Analysis of oil composition in cultivars and wild species of oat (Avena sp.)

Lipid and volatile profiles of Finnish oat batches of pure cultivars: Effect of storage on the volatile formation

Recent data showing the compositional variation and storage behavior among different oat batches for the purpose of food remains limited. Lipids of twenty oat flour samples of pure cultivars grown in Finland during 2019 were extracted and fractionated into neutral and polar-rich lipids. Flour was stored for nine months, and profiles of volatiles and tocols were analyzed to reveal oxidative stability. The lipid content was 5.9-8.9 g per 100 g of flour [DW] and consisted of 78.7 ± 2.5 % neutral and 21.3 ± 2.5 % polar lipids. Palmitic (16 %), oleic (36 %), and linoleic (39 %) acids were the most abundant fatty acids. Neutral lipids had more oleic and less linoleic and palmitic acids than polar lipids. The fresh samples correlated with tocols, pentanal, 2-pentylfuran, 2-heptanone, nonanal, 2-butanone, and heptanal, while stored samples were associated with 3-octen-2-one, 2-octenal, hexanal, and octanal. Lipid composition and oxidative stability are essential factors for selecting oat batches for food applications.

Lipidomics studies reveal dynamic changes in polar lipids of developing endosperm of oat and wheat varieties with differing oil contents

Polar lipids have biosynthetic pathways which intersect and overlap with triacylglycerol biosynthesis; however, polar lipids have not been well characterized in the developing endosperms of oat with high oil accumulation. The polar lipids in endosperms of oat and wheat varieties having different oil contents were analyzed and compared at different developmental stages. Our study shows that the relative contents of polar lipid by mass were decreased more slowly in wheat than in oat. Phosphatidylcholine and phosphatidylethanolamine were the major phospholipids, which showed similar abundance and gradual decreases during endosperm development in oat and wheat, while lysophospholipids were noticeably higher in oat. Monogalactosyldiacylglycerol showed a gradual increase in wheat and a decrease in oat during endosperm development. The relative contents of some polar lipid species and their unsaturation index were significantly different in their endosperms. These characteristics of polar lipids might indicate an adaption of oat to accommodate oil accumulation.

Effects of Genotype and Growing Year on the Nutritional Composition and Pasting Properties of Glabrous Canary Seed (Phalaris canariensis L.) Groat Flours

Canary seed flour is a new food ingredient that the United States Food and Drug Administration (FDA) and Health Canada recently granted Generally Regarded as Safe (GRAS) status. Stability in nutritional composition and functional properties is an essential characteristic of food ingredients for consistency in nutritional quality and performance in processing. This work assessed the effect of genotypic and environmental variation on the nutritional (protein, starch, amylose, oil, dietary fiber, minerals and fat-soluble vitamins) and pasting (as measured in viscosity (peak, trough, breakdown, final, and setback), peak time, and pasting temperatures) properties of Canary seed. The samples included four Canary seed varieties grown in randomized complete block design experiments at one location for two growing seasons. In general, the nutritional composition of Canary seed flour was not affected by genotype, growing year, and their interaction except for starch content, which was significantly affected by the growing year (p < 0.0001), and iron content, which was affected by genotypic variation (p < 0.0001). The pasting properties of Canary seed flour were significantly (p < 0.001) affected by both genotypic and growing year variation but not their interaction. Our results suggest that the food industry should measure starch and iron content prior to processing to ensure consistency in nutritional labeling. Also, for those applications where starch pasting properties are essential, the manufacturer should consider measuring the RVA pasting viscosities for every batch of raw material. The results have provided the baseline knowledge of which nutritional or functional properties of Canary seed flour can be improved through breeding and agronomy programs to ensure the reliability of Canary seed as an ingredient.

Exploring the genetic variability in yield, nutritional and digestibility traits in oat grains through ruminant nutrition

Oat is a dual-purpose crop used for both food and feed for animals. The objective of this work is to characterize oat varieties for their genetic diversity in yield, physical traits, and nutritional composition, aiming to identify potential parent varieties for breeding programs to develop new oat varieties for improved livestock feed and diverse industrial applications. To conduct, chemical analysis for protein and carbohydare fractions, energy and digestible nutrient estimated, stastical analyses performed to assess genetic variations for traits among vaieties. Significant genetic variation (p < 0.05) for grain yield, grain density, sieving percentage, crude protein, ether extract, neutral and acid detergent fiber, cellulose, lignin, neutral and acid detergent insoluble nitrogen were observed in grains of eight oat varieties. All protein fractions exhibited significant differences (p < 0.05). Total carbohydrate content ranged significantly (p < 0.05) from 73 % to 79 %. The grains contained higher levels of intermediately degradable starch and pectin (54.12-60.16 %) compared to the slowly degradable cell wall (26-33 %), lignin bounded cell wall (6-10 %), and rapidly degradable sugars (2-8%). Significant variation (p < 0.05) was observed in terms of gross energy, digestible energy, metabolizable energy, net energy for maintenance and lactation about (2 Mcal/kg dry matter), gain (1.6-1.8 Mcal/kg dry matter), total digestible nutrients, digestible dry matter, rumen degradable protein, and total digestible nutrients related to crude protein, fatty acid, neutral detergent fiber, and non-fiber carbohydrate. Organic matter and ether extract were positively associated (p < 0.01) with total digestible nutrients, digestible and metabolizable energy, dry matter digestible and truly digestible non fibrous cabohydrates, while neutral and acid detergent fiber and cellulose showed negative correlation. The research shows that oat varieties vary widely in their yield, physical features, and nutritional content, offering potential for breeding better varieties for both animal feed and industrial uses.

The effect of stir-frying on the aging of oat flour during storage: A study based on lipidomics

In this study, we used the LC-ESI-MS/MS technique to elucidate the effects of stir-frying on the lipidomics of oat flour before and after storage. We detected 1540 lipids in 54 subclasses; triglycerides were the most abundant, followed by diacylglycerol, ceramide (Cer), digalactosyldiacylglycerol, cardiolipin, and phosphatidylcholine. Principal component analysis and orthogonal least squares discriminant analysis analyses showed that oat flour lipids were significantly different before and after storage in stir-fried oat flour and raw oat flour. After oat flour was stir-fried, most of the lipid metabolites in it were significantly downregulated, and the changes in lipids during storage were reduced. Sphingolipid metabolism and ether lipid metabolism were the key metabolic pathways, and Cer, PC, and lyso-phosphatidylcholine were the key lipid metabolites identified in the related metabolic pathways during oat flour storage. Frying inhibits lipid metabolic pathways during storage of oat flour, thereby improving lipid stability and quality during storage. This study laid the foundation for further investigating quality control and the mechanism of changes in lipids during the storage of oat flour.

Inclusion of Oat Polar Lipids in a Solid Breakfast Improves Glucose Tolerance, Triglyceridemia, and Gut Hormone Responses Postprandially and after a Standardized Second Meal: A Randomized Crossover Study in Healthy Subjects

Previously, it has been indicated that oat polar lipids included in a liquid meal may have the potential to beneficially modulate various cardiometabolic variables. The purpose of this study was to evaluate the effects of oat polar lipids in a solid food matrix on acute and second meal glucose tolerance, blood lipids, and concentrations of gut-derived hormones. The oat polar lipids were consumed at breakfast and effects on the biomarkers were investigated in the postprandial period and following a standardized lunch. Twenty young, healthy subjects consumed in total four different breakfast meals in a crossover study design. The breakfasts consisted of 1. White wheat bread (WWB) with an added 7.5 g of oat polar lipids (PLL); 2. WWB with an added 15 g of oat polar lipids (PLH); 3. WWB with and added 16.6 g of rapeseed oil (RSO) as a representative of commonly consumed oils; and 4. WWB consumed alone, included as a reference. All products with added lipids contained equivalent amounts of fat (16.6 g) and available carbohydrates (50 g). Rapeseed oil was added to the oat polar lipid meals to equal 16.6 g of total fat. The standardized lunch was composed of WWB and meatballs and was served 3.5 h after the breakfast. Test variables (blood glucose, serum insulin, triglyceride (TG), free fatty acids (FFA), ghrelin, GLP-1, PYY, and GIP) were measured at fasting and repeatedly during the 5.5 h after ingestion of the breakfast. After breakfast, PLH substantially lowered postprandial glucose and insulin responses (iAUC 0-120 min) compared with RSO and WWB (p < 0.05). Furthermore, a reduced glycaemic response to lunch (210-330 min) was observed following the PLH breakfast compared to all of the other breakfasts served (p < 0.05). Oat polar lipids (PLH) significantly reduced TG and ghrelin and increased circulating gut hormones GLP-1 and PYY compared to RSO (p < 0.05). The results show that exchanging part of the dietary lipids with oat polar lipids has the potential to improve postprandial blood glucose regulation and gut hormones and thus may have a preventive effect against type 2 diabetes.

The Impact of the Individual and Combined Application of Phosphorus and Sulfur Fertilizers on Potato Tuber Flavor

Sulfur and phosphorus are important plant nutrients required for potato growth, influencing the synthesis of primary metabolites that serve as the material foundation of potato flavor quality. However, little is known about the effects of sulfur and phosphorus application on potato tuber flavor. This study experimentally compared the effects of the individual and combined application of phosphorus and sulfur fertilizers on the flavor of potato tubers. The research examined the sensory characteristics of flavor under various fertilization methods, investigated changes in the types and contents of volatile flavor compounds, and conducted analyses on flavor precursor compounds. The experimental results showed that the application of phosphorus and sulfur fertilizers, either individually or in combination significantly increased the content of linoleic acid and linolenic acid. After the combined application of phosphorus and sulfur fertilizers, the starch and the reducing sugar content also significantly increased. (E,E)-2,4-Nonadienal and Decanal are closely correlated with fatty acid content. Dimethyl sulfide and Trimethyl sulfide contents are significantly related to methionine content. This also significantly enhances the fatty taste characteristics of the tubers but weakens the potato flavor characteristics. Hence, the application of phosphorus and sulfur can affect the accumulation of primary metabolic products in tubers, thereby affecting flavor quality. Compared with the individual application of phosphorus or sulfur fertilizers, when phosphorus fertilizer is applied at 180 kg·ha-1 and sulfur fertilizer at 90 kg·ha-1 in combination, it can further enrich the roasted flavor characteristics of potatoes and maximize the enhancement of potato flavor quality. This provides valuable theoretical support for achieving high-quality agricultural development.

Beyond Autoxidation and Lipoxygenases: Fatty Acid Oxidation Products in Plant Oils

For decades, research on oxidation of linoleic acid (LA, C18:2 n6) and α-linolenic acid (ALA, C18:3 n3) in plant oils has focused on autoxidatively formed and lipoxygenase-derived 9-hydro(pero)xy- and 13-hydro(pero)xy-LA and -ALA. Here, using a non-targeted approach, we show that other hydroxy fatty acids are more abundant in plant oils. Liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry analyses unveiled highly abundant peaks in flaxseed and rapeseed oils. Using authentic reference standards, seven of the peaks were identified as 9-, 10-, 12-, 13-, and 15-HODE as well as 9- and 13-HOTrE. Additionally, six peaks were characterized based on the retention time, the exact mass of the [M-H]- ion, and its fragment ions as 16-OH-C18:3, 18-OH-C18:3, three isomers of 12-OH-C18:2, and one of 15-OH-C18:2. 16-OH-C18:3 and 18-OH-C18:3 were tentatively identified as 16-OH-ALA and 18-OH-ALA, respectively, based on autoxidation and terminal hydroxylation of ALA using CYP4F2. Investigation of formation pathways suggests that fatty acid desaturase 3 is involved in the formation of the 12-OH-C18:2 isomers, 15-HODE, and its isomer. The dominantly occurring 12-OH-C18:2 isomer was identified as 12R,S-OH-9Z,15Z-octadecadienoic acid (densipolic acid) based on a synthetic standard. The characterized oxylipins occurred in cold-pressed flaxseed and rapeseed oils at concentrations of up to 0.1 g/100 g and thus about sixfold higher than the well-known 9-hydro(pero)xy- and 13-hydro(pero)xy-LA and -ALA. Concentrations in sunflower oil were lower but increased when oil was pressed from preheated seeds. Overall, this study provides fundamental new information about the occurrence of oxidized fatty acids in plant oils, having the potential to characterize their quality and authenticity.

Determination of Polar Lipids in Wheat and Oat by a Complementary Approach of Hydrophilic Interaction Liquid Chromatography and Reversed-Phase High-Performance Liquid Chromatography Hyphenated with High-Resolution Mass Spectrometry

Cereals contain lipids that fulfill important physiological roles and are associated with stress in the plant. However, many of the specific biological roles of lipids are yet unknown. Comprehensive analysis of these polar lipid categories in whole grain wheat and oat, cereals highly relevant also in nutrition, was performed. Hydrophilic interaction liquid chromatography (HILIC) and reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with high-resolution mass spectrometry using electrospray ionization in both positive and negative ionization mode was used. Exploiting the different separation mechanisms, HILIC was used as a screening method for straightforward lipid class assignment and enabled differentiation of isomeric lipid classes, like phosphatidylethanolamine and lyso-N-acylphosphatidylethanolamine, while RP-HPLC facilitated separation of constitutional isomers. In combination with data-dependent MS/MS experiments, 67 lipid species belonging to nine polar lipid classes could be identified. Furthermore, with both ionization modes, fatty acyl chains directly connected to the lipid headgroups could be assigned. This work focused on the four lipid classes N-acylphosphatidylethanolamines, acyl-monogalactosyldiacylglycerols, digalactosyldiacylglycerols, and monogalactosyldiacylglycerols as they were less studied in detail in the past. Applying the complementary approach, the relative lipid species compositions in these lipid classes was investigated in detail.

Evaluating Germplasm of Cultivated Oat Species from the VIR Collection under the Russian Northwest Conditions

Oat is one of the most widespread and important cereal crops in the global agricultural production. Searching for new high-yielding and nutritious forms continues to be relevant, especially under the global trend of climate change, when most local oat cultivars may become economically inefficient. Spring oat accessions from VIR collection served as the material for this study; their origin is diverse, as they came from 11 countries. The basic nutritional value (the content of protein, oil, starch, and β-glucans) and characters important for breeding (plant height, panicle length, number of spikelets, number of grains per panicle, 1000 grain weight, and grain yield) were analyzed in 49 accessions of the cultivated covered oat species: Avena sativa L., A. strigosa Schreb., A. abyssinica Hochst., and A. byzantina Coch., grown under the conditions of the Russian Northwest (Leningrad Province) for two years. Variability parameters, interspecific and intervarietal differences, and the effect of weather conditions were assessed. Sources of useful agronomic traits were identified; they can be used to expand the range of the source material for the development of new high-yielding and highly nutritious oat cultivars adapted to local cultivation conditions. It is demonstrated that the VIR collection has a great potential for contemporary food and feed production and for the breeding of new oat cultivars for various purposes. Thus, the contribution of Nikolai Vavilov to the plant genetic resources investigation for the benefit of humanity is invaluable.

Characterization of the Oxylipin Pattern and Other Fatty Acid Oxidation Products in Freshly Pressed and Stored Plant Oils

Enzymatic and nonenzymatic oxidation of linoleic (LA) and α-linolenic acid (ALA) during pressing and storage of plant oils leads to a variety of oxylipins. We pressed oils from flaxseeds, rapeseeds, and sunflower seeds and analyzed the oxylipin pattern in freshly pressed oils. 9-/13-Hydro(pero)xy-LA/-ALA occurred in high concentration resulting probably from lipoxygenase-catalyzed reactions as well as autoxidation and photooxidation. However, in flaxseed and rapeseed oil, the highest concentrations were found for the terminal epoxy-ALA (15(16)-EpODE) and the hardly known 15-hydroxy-LA (15-HODE, 80 mg/100 g in flaxseed oil). Oils were stored for 6 months and the peroxide value (PV) as well as oxylipin and secondary volatile aldehyde concentrations were determined. While lipid peroxidation in flaxseed oil was surprisingly low, the oxylipin concentration and PV massively increased in rapeseed oil dependent on oxygen availability. Oxylipin concentrations correlated well with the PV, while secondary volatile aldehydes did not reflect the changes of oxylipins and PVs. The comprehensive analysis of hydroxy-, epoxy-, and dihydroxy-LA/-ALA reveals new and unique insights into the composition of plant oils and ongoing oxidation processes.

Almutairi K, El Sabagh A. Genetic diversity analysis for wild and cultivated accessions of Cymbopogon citratus (D.C.) Stapf using phytochemical and molecular markers

Background

Genetic diversity is being lost because of increasing urbanization and decreasing cultivation land, which leads to the abrupt use of wild resources of medicinally aromatic plants (MAPs). Cymbopogon citratus is a morphologically diverse MAP that is largely exploited in the food, cosmetics, and pharmaceutical industries. However, the intraspecific phytochemical and molecular diversity of C. citratus has yet to be explored.

Methodology

The germplasm was obtained from four different countries representing Pakistan, India, Bangladesh, and the United States. Oil extraction was performed by hydro distillation, and metabolic profiles of different accessions were generated by GC-MS. Seventeen functional molecular markers based on three genes encoding cytochrome P450, uridyl diphosphate glycosyltransferase and the 5S rRNA gene family were used to explore genetic diversity. Principal component analysis (PCA) and heatmaps were constructed using R software with the help of the gg-plot R package v1.0.5 for data validation.

Results

Among the 208 identified metabolites, citral was maximal, with a phytochemical contribution (1.92-27.73%), α-pinene (0.82-15.57%), verbenol (0.24-22.84%), neral (0.23-21.31%) and geranial acetate (0.43-15.65%). In the majority of accessions, citral was the dominant component. The highest concentration of citral was detected in 384541 (27.74%), 384527 (27.52%) belonging to Pakistan and one USA-based accession 38456 (27.71%). Region-specific grouping revealed a relationship between genetic diversity and geographical location. Pakistani accessions 384518, 38452, and 384544 genetically and 384535, 384518, and 384510 were phytochemically diverse.

Conclusion

The genetic diversity was more pronounced in cultivated accessions than in wild accessions. Moreover, it was observed that phytochemical diversity correlated with the altitude and temperature of the region.

Importance of New Edible Oil Extracted from Seeds of Seven Cereals Species

Cereals constitute a major source of human and animal nutrition. In spite of the extensive production of numerous cereal species, some information is unavailable in terms of lipid composition. Due to the oil increasing demand by the overgrowth of the world population, oleaginous species have encountered problems in recent years. In order to find new sources of edible oil, the aim of this study was to describe the importance of seventeen varieties oil of seven cereal species. Oils were extracted by the Soxhlet method, and fatty acids were measured by gas chromatography. The present study demonstrated that the lipid content of cereal seeds ranged from 1.42% to 5.97%. In average, oat, millet, and maize had significantly higher lipid content, respectively, 5.97%, 5.06%, and 4.71%. The main fatty acid recorded in the studied cereal species, except oat, was linoleic acid C18 : 2 (ω6). Regarding the essential fatty acids linoleic acid C18 : 2 and linolenic acid C18 : 3 (ω3), the oil of all studied species, except oat, was rich in ω6 fatty acids (47.50 to 60.13%) and poor in ω3 (0.45% to 5.33%). The content of unsaturated fatty acids in all studied species ranged from 77.22 to 81.89%. Cereal oil was considered as highly unsaturated oil with the presence of the essential fatty acids necessary for human health. Therefore, cereal oils could be commercialized in small quantities in pharmacies or parapharmacies.

Importance of New Edible Oil Extracted from Seeds of Seven Cereals Species

Cereals constitute a major source of human and animal nutrition. In spite of the extensive production of numerous cereal species, some information is unavailable in terms of lipid composition. Due to the oil increasing demand by the overgrowth of the world population, oleaginous species have encountered problems in recent years. In order to find new sources of edible oil, the aim of this study was to describe the importance of seventeen varieties oil of seven cereal species. Oils were extracted by the Soxhlet method, and fatty acids were measured by gas chromatography. The present study demonstrated that the lipid content of cereal seeds ranged from 1.42% to 5.97%. In average, oat, millet, and maize had significantly higher lipid content, respectively, 5.97%, 5.06%, and 4.71%. The main fatty acid recorded in the studied cereal species, except oat, was linoleic acid C18 : 2 (ω6). Regarding the essential fatty acids linoleic acid C18 : 2 and linolenic acid C18 : 3 (ω3), the oil of all studied species, except oat, was rich in ω6 fatty acids (47.50 to 60.13%) and poor in ω3 (0.45% to 5.33%). The content of unsaturated fatty acids in all studied species ranged from 77.22 to 81.89%. Cereal oil was considered as highly unsaturated oil with the presence of the essential fatty acids necessary for human health. Therefore, cereal oils could be commercialized in small quantities in pharmacies or parapharmacies.

Bioactive Components in Oat and Barley Grain as a Promising Breeding Trend for Functional Food Production

Cereal crops, such as oats and barley, possess a number of valuable properties that meet the requirements for functional diet components. This review summarized the available information about bioactive compounds of oat and barley grain. The results of studying the structure and physicochemical properties of the cell wall polysaccharides of barley and oat are presented. The main components of the flavonoids formation pathway are shown and data, concerning anthocyanins biosynthesis in various barley tissues, are discussed. Moreover, we analyzed the available information about structural and regulatory genes of anthocyanin biosynthesis in Hordeum vulgare L. genome, including β-glucan biosynthesis genes in Avena sativa L species. However, there is not enough knowledge about the genes responsible for biosynthesis of β-glucans and corresponding enzymes and plant polyphenols. The review also covers contemporary studies about collections of oat and barley genetic resources held by the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). This review intended to provide information on the processes of biosynthesis of biologically active compounds in cereals that will promote further researches devoted to transcription factors controlling expression of structural genes and their role in other physiological processes in higher plants. Found achievements will allow breeders to create new highly productive varieties with the desirable properties.

Improving Genomic Prediction for Seed Quality Traits in Oat (Avena sativa L.) Using Trait-Specific Relationship Matrices

The observable phenotype is the manifestation of information that is passed along different organization levels (transcriptional, translational, and metabolic) of a biological system. The widespread use of various omic technologies (RNA-sequencing, metabolomics, etc.) has provided plant genetics and breeders with a wealth of information on pertinent intermediate molecular processes that may help explain variation in conventional traits such as yield, seed quality, and fitness, among others. A major challenge is effectively using these data to help predict the genetic merit of new, unobserved individuals for conventional agronomic traits. Trait-specific genomic relationship matrices (TGRMs) model the relationships between individuals using genome-wide markers (SNPs) and place greater emphasis on markers that most relevant to the trait compared to conventional genomic relationship matrices. Given that these approaches define relationships based on putative causal loci, it is expected that these approaches should improve predictions for related traits. In this study we evaluated the use of TGRMs to accommodate information on intermediate molecular phenotypes (referred to as endophenotypes) and to predict an agronomic trait, total lipid content, in oat seed. Nine fatty acids were quantified in a panel of 336 oat lines. Marker effects were estimated for each endophenotype, and were used to construct TGRMs. A multikernel TRGM model (MK-TRGM-BLUP) was used to predict total seed lipid content in an independent panel of 210 oat lines. The MK-TRGM-BLUP approach significantly improved predictions for total lipid content when compared to a conventional genomic BLUP (gBLUP) approach. Given that the MK-TGRM-BLUP approach leverages information on the nine fatty acids to predict genetic values for total lipid content in unobserved individuals, we compared the MK-TGRM-BLUP approach to a multi-trait gBLUP (MT-gBLUP) approach that jointly fits phenotypes for fatty acids and total lipid content. The MK-TGRM-BLUP approach significantly outperformed MT-gBLUP. Collectively, these results highlight the utility of using TGRM to accommodate information on endophenotypes and improve genomic prediction for a conventional agronomic trait.

Mineral and Fatty Acid Content Variation in White Oat Genotypes Grown in Brazil

A healthy diet is directly associated with a nutrient-rich and toxic contaminant poor intake. A diet poor in diversity can lead to micronutrient deficiency. The intake of functional foods can provide benefits in the prevention and treatment of diseases. Oats are a functional food; are a source of soluble fiber, lipids, proteins, vitamins, minerals, and polyphenols; and are low in carbohydrate content. Thus, in this study, we characterize mineral accumulation, fatty acid composition, and the absence of contaminants in oat genotypes to evaluate the potential of this cereal as food to minimize the effects of micronutrient deficiency. Most of the oat genotypes showed higher mineral levels than other cereals such as wheat, rice, and maize. FAEM 5 Chiarasul, Barbarasul, UPFA Ouro, URS Altiva, URS Brava, and URS Taura showed higher iron concentration while URS Brava showed the highest zinc concentration. The oat genotypes did not show significant arsenic, strontium, and cadmium accumulation. Considering the accumulation of trace elements in the grain, little genetic diversity among the analyzed oat accessions was detected, dividing into two groups. Regarding fatty acid composition, IPR Afrodite, FAEM 4 Carlasul, FAEM 5 Chiarasul, URS Taura, Barbarasul, and URS 21 showed higher essential fatty acid concentrations. These genotypes can be used in crosses with URS Brava, which displayed a higher Fe and Zn accumulation and is genetically distant from the other cultivars. Oat is a functional food showing ability for the accumulation of minerals and also essential fatty acids.

Wheat, Barley, and Oat Breeding for Health Benefit Components in Grain

Cereal grains provide half of the calories consumed by humans. In addition, they contain important compounds beneficial for health. During the last years, a broad spectrum of new cereal grain-derived products for dietary purposes emerged on the global food market. Special breeding programs aimed at cultivars utilizable for these new products have been launched for both the main sources of staple foods (such as rice, wheat, and maize) and other cereal crops (oat, barley, sorghum, millet, etc.). The breeding paradigm has been switched from traditional grain quality indicators (for example, high breadmaking quality and protein content for common wheat or content of protein, lysine, and starch for barley and oat) to more specialized ones (high content of bioactive compounds, vitamins, dietary fibers, and oils, etc.). To enrich cereal grain with functional components while growing plants in contrast to the post-harvesting improvement of staple foods with natural and synthetic additives, the new breeding programs need a source of genes for the improvement of the content of health benefit components in grain. The current review aims to consider current trends and achievements in wheat, barley, and oat breeding for health-benefiting components. The sources of these valuable genes are plant genetic resources deposited in genebanks: landraces, rare crop species, or even wild relatives of cultivated plants. Traditional plant breeding approaches supplemented with marker-assisted selection and genetic editing, as well as high-throughput chemotyping techniques, are exploited to speed up the breeding for the desired genotуpes. Biochemical and genetic bases for the enrichment of the grain of modern cereal crop cultivars with micronutrients, oils, phenolics, and other compounds are discussed, and certain cases of contributions to special health-improving diets are summarized. Correlations between the content of certain bioactive compounds and the resistance to diseases or tolerance to certain abiotic stressors suggest that breeding programs aimed at raising the levels of health-benefiting components in cereal grain might at the same time match the task of developing cultivars adapted to unfavorable environmental conditions.

A systematic review of phytochemicals in oat and buckwheat

Consumption of oat and buckwheat have been associated with various health benefits that may be attributed to their nutritional composition. We performed a systematic review to evaluate the profile and quantity of bioactive compounds present in oat and buckwheat. Among 154 studies included in final analysis, 113 and 178 bioactive compounds were reported in oat and buckwheat, respectively. Total phytosterols, tocols, flavonoids and rutin content were generally higher in buckwheat, β-glucans were significantly higher in oat, while avenanthramides and saponins were characteristically present in oat. The majority of studies included in current review were published before 2010s. The heterogeneous methodological procedures used across the studies precluded our possibility to meta-analyse the evidence and raises the need for harmonization of separation and extraction methods in future studies. Our findings should further stimulate the exploration of metabolites related to identified phytochemicals and their roles in human health.

Multivariate Genome-Wide Association Analyses Reveal the Genetic Basis of Seed Fatty Acid Composition in Oat (Avena sativa L.)

Oat (Avena sativa L.) has a high concentration of oils, comprised primarily of healthful unsaturated oleic and linoleic fatty acids. To accelerate oat plant breeding efforts, we sought to identify loci associated with variation in fatty acid composition, defined as the types and quantities of fatty acids. We genotyped a panel of 500 oat cultivars with genotyping-by-sequencing and measured the concentrations of ten fatty acids in these oat cultivars grown in two environments. Measurements of individual fatty acids were highly correlated across samples, consistent with fatty acids participating in shared biosynthetic pathways. We leveraged these phenotypic correlations in two multivariate genome-wide association study (GWAS) approaches. In the first analysis, we fitted a multivariate linear mixed model for all ten fatty acids simultaneously while accounting for population structure and relatedness among cultivars. In the second, we performed a univariate association test for each principal component (PC) derived from a singular value decomposition of the phenotypic data matrix. To aid interpretation of results from the multivariate analyses, we also conducted univariate association tests for each trait. The multivariate mixed model approach yielded 148 genome-wide significant single-nucleotide polymorphisms (SNPs) at a 10% false-discovery rate, compared to 129 and 73 significant SNPs in the PC and univariate analyses, respectively. Thus, explicit modeling of the correlation structure between fatty acids in a multivariate framework enabled identification of loci associated with variation in seed fatty acid concentration that were not detected in the univariate analyses. Ultimately, a detailed characterization of the loci underlying fatty acid variation can be used to enhance the nutritional profile of oats through breeding.

Safety Assessment of Plant-Derived Fatty Acid Oils

The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of 244 plant-derived fatty acid oils as used in cosmetics. Oils are used in a wide variety of cosmetic products for their skin conditioning, occlusive, emollient, and moisturizing properties. Since many of these oils are edible, and their systemic toxicity potential is low, the review focused on potential dermal effects. The Panel concluded that the 244 plant-derived fatty acid oils are safe as used in cosmetics.

Identification and functional analysis of new peroxygenases in oat

Two new peroxygenases for the biosynthesis of epoxy fatty acids in oat were identified and functionally analyzed by heterologous expression along with rationally designed site-directed mutagenesis. Oat (Avena sativa L.) contains a large family of peroxygenases, a group of heme-containing monooxygenases catalyzing hydroperoxide-dependent epoxidation of unsaturated fatty acids. Here, we report identification and functional analysis of two new peroxygenases AsPXG2 and AsPXG3 from oat. The open reading frame (ORF) of AsPXG2 contains 702 bps encoding a polypeptide of 233 amino acids, while the ORF of AsPXG3 is 627 bps coding for 208 amino acids. Both AsPXG2 and AsPXG3 comprise a single transmembrane domain, conserved histidines for heme binding and a conserved EF-hand motif for calcium binding, but they only share about 50% amino acid sequence identity with each other. When expressed in Escherichia coli and Pichia pastoris, AsPXG3 showed high epoxidation activity, while AsPXG2 exhibited no activity in E. coli and low activity in P. pastoris. AsPXG3 could effectively epoxidize both mono- and polyunsaturated fatty acids with linolenic acid being the most preferred substrate. Site-directed mutagenesis was employed to investigate the structure-function relationship of oat peroxygenase on 12 conserved residues of AsPXG3. Replacement of two conserved histidines, the ligands to the prosthetic heme group of the peroxygenase, by alanine resulted in complete loss of activity. Substitution of three conserved residues surrounding the two histidines resulted in reduction of the enzymatic activity by more than 80%. These results imply that these conserved residues might be located in or near the catalytic pocket, where the two histidine residues coordinate the heme group and the surrounding residues define the shape and size of the pocket for interaction with the heme as well as two substrates.

Potato tuber expression of Arabidopsis WRINKLED1 increase triacylglycerol and membrane lipids while affecting central carbohydrate metabolism

Tuber and root crops virtually exclusively accumulate storage products in the form of carbohydrates. An exception is yellow nutsedge (Cyperus esculentus) in which tubers have the capacity to store starch and triacylglycerols (TAG) in roughly equal amounts. This suggests that a tuber crop can efficiently handle accumulation of energy dense oil. From a nutritional as well as economic aspect, it would be of interest to utilize the high yield capacity of tuber or root crops for oil accumulation similar to yellow nutsedge. The transcription factor WRINKLED1 from Arabidopsis thaliana, which in seed embryos induce fatty acid synthesis, has been shown to be a major factor for oil accumulation. WRINKLED1 was expressed in potato (Solanum tuberosum) tubers to explore whether this factor could impact tuber metabolism. This study shows that a WRINKLED1 transcription factor could induce triacylglycerol accumulation in tubers of transformed potato plants grown in field (up to 12 nmol TAG/mg dry weight, 1% of dry weight) together with a large increase in polar membrane lipids. The changes in metabolism further affected starch accumulation and composition concomitant with massive increases in sugar content.

New insights into the antioxidant activity and components in crude oat oil and soybean oil

Developing new antioxidants and using natural examples is of current interest. This study evaluated the antioxidant activities and the ability to inhibit soybean oil oxidation of oat oil obtained with different solvents. Oat oil extract obtained by ethanol extraction gave the highest antioxidant activity with a DPPH radical (1,1-diphenyl-2-picrylhydrazyl) scavenging activity of 88.2 % and a reducing power (A 700) of 0.83. Oat oil extracted by ethanol contained the highest polyphenol and α-tocopherol content. Significant correlation was observed between the total polyphenol contents, individual phenolic acid, α-tocopherol, and DPPH radical scavenging activity. Soybean oil with 2 % added oat oil showed low malondialdehyde content (8.35 mmol mL(-1)), suggesting that the added oat oil inhibited oxidation. Oat oil showed good antioxidant activity, especially when extracted with ethanol which could also retard the oxidation of soybean oil . DPPH radical scavenging activity was the best method to evaluate the antioxidant activity and components of oat oil.

Mitochondrial structural and antioxidant system responses to aging in oat (Avena sativa L.) seeds with different moisture contents

We observed the relationship between lifespan and mitochondria, including antioxidant systems, ultrastructure, and the hydrogen peroxide and malondialdehyde contents in 4 h imbibed oat (Avena sativa L.) seeds that were aged with different moisture contents (4%, 10% and 16%) for 0 (the control), 8, 16, 24, 32 and 40 d at 45 °C. The results showed that the decline in the oat seed vigor and in the integrity of the mitochondrial ultrastructure occurred during the aging process, and that these changes were enhanced by higher moisture contents. Mitochondrial antioxidants in imbibed oat seeds aged with a 4% moisture content were maintained at higher levels than imbibed oat seeds aged with a 10% and 16% moisture content. These results indicated that the levels of mitochondrial antioxidants and malondialdehyde after imbibition were related to the integrity of the mitochondrial membrane in aged oat seeds. The scavenging role of mitochondrial superoxide dismutase was inhibited in imbibed oat seeds aged at the early stage. Monodehydroascorbate reductase and dehydroascorbate reductase played more important roles than glutathione reductase in ascorbate regeneration in aged oat seeds during imbibition.

Transcriptional transitions in Nicotiana benthamiana leaves upon induction of oil synthesis by WRINKLED1 homologs from diverse species and tissues

BACKGROUND

Carbon accumulation and remobilization are essential mechanisms in plants to ensure energy transfer between plant tissues with different functions or metabolic needs and to support new generations. Knowledge about the regulation of carbon allocation into oil (triacylglycerol) in plant storage tissue can be of great economic and environmental importance for developing new high-yielding oil crops. Here, the effect on global gene expression as well as on physiological changes in leaves transiently expressing five homologs of the transcription factor WRINKLED1 (WRI1) originating from diverse species and tissues; Arabidopsis thaliana and potato (Solanum tuberosum) seed embryo, poplar (Populus trichocarpa) stem cambium, oat (Avena sativa) grain endosperm, and nutsedge (Cyperus esculentus) tuber parenchyma, were studied by agroinfiltration in Nicotiana benthamiana.

RESULTS

All WRI1 homologs induced oil accumulation when expressed in leaf tissue. Transcriptome sequencing revealed that all homologs induced the same general patterns with a drastic shift in gene expression profiles of leaves from that of a typical source tissue to a source-limited sink-like tissue: Transcripts encoding enzymes for plastid uptake and metabolism of phosphoenolpyruvate, fatty acid and oil biosynthesis were up-regulated, as were also transcripts encoding starch degradation. Transcripts encoding enzymes in photosynthesis and starch synthesis were instead down-regulated. Moreover, transcripts representing fatty acid degradation were up-regulated indicating that fatty acids might be degraded to feed the increased need to channel carbons into fatty acid synthesis creating a futile cycle. RT-qPCR analysis of leaves expressing Arabidopsis WRI1 showed the temporal trends of transcripts selected as 'markers' for key metabolic pathways one to five days after agroinfiltration. Chlorophyll fluorescence measurements of leaves expressing Arabidopsis WRI1 showed a significant decrease in photosynthesis, even though effect on starch content could not be observed.

CONCLUSIONS

This data gives for the first time a general view on the transcriptional transitions in leaf tissue upon induction of oil synthesis by WRI1. This yields important information about what effects WRI1 may exert on global gene expression during seed and embryo development. The results suggest why high oil content in leaf tissue cannot be achieved by solely transcriptional activation by WRI1, which can be essential knowledge in the development of new high-yielding oil crops.

Oat (Avena sativa L.): Oil and Nutriment Compounds Valorization for Potential Use in Industrial Applications

Oat is a promising plant for the future. It is edible and beneficial thanks to its nutritional, medicinal and pharmaceutical uses and, hence, recognized to be useful for a healthier world. The assessment of the vital functions of oat components is important for industries requiring correct health labelling, valid during the shelf life of any product. Oil, enzymes and other biomolecules of nutraceutic or dietary usage from oats would be valorized for this purpose. Although oats have a unique and versatile composition including antioxidants and biomolecules indispensable for health, they are undervalued in comparison with other staple cereals such as wheat, barley and rice. Furthermore, oats, apart from maize, comprise a high oil content used for a wide range of beneficial purposes. In addition, they contain beta glucan that has proven to be very helpful in reducing blood cholesterol levels and other cardiovascular diseases risks. In fact, there is diversity in the composition and content of the beneficial oat components within their genotypes and the different environmental conditions and, thus, oats are amenable to be enhanced by agronomic practices and genetic approaches.

Protective effects of oat oil on deltamethrin-induced reprotoxicity in male mice

Oats (Avena sativa L.), which are used in foods, are a potential economically viable source of oil. The purpose of this study was to determine the efficiency of oats oil to alleviate oxidative damage of testis induced by deltamethrin, which is a pyrethroid pesticide that exerts a wide range of effects on non-targeted organisms. The reprotoxicity caused by orally administered deltamethrin (DEL) to mice can be effectively antagonized by the beneficial effects of oats oil (OO) as an antioxidant. Thirty-two male albino mice were divided into four equal groups: a control group, a group of mice given deltamethrin (5 mg per kg b.w.), a group administered deltamethrin after receiving oats oil (6 g per kg b.w.), and a group receiving only OO. Exposure to deltamethrin at a dose of 5 mg per kg b.w. per day caused oxidative stress in testis, proven by a decrease in the epididymal sperm count and motility, an increase in the number of abnormal morphologies in spermatozoa and a significant increase of lipid peroxidation (LP) in the testis when compared to control animals. Co-administration of oats oil to the DEL-treated mice ameliorated the testicular biochemical parameters as well as the histological impairments in testis. We concluded that oats oil ameliorated the toxic effects of deltamethrin in testis explored by reduced LP and improved total sperm density, motility and morphology in mice spermatozoa, suggesting its role as a potential antioxidant.

Oat agriculture, cultivation and breeding targets: implications for human nutrition and health

Oats are undervalued in comparison with wheat, rice and barley, despite their unique composition that includes many of the nutrients required for health and a reduced risk of degenerative disease incidence. Furthermore, oats as whole grain and some of their associated products also contain β-glucan, a complex polysaccharide that has an approved health claim to reduce blood cholesterol levels and reduce the risk of CHD incidence if consumed at ≥ 3 g/d. At the agronomic level, oats exhibit optimal growth in regions of moderate temperature and long day length. In addition, they can tolerate wet weather and acidic soils more effectively than other cereals, such as wheat. Studies have shown that there is diversity in the content and composition of nutrients and health-beneficial components within the available wild and cultivated germplasm and that these are amenable to be enhanced by different agronomic practices as well as are susceptible to climatic variation. The advances in modern plant genetics, developed in sister cereals such as wheat, rice and barley, mean that oat development and exploitation should see an acceleration in the coming decade as they are adopted and applied. These advances include approaches such as genome sequencing, genotyping by sequencing and the allied next-level analytical approaches of RNA sequencing, transcriptome profiling and metabolomics. The collation and coordination of these approaches should lead to the generation of new, tailored oat varieties that are nutritionally enhanced and contain a greater proportion of health-beneficial components that can be translated through into a wide(r) range of consumer products with the ultimate hope of associated benefits to human health and nutrition.

Postprandial effects on plasma lipids and satiety hormones from intake of liposomes made from fractionated oat oil: two randomized crossover studies

Background

The composition and surface structure of dietary lipids influence their intestinal degradation. Intake of liposomes made of fractionated oat oil (LOO) is suggested to affect the digestion process and postprandial lipemia and also induce satiety.

Objective

In the present study, the metabolic effects on plasma lipids and gut hormones related to satiety were investigated in healthy individuals after intake of LOO, with dairy lipids as placebo.

Design

Two blinded randomized studies with crossover design were performed. In the first study, 19 subjects consumed 35 g lipids from LOO or yoghurt in a breakfast meal. In a follow-up study, 15 women consumed 14 or 1.8 g lipids from LOO mixed in yoghurt. Blood samples were analyzed for plasma lipids, insulin, glucose, and intestinal hormones CCK, PYY, GLP-1, and GLP-2 before and four times after the meal. Subjective analysis of satiety was measured using a visual analog scale questionnaire. Participants recorded their food intake during the rest of the day.

Results

Intake of 35 and 14 g lipids from LOO significantly increased plasma concentrations of CCK, GLP-1, GLP-2, and PYY postprandially. This coincided with a prolonged elevation of triglycerides and large cholesterol-containing particles. Non-esterified fatty acids decreased after intake of 14 and 1.8 g lipids from LOO. The subjective sensation of satiety in women was increased 7 h after intake of 35 g lipids from LOO without any difference in food intake. Our results indicate that intake of 14 g lipids from LOO at breakfast substantially reduced energy intake during the rest of the day.

Conclusions

This study suggests that intake of LOO prolong lipid digestion, affect postprandial plasma lipids and have an effect on satiety. The effect of LOO on GLP-2 indicates that intake of LOO also improve gut health.

Relationship between volatile profile and sensory development of an oat-based biscuit

The shelf-life of plain oatcakes and oatcakes containing a natural antioxidant (rosemary extract) was studied for 28 weeks. The biscuits were evaluated using several chemical analyses to determine oxidation (headspace analysis, free fatty acids profile, peroxide value and anisidine value), in addition to sensory testing. A selection of volatiles, including hexanal, were found to be positively correlated to three sensory parameters (aroma, flavour and aftertaste). These volatiles, responsible for the perception of off-flavour in oat biscuits, were predominantly secondary lipid breakdown products, primarily from the unsaturated fatty acids C18:1 and C18:2. The peroxide value was also found to be a useful tool to assess oxidation in oatcakes. The impact of the antioxidant was insufficient at the concentration tested to be used as a solution to prevent the development of off-flavour; however the antioxidant did appear to slow down the rancidity process.

Controlling lipid accumulation in cereal grains

Plant oils have so far been mostly directed toward food and feed production. Nowadays however, these oils are more and more used as competitive alternatives to mineral hydrocarbon-based products. This increasing demand for vegetable oils has led to a renewed interest in elucidating the metabolism of storage lipids and its regulation in various plant systems. Cereal grains store carbon in the form of starch in a large endosperm and as oil in an embryo of limited size. Complementary studies on kernel development and metabolism have paved the way for breeding or engineering new varieties with higher grain oil content. This could be achieved either by increasing the relative proportion of the oil-rich embryo within the grain, or by enhancing oil synthesis and accumulation in embryonic structures. For instance, diacylglycerol acyltransferase (DGAT) that catalyses the ultimate reaction in the biosynthesis of triacylglycerol appears to be a promising target for increasing oil content in maize embryos. Similarly, over-expression of the maize transcriptional regulators ZmLEAFY COTYLEDON1 and ZmWRINKLED1 efficiently stimulates oil accumulation in the kernels of transgenic lines. Redirecting carbon from starch to oil in the endosperm, though not yet realized, is discussed.

Comparison of two headspace sampling techniques for the analysis of off-flavour volatiles from oat based products

Two different headspace sampling techniques were compared for analysis of aroma volatiles from freshly produced and aged plain oatcakes. Solid phase microextraction (SPME) using a Carboxen-Polydimethylsiloxane (PDMS) fibre and entrainment on Tenax TA within an adsorbent tube were used for collection of volatiles. The effects of variation in the sampling method were also considered using SPME. The data obtained using both techniques were processed by multivariate statistical analysis (PCA). Both techniques showed similar capacities to discriminate between the samples at different ages. Discrimination between fresh and rancid samples could be made on the basis of changes in the relative abundances of 14-15 of the constituents in the volatile profiles. A significant effect on the detection level of volatile compounds was observed when samples were crushed and analysed by SPME-GC-MS, in comparison to undisturbed product. The applicability and cost effectiveness of both methods were considered.

A comprehensive overview of grain development in Brachypodium distachyon variety Bd21

A detailed and comprehensive understanding of seed reserve accumulation is of great importance for agriculture and crop improvement strategies. This work is part of a research programme aimed at using Brachypodium distachyon as a model plant for cereal grain development and filling. The focus was on the Bd21-3 accession, gathering morphological, cytological, and biochemical data, including protein, lipid, sugars, starch, and cell-wall analyses during grain development. This study highlighted the existence of three main developmental phases in Brachypodium caryopsis and provided an extensive description of Brachypodium grain development. In the first phase, namely morphogenesis, the embryo developed rapidly reaching its final morphology about 18 d after fertilization (DAF). Over the same period the endosperm enlarged, finally to occupy 80% of the grain volume. During the maturation phase, carbohydrates were continuously stored, mainly in the endosperm, switching from sucrose to starch accumulation. Large quantities of β-glucans accumulated in the endosperm with local variations in the deposition pattern. Interestingly, new β-glucans were found in Brachypodium compared with other cereals. Proteins (i.e. globulins and prolamins) were found in large quantities from 15 DAF onwards. These proteins were stored in two different sub-cellular structures which are also found in rice, but are unusual for the Pooideae. During the late stage of development, the grain desiccated while the dry matter remained fairly constant. Brachypodium exhibits some significant differences with domesticated cereals. Beta-glucan accumulates during grain development and this cell wall polysaccharide is the main storage carbohydrate at the expense of starch.

A peroxygenase pathway involved in the biosynthesis of epoxy fatty acids in oat

While oat (Avena sativa) has long been known to produce epoxy fatty acids in seeds, synthesized by a peroxygenase pathway, the gene encoding the peroxygenase remains to be determined. Here we report identification of a peroxygenase cDNA AsPXG1 from developing seeds of oat. AsPXG1 is a small protein with 249 amino acids in length and contains conserved heme-binding residues and a calcium-binding motif. When expressed in Pichia pastoris and Escherichia coli, AsPXG1 catalyzes the strictly hydroperoxide-dependent epoxidation of unsaturated fatty acids. It prefers hydroperoxy-trienoic acids over hydroperoxy-dienoic acids as oxygen donors to oxidize a wide range of unsaturated fatty acids with cis double bonds. Oleic acid is the most preferred substrate. The acyl carrier substrate specificity assay showed phospholipid and acyl-CoA were not effective substrate forms for AsPXG1 and it could only use free fatty acid or fatty acid methyl esters as substrates. A second gene, AsLOX2, cloned from oat codes for a 9-lipoxygenase catalyzing the synthesis of 9-hydroperoxy-dienoic and 9-hydroperoxy-trienoic acids, respectively, when linoleic (18:2-9c,12c) and linolenic (18:3-9c,12c,15c) acids were used as substrates. The peroxygenase pathway was reconstituted in vitro using a mixture of AsPXG1 and AsLOX2 extracts from E. coli. Incubation of methyl oleate and linoleic acid or linolenic acid with the enzyme mixture produced methyl 9,10-epoxy stearate. Incubation of linoleic acid alone with a mixture of AsPXG1 and AsLOX2 produced two major epoxy fatty acids, 9,10-epoxy-12-cis-octadecenoic acid and 12,13-epoxy-9-cis-octadecenoic acid, and a minor epoxy fatty acid, probably 12,13-epoxy-9-hydroxy-10-transoctadecenoic acid. AsPXG1 predominately catalyzes intermolecular peroxygenation.