Effects of different temperature profiles and corn-sago starch ratios on physical properties of extruded tilapia diets

Sago starch is a locally grown and produced starch resource in Malaysia. In this study, corn starch to sago starch ratios (CS:SS) of ۰:۲۰, ۵:۱۵, ۱۰:۱۰, ۱۵:۵ and ۲۰:۰ were included in feed mixture to contain ۲۰% starch and produce five isonitrogenous and isocaloric (۳۰% crude protein and ۱۶.۷ kJ/g, respectively) tilapia Oreochromis sp. diets. Diets were preconditioned to contain ۴۰% moisture and extruded using a single-screw extruder at screw speed of ۱۲۰ rpm using three different temperature profiles (I ۶۰-۱۰۰-۱۴۰-۱۸۰˚C; II ۶۰-۱۰۰-۱۲۰-۱۶۰˚C; and III ۶۰-۱۲۰-۱۲۰-۱۸۰˚C). Effects of these factors were evaluated on physical properties of extrudates including expansion ratio, bulk density, water stability, floatability, sinking velocity and durability. From the results, different temperature profiles and CS:SS had significant effects (p<۰.۰۵) on expansion ratio and floatability. Sago starch performed as a good binder as it gave higher percentage of water stability and pellet durability. The mixture with ۱۰:۱۰ of corn to sago starch extruded using temperature profile II (۶۰-۱۰۰-۱۲۰-۱۶۰˚C) produced the best extrudates with desirable physical properties.

Keywords:

Aquafeed , Corn starch , Extrudates , Pellet physical properties , Sago starch , Tilapia , Temperature profiles