In the Palm Oil industry, the palm oil is usually obtained by
means of a string of processes in the mill that involves mechanical
systems. There are many operation units in a typical mill. In sum-
mary, oil palm processing in mill involves the reception of fresh
fruit bunches from the plantations, sterilizing and threshing of
the bunches to free the palm fruits, digesting and mashing of the
fruits and pressing out the crude palm oil, clarification, purifica-
tion, drying and storage. For the kernel line, there are steps such
as nut/fiber separation, nut conditioning and cracking, cracked
mixture separation, kernel drying and storage (Poku, 2002). Kernel
crushing facilities often existed in some integrated plants for the
extraction of the crude palm kernel oil, which are then further trea-
ted to purify and to dry it for storage and export.
2.1. The sterilization process
The first step in the sequence of processes to extract the oil in
palm oil mill is the sterilization process, which is a heat pre-
treatment process subjected to the fruits. Pre-treatment refers to
the solubilization and separation of one or more of the four major
components of biomass-hemicellulose, cellulose, lignin and extrac-
tives: to make the remaining solid biomass more accessible to fur-
ther chemical and biological treatment (Graf and Koehler, 2000).
Pre-treatments are sometimes crucial in order to make material
handling easier through subsequent processing steps. The steriliza-
tion process functions in supplying heat for fruits softening and
encourage loosening and easier detachment of the fruits from fresh