油菜籽在挤压机腔体内变化规律的研究

Change law on rapeseed in extruder chamber

利用带有榨笼的单螺杆挤压膨化机开展油菜籽挤压膨化试验,沿螺杆轴向选取挤压机腔体内6个位置的物料进行颜色观察,考察容重、含水率、含油率、蛋白质变性情况等,通过扫描电镜观察物料微观结构。结果表明：沿着螺杆轴向,油菜籽的颜色越来越深,物料逐步被压实,螺杆末端腔体物料容重达到1.42 g/cm^3,腔体内油菜籽细胞壁被破坏,油脂流出转移至物料表面直至被从榨笼缝隙挤出,腔体内物料含油率逐渐减少,而含水率由于油脂的挤出相对升高;在整个腔体中,蛋白质变性逐步加剧,在前半段蛋白质变性程度变幅不大,NSI基本保持在32.45%-35.37%之间,后半段蛋白质变性程度剧烈,NSI显著下降,从32.45%下降到19.52%。

The extrusion experiment of rapeseed was carried out using single-screw extruder with bar cage. The samples in six positions were selected along the screw axis to observe color and measure bulk density,moisture content,oil content,protein denaturation,etc. The microstructure of sample was observed by scanning electron microscopy（ SEM）. The results showed that along the screw axis,the color of rapeseed became deeper and deeper,and the rapeseed was compacted gradually. The bulk density of rapeseed at the end of screw in chamber was 1. 42 g / cm^3. The cell wall of rapeseed in chamber was broken and the oil was transferred to surface until extruded from the slit of bar cage. The oil content of rapeseed decreased gradually,while the moisture content increased relatively because the oil was extruded. In the whole chamber,the denaturation degree of protein became serious gradually. In the first half,the denaturation degree of protein was low and NSI kept 32. 45%-35. 37%,however,in the latter half,the denaturation degree of protein was high and NSI decreased significantly from 32. 45% to 19. 52%.