鱼肉蛋白质挤压过程中操作参数对挤出物水分含量及堆积密度的影响

Effect of processing variables on both moisture and bulk density of extrudates in wet extrusion of fish protein

研究了鱼肉蛋白质在双轴挤压蒸煮处理过程中,主要操作参数末段腔体温度,螺杆转速和供料水分含量对挤出物的水分含量和堆积密度两个物理性质的影响。研究的3个操作参数每一个变量设5个水平,测量相应挤出产物的水分含量和堆积密度,分别建立挤出物水分含量与操作参数,挤出物堆积密度与操作参数的回归拟合方程。结果表明,供料湿度明显影响挤出物的水分含量。供料水分含量、腔体温度和螺杆转速对挤出物的堆积密度都有影响;水分含量与操作参数,堆积密度与操作参数的回归拟合方程的相关系数R2分别是1.000和0.926,拟合的统计模型可信度高。

In this trial, effect of extrusion process parameters on the physical properties of extruded fish protein using a twin screw extruder was studied employing Response Surface Methodology. As input variables, twin-extrusion cooking running parameters examined were barrel temperature in the last zone, screw speed and feed moisture, each at 5 levels. Meanwhile, as output variables, physical properties of the resultant extrudates included water content and bulk density. Results showed that moisture content of extrudates were affected intensely by feed moisture, and bulk density was effectively controlled by controlling the feed moisture, barrel temperature and screw rotation speed. Polynomial regression equations of process variables with two physical properties were obtained with R^2 = 1.000, and R^2 =0.926, respectively. Both of two regression equations were highly credible. It is the first domestic study on the effects of thermoplastic extrusion cooking conditions on physical properties of extrudates for the case of wet fish protein extrusion cooking. From the results discussed above, it is evident that for the extrusion of products with specific characteristics from wet fish protein, operating conditions can be defined fairly accurately. Variation of barrel temperature, screw speed and feed moisture enables extrudates with specific physical properties to be made for various applications. Moreover, response surface analysis can be seen to provide a quite effective means for the study and optimization of operating conditions in extrusion technology. By extrusion cooking, it is possible to produce products with attractive textures such as textured products with meat structure. Extrusion of proteinrich materials can be used to create various ＂fabricated＂ foods, most commonly meat analogues or extenders. Experience has proven that it must be delivered in forms that fall within the organoleptic limits established by traditional human eating habits. So, by converting low value fish into protein food ingredients, the products should have a functional value in the food systems already familiar to a populace. Texturized fish protein products from low value fish protein by extrusion conking can be used as meatlike products or meat extenders after rehydration with water or flavored liquids. The investigation of the relationships between chewy properties or eating quality and physical parameters for extrusion texturized fish protein are still unexplored. The work on these issues will be continued.