Martin Anna, Osen Raffael, Karbstein Heike Petra, Emin M Azad
Department of Food Process Development, Fraunhofer Institute for Process Engineering and Packaging IVV, 85354 Freising, Germany.
Food Process Engineering, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
Polymers (Basel). 2021 Jan 9;13(2):215. doi: 10.3390/polym13020215.
In order to valorise food by-products into healthy and sustainable products, extrusion technology can be used. Thereby, a high expansion rate is often a targeted product property. Rapeseed press cake (RPC) is a protein- and fibre-rich side product of oil pressing. Although there is detailed knowledge about the expansion mechanism of starch, only a few studies describe the influence of press cake addition on the expansion and the physical quality of the extruded products. This study assessed the effect of RPC inclusion on the physical and technofunctional properties of starch-containing directly expanded products. The effect of starch type (native and waxy), RPC level (10, 40, 70 g/100 g), extrusion moisture content (24, 29 g/100 g) and barrel temperature (20-140 °C) on expansion, hardness, water absorption, and solubility of the extrudates and extruder response was evaluated. At temperatures above 120 °C, 70 g/100 g of RPC increased the sectional and volumetric expansion of extrudates, irrespective of starch type. Since expansion correlates with the rheological properties of the melt, RPC and RPC/starch blends were investigated pre- and postextrusion in a closed cavity rheometer at extrusion-like conditions. It was shown that with increasing RPC level the complex viscosity |ƞ*| of extruded starch/RPC blends increased, which could be linked to expansion behaviour.
为了将食品副产品转化为健康且可持续的产品，可以采用挤压技术。因此，高膨胀率通常是目标产品特性。菜籽饼粕（RPC）是榨油过程中富含蛋白质和纤维的副产品。尽管对淀粉的膨胀机制已有详细了解，但仅有少数研究描述了添加饼粕对挤压产品膨胀及物理品质的影响。本研究评估了添加RPC对含淀粉直接膨化产品物理和技术功能特性的影响。评估了淀粉类型（天然淀粉和蜡质淀粉）、RPC添加量（10、40、70克/100克）、挤压水分含量（24、29克/100克）和机筒温度（20 - 140℃）对挤出物膨胀、硬度、吸水性、溶解性以及挤出机响应的影响。在120℃以上的温度下，无论淀粉类型如何，70克/100克的RPC都会增加挤出物的截面和体积膨胀。由于膨胀与熔体的流变特性相关，因此在类似挤压条件下，于密闭腔流变仪中对RPC以及RPC/淀粉共混物在挤压前后进行了研究。结果表明，随着RPC添加量的增加，挤出的淀粉/RPC共混物的复数黏度|η*|增加，这可能与膨胀行为有关。
