| Oats are generally considered as a nutritious food and widely accepted by human beings around the world. In China, oats rank around the sixth position in cereal production, after wheat, maize, rice, barley, and sorghum. The qualities and properties of protein and polyphenols in different oat varieties and area were conducted in this research, so as to make good use of oat resource, expand the fields of oat products in food processing and provide theoretical basis of oat applications.In this research, three oat samples were collected from Hebei and Inner Mongolia, which were the two main producing regions in China. Another sample was purchased from Australia, and the last sample was hulless-barley from Tibet, which was rather rich in the content of ?-glucan. In this paper, the nutritional compositions of four samples, including the moisture, ash content, crude oil and protein, ?-glucan, amino acids and nutritional assessment, composition of fatty acids and trace elements were investigated and compared. On the basis of previous research, the protein was extracted by the method of alkaline solution and acid precipitation from four samples. The compositions of amino acids and nutritional assessment and the properties including solubility, foaming properties, and emulsifying properties, were determined. The oat polyphenols were extracted by the method of ethanol-water solution. Meanwhile, the composition of polyphenols in different samples were analysed by HPLC and LC-MS. Their antioxidant capacities were evaluated by chemical-based antioxidant activities assay. The main results are as follows:1. In this paper, we investigated and compared the nutritional compositions of four samples, including the moisture content, ash content, crude protein and oil, composition of fatty acids, amino acids and trace elements. Results showed that Tibetan hulless-barley flakes were higher(p<0.01) in contents of ash, ?-glucan, Oleic acid and K?Fe?Cu, lower(p<0.01) contents of protein and crude oil compared to oat flakes. The content of essential amino acids and nutritional parameters of four samples met the ideal nutritional requirements according to the FAO/WHO. In addition, Hebei oat flakes were shown to have highest essential amino acids than any others. What is more, all four samples were rich in unsaturated fatty acids, accounted for more than 85% of the total fatty acids, especially the linoleic of Australian oat was up to 44.1%.2. The protein was extracted by the method of alkaline solution and acid precipitation from four samples. The compositions of amino acids and nutritional assessment, SDS-PAGE electrophoresis, Fourier transform infrared spectroscopy(FT-IR) analysis and the properties including solubility, foaming properties, and emulsifying properties were measured to compare the differences between the four kinds of protein isolate in this study. The solubility of protein extracted from four samples under different p H conditions was significantly different. With the increasing of p H, the four kinds of protein were all presented typical bell-shaped solubility curves. The minimum solubility was at p H 5, which was rather close to the isoelectric point of oat protein. Meanwhile, the solubility of Inner Mongolia oat protein at p H 5 was best, and Tibetan hulless-barley protein was worst. The SDS-PAGE patterns of oat protein showed that the major molecular weight distribution regions were 10-15 k Da?20-25 k Da?25-34 k Da?34-40 k Da and 40-55 k Da, which were almost globulins. The subunit composition of oat protein in different varieties did not differ significantly. The ?-turn content of Australian oat protein isolates was highest, indicating that the structural of Australian oat protein isolates was most stable. At last, the EAAI index of Hebei oat protein isolates rang first among the four samples, which indicated the highest nutritional value.3. The oat polyphenols in different varieties were extracted by the method of ethanol-water solution. The compositions of polyphenols antioxidant activities were measured in this study. The results indicateded that the total polyphenols contents in four samples were from 109.47 mg/100 g to 155.51 mg/100 g. Tibetan hulless-barley were higher in contents of total polyphenols compared to any others. Vanillin, chlorogenic acid, ferulic acid, caffeic acid and avenanthramides(Bc?Bf?Bp) were main component of oat polyphenols. In addition, the antioxidant experiment showed that polyphenols in oat and hulless-barley have excellent reducing capacity and antioxidant capacity to scavenge DPPH·?·OH and ABTS. Moreover, the antioxidant capacity of Inner Mongolia oat polyphenols were best.4. This study was conducted to study the effects of different manufacturing conditions in the oat processing, so as to provide theoretical and technical guidance in the oat industry. The oat flour(OF) was separately processed by Extrusion(EOF)?Drum drying(RDOF)and Spray drying(SDOF). The differences in angle of repose, bulk density, water-holding capacity, oil holding capacity, microscopic structure and rheological properties were determined for the dried oat flour. The results showed that oat flour after processing were lower in contents of moisture, protein lipid and total starch, higher contents of ash. The flowability and reconstitution of EOF were best. Among the four samples, SDOF had the highest score in whiteness and looked brighter, while the water capacity of RDOF was the best. SEM results further suggested that the particles of oat flour after extruding or drum drying become smaller, incomplete and more uniform. The particle size analysis have showed that the three kind of processing conditions can make the oat flour more uniform, especially the SDOF.Data of rheology measurement suggested that the viscosity of all samples showed a trend of decreasing with the shear rate increasing. With the increasing of shear rate, apparent viscosity of all samples showed shear-thinning phenomenon. In addition, the gel network of RDOF was the most stable among the four samples. |
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