Oil quality and content were analyzed in 33 accessions from 13 wild species and 10 accessions of cultivated oat. Wild oat species tended to have higher oil and 18:1 fatty acid (FA) contents and lower amounts of 18:2 and 18:3 FAs as compared to cultivated oats. In addition to common FAs, minor amounts of several hydroxy and epoxy FAs were also present in the oat oil and mainly confined to specific lipid classes. These unusual FAs included the previously reported 15-hydroxy 18:2 (Delta9,12) (avenoleic acid) mostly found among polar lipids and a novel 7-hydroxyhexadecanoic acid located to 1,2-diacylglycerol. The present study highlights the potential of making use of the existing germplasm, consisting of wild oat species, in breeding programs for achieving new oat varieties that produce a range of oils with different FA compositions as well as having high oil contents. However, in one matter, oats apparently lack genetic diversity and that is for oil qualities that are highly enriched in the omega 3 (omega-3) FA 18:3. Consequently, developing oat cultivars with highly unsaturated oils will need involvement of other techniques such as biotechnology.

In a future bio-based economy, renewable sources for lipid compounds at attractive cost are needed for applications where today petrochemical derivatives are dominating. Wax esters and fatty alcohols provide diverse industrial uses, such as in lubricant and surfactant production. In this study, chloroplast metabolism was engineered to divert intermediates from de novo fatty acid biosynthesis to wax ester synthesis. To accomplish this, chloroplast targeted fatty acyl reductases (FAR) and wax ester synthases (WS) were transiently expressed in Nicotiana benthamiana leaves. Wax esters of different qualities and quantities were produced providing insights to the properties and interaction of the individual enzymes used. In particular, a phytyl ester synthase was found to be a premium candidate for medium chain wax ester synthesis. Catalytic activities of FAR and WS were also expressed as a fusion protein and determined functionally equivalent to the expression of individual enzymes for wax ester synthesis in chloroplasts.

Few microscopical studies have been made on lipid storage in oat grains, with variable results as to the extent of lipid accumulation in the starchy endosperm. Grains of medium- and high-lipid oat (Avena sativa L.) were studied at two developmental stages and at maturity, by light microscopy using different staining methods, and by scanning and transmission electron microscopy. Discrete oil bodies occurred in the aleurone layer, scutellum and embryo. In contrast, oil bodies in the starchy endosperm often had diffuse boundaries and fused with each other and with protein vacuoles during grain development, forming a continuous oil matrix between the protein and starch components. The different microscopical methods were confirmative to each other regarding the coalescence of oil bodies, a phenomenon probably correlated with the reduced amount of oil-body associated proteins in the endosperm. This was supported experimentally by SDS-PAGE separation of oil-body proteins and immunoblotting and immunolocalization with antibodies against a 16 kD oil-body protein. Much more oil-body proteins per amount of oil occurred in the embryo and scutellum than in the endosperm. Immunolocalization of 14 and 16 kD oil-body associated proteins on sectioned grains resulted in more heavy labeling of the embryo, scutellum and aleurone layer than the rest of the endosperm. Observations on the appearance of oil bodies at an early stage of development pertain to the prevailing hypotheses of oil-body biogenesis.

Since the cereal endosperm is a dead tissue in the mature grain, β-oxidation is not possible there. This raises the question about the use of the endosperm oil in cereal grains during germination. In this study, mobilization of lipids in different tissues of germinating oat grains was analysed using thin-layer and gas chromatography. The data imply that the oat endosperm oil [triacylglycerol (TAG)] is not a dead-end product as it was absorbed by the scutellum, either as free fatty acids (FFAs) released from TAG or as intact TAG immediately degraded to FFAs. These data were supported by light and transmission electron microscopy (LM and TEM) studies where close contact between endosperm lipid droplets and the scutellum was observed. The appearance of the fused oil in the oat endosperm changed into oil droplets during germination in areas close to the aleurone and the scutellar epithelium. However, according to the data obtained by TEM these oil droplets are unlikely to be oil bodies surrounded by oleosins. Accumulation of FFA pools in the embryo suggested further transport of FFAs from the scutellum. Noticeably high levels of TAG were also accumulated in the embryo but were not synthesized by re-esterification from imported FFAs. Comparison between two oat cultivars with different amounts of oil and starch in the endosperm suggests that an increased oil to starch ratio in oat grains does not significantly impact the germination process.

Background. Oat grains accumulate substantial amounts of various phenolic compounds that possess biological activity and have a potential to considerably increase health benefits of oats as a food. Avenanthramides (AVA) is an important group of these compounds due to their antioxidant, anti-itching, anti-inflammatory, antiproliferative activities.Materials and methods. Using combined HPLC and LC-MS analyses, we provide the first comprehensive review of the total avenanthramide content and composition in cultivated and wild oats. The AVA content was measured in 32 wild and 120 cultivated oat accessions obtained from the global collection of the N.I. Vavilov Institute of Plant Genetic Resources (VIR), St. Petersburg, Russia.Results and conclusion. The wild hexaploid A. sterilis L. had the highest total AVA content, reaching 1825 mg kg–1. Among cultivated accessions, naked oat cv. ‘Numbat’ (Australia) had the highest AVA content, 586 mg kg–1. The AVA composition exhibited a wide diversity among the analyzed samples. Accessions were identified where AVAs A, B and C, which are generally considered as major AVA, had a low percentage, and instead other AVAs prevailed. The AVA content in eight oat cultivars revealed significant annual changes in both the total AVA content and the proportions of individual AVAs. Using HPLC analyses, 22 distinguishable peaks in AVA extracts of oat seeds were detected and quantified. Several of these peaks, which have not been previously documented, presumably represent different AVAs. Further analyses are needed to detail these findings and to determine the specific AVA structures in oat grains.

High-lipid oat is a potential oil crop. Chemical and microscopical analyses have shown that the major part of the grain lipids are stored in the endosperm. While oil bodies are intact in the aleurone layer, scutellum and embryo, they have less associated proteins (oleosins) and undergo fusion in the starchy endosperm. In this report, we document the distribution of lipids in the endosperm microscopically. Underneath the aleurone layer, lipids are most abundant in the subaleurone cells and in the endosperm cells in the vicinity of the scutellum and embryo. Thus the major areas of oil storage are close to the living tissues of the grain, the sites of enzyme production in connection with germination and mobilization. The documentation of cellular structural changes, and implication of the fused state of oil bodies, during germination, remains to be elucidated.Oat (Avena sativa L.) is a cereal crop that accumulates up to 18% of lipids. 1 Most of the lipids are stored in the endosperm tissues of the grain. [2][3][4] This has been also demonstrated using fluorescence microscopy, 1,5 light microscopy as well as scanning and transmission electron microscopy. 4,6 White et al., 7 on the other hand, interpreted their transmission electron microscopy pictures as if indicating scarcity or absence of lipids beneath the subaleurone layer. Applying different microscopical approaches, it has been shown that oil bodies appear as distinct entities in the embryonic axis and the aleurone layer, and that they loose their integrity and fuse with each other into large masses in the rest of the endosperm during grain development. 6 The fusion of oil bodies in the starchy endosperm is probably correlated with the reduced amount of the protecting oil-body associated proteins (oleosins) documented in this tissue. 6 The aim of this report is to present microscopical data on the distribution of oil throughout the oat endosperm, not shown in Heneen et al. 6 The structural observations were made on the highlipid oat cultivar Matilda with 10.3% lipids. 6 Sectioned sectors of grains at early and late developmental stages, 14 and 40 days after anthesis, were stained with Sudan Black B or Toluidine Blue O. 6 The low magnifications of whole sectors of the grain and higher magnifications of defined sites (Fig. 1) provide information on the distribution and appearance of lipids throughout the grain. A further step would be simultaneous visualization and quantification of lipids, as has been elegantly demonstrated in developing barley grains and soybean seeds in vivo, applying frequency-selected magnetic resonance imaging. 8 At the early developmental stage of oat grains (Fig. 1A), lipids were less densely stained in the aleurone layer than in the rest of the endosperm, inferring tissue-specific differences. Oil was not evenly distributed in the starchy endosperm. It was most frequent in the subaleurone cells, and decreased in cells of middle and inner endosperm, in accordance with earlier findings. 5 This was valid for the discrete oil bodies observe...

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Increased man-caused impact, imbalance in diets lead to diseases, premature aging and life shortening. To overcome this imbalance, there is an active search for raw materials containing the physiologically functional ingredients necessary for human health or the raw materials containing biologically active substances, vitamins, mineral substances. To enrich traditional recipes with these components and to give functional purpose to products of mass demand, it is advisable to include, oat meal (talcan) and pea meal into the bee-keeping products composition which have a high biological value. Standard methods for analyzing the quality of raw materials and confectionery were used for the study, as well as modern instrumental methods for analysis, such as high performance liquid chromatography and atomic absorption spectrophotometry. The physical and chemical and quality parameters of talcan, pollen pellet, honey and pea meal (by-product of pea processing) have been studied as well as formulas of confectionery products with the indicated components have been developed. The national confectionery dish chak-chak, which recipe included talcan, pollen pellet and honey, contained an increased amount of vitamins and minerals in comparison with the control sample. It has been experimentally proved that the inclusion of these components into the formula allowed obtaining a product with a high nutrient content. It was also found that with the inclusion of pollen pellet into the marshmallow recipe, the amount of vitamins and minerals in the developed product increases. The analysis of the results showed that the enrichment of sugar cookies with pea forage leads to an increase in the content of protein, carotenoids and vitamins. It is established that in comparison with the control sample the content of mineral substances increased.