Deacidification is an essential step in the fish oil refining process, and the currently applicable deacidification methods include molecular distillation deacidification, alkaline refining deacidification, physical refining deacidification (deodorization), organic solvent extraction deacidification, and supercritical fluid extraction deacidification, etc.
Among them, alkaline refining deacidification is the most commonly used method in the industry, which has the best deacidification effect. Following up with effective chemical neutralization to remove free fatty acids (FFA) from fish oils.
Still, it needs to be followed up by several times washing to remove the fatty acid salts, and vacuum dewatering, which makes the process more complicated, with high energy consumption, and may result in environmental pollution.
Molecular distillation pretreatment requires high vacuum and temperature control facilities, and the equipment is expensive.
The physical refining and deacidification process is not applicable to heat-sensitive fats and oils. As it is carried out in a high-temperature and vacuum environment. High-temperature water vapor is used to carry away FFA from the oil during deodorization process.
The extraction method is relatively costly and requires large amounts of solvents and energy consumption.
Adsorption deacidification refers to the use of solid materials with an adsorption effect on free fatty acids to remove FFA in oil, this method is low cost, easy to operate, has no wastewater generated, and has no impact on the environment, so it is green sustainable deacidification method.
This article is mainly introducing effective process equipment for the marine refined fish oil deacidification process, the process is capable to be controlled with highly efficient deacidification performance, less waste, and no pollution, do not destroy the effective nutrients in fish oil.
Why Does Refined Fish Oil Need To Be Deacidified?
During the processing of food-grade oils and lipids, the refinery must carry out refining and decontamination in order to ensure the quality of oils and the safety of consumption, the main processes are degumming, deacidification, dehydration, decolorization, deodorization, winterization, and other processes.
The purpose of the deacidification process is to remove FFA as much as possible from the crude oil, which originates from incomplete esterification, breakdown by de-esterifying enzymes, decomposition, and oxidation during processing and storage, etc.
The quality of the oil is closely related to the content of FFA, i.e. the acid value is measured. The smaller the acid value, the better the freshness and refining, i.e. the better the quality of the oil.
When the operation process is not strictly controlled in the processing and production, in case the temperature is too high, the process duration is too long, which will promote the accelerated decomposition of oil.
Especially when ester exchange in the modification process, triglyceride interaction causes ester group exchange or molecular rearrangement. Triglycerides are decomposed under the action of heat or esterase to produce FFA, thus increasing the acid value.
Therefore, complete refining and deacidification have a significant impact on the finished oil quality, and high FFA content can have the following impacts.
- Producing odor: Low-grade FFA has an irritating odor, when the content of FFA in oil is too high, it affects the flavor and reduces the value of products.
- FFA will promote the solubility of phospholipids, glycolipids, proteins, and other colloidal substances and fat-soluble substances. It is also a catalyst for the hydrolysis of oil and phospholipids, which will promote the hydrolysis of oil rancidity.
- FFA has poor stability to heat and oxygen, which will promote the oxidation and rancidity of oil, prevent the smooth proceeding of the concentration process, and even corrode the equipment.
The presence of FFA weakens the physicochemical stability of oil, and can easily be degraded into aldehydes, ketones, acids, and destruct nutrients ingredients, which will adversely affect human health and lead to the deterioration of the quality.
When the human body consumes oils with a high acid value, it can lead to gastrointestinal discomfort, diarrhea, and possibly liver damage. Therefore FFA must be controlled below the limit standard.
How to Reduce and Control the Acid Value of Fish Oil
The acid value is an important indicator of the FFA content. Reducing and controlling the acid value of fish oil involves several steps to prevent and mitigate oxidation and hydrolysis.
Here are some fundamental strategies you can employ to reduce and control the acid value in fish oil processing production:
- Raw Material Selection: Choose high-quality, fresh fish as the raw material for oil extraction. Proper handling and storage of fish prior to extraction can help reduce initial levels of FFA.
- Extraction and Processing: Ensure that the fish oil is extracted using methods that minimize exposure to heat, light, and oxygen, as these factors can promote oxidation and hydrolysis. Cold-press or low-temperature extraction methods are preferred.
- Antioxidants: Add antioxidants like tocopherols (Vitamin E), ascorbic acid (Vitamin C), and rosemary extract to the fish oil. These compounds can help prevent oxidation and reduce the development of FFA.
- Storage Conditions: Store the fish oil material in a cool, dark place to reduce exposure to light and heat. Oxygen-free packaging, such as nitrogen-flushed containers, can also slow down oxidation.
- Hydrolysis Prevention: Prevent water from coming into contact with the fish oil during processing and storage. Water can lead to hydrolysis of triglycerides into FFA and glycerol.
- pH Control: Maintain the oil’s pH within a suitable scale to prevent acidic conditions. The pH value needs to be constantly checked during the reaction to ensure that it is between 8 and 9 to avoid over-neutralization or inadequate reaction. However, drastic changes in pH could also affect the oil’s stability, so balance is important.
- Processing Aids: Use processing aids, such as enzymes or clay adsorbents, that can effectively remove impurities and contaminants that contribute to increased acidity.
- Regular Testing: Implement a regular testing program to monitor the acid value of the fish oil over the whole production process. This can help you identify any potential issues earlier and take corrective actions promptly.
- Proper Handling and Transportation: Ensure that the fish oil is handled in a closed-loop circulation system, and transported with proper facilities to avoid exposure to heat, light, and oxygen during transfer.
- Quality Assurance: Implement a comprehensive quality assurance program that includes proper documentation, tracking, and compliance with industry standards for fish oil production and storage.
Obviously, each step in the production process plays an important role in controlling the acid value of fish oil. By following these guidelines and maintaining strict quality control, you can help ensure that the fish oil remains stable and of high quality with a low acid value.
What are Qualified Crude Fish Oil and Standards for Refined Fish Oil?
Different species of fish oil have different testing items and indicator requirements. Especially key indicators such as DHA content, EPA content, or the total amount of both are required.
Understanding the relevant physical and chemical properties of raw materials and the main components is not only an important link in the separation and purification of fatty acids and the basis of the subsequent process operation, but also contributes to reasonable optimization of the process route, which is in line with the needs of the actual production.
As there are various classification standards for fish oil at different stages of production, processing, application, and finished products, the requirements for its physical and chemical indexes are all different.
China has formulated different standards for fish oil testing, and we will introduce some of them below.
SC/T3502-2016 specifies crude fish oil and refined fish oil used as raw material oil. Crude fish oil is mainly classified into three categories: Grade I, Grade II and Grade III, while refined fish oil is mainly classified into two grades: Grade I and Grade II.
The main testing items are sensory evaluation, physical and chemical index determination, pollutant index, antioxidant index. The most important physicochemical index requirements are as follows:
- The key index requirements of the refined fish oil are iodine price >140g/100g oil and total EPA+DHA >28%. The test items are divided into raw materials and additives requirements, sensory, physical and chemical indicators, hygiene indicators and so on.
- Fish oil microcapsules are mainly microencapsulated products made from first grade refined fish oil. The testing items mainly include raw materials, sensory, net content, physical and chemical indexes, safety and health indexes.
- Fish oil is also commonly added as an ingredient in compound feeds or highly unsaturated fatty acid nutritional supplements. Fish oil for feed is divided into three categories: primary, secondary and nutritionally enhanced. The testing items are simple, mainly sensory, physical and chemical, antioxidant.
- Health food raw material fish oil is divided into triglyceride fish oil and ethyl ester fish oil. The symbolic composition requires that the total amount of EPA+DHA＞25g/100g oil. In addition to organoleptic indexes, the main physical and chemical indexes of fish oil for health food ingredients are as follows:
| Item | Index |
| Moisture and volatiles，%, | ≤0.2 |
| Acid value (as KOH), mg/g | ≤3.0 |
| Peroxide value, mmol/kg | ≤5.0 |
| Anisidine value | ≤20.0 |
| Iodine value, g/100g | ≥140 |
| unsaponifiable substance, % | ≤3.0 |
| Lead (Pb), mg/kg | ≤0.1 |
| Total arsenic (As), mg/kg | ≤0.1 |
| Benzo(a)pyrene (as a), ug/kg | ≤10 |
Determining the fatty acid composition of the raw material enables the selection of suitable separation technologies and process parameters accordingly.
Process Equipment for Efficient Deacidification Process
The deacidification of fish oil involves the removal of FFA, which can be achieved through processes of esterification, decolorization and deodorization.
There are several efficient process equipment options including:
- Transesterification Reactors: The process vessels can be specially designed with agitators or mixers to ensure proper mixing of reactants. Heating and cooling systems are used to control the temperature of the reaction, and catalysts might be employed to speed up the esterification process.
- Physical deacidification (deodorization) tower, which use steam deacidification process to effectively evaporate out the FFA under negative pressure, and at the same time remove the odour substances in the oil. It will not only improve the smoke point of the oil, also improve the flavour of the fish oil. So so improve the stability, colour and quality of the oil.
These process equipment are specially designed according to the actual situation of processing fish oil (especially deep-sea fish oil), to achieve the best performance of reasonable process, easy operation, stable production, energy saving and emission reduction.
The whole production line can achieve different quality grades of fish oil processing by choosing the processing line appropriately.
In order to ensure the deodorization effect, the vacuum pump in the process is energy-saving and environmentally friendly, with no wastewater discharge and no steam consumption.
At the same time, a fatty acid trap is especially designed to increase the fatty acid trapping, which can effectively reduce the fatty acid inhalation into the vacuum pump system as well as increasing the capacity of fatty acid capture.
The deacidification (deodorisation) is a very important part of the oil refining process, it has a direct influence on the quality indexes such as odour, smoke point, free fatty acid content, colour and lustre of the finished fish oil.
The combined continuous deodorization tower is specially designed for the physical deacidification of fish oils, with highly efficient capacity ranging from 2 tons per day to 300 tons per day.
The process is completed under high vacuum and steam, which shortens the residence time of fish oil at high temperatures, thus reducing energy consumption.
Especially, it can prevent the local overheating of deacidified oil in the heating process, reduce the content of trans acid, and improve the quality and flavour of oil.
Efficient monitoring with control systems design are crucial for maintaining optimal process conditions, ensuring safety, and achieving consistent product quality.
Workshop process operation can be designed for automation, also can be designed to manual operation, key parts or some points with mandatory requirements shall use local automatic control, such as tank level alarm, feed and discharge of oil, high level self-control pump, etc.
Conclusion
As consumers of fish oil supplements become more discerning about the products they choose, it is imperative for manufacturers to maintain high standards of quality.
The presence of free fatty acids in fish oil can compromise its stability, nutritional value, and overall effectiveness.
We aim to provide a comprehensive understanding of the methods to remove free fatty acids during fish oil processing. Only by offering consumers a potent and reliable source of essential omega-3 fatty acids.
Informed consumers can confidently select fish oil supplements that align with their health goals.
As the demand for high-quality supplements continues to rise, mastering the art of removing free fatty acids in fish oil processing is a commitment to both excellence and consumer well-being.
Resource Reference:
Fish Oil Manufacturing Process | Molecular Distillation | Nordic Naturals
