Texturization of a Blend of Pea and Destarched Oat Protein Using High-Moisture Extrusion

Grain protein fractions have great potential as ingredients that contain high amounts of valuable nutritional components. The aim of this study was to study the rheological behavior of destarched oat and pea proteins and their blends in extrusion-like conditions with a closed cavity rheometer. Additionally, the possibility of producing fibrous structures with high-moisture extrusion from a blend of destarched oat and pea protein was investigated. In the temperature sweep measurement (60-160 degrees C) of the destarched oat protein concentrate and pea protein isolate blend, three denaturation and polymerization sections were observed. In addition, polymerization as a function of time was recorded in the time sweep measurements. The melting temperature of grain proteins was an important factor when producing texturized structures with a high-moisture extrusion. The formation of fibrillar structures was investigated with high-moisture extrusion from the destarched oat and pea protein blend at temperatures ranging from 140 to 170 degrees C. The protein-protein interactions were significantly influenced in the extruded samples. This was due to a decrease in the amount of extractable protein in selective buffers. In particular, there was a decrease in non-covalent and covalent bonds due to the formation of insoluble protein complexes.Peer reviewe

The effect of deamidation and lipids on the interfacial and foaming properties of ultrafiltered oat protein concentrates

The aim of this study was to investigate the air-water interfacial and foaming properties of oat protein concentrates produced by an enzyme-aided ultrafiltration method with and without deamidation. A further aim was to determine the role of polar and non-polar lipids at the air-water interface and in foams. The deamidated and ultrafiltered oat protein concentrate (DE-UF-OPC) exhibited higher surface tension compared to the ultrafiltered oat protein concentrate (UF-OPC). DE-UF-OPC had a significantly higher negative zeta potential value (−50 mV) compared to the UF-OPC (−38 mV) at pH 7.0. The higher net charge of the DE-UF-OPC may have decreased the equilibrium concentration of oat proteins at the interfacial layer due to higher repulsion between them. Both of the ethanol extracted OPCs exhibited higher surface tension values most likely due to the partial denaturation of albumins and/or globulins. Removal of the majority of non-polar lipids had no effect on the equilibrium surface tension of OPCs. DE-UF-OPC and UF-OPC exhibited some, but limited foaming ability. The removal of non-polar lipids significantly improved the foamability and stability of DE-UF-OPC and UF-OPC, but the removal of polar lipids only improved the foamability of DE-UF-OPC.Peer reviewe

Functionalisation of oat protein concentrate towards semi‑solid applications

There is a need to find more sustainable sources of protein due to increasing demand and population growth. Dry milling and air classification yields oat protein concentrate (OPC, 45.5% protein) from defatted oat kernels. However, applications of oat protein in foods require improved technological functionalities. The literature review of this study discusses the chemical composition of oats, and modifications of plant protein through thermal treatment, microfluidizer, and high hydrostatic pressure (HHP). The experimental work aimed to understand the effect of heat treatment (40, 60, 80 °C), microfluidization (50 MPa), and high hydrostatic pressure (HPP, 300 and 600 MPa) on the applicability of OPC in semi-solid food matrices. The treatments were performed on OPC suspensions with 2.4, 4.6, 8.5, 12, or 20 % protein. Changes in particle size, protein solubility, surface hydrophobicity, and rheological properties were measured. Stability of OPC dispersion was improved by microfluidizer treatment while HHP at 600 MPa accelerated sedimentation. Viscosity increased significantly by thermal treatment at 80 °C and HHP at 600 MPa. Gel formation occurred at 12 and 20% protein concentration with 80 °C heat treatment. Highest increase in particle size was shown by HHP at 600 MPa resulting in volume mean diameter, d4,3 of 32-38 µm. On the other hand, microfluidizer reduced d4,3 to 3.3-3.4 µm. Protein solubility increased from 13 to 23% by increasing protein concentration from 2.4% to 20%. Protein solubility was improved by 1-1.7% at 2.4-8.5% protein concentration by thermal treatment at 60 °C, homogenization, and HHP at 300 MPa. Protein solubility was reduced by HHP at 600 MPa by 1.4-1.5 %. Protein surface hydrophobicity was increased by thermal treatment at 60 and 80 °C and HHP. Microfluidizer showed slight increase in solubility at 4.6% protein concentration (1.1-1.6 %) and lowered surface hydrophobicity at 8.5% protein concentration. Thermal treatment showed best result in achieving gel-like structure, whereas microfluidization showed potential for stabilising dispersion