ABSTRACT

The effects of incorporation of water yam (Dioscorea alata L.), feed moisture content, and extrusion conditions on physical characteristics of expanded extrudate were studied using response surface methodology. The mixture was prepared using maize grit, rice grit, and gram flour. Yam flour was incorporated at 10–20% level in the feed mix, and the moisture content of the feed was varied from 13% to 15%. The extrusion process was run at varied temperature conditions (90–110°C) in a single screw extruder. A numerical multi-response optimization technique was used for optimizing input variables. Lateral expansion (LE) and starch digestibility had significant (p < 0.05) positive effects due to yam incorporation, while density, water absorption index (WAI), and water solubility index (WSI) had a significantly negative effects. Feed moisture had a significant (p < 0.05) effects on product density and WSI positively. Barrel temperature had a significant (p < 0.05) positive effects on LE and starch digestibility where density and WAI had a significant negative effects. Optimum operating conditions for yam flour addition, feed moisture and barrel temperature were 20%, 13.28%, and 108.83°C, respectively. Corresponding to these process variable, predicted values were 144.65% for LE, 0.222g/cm³ for density, 6.002 g/g for WAI, 7.217% for WSI, and 305.15 µg/g for maltose content with desirability 0.848. The extrusion conditions and response variables reveal the possibility of using yam to produce extruded expanded snacks.

摘要

使用响应面方法研究了掺入水山药 ( Dioscorea alata L. )、饲料水分含量和挤出条件对膨胀挤出物物理特性的影响。该混合物使用玉米砂、大米砂和克面粉制备。山药粉在饲料混合物中的掺入量为 10-20%，饲料的水分含量从 13% 到 15% 不等。挤出过程在单螺杆挤出机中在不同的温度条件 (90–110°C) 下运行。数值多响应优化技术用于优化输入变量。横向膨胀 (LE) 和淀粉消化率具有显着性 ( p< 0.05) 由于山药掺入而产生的积极影响，而密度、吸水指数 (WAI) 和水溶性指数 (WSI) 具有显着的负面影响。饲料水分对产品密度和 WSI具有显着的 ( p < 0.05) 积极影响。桶温对 LE 和淀粉消化率有显着的 ( p < 0.05) 正面影响，其中密度和 WAI 有显着的负面影响。山药粉添加、饲料水分和机筒温度的最佳操作条件分别为 20%、13.28% 和 108.83°C。对应于这些过程变量，LE 的预测值为 144.65%，0.222g/cm ³对于密度，WAI 为 6.002 g/g，WSI 为 7.217%，麦芽糖含量为 305.15 µg/g，合意性为 0.848。挤压条件和响应变量揭示了使用山药生产挤压膨化零食的可能性。