Browsing by Author "Häkämies, Emilia"

Plant-based meat substitutes produced by high-moisture extrusion are a viable option for meeting the increasing demand for protein and reducing meat consumption. Extrudates produced by high-moisture extrusion resemble meat in structure, mouthfeel and appearance. Combining oats (Avena sativa), which contain unsaturated fats and fibers with protein-rich faba beans (Vicia faba) can result in nutritious meat substitutes. The aim of the Master's thesis was to compare the behavior of three different oat products and faba beans under varying process conditions in high-moisture extrusion. The study focused on the effect of the selected raw materials and process parameters on the structure of extrudates and the formation of fibrous structures. The experimental setup investigated the effect of two independent variables water content (50, 52.5 and 55%) and screw speed (400, 600 and 800rpm) on the response variables. Response variables during extrusion included specific mechanical energy, torque, melt temperature and nozzle pressure. Response variables determined from the meat substitutes were hardness, chewiness, gumminess, springiness, perpendicular and longitudinal cutting strength, water content, water and oil absorption capacities and color (L*, a* and b*). All extrudates produced exhibited some fibrous structures. The study found that high specific mechanical energy, torque, nozzle pressure and melt temperature were favorable for fiber formation. High water content lowered these values during extrusion. Higher screw speed was found to improve the formation of fibrous structure in the extrusion of high-fat oat food ingredients. For protein-rich and low-fat oat fiber concentrate, the best fibrous structures were formed at low screw speed. Additionally, the fibrous structure developed optimally for all blends when the water content in extrusion was lowest. The study found that screw speed had a statistically significant effect on extrusion process variables, while the water content had a more significant impact on variables related to the meat substitutes. The study also found that increase in water content decreased the hardness, chewiness, gumminess, and springiness of samples, while screw speed had the opposite effect. Besides extrusion conditions, differences in the composition of the oat products explained the variations in the samples. For instance, high protein content produced in hard, tough and dense samples. According to research results, oats and faba beans are a potential raw materials for environmentally-friendly and health-conscious meat substitutes. However, high fat content created challenges in the production of fibrous meat analogues. With appropriate process conditions, it was also possible to produce fibrous structures for these samples.