Browsing by Subject "TVP"

Oats and peas have good nutritional composition and they could make up a favourable raw material combination for extruded food products. However, there are only few studies on their suitability for dry extrusion, especially for textured vegetable protein products (TVP). Based on protein content, dry extrudates can be divided into TVP products having fibrous structure (> 30% protein) and snack products having puffed structure (< 30 % protein). Differences in the structures of extrudates are formed as a result of the raw materials and extrusion parameters. The structure is formed in the extruder chamber, where different unit operations (for example mixing, ripening and shaping) cause many physicochemical changes in the raw materials, such as gelation of starch, denaturation and rearrangement of proteins in flow direction. The aim of the study was to find out how different extrusion parameters, oat raw materials and them concentration affect the properties of TVP products. Oat-based TVP products were targeted to have fibrous structure and resistance for soaking. In the first step, four oat raw materials in three different concentrations (25 %, 30 % and 35 %) were extruded with pea protein isolate. Moisture content, expansion, bulk density, water binding capacity, hardness and chewiness were determined from the products and a soup test simulating cooking was performed. The nutritional contents were calculated based on information received from raw material manufacturers. Based on the analysis results, the best of the oat raw materials (oat protein flour) was chosen for the second stage of the experiments. In the second stage, oat protein flour concentrations of 40%, 50% and 60% of the dry matter were tested. The extrudates were subjected to the same analyses as before. The oat raw material and its concentration were found to have statistically significant effects on many product properties, such as expansion and hardness. The best oat raw material was oat protein flour, from which the extruded products formed a fibrous and soaking-resistant structure. Increasing the oat content of the pulp in the case of oat protein flour resulted in a harder product and the expansion and water binding capacity decreased. Increasing the screw rotation speed was found to increase as well as expansion and water binding capacity. Based on the analyses and sensory observations, it was not possible to decide on the best extrudate, because the evaluation was most influenced by the evaluator's preference questions about for example meat structure. Based on this research, by combining oats and peas it is possible to obtain well-structured TVP products with a concentration of up to 60 % oat protein flour. It may be possible to increase the oat content of the extrudates by combining many oats raw materials, but at the same time it is necessary to ensure that the other properties of the extrudates are preserved.