Research
and development work in many disciplines -biochemistry, chemical and
mechanical engineering - and the establishment of plantations, which
provided the opportunity for large-scale fully mechanised processing,
resulted in the evolution of a sequence of processing steps designed to
extract, from a harvested oil palm bunch, a high yield of a product of
acceptable quality for the international edible oil trade. The oil
winning process, in summary, involves the reception of fresh fruit
bunches from the plantations, sterilizing and threshing of the bunches
to free the palm fruit, mashing the fruit and pressing out the crude
palm oil. The crude oil is further treated to purify and dry it for
storage and export.
Large-scale plants, featuring all stages required to produce palm oil to international standards, are generally handling from 3 to 60 tonnes of FFB/hr. The large installations have mechanical handling systems (bucket and screw conveyers, pumps and pipelines) and operate continuously, depending on the availability of FFB. Boilers, fuelled by fibre and shell, produce superheated steam, used to generate electricity through turbine generators. The lower pressure steam from the turbine is used for heating purposes throughout the factory. Most processing operations areautomatically controlled and routine sampling and analysis by process control laboratories ensure smooth, efficient operation. Although such large installations are capital intensive, extraction rates of 23 - 24 percent palm oil per bunch can be achieved from good quality Tenera.
Conversion of crude palm oil to
refined oil involves removal of the products of hydrolysis and
oxidation, colour and flavour. After refining, the oil may be separated
(fractionated) into liquid and solid phases by thermo-mechanical means
(controlled cooling, crystallization, and filtering), and the liquid
fraction (olein) is used extensively as a liquid cooking oil in tropical
climates, competing successfully with the more expensive groundnut,
corn, and sunflower oils. Extraction of oil from the palm kernels is
generally separate from palm oil extraction, and will often be carried
out in mills that process other oilseeds (such as groundnuts, rapeseed,
cottonseed, shea nuts or copra).
The
stages in this process comprise grinding the kernels into small
particles, heating (cooking), and extracting the oil using an oilseed
expeller or petroleum-derived solvent. The oil then requires
clarification in a filter press or by sedimentation. Extraction is a
well-established industry, with large numbers of international
manufacturers able to offer equipment that can process from 10 kg to
several tonnes per hour.
Alongside the
development of these large-scale fully mechanised oil palm mills and
their installation in plantations supplying the international edible oil
refining industry, small-scale village and artisanal processing has
continued in Africa and Indonesia. Ventures range in throughput from a
few hundred kilograms up to 8 tonnes FFB per day and supply crude oil to
the domestic market. Efforts to mechanise and improve traditional
manual procedures have been undertaken by research bodies, development
agencies, and private sector engineering companies, but these activities
have been piecemeal and uncoordinated. They have generally concentrated
on removing the tedium and drudgery from the mashing or pounding stage
(digestion), and improving the efficiency of oil extraction. Small
mechanical, motorised digesters (mainly scaled-down but unheated
versions of the large-scale units described above), have been developed
in most oil palm cultivating African and Asian countries.
Palm oil processors of all sizes go through these unit operational stages.
They
differ in the level of mechanisation of each unit operation and the
interconnecting materials transfer mechanisms that make the system batch
or continuous. The scale of operations differs at the level of process
and product quality control that may be achieved by the method of mechanization adopted.
The general flow diagram is as follows:
PALM OIL PROCESSING UNIT OPERATIONS 
Harvesting technique and handling effects
In the early stages of fruit formation, the oil content of the fruit is very low. As the fruit approaches maturity the formation of oil increases rapidly to about 50 percent of mesocarp weigh.In a fresh ripe, un-bruised fruit the free fatty acid (FFA) content of the oil is below 0.3 percent.
However, in the ripe fruit the exocarp becomes soft and is more easily attacked by lipolytic enzymes, especially at the
base when the fruit becomes detached from the bunch. The enzymatic attack results in an increase in the FFA of the
oil
through hydrolysis. Research has shown that if the fruit is bruised,
the FFA in the damaged part of the fruit increases rapidly to 60 percent
in an hour. There is therefore great variation in the composition and
qualitywithin the bunch, depending on how much the bunch has been bruised.
Harvesting
involves the cutting of the bunch from the tree and allowing it to fall
to the ground by gravity. Fruits may be damaged in the process of
pruning palm fronds to expose the bunch base to facilitate bunch
cutting.
As the bunch (weighing about 25
kg) falls to the ground the impact bruises the fruit. During loading and
unloading of bunches into and out of transport containers there are
further opportunities for the fruit to be bruised.
In
Africa most bunches are conveyed to the processing site in baskets
carried on the head. In Indonesia some do that but now mostly by truck
bring bunches. To dismount the load, the tendency is to dump contents of
the basket onto the ground. This results in more bruises. Sometimes
trucks and push carts, unable to set bunches down gently, convey the
cargo from
the villages to the processing
site. Again, tumbling the fruit bunches from the carriers is rough,
resulting in bruising of the soft exocarp. In any case care should be
exercised in handling the fruit to avoid excessive bruising.
One
answer to the many ways in which harvesting, transportation and
handling of bunches can cause fruit to be damaged is to process the
fruit as early as possible after harvest, say within 48 hours. However
the author believes it is better to leave the fruit to ferment for a few
days before
processing. Connoisseurs of good
edible palm oil know that the increased FFA only adds ‘bite’ to the oil
flavour. At worst, the high FFA content oil has good laxative effects.
The free fatty acid content is not a quality issue for those who consume
the crude oil directly, although it is for oil
refiners, who have a problem with neutralization of high FFA content palm oil.
The
main point of clarification is to separate the oil from its entrained
impurities. The fluid coming out of the press is a mixture of palm oil,
water, cell debris, fibrous material and ‘non-oily solids’. Because of
the non-oily solids the mixture is very thick (viscous). Hot water is
therefore added to the press output mixture to thin it. The dilution
(addition of water) provides a barrier causing the heavy solids to fall
to the bottom of the container while the lighter oil droplets flow
through the watery mixture to the top when heat is applied to break the
emulsion (oil suspended in water with the aid of gums and resins). Water
is added in a ratio of 3:1. The diluted mixture is passed through a screen to remove coarse fibre.
The
screened mixture is boiled from one or two hours and then allowed to
settle by gravity in the large tank so that the palm oil, being lighter
than water, will separate and rise to the top. The clear oil is decanted
into a reception tank. This clarified oil still contains traces of
water and dirt.
To
prevent increasing FFA through autocatalytic hydrolysis of the oil, the
moisture content of the oil must be reduced to 0.15 to 0.25 percent.
Re-heating
the decanted oil in a cooking pot and carefully skimming off the dried
oil from any engrained dirt removes any residual moisture. Continuous
clarifiers consist of three compartments to treat the crude mixture, dry
decanted oil and hold finished oil in an outer shell as a heat
exchanger.
In
next year our team will plan to build small scale CPO (5 tonnes
FFB/day) processing for remotes area of Indonesia especially Sumatra
island for first priority.
We make machine
processing from FFB to CPO and CPO to cooking oil and bar soap. For oil
that are produced from kernel is used for medical industry.
Many
farmer could not process their bunches because of CPO price is too low
or already decompose on the way to the factory. With this small scale
machine process, they can process by themself for their welfare.
So we prepare for all technic manufacturing and make improvement on machine so can used by unskill man(the farmer itself).
READ MORE
PALM OIL MILL FREE RESEARCH INSTITUTE
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6. PALM OIL (ELAEIS GUINEENSIS) | PALM OIL FRUIT DESCRIPTION | SPECIFICATION | FEATURES | PURITY \ HEALTH BENEFITS
7. PALM OIL ANALYSIS | COMPLETE PROJECT WORK ON PALM OIL MILL INDUSTRY
2. HOW TO SETUP AN INTEGRATED PALM OIL MILL INDUSTRY FOR EXPORTATION | PALM OIL TREES PLANTATION
3. A BUSINESS PROPOSAL ON THE ESTABLISHMENT OF PALM OIL MILL INDUSTRY | FEASIBILITY STUDY | BUSINESS PLAN
4. PALM OIL TESTER | THE FAST, SIMPLE AND RELIABLE PALM OIL ANALYSIS SYSTEM
5. PROCESSING STEPS TO PRODUCE PALM OIL | TRADITIONAL METHOD | POWER MECHANICAL MILL
6. PALM OIL (ELAEIS GUINEENSIS) | PALM OIL FRUIT DESCRIPTION | SPECIFICATION | FEATURES | PURITY \ HEALTH BENEFITS
7. PALM OIL ANALYSIS | COMPLETE PROJECT WORK ON PALM OIL MILL INDUSTRY