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Microencapsulation of Omega-3 Fatty Acids: Application and Challenges
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Wednesday, 18 November, 2015, 08 : 00 AM [IST]
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Jeyakumari A, Zynudheen AA, Parvathy U, Narasimha
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fiogf49gjkf0d Introduction
Omega-3 fatty acids are a group of essential fatty acids that are required but not synthesised by the human body. Biochemically, Omega-3 fatty acids belong to the family of polyunsaturated fatty acids (PUFA) which have their first unsaturated double bond on the third carbon from the methyl end, or the terminal (n) carbon bond. This may be represented as either the lower case (O) or the upper case (O) of “omega” (“last” in Greek). There are two subgroups of Omega-3 fatty acids. One is a-linolenic acid (ALA, 18:3n-3) derived from green leafy vegetables, nuts and plant oils and the other group of ? -3 PUFA is derived from marine source; the major being eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). The major dietary sources of ALA, EPA and DHA are given below:
Major Sources of Omega-3 Fatty Acids
Omega-3 Fatty Acids |
Sources |
Alpha-linolenic acid (ALA) |
Dark green leafy vegetables, perilla, chia, kiwifruit,
certain nuts, seeds and their oils, flaxseed,
hempseed and walnut, canola oil |
Eicosapentaenoic acid (EPA) and
Docosahexaenoic acid (DHA) |
Fatty fish such as mackerel, sardine, tuna,
herring, liver of lean white fish such as cod and halibut,
blubber of marine mammals such as whales and seals, algal species |
(Source: Kris-Etherton, P.M., et al. AJCN. 71: 179-188, 2000)
Heath Benefits of Omega-3 Fatty Acids
The Omega-3 fatty acids have been recognised for their important role in human health. They are essential not only for normal growth and development but also implicated in the prevention of coronary artery disease, hypertension, diabetes, arthritis, other inflammatory and autoimmune disorders, and cancer. Many studies encourage the adequate intake of Omega-3 fatty acids by pregnant and lactating women to support overall health and development of retina and brain in foetus.
Omega -3 Fatty Acid content in Seafood & Fish Oil
Seafood | Omega -3 (EPA + DHA) g /100 g | Fish oil | Fatty acid | Mackerel | 1.8-5.3 | Sardine oil | 10 - 20% EPA | Salmon | 1.0-2.0 | Tuna oil | 5 - 6% EPA | Trout | 0.5-1.6 | Mackerel oil | 10 - 15% EPA | Tuna | 0.5-1.6 | Eel oil | 8 - 12% EPA | Halibut | 0.5-1.0 | Salmon egg oil | 15 - 30% EPA | Shrimp | 0.2-0.4 | Shark oil | 20.6% EPA + DHA | Cod, Plaice, Flounder | ~ 0.2 | Cod liver oil | 10% EPA + DHA |
Adapted from Belda and Pourchet-Campos (1991) and Park et al. (1997).
Plant derived Omega-3 Fatty Acids (ALA)
Seafood | Omega-3 ( g /100 g) | Flaxseed Oil | 52.1 | Flaxseed, Ground | 22.9 | Walnuts, Black | 2.1 | Walnut Oil | 10 | Canola Oil | 9.3 | Soybean Oil | 6.4 | Mustard Oil | 5.7 |
Source: http://www.gbhealthwatch.com/Nutrient-Omega3-TopFoods.php
Guidelines for EPA and DHA Intake by Different Organisations
Organisation | Recommendation | American Heart Association | 0.5-1.0 g/day | British Nutrition Foundation Task Force | 1.0-1.5 g/day | UK Department of Health | 0.2 g/day | World Health Organization | 0.7 g/day | Institutes of Medicine Dietary Reference Intakes | 0.11-0.16 g/day | Health and Welfare Canada | 1.0g/day |
Source: Functional food fact sheet from Food Insight, Published on May 23, 2014
Nowadays, functional foods and bioactive compounds are gaining more importance due to consumer’s awareness towards nutrition. Despite the proven health benefits, the intake of Omega-3 PUFA does not meet the recommended intake of 250 mg per day in most countries. In this respect, enrichment of food products with Omega-3 fatty acids has received an increasing interest in the past few years. However, Omega-3 PUFA oils cannot be added directly to the food matrix because when exposed to oxygen and heat they promote oxidation during food processing resulting in undesirable taste, and odour in fortified food products. Lipid oxidation products are known to be health hazards as they are associated with ageing, membrane damage, heart disease and cancer. Microencapsulation is one of the alternative approaches to protect Omega-3 PUFA oils from oxidation during processing. Encapsulation is a rapidly expanding technology with wide application in food and pharmaceutical industries.
What is microencapsulation?
Microencapsulation is a technology of coating small particles of finely ground solids, drops of liquids, or gaseous components, with protective membranes/microcapsule walls. The substance that is encapsulated may be called the core material, the active agent or internal phase. The substance that is encapsulating may be called the coating, membrane, shell, wall material or external phase. This wall protects the core compound from biological degradation and enhances its stability. Microcapsules or micron size ranges from 2-5000 µm. It has been reported that these microcapsules can release their contents at controlled rates over a long period of time.
Reasons for Encapsulation
A substance may be microencapsulated for a number of reasons. Examples may include protection of reactive material from their environment, safe and convenient handling of the materials which are toxic or noxious, taste making, for controlled or modified release properties, means of handling liquids as solids, preparation of free-flow powders or modification of physical properties of the drug.
Microencapsulation Methods
Microencapsulation methods can be divided into physical and chemical processes. Physical process includes Spray Drying, Spray Chilling, Rotary Disk Atomisation, Fluid Bed Coating, Stationary Nozzle Coextrusion, Centrifugal Head Coextrusion, Submerged Nozzle Coextrusion and Pan Coating. Chemical process includes Phase Separation, Solvent Evaporation, Solvent Extraction, Interfacial Polymerisation, Simple and Complex Coacervation, in-situ Polymerisation, Liposome Technology and Nanoencapsulation. So far, Spray Drying, Complex Coacervation and Freeze Drying are the most commonly used commercial techniques for microencapsulation of Omega-3 fatty acids. Emerging microencapsulation methods of Omega-3 oils include Spray Granulation and Fluid Bed Film Coating; Electrospraying for Ultrathin Coating and Encapsulation using Ultrasonic Atomiser.
Spray Drying: The general process of spray drying involves dispersion of a core material into a polymer solution, forming an emulsion or dispersion, pumping of the feed solution/emulsion, atomisation of the mixture and dehydration of the atomised droplets to produce microcapsules. Depending on the feeding solution and operating conditions, the size of the microcapsules varies from 10–50 µm or large size particles of 2–3 mm with active load of 5–50%.
Freeze Drying: In this method, the emulsion is frozen at temperature between -90°C and -40 °C and then dried by sublimation under low pressure. In general, less than 40% of active load can be achieved by this method. Encapsulates made by Freeze Drying have particle size ranging from 1 to 100 µm.
Coacervation: In Simple Coacervation, the oil component is usually dispersed in gelatin solution and then a pH adjustment causes the gelatin to coacervate and form a coating over oil droplets. The subsequent cooling step hardens the coating and encapsulates the oil. Complex Coacervation uses two oppositely charged polymers and is one of the most promising technologies for stabilisation of Omega-3 oils by microencapsulation delivering highest pay load of 40–90%. In this method, the isolated coacervates might be dried by Spray Drying or Fluid Bed Drying. Encapsulates made by Coacervation have particle sizes ranging from 10 to 800 µm.
Application of Microencapsulated Omega-3 Fatty Acids for Innovative Food Products
New food and beverage products with added Omega-3 fatty acids have emerged in the market because of the mounting evidence of the overall health benefits associated with Omega-3 fatty acids. Microencapsulated Omega-3 fatty acids can be used in a wide assortment of foods. Examples of foods being fortified with Omega-3 fatty acids include milk-based products, juices, table spreads, salad dressings, yogurt, sauces, breakfast cereals, baked goods, pastas, infant formulas, baby foods and juices. Omega-3 fatty acids are also available in the form of dietary supplements.
Commercially Available Omega-3 Enriched Foods
Product | Total omega-3 content | Omega-3 enriched milk (Neilson dairy) | 0.02mg/cup (2%) | Omega-3 enriched bread (Tip Top Up) | 0.27g/2 slices | Powder loc- Omega-3 encapsulated powders. | 0.5-0.8g oil/g of dry powder | Omega-3 powder (Ocean Nutrition) | 22% | ROUPA ‘10’ n-3 Food (DSM) | 9% | Driphorm HiDHA Bake D101 (Nu-Mega) | 7.4% | Omega-3 enriched eggs (Gray Ridge Egg Farms) | 0.4g/egg |
Source: Marine Nutraceutical and Functional Foods, 2008, Barrow and Shahidi (Etd), P.139
Challenges and Future Prospects of Omega-3 Microencapsulates
There are various challenges ahead for use of Omega-3 fatty acids as functional ingredients in daily diet. These include low consumer awareness about potential health benefits and harsh processing conditions negatively affecting the integrity of the microcapsules. Regulatory compliance narrows the selection of generally regarded as safe (GRAS) materials for use in encapsulation of food ingredients and hence only very limited number of matrix/coating materials have been approved for use in food. In spite of all challenges, the use of microencapsulated ingredients in food is steadily growing with the demand for technology to protect, mask and control delivery of food ingredients. Also, there is still need for increased stability of Omega-3 microcapsules to broaden the range of food application. However, due to health benefits of Omega -3 fatty acids, the Omega-3 functional food market is predicted to expand tremendously in the near future.
(The authors are scientists from ICAR- Central Institute of Fisheries Technology. They can be contacted on ciftmum@gmail.com)
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