Processing of fish oil
In general terms, all crude oils and fats contain minor amounts of non triglyceride
substances. While some of these are considered beneficial to the stability of the oil,
such as tocopherols and astaxanthin (in salmon and krill oils) which protect the oil
from oxidation, other impurities are objectionable because they render the oil dark
colored, cause it to foam or smoke or are precipitated when the oil is heated in
subsequent processing operations. Other impurities reduce acceptability because of
the flavors and odors they produce in the fat or because they reduce stability and
shelf life of the foods to which the fats are added.
Some impurities are common to all fats regardless of the source or end use:
• Suspended matter (insoluble impurities).
• Naturally occurring color bodies.
• Free fatty acids.
• Volatile, malodorous compounds dissolved in the fat or oil.
These non-triglyceride substances have also been classified according to their
effect:
• Hydrolytic - moisture, insoluble impurities, free fatty acids, mono and
diglycerides, enzymes, and soap.
• Oxidative - trace metals, oxidation products, pigments, tocopherols, and
phospholipids.
• Catalyst poisons - substances which inhibit the hydrogenation reaction e.g.
phosphatides, oxidation products, and compounds containing nitrogen, sulfur,
and halogens.
• Miscellaneous - hydrocarbons, terpenes, resins, sterols, waxes, trace metals
and sugars whose effect is less well known but can be classified as
contaminants and also may have an effect on the final flavor of the oil
• Processing steps and the compounds removed by them in purification of
fish oil
Carbon Treatment
Removal of dioxins, furans, and polyaromatic hydrocarbons (PAH). This can be
performed on the starting crude oil if the oil is to be sold into the non-industrial
market.
Oil Storage
Insoluble impurities, trace moisture and some phospholipids will precipitate out
in the tanks. The combination is known as "foots".
Degumming
Phospholipids, sugars, resins, proteinaceous compounds, trace metals and
other materials.
Alkali Refining
Free fatty acids, pigments, phospholipids, oil insoluble material, water soluble
material, trace metals
Water Washing / Silica Treatment: Soaps, oxidation products and trace
metals
Drying: Moisture
Adsorptive Bleaching& Carbon Treatment
Pigments, oxidation products, trace metals, sulfur compounds, dioxins, furans,
PAH and possibly some PCB's
Winterization
Higher melting triglycerides, waxes. Used to enhance the unsaturated
triglycerides
Deodorization
Free fatty acids, mono-diglycerides, aldehydes, ketones, chlorinated
hydrocarbons and pigment decomposition products. This is usually the finishing
step and results in a bland tasting oil.
Vacuum Stripping or Thin Film, Molecular or Short Path Distillation
Removal of chlorinated hydrocarbons, fatty acids, oxidation products, PCB and
free cholesterol. Sometimes this step is used as a replacement for the
deodorization step
9.9. Unsaturated Fatty acids
Importance of Unsaturated Fatty acids
• Fish oil is rich in poly unsaturated fatty acids (PUFA). Unsaturated fatty acids
are more to oxidation and cause rancidity which affect the quality as well as
nutritive value of fish oil.
• Refined fish oils are rich in polyunsaturated fatty acids of the linolenic acid
family. Current medical research suggests that these fatty acids might have a
unique role to play in prevention of coronary artery disease and the growth of
different types of cancers.
• The highly unsaturated properties make the oils (and particularly their highly
unsaturated fractions) suitable for a number of technical applications,
particularly as drying oils and varnishes. The saturated fatty acid fraction is a
disadvantage for these purposes and must be reduced. Several specialized
processes for this reduction are available.
• Fish oils are a significant source for the production of fatty acids with a wide
spectrum of chain lengths. From these acids are produced several types of
metallic soaps, some of which are used in lubricating greases while others are
used as waterproofing agents. Small quantities of fatty; acids are used
pharmaceutically and medicinally, and for scientific research purposes.
Health beneficial effects
• Fish oil helps with cholesterol by lowering levels of LDL while also increasing
levels of HDL
• Heart problems, cholesterol, arthritis, and diabetes are some of the major
conditions in which fish oil provides some form of benefit or improved health.
• Fish oil supplements seem to have an anti-arrhythmic effect on the heart as
well as prevent cardiac arrest. In doing this, fish oil can help lower the mortality
rate of those individuals having heart complications
• Fish oil can benefit the heart because the EPA and DHA that make up the
supplement helps to prevent plaque deposits and blood clots inside arteries.
• Fish oil improves the ability of muscle cells to take up glucose in the presence
of insulin. This proves to be beneficial to those with type II diabetes
• Fish oil has been shown to have anti-inflammatory effects, especially the
Eicosapentaenoic acids (EPA). They can improve overall function in joints as
well as limit the amount of other anti-inflammatory drugs that a patient must
consume with conditions such as arthritis or other inflammatory disorders such
as Inflammatory Bowel Disease.
• Fish oil has been shown to have effects in dealing with certain psychological
disorders.It has been found that omega- 3 fatty acids are known to have
membrane enhancing capabilities in brain cells.They cause more production of
two neurotransmitters, serotonin and dopamine.This allows patients to focus
better on tasks that are at hand without as many distractions. The effects of
Serotonin have been shown to help individuals better deal with stress and other
activities.
• Fish oil has also been shown to have a number of beneficial effect on the brain.
It has been shown that 60% of the brain is made up of a structural fat, which
has a high number of DHA in it, and the brain requires a regular intake of good
fats such as the ones from omega-3 fatty acids. Low intake of omega-3 fatty acids can lead to conditions such as ADHD, dyslexia, depression, aggression,
Alzheimer’s Disease, or other dementia.
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