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TriglycerideTo really understand palm oil, one has to know what a

triglyceride is. If we had special eyes, we will be able to see the

individual brick in a plastered wall. Likewise, we will see that

palm oil is made up of triglyceride molecules (the smallestparticle of a pure chemical substance that still retains its chemical

composition and properties).

Chemical analysis reveals that the triglyceride molecule is made

up of carbon, hydrogen and oxygen atoms, which can be

presented in a structural formula. This is one triglyceride

structure prevalent in palm oil.

At first glance, the triglyceride structure looks rather

intimidating. The prefix tri, gives us a clue that there are three

in the structure. A closer look shows that it is shaped like an E.

It has three long horizontal arms called fatty acids and each of

them, is attached to the same vertical frame called glycerol. The

arrangement puts the triglyceride structure in a more manageable

form.

Brick

Wall

Triglyceride

Crude

Palm Oil

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A triglyceride

What does palm oil comprise?

Malaysia, the worlds largest producer and exporter ofpalm oil, is always looking to step up the quality of this widely-used commodity by starting where it counts at home.

In July 2004, it added a compulsory quality parameter called

Deterioration of Bleachability Index, (DOBI) to the Domestic

Sales of Crude Palm Oil (CPO) Contract.

The inclusion of this new quality parameter reflects the

seriousness and commitment of the industry towards improving

Malaysian palm oil quality.

To better understand the key contractual quality parameters

DOBI and free fatty acids it is first necessary to delve into the

chemistry of palm oil.

This simplified guide will then explain the process of oxidation

and hydrolysis, and look at trans fatty acids which are of current

significance in the area of nutrition.

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Fatty acidsThe next step is to be familiar with the individual fatty acids.

There are nine main fatty acids in palm oil these are named

according to the number of carbon atoms present in the acid.

The behaviour of palm oil and its physical characteristics are

strongly influenced by the chemistry of these individual fatty

acids and the position they occupy in the triglyceride structure.

Kowing their behaviour is a pre-requisite to understanding palm

oil.

In the area of nutrition, fatty acids are categorised into two very

distinct groups saturated and unsaturated. The unsaturated is

further divided into monounsaturated and polyunsaturated. For

simplicitys sake, the example that follows is for the 18-carbon

chain acids. The same applies to fatty acids of other chain

lengths.

Saturated acidThis is best explained by thinking of a fatty acid as a special train

with a large number of carriages. Within each carriage, there are

only two seats. If the seats in all the carriages are taken, the train

is said to be full or saturated.

Similarly, if a fatty acid chain does not have any vacant seats in

the carbon chain, it is a saturated acid. The name given to this

particular 18-carbon chain acid is Stearic acid. The empirical

formula which follows is written as C18:0.

Unsaturated acid - monounsaturatedThere are other types of 18-carbon chain acids and one of them

has in the ninth and tenth carbon chain one set of vacant

seat on the same side of the carbon chain. This is a

monounsaturated acid. It is named Oleic acid, written as C18:1.

What is the difference between saturated and unsaturated fatty acids?

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Unsaturated acid - polyunsaturatedSimilarly, the other 18-carbon chain acids, namely Linoleic and

Linolenic acids have two and three sets of vacant seats in their

carbon chains respectively. These are collectively called

polyunsaturated acids, written as C18:2 and C18:3.

Palm oil is it an oil or a fat?

The terms oils and fats are often used interchangeably to mean

the same thing. In reality, there is a difference. At a temperature

of 20C, oil is liquid while fat is solid. Generally, oil contains

more unsaturated fatty acids. It should be remembered that fat

will turn into oil by just raising the temperature slightly. The fact

that palm oil has both oil and fat fractions is a big advantage over

other oils. The natural fat fraction can be used in many solid

applications without the need for hydrogenation. If at all this is

required, it is minor.

Oil

Fat

Why hydrogenate?

Highly unsaturated oils (those with high levels of Linoleic and

Linolenic acids) are liquid at room temperature. They needhydrogenation for two reasons.

To harden the oil for use in solid applications; and

To stabilise the oil because highly unsaturated oils are

susceptible to oxidation (it reacts with oxygen and turns

rancid.)

Hydrogenation is a chemical process where hydrogen is added to

the oil at high temperature and pressure, in the presence of a

catalyst, to fill up the vacant seats in the carbon chain. This, in

effect, is the artificial way to saturate the oil by converting

the polyunsaturated acids into the less unsaturated and saturated

acids. The resultant hydrogenated oil becomes harder and more

stable. Such oil can then be used for solid application. It can also

resist turning rancid for a longer period of time.

High unsaturated oil Palm oil with naturalsolid fraction

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When the oil is hydrogenated, not all the polyunsaturated acids

are converted into the desired less unsaturated and saturated acid.

Inevitably, some ends up as trans fatty acids (TFA) as seen in the

following example:

There appears to be little difference between the two acids as they

contain the same vacant seats. However, trans-oleic acid has a

portion that is twisted, as opposed to natural Oleic acid. This is

shown in the following diagram where the carriages from one to

nine are inverted. The vacant seat is no longer on the same side

of the carriage as the adjoining one. Messing around with Mother

Nature does have its consequences!

This different structural arrangement, which is the result of

hydrogenation, has serious effects on nutrition. Studies have

raised serious concerns about the negative health effects of high

dietary intakes of TFA. (More information is available in the

report, Studies link TFA to diseases in Global Oils & Fats

Business Magazine, Volume 1, Issue 4, 2004.)

What are trans fatty acids (TFA)?

TFA consumption has been linked with the risk for heart disease.

The danger is serious enough to have led to the following actions:

United States Food and Drug Administration has made it

mandatory for TFA to be labelled in food products from

Jan 1, 2006.

Denmark has taken a bolder step by banning food products

containing more than 2% TFA.

Canadas House of Commons has passed a law to limit TFA

acids in all food products.

A simple example of oxidation is easily illustrated by slicing an

apple and leaving it in the open. With time, the exposed half

turns brown because of oxidation.

In oil, oxidation is not as obvious. It can, however, be detected inthe laboratory one example is the Deterioration of

Bleachability Index (DOBI) test developed by the Malaysian

Palm Oil Board.Freshly-cut apple Cut apple exposed to air

What is oxidation?

What are the dangers associatedwith TFA?

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Oxidation is a process by which the unsaturated fatty acids of oils

and fats react with oxygen from the air, resulting in rancidity. The

more unsaturated the oil is, the more susceptible it is to

oxidation. This can be explained using the analogy of a train.

Linolenic acid, a highly unsaturated acid, has vacant seats in

three sets of carbon chains and is therefore highly vulnerable to

oxidation as these vacant seats can be easily taken up by oxygen.

About DOBI

A main objective in producing CPO is to ensure that the oil is

harvested, processed, stored and transported to the refineries

with minimum oxidation.

One step involved in refining CPO is to bleach it to removeimpurities, trace metals and oxidised products by using bleaching

earth. The final oil, called Refined, Bleached and Deodorised

(RBD) palm oil is light yellow in colour. The DOBI test is a

simple, yet quick and reliable way to ascertain the ease of

bleaching the deep-orange CPO into the final desired colour.

DOBI is a ratio of carotene (pro-Vitamin A) and secondary

oxidation (extinction at 269 nanometers). As the oil deteriorates,

carotene breaks down as more and more secondary oxidised

products are formed. Dividing the two gives an indirect net result

of oxidation that is amplified and is picked up by the DOBI test.

The test is carried out using a spectrophotometer, which

measures the absorption of a known light wavelength by carotene

and the secondary oxidation products present in the oil.

What is the rationale of the DOBI test?

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Crudepalm oil

Refining

Refined, Bleachedand Deodorised

(RBD) palm oil

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Badly oxidised oil is difficult to refine and products made from it

will be off-flavour, off-colour and have poor shelf life. Such

products can be easily detected by the palate even at very low

concentrations. This simply means the oil smells and tastes bad.

The DOBI readings can be used to differentiate CPO as the

colour of the final oil is as shown. (For more information, refer

to the MPOA booklet, What is DOBI?)

Both field and mill conditions play a big part in ensuring the

DOBI value is not just high, but remains high throughout until

the oil reaches the refineries. It is useful to be aware of salient

points for handling and storage:

Estates

Black bunches devoid of Carotene should be avoided

Over-ripe crop are prone to damage, so minimise handling

Avoid excessive handling

Reduce crop backlog

Mills

Prevent damage to fruits due to dumping on hopper top

Avoid delays in processing by adopting first in, first

out basis

Be alert for heavy metal contamination, especially copper

and iron

Optimise storage conditions, including length of storage

and temperature

Avoid blending of fresh and low DOBI oil

Palm fruit contains an active enzyme called lipase. The minute

the fruit is bruised, the enzyme present is released. This attacks

the triglyceride and breaks up the fatty acid into free fatty acid.

This irreversible process, called hydrolysis, is a fast reaction and

it is done in the presence of water. The enzyme, however, can be

inactivated by temperatures above 55C.

What are Free Fatty Acids (FFA)?

How can a high reading be obtained?

Why is the test significant?

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DOBI : 3.5 DOBI : 1.7

COLOR : 2 RED COLOR : 6.5 RED

Difference in colour readings betweenhigh and low DOBI oil

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The aim in extracting oil from palm fruits must therefore be to

minimise hydrolysis, bearing in mind that as fruits ripen, there

will also be a corresponding increase in FFA. The change is not

as rapid as when the fruits are damaged. The other period where

FFA can increase is during storage due to microbial action in the

presence of water.

The more the palm fruits are handled, the higher the damage.

The higher the content of FFA, the poorer the oil quality since

FFA will have to be removed during refining.

The key lies in ensuring that bruising is minimised and the crop

is sterilised as soon as possible. This calls for close co-operation

between the estate and mill. Once again, the salient points:

Estates

Harvest only ripe crop

Reduce handling of fruits after harvesting

Reduce backlog

Mill

Avoid dumping of fruits on hopper top

Operate first in, first out principle

Sterilise fruits as soon as possible

Minimise contamination of oil

Carry out programmed cleaning of storage tanks

If one compares triglycerides to a train station with three trains

at their allocated platforms, then the structure and parametersdescribed can be easily grasped.

FFA is formed when one of the three trains detaches itself and

leaves the station.

When all the seats are taken, the train is said to be full

or saturated.

When there are still vacant seats the train is unsaturated. Too

many vacant seats and the train are vulnerable to unwanted

elements occupying those seats.

Oxidation occurs when Oxygen, the unwanted element gets

a seat in the train.

Trans fatty acids are created when the train that perpetually

has two or three sets of vacant seats is modified to

accommodate valid passengers i.e. Hydrogen, but the

modification went awry.

How can FFA be controlled?

How do all these parameters link up?

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