Effects of processing conditions on the system parameters during single screw extrusion of blend containing apple pomace

Abstract

AbstractThe nutritional profile of apple pomace and soy makes them ideal for development of a new extruded snack food with health benefits. Understanding how blend of apple pomace, defatted soy flour, and corn grits behave under different process conditions during extrusion will help in formulating the extrusion process. Experimental design with apple pomace level (0–20%), barrel and die temperature (100–140 °C), screw speed (100–200 rpm), and moisture content of blend (14–20% wet basis) as independent variables produced 27 different combinations that were studied using response surface methodology to investigate the effect of these variables on system parameters (apparent viscosity, mass flow rate, torque, die pressure, dough temperature, and SME). As the temperature profile increased, apparent viscosity, die pressure and specific mechanical energy decreased. Increase in apple pomace level resulted in significant (p < .05) decrease in apparent viscosity, SME, and torque, and significant (p < .05) increase in the mass flow rate. Response surface regression models were established to correlate the system parameters to the process variables. The data obtained from the study could be used for control of extrusion process of blends containing the aforementioned ingredients.Practical applicationsDuring extrusion process, the shearing effect of screws along with thermal energy and other extruding conditions modifies the rheological, physical and chemical properties of the raw materials. Investigating the changes in system parameters will provide better insight into understanding such modifications. In this study, we have chosen raw materials that are high in protein and fiber, and the effect of extrusion processing on the system parameters such as viscosity, SME, MFR, and torque was evaluated. The study provides new experimental data of system parameters of apple pomace‐soy flour‐corn grits dough during single screw extrusion. The results obtained will be of great significance for formulation and development of snacks using the above mentioned raw materials.