Physical characteristics of extrudate from mixed corn gritsoybean flour with treatments of moisture content and extruder barrel temperature

Departement of Agricultural and Biosystem Engineering, Universitas Gadjah Mada, Jl. Flora No.1, Bulaksumur, Yogyakarta 55281, Indonesia

^* Corresponding author: jknugroho@ugm.ac.id

Abstract

Corn is a commonly used raw material for snack production. However, corn has a relatively low protein content, approximately 7%. Consequently, adding soybean flour is expected to enhance the protein content in snacks. This study investigates the impact of moisture content and barrel temperature treatments on the physical properties of the produced extrudates. Snacks were manufactured using a SYSLG-IV twinscrew extruder with a capacity of 10-15 kg/h and a die diameter of 6 mm. The raw material utilized in the experiment comprised a mixture of 20% soybean flour and 80% corn grit. The study involved two main treatments: barrel temperature (at 120°C, 130°C, and 140°C) and moisture content (at 14%, 16%, and 18%). Parameters assessing the physical properties of the extrudates included expansion ratio, hardness, moisture content, water absorption index, and water solubility index. The results demonstrated that increased moisture content led to increased extrudate moisture content (ranging from 1.80% to 4.71%) and hardness (ranging from 17.45 N to 40.16 N). Conversely, it caused a decrease in the expansion ratio (ranging from 2.11 to 2.03), water solubility index (ranging from 8.82% to 7.01%), and water absorption index (ranging from 5.70 to 4.92).