This thesis describes a study on the design, fabrication and testing of a
prototype grating machine for wet sago starch production. In order to extract
the starch, the mechanical method is required to break the trunk and producing
fine grated sago. The more refined the grated sago produce, the more sago
starch can be dissolved in water during the extraction process. In this case, it
was reported that 65.7% of sago starch remained inside the residue. A new
technology has been developed to overcome the issue. The determination of
physical and mechanical properties of sago trunk was conducted as a
prerequisite for designing process. A primarily study was conducted on
Handheld Chainsaw, Roller Grater, Coconut Husk Decorticator and Coconut
Grinder to determine the grating speed, grated sago size distribution and
grating contact area. The result shown that the hand chainsaw produced the
highest percentage of finer grated sago (56.80%: X≤0.85 mm) and the lowest
teeth contact surface area of 4 mm2. However, it has the lowest capacity. A
further study was conducted to determine the effect of grated sago sizes on
starch recovery at different steeping periods and. As a result, 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 min up to 24 hours increased the
starch recovery. However, a longer steeping period showed an insignificant
difference (P>0.05).
A new concept of sago grater was designed and developed. Initially, an
assessment of sago grating machine design requirement was conducted using
surveys. All the needs and goals were divided into several sub-objectives. The
sub-objective was converted into functions modeling to generate sub-functions
and then select the appropriate technology. A Morphological Chart was used to
produce 6 complete system concepts. The selection of complete system concepts was based on matrix assessment and detail design of concept was
generated for the fabrication process. The newness of sago grating machine
has the advantages over the existing machines. It does not require conducting
a debarking process (20 minutes per log). The machine has the capability to
adjust the feeding height (0 cm to 5 cm) according to the sago trunk diameter
size which is minimizing the losses during the grating process. The design
novelty, the grater disc has ability of adjusting the disc diameter size (40 cm to
48 cm), which is no need to be made in various of sizes and each single part of
grater teeth can be replaced to reduce the maintenance costs. The grating
capacity was 45.9 kg/min with a total starch recovery percentage was
19.86±0.14% and at 47.97%.of extraction efficiency
