Effects of Extrusion Cooking of Sweet Potato on System Parameters and Product Properties

Abstract

Effects of barrel temperature (83–117 °C), feed-moisture content (17–33% w.b.) and screw speed (60–110 rpm) on the system parameters (product temperature, die pressure, motor torque and specific mechanical energy (SME)) and product responses (expansion ratio, waterholding capacity (WHC), swelling power and throughput) during the extrusion cooking of sweet potato were studied using response surface methodology. Second-order polynomial models were fitted for the system parameters and the product responses as a function of process parameters. The relationship between the system parameters and the product responses was also investigated using Pearson’s correlation. Results showed that product temperature and die pressure were significantly affected by all the process variables. SME and torque decreased with the increase in barrel temperature and feed-moisture content. SME was found to be varying with screw speed for different conditions of barrel temperature and feed moisture content. Expansion ratio and WHC had a negative correlation with feedmoisture content. Swelling power increased with increase in feed moisture content and barrel temperature. Throughput was significantly affected by the screw speed. A good correlation was obtained between the system parameters and the product responses which facilitates in understanding the product characteristics and enables the manipulation of process variables and system parameters to acquire desired product properties.

Keywords: Twin screw extrusion, specific mechanical energy, torque, swelling power throughput

Cite this Article: Danie Shajie A, Mishra Hari Niwas. Effects of extrusion cooking of sweet potato on system parameters and product properties. Research & Reviews: Journal of Food Science and Technology. 2015; 4(1): 32–42p.