 from 0 to 22%. These values do not give serious guarantees for the possible utilisation of oats in the gluten-free diet. The results of the immunological evaluation of the amount of prolamins in oats grains using ELISA showed great differences between different varieties and the experimental years. In 2001, 7 oats samples out of 13 evaluated, and in 2002 10 samples out of 12 evaluated were below the limit for the gluten-free diet (10 mg prolamins (gliadins)/100 g of sample dry matter), but the other varieties exceeded the limit, particularly in 2001, very significantly. The results obtained in the evaluated collection of species and varieties of oats revealed a great variability in the structure of the protein complex and in the immunological testing. In addition a significant effect of the year on the results of all analyses was evident. Based on our results, the use of oats in the diet for coeliac disease can be very risky for these reasons. &amp;nbsp;