In the dynamic world of Omega-3 fatty acids, the transformation from crude fish oil to a highly valued product is nothing short of remarkable. As a process equipment supplier in the field, I’ve witnessed firsthand how molecular distillation technology has revolutionized this industry.
Today, I’m thrilled to share with you a successful application case that not only showcases the technological advancements but also the immense potential of this industry.
The Genesis of Change: Upgrading Fish Oil Products
Deep-sea fish oil, rich in polyunsaturated fatty acids like EPA and DHA, has long been recognized for its significant health benefits. From cardiovascular protection to aiding in brain and retinal development, its importance cannot be overstated.
The journey of refining fish oil has undergone remarkable transformations over the decades. As crude fish oil predominantly exists in the form of triglycerides, its distillation traditionally required high temperatures. However, this posed risks of thermal decomposition or transisomerisation of the unsaturated fatty acids, critical components for the oil’s health benefits.
The state-of-the-art in concentrating Omega-3 fatty acids, a process pivotal in this evolution, shifted towards the fractionation of their ethyl or methyl esters. This method circumvents the high-temperature problem by employing multi-stage Short Path Distillation. This innovative approach has significantly improved the purity and concentration of Omega-3 fatty acids, with total EPA and DHA content achievable up to 70% or higher. Additionally, the variability of the EPA to DHA ratio can be finely tuned through control of distillation conditions and the degree of concentration. Click Here for complete solution.
This evolution of fish oil products has been marked by three distinct phases:
- The 1970s: The initial phase of fish oil processing primarily dealt with natural triglyceride forms of deep-sea fish oil. The raw fish oil, obtained through steaming and pressing fish flesh, underwent a series of refining processes like degumming, deacidification, bleaching, and deodorization to yield purified fish oil triglycerides, containing 15-30% Omega-3 fatty acids.
- The 1980s: With advancements in chemical synthesis and separation technologies, the industry began converting fish oil triglycerides with approximately 25% Omega-3 fatty acids into their methyl or ethyl esters. These esterified forms, upon further purification through molecular distillation, resulted in products with 40-80% Omega-3 fatty acids. These products, due to their low viscosity and higher Omega-3 content, became highly favored in the market, dominating both domestic and international sectors of fish oil health products. During this period, high-concentration EPA and DHA ethyl esters emerged as pharmaceuticals, with products like Norway’s Pronova Biocare’s Omacor and Japan’s Mochida Pharmaceutical’s Epadel treating conditions like recurrent myocardial infarction and hyperlipidemia.
- The 1990s: Modern medical research indicated that the absorption rates of ethyl ester forms of fish oil in the human gastrointestinal tract were low, posing potential food safety risks, especially for infants and those with alcohol intolerance. Glyceryl esters of Omega-3 fatty acids were found to be more readily absorbed, with a higher hydrolysis rate in the digestive tract and enhanced safety. Functional studies showed that glyceryl ester forms of fish oil had about 70% higher bioavailability compared to their ethyl ester counterparts. Furthermore, the natural triglyceride form of fish oil proved to be more suitable for certain medicinal formulations, like those intended for blood clot inhibition, and for infant nutrition, mirroring the presence of Omega-3 fatty acids in human breast milk.
Consequently, high-concentration Omega-3 polyunsaturated fatty acid ester products gained attention for their excellent safety profile, naturalness, and high bioavailability. These attributes have made them a new growth point in the global fish oil industry. However, for a long time, the fish oil market in many countries was dominated by imported products. Local products were primarily ethyl ester fish oil and low-concentration Omega-3 fish oil. In contrast, regions like North America, Western Europe, and Japan, leveraging biotechnological advancements, have commercialized high-concentration Omega-3 glyceryl ester fish oil, with expanding sales scale.
The Shift to Esterified Fish Oil: A Game Changer in the Industry
The transition to esterified fish oil marks a pivotal moment in the omega-3 industry, a shift driven by both technological innovation and changing global circumstances. Particularly noteworthy is the impact of the COVID-19 pandemic, which, since 2020, has significantly disrupted the production of food-grade fish oil in Europe and America. This disruption presented a unique opportunity for other nations, notably evidenced by the substantial increase in imported food-grade fish oil. In 2021, the import volume of food-grade raw fish oil in China more than doubled compared to the previous year, reaching over 50,000 tons. This surge underscores the robust and growing demand for high-quality fish oil products.
In light of these developments, it became imperative to seize this opportunity, accelerating industry restructuring and product upgrading to meet the global market’s growing demand for high-concentration omega-3 ester fish oil products. The preparation method for high-content omega-3 fatty acid ester fish oil has become a key technology in the deep processing of fish oil. Both traditional physicochemical methods and biotechnological synthesis are employed in laboratories and industrial production.
Among the techniques used, low-temperature crystallization stands out. This method, also known as winterization or solvent separation, operates under low temperatures to separate different types of fatty acids based on melting points and solubility differences in supercooled working mode. Studies have shown that using low-temperature crystallization, the content of polyunsaturated fatty acids in fish oil can be increased by about 5%-8%, with total EPA and DHA content rising by approximately 4%. This method, while simple, economical, and safe, has limitations such as high energy consumption, significant organic solvent waste, and pollution, and it does not achieve a high concentration of omega-3 fatty acids. Therefore, it is often used as an auxiliary method to other techniques.
Lipase technology, which has been applied in the edible oil industry for nearly half a century, offers a more advanced approach. Lipase reactions are characterized by mild operating conditions, high catalytic efficiency, strong specificity, and easy separation of products, making them particularly suitable for processing omega-3 fatty acids prone to high-temperature oxidation. Microorganisms are a primary source of lipases, with major producing strains found in genera such as Rhizopus, Aspergillus, Candida, Mucoraceae, Phycomyces, and Pseudomonas. Lipases can catalyze a variety of reactions, including hydrolysis, ester exchange, esterification, acidolysis, and alcoholysis, playing a crucial role in the preparation of deep-sea fish oil products.
The current use of lipase technology for preparing high-content omega-3 fatty acid ester fish oil involves selective hydrolysis, esterification, and transesterification processes. The majority of lipases show Sn-1,3 positional selectivity, preferentially hydrolyzing the fatty acids at these positions. In deep-sea fish oil triglycerides, the Sn-2 position is often occupied by polyunsaturated fatty acids like EPA and DHA, with other fatty acids attached at the Sn-1,3 positions. By utilizing specific lipases, it is possible to hydrolyze most of the Sn-1,3 fatty acids, thereby enriching the glyceryl ester form of fish oil in EPA and DHA.
Furthermore, lipase-catalyzed esterification methods, where monounsaturated and saturated fatty acids preferentially react with alcohol, allow for the enrichment of unreacted EPA and DHA. These acids can also be converted into esters, separating them from other fatty acids. The lipase-catalyzed transesterification or ester exchange method, involving the exchange of acyl groups between ester fish oil and free fatty acids, short-chain alcohols, or another type of fatty acid ester, further refines the product.
The separation of ethyl ester fish oil products prepared through enzymatic methods is crucial for quality. The final product contains free fatty acids, fatty acid methyl and ethyl esters, and glycerol, which can degrade product quality and accelerate oxidation. Traditional industrial alkali refining methods, designed to remove free fatty acids, have given way to more effective techniques like vacuum distillation and molecular distillation. These methods not only remove free fatty acids but also solvents, plasticizers, PCBs, Doxin and other impurities.
The Role of Short-Path Molecular Distillation in Fish Oil Refinement
Short-Path Distillation (SPD), often referred to as “molecular distillation,” plays a pivotal role in the modern fish oil refinement process. This technology provides the distinct advantage of conducting distillation at significantly reduced pressures, resulting in considerably lower evaporation temperatures.
The project I’m highlighting today involves the implementation of this technology in a 10-ton-per-day fish oil refining and concentration unit. This setup has been running continuously for six months, showcasing not only its efficiency but also its reliability.
Achieving distillation rates of 100-150 kg per square meter of evaporator surface area per hour, SPD operates efficiently in the fine vacuum range, typically within 0.001 to 1 mbar. This attribute makes it an exemplary method for the gentle thermal treatment of heat-sensitive and high-boiling PUFA products.
In industrial production, Short Path Distillation plants utilize a unique approach for the evaporation of substance mixtures.
The process involves distributing the material as a very thin film across the evaporator surface. This thin film is formed and continuously mixed by a mechanical agitation system, enhancing the material and heat transfer as it flows down the evaporator wall.
The incorporation of wiping elements into this mixing process further improves efficiency. An internal condenser, centrally located within the apparatus, facilitates distillation even in the fine vacuum pressure range.
The primary features of Short Path Distillation include:
- High Vacuum Degree: Operates under extremely low pressures, minimizing thermal stress on the fish oil.
- Low Evaporation Temperature: Ensures gentle processing, preserving the integrity of heat-sensitive compounds.
- Short Residence Time for Heating: Reduces the risk of thermal degradation of the fish oil components.
- High Evaporating Efficiency: Achieved through the wiped thin film technique, ensuring uniform heating and evaporation.
- High Flexibility: Adapts to varying requirements in separation degrees, making it suitable for a range of fish oil compositions.
This technology marks a significant departure from traditional physical or chemical refining methods, especially in the removal of free fatty acids and undesirable taste and odor components. These impurities are primarily found in the first stage of a molecular distillation process. Operating at comparatively low temperatures, typically between 80°C and 120°C, within the appropriate vacuum range, SPD effectively eliminates these unwanted elements.
The fish oil refined through Short Path Distillation Technology exhibits superior quality characteristics:
- Low Levels of Trans-fatty Acids (TFAs): Ensuring a healthier product profile.
- Minimal Oxidation: Preserving the oil’s nutritional value and shelf life.
- Odorless and Colorless: Enhancing the appeal and purity of the final product.
- High Purity: Resulting in a premium quality oil, rich in omega-3 fatty acids.
Bridging the Gap: From Fish Oil to Biodiesel
The transformation of crude fish oil into biodiesel represents a significant leap in sustainable energy solutions. This process begins with the esterification of plant or animal oils, producing rough methyl or ethyl esters as intermediate products. The molecular distillation technique then plays a crucial role, in separating and refining these esters into high-quality biodiesel.
In this project, short-path molecular distillation is employed for multiple key steps: deacidification, solvent removal, high-temperature thermal decomposition of ester-soluble impurities, and deodorization. This results in the continuous production of light yellow, high-quality fatty acid methyl esters, commonly known as biodiesel.
The entire process is conducted under high vacuum conditions at specific temperatures, ensuring a semi-automatic, rapid, and efficient operation. This method is notable for its environmentally friendly approach, producing no harmful waste. Additionally, it significantly reduces labor intensity, two person are easy to operate the complete equipment line, consumes less energy, and effectively lowers the production costs of biodiesel. The rapid thin film centrifugal scraping and high productivity make this process particularly suited for large-scale industrial production.
After the initial preheating, the rough methyl esters are fed into a film evaporator for degassing and solvent removal. The substance then enters the first stage of the molecular distillation system, where it undergoes fractional distillation. This stage produces a primary distillate and a primary residue fraction. The residue is subsequently pumped into the secondary molecular distillation system for further separation, yielding biodiesel and a concentrated fish oil ester fraction.
Biodiesel, a form of biomass energy, is a long-chain fatty acid monoalkyl ester obtained through techniques like thermal pyrolysis. It is a complex mixture with a high oxygen content and can be used as fuel in boilers, turbines, and diesel engines.
The primary industrial application of biodiesel is its use as a high-quality, clean diesel fuel. Derived from various biomass sources, biodiesel represents an inexhaustible and sustainable energy source. In an era of depleting natural resources, biodiesel emerges as a promising alternative to petroleum-based fuels.
The Future is Bright and Sustainable
The success of this project serves as a beacon, guiding the way toward more sustainable and efficient practices in both the nutraceutical and biofuel industries. The potential for growth and innovation is boundless, and it’s an exciting time to be part of this journey.
To delve deeper into the fascinating world of molecular distillation and its applications, check out these resources for further reading and data support:
- Omega-3 Institute Analysis
- Molecular Distillation Technology Overview
- Sustainable Biodiesel Production
As we continue to push the boundaries of what’s possible, the future indeed looks bright. The success of this project is not just a win for the industry but also for the environment.
Stay tuned for more insights and updates from the forefront of the Omega-3 industry.
References:
https://www.sciencedirect.com/science/article/abs/pii/S0960852410007492
https://www.sciencedirect.com/science/article/pii/S1110062117300624
