Characterization and Analysis of Protein Structures in Oat Bran

Effect of Stir-Frying on Physicochemical and Functional Properties of Oat Protein Isolates

The heat treatment required for the deactivation of enzymes was carried out on crop species such as oats. Stir-frying, a frequently employed method for enzyme inactivation to preserve their desirable shelf life, can result in diminished nutritional value and protein degeneration. The mechanism by which stir-frying affects the oat protein remains largely unknown. Therefore, this study aimed to investigate the physicochemical and functional properties of the extracted oat protein isolates (OPI) at different stir-frying durations (0, 10, 20, and 30 min) at a temperature of 230 °C. The findings of this study demonstrated that stir-frying led to a decrease in the content of amino acids (AA), potentially attributed to the involvement of certain amino acids in the Maillard reaction. As the time of stir-frying increased, the secondary structure of OPI underwent changes: specifically, β-turns transformed into β-sheets. The process of protein denaturation and redistribution of chemical bonds resulted in an increase in the disulfide bond content of OPI, leading to aggregation, large particle size, and reduced digestibility. However, the water retention properties, foaming properties, and emulsification properties of OPI showed improvement. These findings provide valuable insights for the controlled and precise processing of oats and highlight the potential of OPI as a functional food.

Characterisation of the Enzymatically Extracted Oat Protein Concentrate after Defatting and Its Applicability for Wet Extrusion

An oat protein concentrate (OC1) was isolated from oat flour through starch enzymatic hydrolysis, by subsequent defatting by ethanol and supercritical fluid extraction (SFE) reaching protein concentrations of 78% and 77% by weight in dry matter, respectively. The protein characterisation and functional properties of the defatted oat protein concentrates were evaluated, compared and discussed. The solubility of defatted oat protein was minor in all ranges of measured pH (3-9), and foamability reached up to 27%. Further, an oat protein concentrate defatted by ethanol (ODE1) was extruded by a single screw extruder. The obtained extrudate was evaluated by scanning electron microscope (SEM), texture and colour analysers. The extrudate's surface was well formed, smooth, and lacking a tendency to form a fibrillar structure. Textural analysis revealed a non-unform structure (fracturability 8.8-20.9 kg, hardness 26.3-44.1 kg) of the oat protein extrudate.

Effect of Enzymatic Pre-Treatment on Oat Flakes Protein Recovery and Properties

Oats are considered an exceptional source of high-quality protein. Protein isolation methods define their nutritional value and further applicability in food systems. The aim of this study was to recover the oat protein using a wet-fractioning method and investigate the protein functional properties and nutritional values among the processing streams. The oat protein was concentrated through enzymatic extraction, eliminating starch and non-starch polysaccharides (NSP), treating oat flakes with hydrolases, and reaching protein concentrations of up to about 86% in dry matter. The increased ionic strength from adding sodium chloride (NaCl) improved protein aggregation and resulted in increased protein recovery. Ionic changes improved protein recovery in provided methods by up to 24.8 % by weight. Amino acid (AA) profiles were determined in the obtained samples, and protein quality was compared with the required pattern of indispensable amino acids. Furthermore, functional properties of the oat protein, such as solubility, foamability, and liquid holding capacity, were investigated. The solubility of the oat protein was below 7 %; foamability averaged below 8%. The water and oil-holding reached a ratio of up to 3.0 and 2.1 for water and oil, respectively. Our findings suggest that oat protein could be a potential ingredient for food industries requiring a protein of high purity and nutritional value.

Dietary-Nutraceutical Properties of Oat Protein and Peptides

Oats are considered the healthiest grain due to their high content of phytochemicals, dietary fibers, and protein. In recent years, oat protein and peptides have gained popularity as possible therapeutic or nutraceutical candidates. Generally, oat peptides with bioactive properties can be obtained by the enzymatic hydrolysis of proteins and are known to have a variety of regulatory functions. This review article focused on the nutraceutical worth of oat proteins and peptides and also describes the application of oat protein as a functional ingredient. Outcomes of this study indicated that oat protein and peptides present various therapeutical properties, including antidiabetic, antioxidant, antihypoxic, antihypertensive, antithrombotic, antifatigue, immunomodulatory, and hypocholestrolaemic. However, most of the conducted studies are limited to in vitro conditions and less data is available on assessing the effectiveness of the oat peptides in vivo. Future efforts should be directed at performing systematic animal studies; in addition, clinical trials also need to be conducted to fully support the development of functional food products, nutraceutical, and therapeutical applications.

Naked Oat (Avena nuda L.) Oligopeptides:Immunomodulatory Effects on Innate and AdaptiveImmunity in Mice via Cytokine Secretion, AntibodyProduction, and Th Cells Stimulation

The study aimed to investigate the immunomodulatory activity of oligopeptides derived from oat (Avena nuda L.) (OOPs). Healthy female BALB/c mice were randomly assigned to five groups, given deionized water (control) and 0.25, 0.5, 1.0, and 2.0 g/kg body weight (BW) of OOPs daily by intragastric administration. Seven assays were performed to determine the immunomodulatory effects of OOPs on immune organ ratios, cellular and humoral immune responses, macrophage phagocytosis, and natural killer (NK) cell activity. Spleen T lymphocyte subpopulations (by flow cytometry), serum cytokine and immunoglobulin levels (by multiplex sandwich immunoassays) were determined to evaluate how OOPs affected the immune system. Our results showed that OOPs could significantly improve innate and adaptive immune responses in mice through the enhancement of cell-mediated and humoral immunity, macrophage phagocytosis capacity, and NK cell activity. We concluded that the immunomodulatory effects might be attributed to increased T and Th cell percentages, serum interferon (IFN)-γ, interleukin (IL)-1 α, IL-2, IL-6, IL-10, IL-12, tumor necrosis factor (TNF)- α, and granulocyte-macrophage colony-stimulating factor (GM-CSF) secretions as well as immunoglobulin (Ig) A, IgG, and IgM productions. These results indicate that dietary OOPs could be considered as promising immunomodulators with dosages ranging from 0.25 to 2.0 g/kg BW.