TUGAS PERANCANGAN PABRIK KIMIA

PABRIK OMEGA-3

BAB II – SELEKSI PROSES

DISUSUN OLEH:

Afida Khofsoh (115061100111031)

Dhanang Edy Pratama (115061101111007)

Dewi Ariesi Rachmadianty (115061105111007)

TEKNIK KIMIA

FAKULTAS TEKNIK

UNIVERSITAS BRAWIJAYA

2014

CHAPTER II – GENERAL PROCESS DESCRIPTION

In fish oil industry, there are two main processes:

1. Process to obtain fish oil from fish2. Process to obtain omega-3 from fish oil

A. Process Selection to Obtain Fish Oil

a. Wet ProcessingThis process is the most common. Important step in this process are as below:

- Cooking : Coagulating the fish protein, breaking the fatty acid carbon chain, liberating the fish oil and another water-bound component.

- Pressing : Separating most of liquid from solid.- Separation : Separating oil and water. This step can be skipped if oil content is

below 3%- Evaporation : Concentrating the stickwater.- Drying : Drying the presscake (solid from pressing step) to remove most of

water.- Grinding : Homogenizing the fish meal size

Brief description for wet processing are below:

Raw material : Can be used for both lean (less than 2,5% fat) and oily (more than 2,5% fat) fish

Type of process : Continuous Process : Cooking and drying done separately Main equipment : Rotary-type cooker-type drier with steam injection (in direct

case) or steam jacket/coil (in indirect case), sometimes occurring with drying under vacuum, slowly agitate

Capacity : - For direct steam processing up to 60 ton fish per hour- For indirect steam processing up to 20 ton fish per hour

Capital cost : Expensive Operating cost : Cheap

The steps in wet processing are described below:

1. CookingFish oil cooking is done to recover water and oil. This step is considered the most critical step in fish processing plant. Temperature and time for cooking depends on many factors. Fish species, size, condition, temperature, and oil content is the main factor determining cooking’s operational condition. Undercooking can make the protein coagulation undone, and reduce the oil and water recovered from pressing step. Overcooking cause the destruction of fish’ skin tissue, and also reduce the oil and water recovered from pressing step.

There are two types of cooking, direct steam injection and indirect cooking.a) Direct steam injection

Direct steam process is simple and cheap, but need a considerable amount of steam. Assuming the fish’ specific heat is 1 Btu/lb.˚F and fish’ temperature 15.5˚C, it would need about 270,000 Btu heat or approximately 300 lb. steam to raise 1 tonne fish’ temperature to 90˚C. In this process, water is significant factor, relating with capital investment and operating costs.

b) Indirect steamCooker used in this process consist of a steam jacket and internal coil where the steam flows.Fuel economy can be achieved by indirect cooker, because steam used here can be from residual heat from another unit, such as evaporator. Heat from can this cooker can also be utilized to heating another unit.

2. PressingPressing usually use single-screw press or twin-screw press.

3. SeparationPressed liquor usually still contains considerable amount of solids. Those solids are coagulated protein, shell, and bone fragments. These solids is separated by screening and/or centrifuging. Mostly, separaton is done by screening, continued by smoother screening or centrifuging. Solids obtained usually still contains many oil, so they are usually recycled back to pressing step, or pressed separately. Liquid obtained is processed further to purification step.

By centrifuging, contact time between oil, water, and meal is short, so oxidation and degradation can be reduced significantly. This good oil quality can be seen from its clearer color and low free fatty acid content.

Raw fish

Press cake

Press liquor

GrinderCookerDirect steamIndirect steam

Press machine

Screening cv[;p

Centrifuge Stripper Centrifuge

Steam drier

Vibrating screen Mill

Fish meal

Fish oil

4. PurificationLiquid from separation step usually still contains a trace amount of water and meal. It can cause oil degradation and increase in free fatty acid content. The fish oil usually must be stored for a while, so it need a “final polishing”. This operation consists of stripping the fish oil by steam or hot water and centrifuging to removes the degrading-oil contaminant.

These are an example of sardine oil that has been processed by this system:

Moisture and volatiles 0.11%Insoluble impurities 0.01%Free fatty acid (as oleic ) 0.45%Oil with these specification would not degrade significantly while it is stored.

Figure 1.1 a. Block Diagram of Wet Process

b. Dry Processing

Raw material : Used for raw materials that have a low oil levels with a low number anyway

Type of process : Batch Process : Combining cooking and drying Main equipment : Rotary-type cooker-type drier with steam jacketed, sometimes

occurring with drying under vacuum, slowly agitate Capacity : 5 tons per equipment Time : 5-6 hours Capital cost : Relatively cheap Operating cost : Expensive

Figure 2.1 b. Block Diagram of Dry Process

The dry rendering process which is commonly employed for preparing meal from meat scraps finds limited use in manufacture of fish oil and meal. It is employed primarily for raw material which is both relatively low in oil content and available in relatively small quantities.

The process, nearly always of batch-type of operation, involves a combined cooking and drying step. The material to be rendered, often whole fish, is processed in a rotary-type cooker-drier, which is often of the steam jacketed type, with drying sometimes occurring under vacuum. A paddle-type stirrer may be used to slowly agitate the material during drying. Equipment with a capacity of up to five tons of raw material is common. This might be about 5 ft. in diameter by 18 ft. in length. The cooking drying operation is completed in 5 to 6 hr.

The dried meal which at this stage contains the oil then goes to a batch-type hydraulic press which removes most of the oil. This process, however, generally leaves about ten percent of oil in the meal. The recovered oil is generally much darker in color than oil rendered by the usual wet rendering method. If refined promptly after manufacture, the usual alkali refining and clay-bleaching methods yield an oil of acceptable color.The dry rendering method, being a batch process requires considerable labor and is more expensive to operate than the conventional method. It does have the advantage of being highly flexible and can be used for a wide variety of raw material available in irregular supply. It is common practice to employ a dry rendering operation alternately for meat scrap and fish reduction.

c. Azeotropic Solvent Extraction (VioBin) Process

Meat scraps

Cooker-dryer (5-6 hr) pressingDried meal

bleaching

Raw fish

Ethylene dichloride

Grinder Evaporator Extractor 1Desolventizer

tank Extractor 2

Isopropanol

Steam out + impurities

Raw material : Can be used for both lean (less than 2,5% fat) and oily (more than 2,5% fat) fish

Type of process : Continuous Process : Extracting fish oil using ethylene dichloride, then removing

ethylene dichloride from the solution using isopropanol Main equipment : Agitated vessel Capacity : Flexible Capital cost : Relatively cheap Operating cost : Relatively expensive

Beside cooking and pressing, fish oil can also obtained by extraction using a proper solvent. In VioBin process, ethylene dichloride is used as solvent.

Before extraction takes place, water is removed by distillation, thus preventing any water-soluble nutrients from being extracted from the fish. There are two-step extraction process. The first extraction takes place between 71°C (the azeotropic temperature) and 83°C (the normal boiling point of ethylene dichloride). The extracted meal is desolventized by purging with direct steam and by agitating under vacuum. This meal (commonly called undeodorized fish flour ) can be competitively sold on the animal feed market. The second extraction uses isopropanol to remove any traces of ethylene dichloride until its content in meal below 150 ppm. The meal is a high-quality deodorized fish flour for human consumption which is generally referred to as "fish protein concentrate" (FPC). The small amount of oil recovered from the second extraction is highly polymerized and cannot be added to the oil recovered by distillation from the ethylene dichloride.

The oil obtained from this process is darker and somewhat inferior than other processes, so it must be further processed to remove the various solvent, pigment, etc., that are contained in the oil stream.

Figure 2.1 c. Block Diagram of Solvent Extraction Process

d. Paramaters ConsideredTo choose one of these processes, important parameters that should be considered are:

- ContinuityContinuity is very important parameters, because it determines the overall process.

For wet process, both direct steam or indirect steam. In wet process, the most time-consuming process is cooking and pressing. Cooking by steam can be done continuously by contacting raw material with steam countercurrently. The feed is moved forward using conveyor, while steam is injected from the opposite side. Retention time requirement can be met by adjusting cooker length and conveyor speed.

Pressing is more difficult to be made continuously, because feed and product flow rate cannot be adjusted here. In other words, pressing is batch operation. It can be operated nearly continuous by using fast-moving press machine, so it needs only some minutes to press a feed completely.

Dry processing are done batchwise. Dry processing, as mentioned above, combines cooking and drying process. It needs much time to do both of it in a single vessel, which means done batchwise.

For solvent extraction, it also can be done continuously. Contacting solvent and feed can be done by mixing and agitating both of them. This can be approached to

continuous operation by using multiple vessels in series, therefore reducing the retention time.

From those explanations, it can be concluded that wet processing and solvent extraction are suitable to be applied based on its continuity.

- CapacityBased on capacity, all of the processes described above are suitable for large-scale operation, except dry processing. Dry processing is only 5 ton fish capacity per batch, much lower than the design capacity, 8,75 ton raw material per hour.

- Aid materialOnly solvent extraction process needs aid material, those are ethylene dichloride and isopropanol. This is a negative aspect, as those materials are still possible to contaminate the product.

- Operating temperature and pressureOperating temperature are slightly different from wet/dry processing and solvent extraction.Both wet and dry processing requires feed to be heated until 90˚C for both cooking and drying. In solvent extraction, it requires 71-83˚C. Those processing method operates under atmospheric condition.It can be concluded that temperature and pressure is not main consideration here, as all of them are almost same and not operated under extreme conditions

- Installation difficultyInstallation difficulty is based on total equipment employed and its technology (simple or hi-tech). Fish processing plant doesn’t require too sophisticated technology, as its most important processes is cooking, pressing, and drying, without any chemical reaction.

In wet processing, direct steam and indirect steam injection differs only in cooking operation. Direct steam employs cooker, which doesn’t need any heating jacket or coil, but need small inlet pipes to introduce steam into the feed. Indirect steam employs cooker with jacket and/or heating coil. Both of cookers are almost same and installation difficulty can be considered negligible. For pressing, drying, and other operation are same.

In dry processing, it require simpler equipment installation, because its main operation consists only three operations (can be seen at dry processing flow diagram). It makes equipment easier and cheaper.

In solvent extraction, it is more difficult than other processing method. It is because other method needs only heat to obtain fish oil, whereas in solvent extraction it needs agitation and heat. Heat is used to maintain temperature during extraction, done using

heating jacket and/or coils, same as wet and dry processing method. In addition, agitation also important to extract fish oil and remove solvent after extracting. Because of that, solvent extraction requires more process equipment and process control, so it is more difficult than other method.

In conclusion, wet and dry processing is better than solvent extraction in terms of installation requirement.

- Product yield and purityIt is difficult to give an exact purity from each method, because it greatly depends on raw material condition. It can only be estimated if a process will give low or high degree of purity, not exact number.

In wet processing, by using direct steam generally give product purity almost same as indirect steam, because both of them involves heating by steam. Product yield, however, is slightly different. Indirect steam may give lower yield, because of heat transfer uniformity issue, as there may be scum builds up on heat transfer surface, therefore reducing the cooking efficiency. But it can be carefully controlled and doesn’t significantly alter the product if managed properly.

Dry processing gives lower yield than wet processing, because its solid product still contain about 10% oil. Fish oil obtained using this method gives darker color, which means lower purity than wet processing due to oxidation caused of heating too long.

Solvent extraction probably gives the highest yield. Solvent can penetrate throughout raw material, so it is directly interacted with oil content, unlike heating-pressing. Purity, however, is still questionable. Solvent used may be still remains in fish oil product, although there are solvent removal processes. It may give harmful effect to consumer.

Based on yield and purity, wet processing using direct steam or indirect steam is favorable than others.

- Equipment costWet processing using direct steam and indirect steam both are using relatively same equipment. In direct steam though, steam used will need treatment, as it contains some impurities because of contact directly with fish. It means more cost to provide the treatment. Indirect steam is favorable than direct steam method.

Dry processing is cheapest than any method. It consists of only few unit operations, so fewer equipment requirement than others.

Solvent extraction cost is probably similar to wet processing, difference lies only in cooker and press machine, both are replaced by two extractor and one desolventizer tank.

- Operating costFor wet processing using direct steam, operating cost is relatively high, because using steam directly contacted to raw material will make the steam not pure water again. It requires considerable cost to remove impurities retained in the steam. Steam also must be renewed at all time, further denouncing this method in terms of operating cost.

Wet processing using indirect steam needs low operating cost. Unlike its direct compatriot, steam used here is not contacted directly to raw material, so the steam can be reheated again, which will give steam economy.

Dry processing is out of option. Batch processing needs higher operating cost to process fewer materials than wet processing and solvent extraction.

Solvent extraction requires medium-to-high operating cost. It is because besides heating, it is still requires solvent chemicals to extract oil. Solvent make up cost is relative high, as recycling solvent will only obtain small amount of reusable solvent. It also needs more electricity to operate the agitator, something not present in another method.

Based on operating cost, wet processing using indirect steam is the best option from other methods. It is done continuously without need any chemicals, and it also provides steam economy.

From explanation about consideration in selecting process, it is summarized in table below:

Parameter ProcessWet Process Dry Solvent Extraction

ProcessDirect Steam Indirect Steam

Continuity Continuous Continuous Batch Continuous

Capacity Large Large Up to 5 tpd Large

Aid materials - - - Ethylene dichloride, isopropanol

Temperature (°C) 90 90 90 71 - 83Pressure (atm) 1 1 1 1

Installation difficulty Medium Medium Simple Difficult

Yield Medium to high

Medium to high Low High

Product purity Medium to high

Medium to high Low Medium to high

Equipment cost High Medium Cheap Medium to highOperating cost High Low High Medium to high

Then each process methods is scored based on considerations explained above, except for operating condition (temperature and pressure). Operating condition are similar for all of the methods. Score are ranging from 0 – 100, with 0 is worst and 100 is best. Below is the scoring table:

Parameter Amount

Score (1-100)Wet Process Dry

ProcessSolvent

ExtractionDirect Steam

Indirect Steam

Continuity 20% 75 75 20 80Capacity 10% 90 90 30 85

Need of aid materials 3% 95 95 80 75

Installation difficulty 7% 85 85 93 60

Yield 20% 86 80 40 97Product purity 20% 73 85 50 75Equipment cost 8% 65 80 90 75Operating cost 12% 55 93 40 68

TOTAL SCORE 76.4 83.36 45.91 79.51

Indirect steam wet processing is chosen based on consideration above.

B. Process Selection for Omega-3 Separation

a. Molecular distillation

DistillationP = 0.1-1.0 mmHgT = 120˚C

Fish oil

Omega-3 and other C>18 molecule as product

Fatty acid with C<18

Raw Material : Used for raw materials in form heat-sensitive oils Type of process : Continuous Process : Separation between C<18 and C>18 by distillation Main equipment : Concentrate, distillate, vacuum Time : <10 seconds Pressure : Very low, <0.01 mbar Capital cost : Expensive Operating cost : Rather expensive

Molecular distillation is a technique to partially separate mixtures of fatty acid esters. This method requires temperature below 250˚C and short heating intervals. The most widely used distillation is operated under reduced pressure (0.1-1.0 mmHg). This method takes advantage of differences in the boiling point and molecular weight of fatty acids under reduce pressure. Good separation between smaller C-18 fatty acids and larger C-18 fatty acids can be achieved.

The distillation of menhaden oil, as such, concentrated only EPA from an initial of 16.0 to19.5%. However, distillation of its ethyl esters increased the EPA content from 15.9 to 28.4%. The concentration of DHA was even more dramatic. While DHA doubled from 8.4 to 17.3% in the TAG form, in the simple alkyl esters form it increased from 9.0 to 43.9%.Exposure of long-chain omega-3-PUFA to high temperatures during distillation may induce hydrolysis, thermaloxidation, polymerization and isomerization. Design of a method for preparation of omega-3-PUFA concentrates which involves low process temperature and time to minimize thermal damage is desirable.

Figure 2.1 d. Block Diagram of Molecular Distillation

b. Supercritical Fluid Chromatography

Raw Material : Used for raw materials in form heat-sensitive oils Type of process : Semi-continuous

Process : Chromatography using CO2 at supercritical condition to separating omega-3 from fish oil

Main equipment : Octadecyl silica gel column Time : 2-4 hours Pressure : 100 - 220 bar Capital cost : Expensive Operating cost : Expensive

The supercritical fluid chromatography technology is a highly selective and gentle

process working at temperatures in the range of 40°C –50°C. This method is especially

suitable for the separation of omega-3 PUFA since it combines the high selectivity of

both, the supercritical fluid and the stationary phase. This method to isolate EPA and

DHAfrom a mixture of fatty acid ethyl esters obtained from fish oil, coupling

preparative supercritical chromatography and simulated countercurrent moving bed

chromatography with several columns placed in series. In both cases, octadecyle silica

gel is used as column stationary phase whereas SC-CO2 is the eluent. Following this

method, they obtained EPA and DHA fractions with a high yield (99%) and purity

(92% and 85% respectively).

Figure 2.1 e. Block Diagram of Supercritical Fluid Chromatography

c. Urea complexation

Raw material : Complete removal of saturated fatty acids by urea complexation may be impossible since some of the shorter

Fish Oil

CO2

ChromatographyT=40oC

Omega-3 product

NUCF as crude omega-3 productWater

Urea

Mixer

Urea solution

Fish oil

NaOH

Filtration

chain saturated fatty acids do not complex with urea during the crystallization process.

Type of process : Batch Process : Complexation with urea Main equipment : Crystalizer Capital cost : Expensive Operating cost : Cheap

Urea alone crystallizes in a tightly packed tetragonal structure. In the presence of straight-chain saturated fatty acids it crystallizes in a hexagonal structure with channels of 8-12Å diameter within the hexagonal crystals. So, urea can forms a complex with saturated fatty acids. However, the presence of double bonds or more in carbon chain can reduce the likelihood of its complexation with urea. Therefore, formation of urea inclusion compounds depends on the degree of unsaturation of the fatty acids.

- In this method, KOH or NaOH is added to the fish oil. The oil is split into free fatty acids, whereas unsaponifiables component such as sterols, vitamins, xenobiotics, etc. are removed from it. The free fatty acids are mixed with an alcoholic (methanol or ethanol) solution of urea, then allowed to cool to a temperature depending of the concentration desired. The saturated fatty acids, monoenes, and some dienes are crystallized with urea, therefore it can be separated from non-crystallized fatty acids (NUCF, non-urea complexing fraction) by filtration.

- Methanol and ethanol are referred urea solvents for small-scale fractionation, but for large-scale operations, water is the best choice.

- The extent of crystallization depends on the concentration of urea and the temperature of crystallization. Omega-3 is concentrated more efficiently at -5˚C, whereas omega-3 content maximize at 10 and 15˚C, respectively.

- It is found that urea complexation can protect omega-3 from autoxidation. Therefore, omega-3 from this process is more stable.

hydrolysis process

Oillipase

centrifugation

purification product

Omega-3

T=500K10.34 bar5 h

Figure 2.1 f. Block Diagram of Urea Complexation

d. Enzymatic Method

Type of Process : Hidrolysis use enzyme Main equipment : Agitated vessel Capacity : Low Capital cost : Cheap Operating cost : Relatively expensive

Enzymatic processes in omega-3 concentration are based on the use of specific enzymes, normally lipases, which are able to catalyze reactions such hydrolysis, ethanolysis or transesterification of triglycerides. The reaction is reversible and, under low water activity conditions, the enzyme functions `in reverse', that is the synthesis of an ester bond rather than its hydrolysis. The enzymatic release of omega-3 fatty acids from fish oil represents an attractive alternative to conventional chemical approaches. Enzymatic processes can be carried out under very mild conditions without the formation of undesirable by products. In addition, the selective enzymatic approach provides the advantage of preparing pure samples of each omega-3 fatty acid.

Figure 2.1 g. Block Diagram of Enzymatic Method

e. Parameter Consideration

- ContinuityContinuity is one of major consideration here. This is downstream processing, so it

should follow the main process. Main process used here is continuous, so continuous omega-3 purification is preferably than batch one. Batch also can be used, though, as long as there are fish oil storage after the main process (it added more cost, so why continuous is preferred).

Chromatography provides semi-continuity, because it needs changing the column regularly. Molecular distillation can be operated continuously. In other hand, enzymatic and urea complexation should be operated batchwise to give best result. Those processes need time to extract omega-3 from fish oil. So, molecular distillation is preferred in terms of continuity.

- CapacityThis design is preferring large capacity than small capacity, because it is producing omega-3 directly from huge amount of fish. This plant differs from pharmaceutical industry in terms of capacity. Pharmaceutical industry considers purity more important than capacity, while this omega-3 plant preferring capacity. This is why, capacity is important in process selection.

Processes that provide large-scale capacity are enzymatic, molecular distillation, and urea complexation, while only chromatography isn’t. Molecular distillation is designed to be used in omega-3 industry and has been proven. Enzymatic and urea complexation are essentially extraction process, so it also possible to use it in large-scale capacity. Only chromatography isn’t suitable for large-scale operation until now. Based on those considerations, all of those processes except chromatography are preferred in terms of capacity.

- Aid materialAid material meant here is any additives needed to extract omega-3 directly from fish oil. It is preferred to choose process that doesn’t require any aid materials, because chemicals may alter omega-3 physical and chemical properties. Omega-3 produces here will be used for human consumption, although it is still crude grade, so chemical is unnecessary as it may dangerous to human health.

Only enzymatic and urea complexation need additives. Enzymatic method uses lipase to extract omega-3, and urea complexation uses urea, water, and NaOH. Enzymatic uses relatively safe additives, as it is safe organic material, but urea complexation utilizes urea and NaOH. Urea and, more importantly, NaOH, are dangerous chemical that can cause harmful effects to human health. It makes urea complexation out of option.

- Operating temperature and pressureOperating condition are differs significantly for those processes.

In molecular distillation, temperature and pressure used are 250 ˚C and 0.0013 atm, so

it is high temperature and vacuum operation. To provide these condition requires more equipment and process control, which is drawback for this method.

Enzymatic method requires 100˚C temperature and 10 atm pressure. It is not as extreme as molecular distillation, so it is easier to handle the equipment.

Urea complexation is the easiest process to handle in terms of operating temperature and pressure. It only requires -6˚C and operates at atmospheric pressure, not in extreme condition.

Chromatographic method requires difficult operation, because it needs high pressure, about 180-220 atm pressure. High pressure are difficult to control, and more dangerous than if using ambient pressure.

- Installation and maintenance requirementInstallation requirement is an important aspect, because it affects in incorporating fish oil processing with omega-3 purification. Beside of that, omega-3 purification is the spearhead in this plant, so more difficult the installation requirement, less attractive it is, because this plant needs simple installation and maintenance to ensure the equipment can be fixed in site when any failure happen.

For molecular distillation, it is a well-known technology among omega-3 producers. It is also a relatively simple technology, so it is not too difficult when installing and repairing the equipment.

Chromatography method is also well-known, but only for small capacity plant. It also using many helping material during the process (solvent, column, etc.), which means more installation requirement, thus more care for maintenance.

Enzymatic and urea complexation is uncommon to be employed in omega-3 plant, especially for enzymatic, as it is still new technology and proven only in small scale. For both, installation may be simple, but to adjust the equipment with optimum process conditions is relatively difficult, as data provided are scarce and only for small-scale only.

It can be concluded that molecular distillation is the best option considering installation and maintenance required.

- Equipment costEquipment cost is directly related installation requirement. For molecular distillation, its equipment are rather simple, so equipment cost is not too expensive. Urea complexation is also cheap, as it essentially needs only vessel for mixing and crystallization. Enzymatic method is more expensive, because its main equipment may be cheap, but it needs more control equipment, as it utilizes enzyme, a relatively sensitive substance.

Chromatography method is probably the most expensive, as it needs many equipment that are unusual for industrial-scale operations, for example like chromatographic column.

- Operating costFor molecular distillation, operation cost mostly used in providing heat and vacuum condition. It is not too cheap to provide those extreme conditions continuously, so its cost are in medium-to-high level compared to another processes.

Urea complexation perhaps the cheapest method. Its operation cost lies in providing urea and NaOH continuously, and -6˚C temperature. It is relatively cheap than any other processing method.

Enzymatic is almost same as urea complexation, its operating cost lies in providing additives (lipase enzyme) and adjusting operation conditions. The difference is only in temperature and pressure, where enzymatic requires 50˚C and 10 atm. It is more costly than urea complexation, as it is operated in high temperature.

Chromatographic method is the most expensive method, because its operating pressure are extreme, 180-220 atm. It is also required to change the column periodically. Those requirement makes it to be very expensive operation.

Based on operating cost, all of those methods except chromatographic are feasible to be applied.

- Product yield and purityThis parameter is very important, because it determines total omega-3 product and its quality. Omega-3 production rate and omega-3 price in this plant depends on product yield and purity parameters.

Molecular distillation gives a good yield, but low purity. It is not the most effective separation technology, so purity is low. It can concentrate omega-3 to about 50% by weight.

Urea complexation provides medium yield and purity.It is in “medium” grade because not all fatty acid can be removed by adding urea and NaOH. Urea and NaOH may still present in the product, that is why it cannot give a good purity.

For enzymatic method is in medium level in yield, but high in purity. By using enzyme, it provides medium yield. Purity is high, because enzyme is selective, so it can extract most of omega-3 and remove other contaminant if handled properly.

Chromatographic gives best purity. It is a highly selective process that can separate components in omega-3 almost completely, as high as 99% purity. Its yield are not too high, though, as it is basically not an industrial scale method.

Below are summary table for each omega-3 purification method:Parameter Process Method

Molecular Distillation

Enzymatic Urea Complexatio

Chromatography

nContinuity Continuous Batch Batch Semi-continuousCapacity Large Large Large Small

Aid materials   Lipase enzyme Urea, NaOH SC-CO2 as mobile

phaseTemperature (˚C) 250 50 -6 70

Pressure (atm) 178-217 10 0.001 1Installation and

maintenance requirement

Simple Medium Medium Difficult

Equipment cost Cheap Cheap Medium Expensive

Operation costMedium-to-expensive Medium Cheap Expensive

Product yield High Medium Medium Low

Product purity Low Medium-to-high Medium High

Based on those consideration, score table were made as below:

Parameter Amount

Score (0-10)Molecular Distillatio

n

Enzymatic

Urea Complexatio

n

Chromatography

Continuity 10% 8.5 6 4 7Capacity 12% 8 6.5 6.5 2

Aid materials 13% 8 5 1 6Temperature (˚C) 5% 6 8 6.5 6

Pressure (atm) 5% 4 6 8 2Installation and

maintenance requirement

15% 7.5 4 6 4

Equipment cost 8% 7 6 8 3Operation cost 10% 5 6 6 3Product yield 12% 8 6.5 7 5Product purity 10% 3.5 7 5.5 9

TOTAL SCORE 100% 6.85 5.89 5.57 4.76

So, molecular distillation is chosen as omega-3 purification process.