Extrusion Processing of Rapeseed Press Cake-Starch Blends: Effect of Starch Type and Treatment Temperature on Protein, Fiber and Starch Solubility

Abstract

For the valorization of oilseed press cakes into food products, extrusion can be used. A common way of applying the protein- and fiber-rich press cakes in directly expanded products is the combination thereof with starch, since starch gives a favourable texture, which correlates directly to expansion. To control product properties like expansion of protein and fiber-rich extruded products, the underlying physicochemical changes of proteins, fibers and starch due to thermomechanical input need to be comprehensively described. In this study, rapeseed press cake (RPC) was extruded and treated under defined thermomechanical conditions in a closed-cavity rheometer, pure and in combination with four starches. The impact of starch type (potato PS, waxy potato WPS, maize MS, high-amylose maize HAMS) and temperature (20/25, 80, 100, 120, 140 °C) on protein solubility, starch gelatinization (Dgel), starch hydrolysis (SH) and fiber solubility of the blends was evaluated. The extrusion process conditions were significantly affected by the starch type. In the extruded blends, the starch type had a significant impact on the protein solubility which decreased with increasing barrel temperature. Increasing barrel temperatures significantly increased the amount of soluble fiber fractions in the blends. At defined thermomechanical conditions, the starch type showed no significant impact on the protein solubility of the blends. Therefore, the observed effects of starch type on the protein solubility of extruded blends could be attributed to the indistinct process conditions due to differences in the rheological properties of the starches rather than to molecular interactions of the starches with the rapeseed proteins in the blends.

Study on the Function of Conveying, Kneading Block and Reversing Elements on the Mixing Efficiency and Dispersion Effect inside the Barrel of an Extruder with Numerical Simulation

“…The physical field of the drag force (F D ) is set in the whole fluid domain and can be determined by the properties of the particle velocity response time, mass, velocity and fluid viscosity. The relevant physical field is shown in Equation (11).…”

“…Immonen, M et al, investigated the de-starched oat and pea protein blend under high moisture extrusion [ 9 ]. The component and concentration of the protein isolate, and different starch types, can affect the texture properties of the extrudate [ 10 , 11 ]. However, they ignored the fact that the mixing efficiency can also directly affect the final product’s properties, and the changes in the parameters of the extrusion operation can also affect the flow of the fluid inside the barrel [ 12 ].…”

“…However, they ignored the fact that the mixing efficiency can also directly affect the final product’s properties, and the changes in the parameters of the extrusion operation can also affect the flow of the fluid inside the barrel [ 12 ]. This is due to the fact that the arrangement and combination of different screw elements inside the barrel will directly affect the shearing and mixing effects [ 11 ]. In addition to determining the form of the fluid channel, the geometry of the screw element also impacts the direction and strength of the pressure flow at a specific flow rate and speed.…”

Development and Characterization of Extrudates Based on Rapeseed and Pea Protein Blends Using High-Moisture Extrusion Cooking

“…Meanwhile, in pea, albumin and globulin represent 10-20% and 70-80% of the total seed protein, respectively [20]. Rapeseed protein is also renowned for having a well-balanced amino acid composition [21,22], as well as indications that the proteins are technologically useful [23][24][25]. All these factors point to rapeseed meal being a viable source of high-quality protein for use in the food processing sector.…”

Recovery, Isolation, and Characterization of Food Proteins

“…Manuscript 2 (“Extrusion Processing of Rapeseed Press Cake-Starch Blends: Effect of Starch Type and Treatment Temperature on Protein, Fiber and Starch Solubility”) [ 2 ] is a fascinating study on the behaviour of a protein-rich rapeseed press cake in a starch matrix during extrusion. In the extruded blends, the starch type significantly impacted protein solubility, which decreased with increasing barrel temperature.…”