Physicochemical properties of rice analogs based on multi-level: influence of the interaction of extrusion parameters

Abstract

Rice analog is a kind of ready to eat food prepared by twin-screw extruder. Few people study the drying process of wet-extruded foods and the effects of extrusion parameters on product properties based on multi-level. In this research, the experimental investigation of drying was a two-stage procedure: the evaporation of free water rapidly at first and then expansion at high temperature. The influence of the interaction of extrusion parameters on the physiochemical properties was analyzed by using response surface methodology and principal component analysis. Results showed that with regard to microwave drying in the first step, improving drying efficiency, but made the water distribution uneven. The first and second drying had opposite effects on solubility, peak viscosity, and setback of extruded products. This impact of feeding speed was most evident in hardness. Temperature was the most predominated factor for residence time, final viscosity, water-holding capacity, hardness, adhesiveness, and chewiness. The influence of interaction of extrusion parameters to the properties of rice analogs was orderly. Except for the interaction between feeding speed and screw speed, chewiness was influenced deeply by other interactions. The pasting properties were negatively correlated with elasticity, cohesion, and adhesiveness, but positively correlated with compression work. The adhesiveness had a good reference for optimizing processing parameters and control the properties of extruded foods.

Keywords

• combined drying
• central composite design
• multilevel analysis