Effects of various grated sago sizes, steeping periods and trunk sections on sago starch recovery (Metroxylon spp.)

Abstract

The sago palm stored a native starch between the trunk fiber gap. The trunk needed to be crushed into a fine size using a mechanical system. In general, the grated sago size affects the extraction efficiency, which depends on sago starch that dissolved in water during an extraction process. Therefore, the aim of this study was to determine the effect of grated sago sizes on starch recovery at different steeping periods and trunk sections. The sago trunks used were selected at three palm section (Top, Middle and Bottom). After the grating process using Sago Grater, the grated sago was dried and sieved at different sizes (2.80 mm, 2.00 mm, 1.00 mm, 0.85 mm, 0.45 mm and 0.30 mm). Furthermore, the grated sago with different sizes was steeped in sodium metabisulphite (Na 2 S 2 O 5 ) at different periods (5 mins, 24 hrs, 48 hrs and 72 hrs) for starch extraction. The results showed that the independent variables of grated size most significantly affected starch recovery (P<0.05). A substantial amount of starch could be recovered from grated sago by reducing the grated size at X<0.30 mm which was up to 58% of the extraction efficiency. The increment of the steeping period from 5 mins up to 24 hrs increased the starch recovery; however, a longer steeping period showed an insignificant difference (P>0.05). Additionally, the trunk selection also affects the starch recovery, however, it does not influence the extraction efficiency.