## 1 Introduction  
The increasing demand for nutritious and tasty plant-based processed products is pushing the food industry to continue to develop solutions for substituting processed or unprocessed meat products with meat analogues [1]. Two attractive plant categories in this field are pulses (such as soy, peas, and beans) and cereals (such as oats), which are good sources of complementary essential amino acids and other nutritional components, and have proteins suitable for technological applications after processing, including fractionation and texturization [2]. High-moisture extrusion (HME) is a technology for processing plant-based proteins into a fibrous meat-like structure [3, 4]. The process consists of mechanical shearing of the materials with more than 40% moisture under sufficient pressure and heat treatment (>110-140 \({}^{\circ}\)C depending on the raw material) [5, 6]. This causes the unfolding of the globular proteins, followed by their aggregation and realignment. The fibrous texture is formed in the cooling die where the temperature is significantly reduced (<100 \({}^{\circ}\)C) [3] and crosslinking of the protein molecules occurs [3, 7]. To achieve a fibrous structure, it is essential that the total protein concentration in the raw material or combined ingredients is 50-70 wt% [3, 8]. Protein concentrates from pulses and cereals have gained interest over the last few years as new ingredients in alternative meat applications due to their functional similarity to soy protein glycinin [9]. The application of pea protein in meat analogues has recently increased due to its health benefits such as its antioxidant capacity and ability to modulate intestinal bacteria [10]. Research has shown that pea protein concentrate or isolate can be used in high-moisture extrusion (HME) to create a fibrous meat-like structure [5; 11; 12]. However, the properties of pea protein present some challenges related to the strength, anisotropy, and functionality of the fibers formed [10]. To address these issues, various approaches have been attempted, including mixing pea protein with other materials such as ingredients containing gluten or polysaccharides [13; 14; 15]. Low-moisture extrusion (LME) of oats has been previously reported with a focus on oat bran or oat flour as the raw material. LME products have a moisture content of less than 40% and are primarily produced as snacks or texturized vegetable protein (TVP) [16; 17]. Oat protein concentrates (OPC) can be obtained through wet milling or dry fractionation. As described by [PERSON], et al. [18], Lantmannen produces PrOatein(r), an oat protein concentrate using a combination of dry and wet milling, where dehulled oats are dry milled to separate the oat flour from the bran, which is enzymatically treated with alpha-amylase in hot water to enhance protein separation. The suspension is decanted first to obtain the soluble protein and fiber in the solution, which are heat treated to denature the protein, then decanted and centrifuged to separate the solid protein from the soluble fiber. Solids rich in oat protein are then roller dried to produce the oat protein concentrate powder, characterized with high fat and protein contents of 13-15% and 52-55%, respectively [19]. Although this non-conventional fractionation process does not utilize chemicals or involve any pH-adjustment substances as in conventional wet fractionation for isolates production, there is a significant amount of water used and the protein state is altered due to the heat treatment. Dry fractionation, alternatively, is a more environmentally friendly solution for producing protein concentrates as it does not utilize water [20]. However, for oats, the materials have to be subjected to an initial defatting procedure; otherwise, the air classification procedure fails. Dry fractionation preserves the protein's native state as it does not involve the heat treatment and improves powder functionality [21]. However, the protein's purity is lower [20; 22].