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Algal oils
Algal oils: Properties and processing for use in foods and supplements
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R.J. Winwood DSM Nutritional Products (UK) Ltd., Heanor, Derbyshire, UK
6.1 Introduction The global market for omega-3 fatty acids for human consumption was worth about US$25 billion in 2011 and is expected to grow to US$37.7 billion by 2016, mainly due to increased consumption in India and China (Carr, 2014). Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the key omega-3 fatty acids found in fish oil. The health benefits of EPA and DHA are widely recognized by scientists and regulatory bodies around the world, including authorized health claims issued by the European Food Safety Authority (EFSA). In recent years, intake recommendations for EPA and DHA for health maintenance have risen sharply and it is evident that most of the world’s population is in a state of insufficiency. However, current fish oil production is many fold insufficient to supply this and there is competition for its use from the aquaculture industry. Matters are complicated by the fact that fish catches suitable for fish feed/fish oil production have leveled off at 25–30 million tons per annum. Around 4.5 kg of wet fish is required to generate 1 kg of fish meal and fish oil (Kitessa et al., 2014). The source of EPA and DHA in fish oils is the marine microalgae that the fish consume. The microalgae can be grown in contained fermenters. Oil can then be extracted from the ruptured algal cells. The downstream processing of the algal oil from this stage is very similar to fish oil. The resulting algal oil has no contact with the marine environment at any time during its production. It is of high purity and organoleptic quality and can generally be used to fortify foods in the same way that fish oil is used, but is suitable for vegetarian diets. The story of development of algal oils and how they are processed has been described previously (Barclay et al., 2010; Winwood, 2013a,b—two publications). This chapter will concentrate on the practical aspects of incorporating algal oils into fortified foods and exploring the market demand.
6.2 Enriching foods with marine omega-3 fatty acids The main source in the human diet of EPA and DHA is oily fish. Many diets around the world, including the westernized diet, have minimal consumption of oily fish and are awash with omega-6 fatty acids derived from vegetable oils. The problem is Specialty Oils and Fats in Food and Nutrition. http://dx.doi.org/10.1016/B978-1-78242-376-8.00006-5 © 2015 Elsevier Ltd. All rights reserved.
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e xasperated by the fact that incorporation of fish by-products in animal feeds has declined very significantly, meaning that erstwhile sources such as organ meats and most eggs can no longer contribute nutritionally useful amounts of EPA and DHA to the diet. As an example, the combined EPA and DHA content of farmed Atlantic salmon from Tasmania was around 1750 mg/100 g wet weight with a fish oil diet in winter 2002, but had fallen to around 1050 mg/100 g in autumn 2013 as increasing amounts of chicken fat were added to the fish oil feed (Kitessa et al., 2014). While supplements containing fish oil provide an excellent way of meeting our nutritional requirements for EPA and DHA, sadly those people that need them most are either unable, or unwilling, to buy them. Even among purchasers of fish oil capsules, the level of compliance to achieve recommended intake levels is poor. Food fortification remains the most practical way of increasing EPA and DHA intake across the whole population. While a key aim of fortification is to increase levels of the long-chain marine omega-3 fatty acids EPA and DHA, additional intake will also help reduce the fatty acid ratio n6:n3 to healthy levels.
6.3 Strategies for developing omega-3 enriched functional foods Incorporation of either fish or linseed (flax)/rape seed (canola) oils in the feed of livestock results in higher concentrations of omega-3 in food products based on poultry, eggs, meat, or milk. Transgenic technology can be utilized to produce plants and animals (pigs, beef, poultry) with higher levels of omega-3 fatty acids. While many consumers are suspicious of genetically modified (GM) technology, the development of GM oil seed crops with high levels of EPA and DHA has continued. In 2012, a transgenic version of the oilseed plant Arabidopsis thaliana yielded an oil containing 15% DHA (Kitessa et al., 2014). In 2014, approval was given by the U.K. government body DEFRA to the Rothampsted Research Centre at Harpenden for a trial to grow the oil seed crop Camelina sativa, which had been genetically modified with genes from marine algae to produce high levels of EPA and DHA (Farmers Guardian, 2014). The seed contains 35–45% oil of which levels as high as 30% EPA or 14% DHA/12% EPA combined are possible, depending on the variant. Camelina is of particular interest as a crop as it can be grown on marginal agricultural land and can withstand cool and wet conditions and yet still produce an oil yield of some 800 kg/ha. A full account of the development of the crop has been written by Ruiz-Lopez et al. (2014). Another approach has been taken by Monsanto with their transgenic soybean MON 87769. This GM soybean produces an oil rich in stearidonic acid, which is a significant precursor of EPA, though the onward conversion to DHA is very limited in humans. The EFSA Panel on Genetically Modified Organisms has recently delivered a positive opinion with regard to an application to place the soybean MON 87769 on the European market for use in food and feed (European Food Safety Authority (EFSA), 2014). In Europe, most algal omega-3 oils are covered by the Novel Foods legislation. This specifies the food applications in which the oil may be used and defines a maximum addition level per 100 g of product that must not be exceeded. As an example, the algal
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Table 6.1 Maximum use levels of algal oil derived from Schizochytrium for various food categories in the European Union as of July 2014 (Commission Information Decision, 2014) Food category
Maximum use level of DHA
Dairy products except milk-based drinks
200 mg/100 g or for cheese products 600 mg/100 g 200 mg/100 g or for analogs to cheese products 600 mg/100 g 600 mg/100 g 500 mg/100 g 250 mg DHA per day as recommended by the manufacturer for normal population 450 mg DHA per day as recommended by the manufacturer for pregnant and lactating women 250 mg per meal replacement
Dairy analogs except drinks Spreadable fat and dressings Breakfast cereals Food supplements
Foods intended for use in energy-restricted diets for weight reduction as defined in Directive 96/8/EC Other foods for particular nutritional uses as defined in Directive 2009/39/EC excluding infant and follow-on formulae Dietary foods for special medical purposes
Bakery products (breads and rolls), sweet biscuits Cereal bars Cooking fats Nonalcoholic beverages (including dairy analog and milk-based drinks)
200 mg/100 g
In accordance with the particular nutritional requirements of the persons for whom the products are intended 200 mg/100 g 500 mg/100 g 360 mg/100 g 80 mg/100 ml
DHA oil Life’s DHA™-S is now allowed in the following applications following a recent revision (July 2014) of the approval. The allowed categories and maximum use levels from this algal oil derived from the microalgae Schizochytrium are shown in Table 6.1. Practical advice for the food technologist as regards how to practically incorporate such algal oils into food products is given in Section 6.6.1.
6.4 What are the benefits of using microalgae to produce food ingredients? Microalgae have a higher growth rate and higher biomass density in comparison to land-based crops. They are a source of rare, key bioactive nutrients normally only found in the marine environment and provide an alternative to extraction from fish.
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The fermentation substrates used for microalgal fermentation are widely available and derived from renewable resources. (Glucose syrup is a popular choice as the major constituent and is usually obtained by enzymic degradation of starch.) Microalgal fermenters can be used to fix carbon dioxide. Numerous phototrophic algae are able to adapt their metabolism to heterotrophic conditions; indeed, that is the only way they can function when the sun’s rays are not available! San Francisco-based Solazyme Inc. is a good example of a company making full use of heterotrophic algal fermentation to make a wide range of products aimed at the fuel, green chemistry, nutrition, and the lubricants sector (www.Solazyme.com). They have existing algal oil plants in the United States at Peoria, IL, and Clinton, IA, currently producing 2000 MT and 20,000 MT, respectively. However, a much larger plant, capable of producing 100,000 MT of algal oil per year using massive 625,000 L fermenters started production in Brazil on May 29, 2014, in a joint venture with Bunge Global Innovation LLC. Microalgae such as Chlorella and Spirulina have been grown for many years in open ponds for use as nutritious food ingredients. They can also be a useful, commercial source of natural pigments; for example, carotenoids from Dunaliella, Astaxanthin from Haematococcus, and Lina Blue from Spirulina (Milledge, 2012). The use of open pond systems has been challenging in the past mainly due to economic and contamination issues, but new technology has been developed to overcome these problems and it is reported that yields of up to 5000 US gallons of algal oil per acre are now possible (Carr, 2014).
6.5 Selecting EPA and DHA producing microalgae Currently, the most commonly used microalgae for the production of DHA-rich algal oil and biomass are from the marine members of the families Thraustochytriacea and Crythecodiniacea. The Thraustochytrids include the genera Schizochytrium and Ulkenia, whereas Crypthecodinium is a genus of the family Crypthecodiniaceae. Members of these genera are widely dispersed in the oceans of the world. The selection of suitable heterotrophic microalgae depends on their ability to inexpensively produce large quantities of DHA from glucose in large stainless steel vessels (i.e., absence of light). Autotrophic algae require a source of light, using the light of the sun to drive their metabolism. This seriously limits the design of the fermenter, particularly the size, which in turn limits the yield. Open pond systems, on the other hand, are optimally suited for growing autotrophic algae. Thraustochytrids are heterotrophs with a high oil content (typically 50–77% on a dry weight basis). The oil is >90% triacylglyceride, rich in DHA, and has a low cholesterol content. The precise taxonomy of Thraustochytrids remains a matter of some debate. They are found in the kingdom Chromista and phylum Labyrinthulomycota. In fact, they are often found in association with decomposing plants/algal matter and their nutrition is primarily saprotrophic (Armenta and Valentine, 2013).
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In practice, the strains of microalgae in use today in the production of DHA- and EPA-rich oils are the results of intensive collection, isolation, and screening procedures. The most successful strains shared the following properties (Barclay et al., 2010): ●
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High growth rates High lipid contents Growth unaffected by low salinity conditions High proportion of DHA and EPA as percentage of total lipids in elevated temperature fermentation (30 °C).
All strains in commercial use have undergone extensive toxicological investigation as part of their conditions for regulatory approval. A useful review of the safety and toxicological aspects of producing single cell oils has been written about by Zeller (2006). DSM Nutritional Products use the microalgae Crypthecodinium cohnii (see Figures 6.1 and 6.2) to make their DHASCO™ oil for the infant formula market. This oil has a DHA content of 40–45% w/w, and virtually no EPA. DSM also produce an algal oil for the food, beverage, and supplement industries called Life’s DHA™—S oil. This is made using microalgae Schizochytrium (see Figure 6.3) and is standardized at 35% or 40% DHA, and also contains low levels of EPA (<2%). DSM uses a different strain of Schizochytrium to produce an algal oil with a DHA:EPA ratio of 2:1 to match the ratio found in certain high-quality fish oils. The product targeted at the food fortification market called Life’s Omega™ 45, contains a minimum of 40% total DHA and EPA, and is specified as having minimum levels of 24% DHA and 12% EPA (w/w); while the product targeted at the supplements market, particularly for high potency capsules, is called Life’s Omega™ 60, and contains minimum levels of 30% DHA and 15% EPA (w/w).
Figure 6.1 Photomicrograph of the microalgae Crypthecodinium cohnii. Courtesy of Casey Lippmeier of DSM Nutritional Products. ©DSM Nutritional Products.
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Figure 6.2 Photomicrograph of the microalgae Crypthecodinium cohnii. Courtesy of David L. Spector of Cold Spring Harbor Laboratory, Laurel Hollow, NY, USA. ©DSM Nutritional Products.
Figure 6.3 Photomicrograph of the microalgae Schizochytrium. Courtesy of Casey Lippmeier, DSM Nutritional Products ©DSM Nutritional Products.
There are other producers of DHA-rich algal oils in China and India. In May 2014, the U.S. agri-giant Archer Daniels Midland Company announced its intention to produce a DHA-rich oil from heterotrophic algae (Shultz, 2014) through a partnership with Synthetic Genomics Incorporated (SGI). Until recently, the production of EPA-rich algal oil has been largely restricted to the laboratory scale. According to Milledge (2012), algal oils rich in EPA have been produced from the microalgae Phaedodactylum tricornutum, Nannochloropsis
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Figure 6.4 Photomicrograph of the microalgae Nannochloropsis. Courtesy of Aurora Algae Inc. ©Aurora Algae Inc.
and the diatom, Nitzchia. These organisms have predominantly an autotrophic metabolism. Aurora Algae Inc. cultivate proprietary strains of Nannochloropsis microalgae (see Figure 6.4) in large seawater open ponds, in geographic locations with high solar radiation. They use proprietary techniques to select for strains with high oil yield, high proportion of EPA, and substantially no DHA. Aurora Algae has commercialized a high EPA content (> 65%) oil under the product name A2 EPA Pure™, targeted for use in the supplements and pharmaceuticals sector. EPA-rich algal oils, again with minimal DHA content, are also produced in the southwestern United States by Qualitas Health (www.qualitas-health.com) using shallow, open, and closed pond fermentation systems. Here, a saltwater strain of Nannochlopropsis oculta has been selected to provide optimum yields in the prevailing climatic conditions.
6.6 The difficulties of utilizing omega-3 fatty acids in new food product development Very long-chain polyunsaturated fatty acids (PUFAs) such as EPA and DHA are extremely liable to oxidation. Once the process of oxidation has begun, it is self- propagating and cannot be stopped. The result of this process is highly rancid foods with strong fishy odor and flavors. Fish oil is a by-product of fish protein production, and hence requires extensive refining and purification to remove the odors and tastes associated with its source. This process of oxidation can also lead to a loss of nutritional value of the food in which it is incorporated through co-oxidation of other nutrients.
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A reluctance to use a fish-originated oil can be overcome by using algal oil. The specially selected strains of microalgae are grown in contained fermenters under controlled conditions. However, while algal oil can have superior organoleptic characteristics, the key component omega-3 fatty acids (EPA & DHA) are just as likely to oxidize as those found in fish oil once incorporated in food products—so the same precautions to prevent oxidation are required. The main causes of LC-PUFA oxidation in food products are: ●
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Exposure to oxygen; High temperatures (time dependent); Trace metals (e.g., Fe, Cu, Zn); and Light.
The key techniques available to food technologists for preventing oxidation of LCPUFA during the production and shelf life of food products are as follows: ●
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Limiting exposure to air (i.e., oxygen); Nitrogen blanketing; Preventing air incorporation (e.g., reducing turbulent flow, filling tanks from bottom); Ensuring that on the production line all transportation systems are kept clean and free from components containing ferrous metal, copper, or zinc; Avoiding rework; Ensuring the thermal processing should be for the minimum time possible. High temperature short time (HTST) processing is preferred; and Use deionized water wherever possible.
Selection of suitable raw materials can help prevent oxidation problems: ●
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Good starting quality ingredients should be used at all times; All other ingredients should be low in Fe, Cu, and Zn; and Vegetable oils should be low in oxidative parameters (i.e., low peroxide values (PV), anisidine values (AV), totox values (TV), and long Rancimat oxidative stability values).
Finally, care must be taken with the final product in terms of packaging and storage. ●
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Packaging should be selected that has good barrier properties to oxygen and UV light. Where possible, the package should be sealed immediately after a nitrogen surge. A realistic shelf life should be decided on in accordance with the prevailing storage conditions.
6.6.1 Algal oil handling and incorporation into foods Algal oils are best stored frozen at −20 °C, or kept chilled at 4 °C if freezing is not possible. Frozen oil should be subjected to a minimal number of freeze–thaw cycles—an absolute maximum of twice. Algal oil may be thawed at room temperature (15–30 °C) overnight. If the oil is not completely thawed, it may be heated in a water bath at 50 °C for a maximum of 60 min. Whenever possible, the entire amount of thawed oil should be used during the day’s production, but where this is not possible, the remainder should be flushed with nitrogen and frozen again as soon as possible. The exception to
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this rule is where a further production is to be made within 1 week. In this case, the oil should be kept covered, flushed with nitrogen, and chilled at 4 °C prior to use. During the production process itself, it is important that the other ingredients should be fresh and high quality. The following advice will be useful for the incorporation of algal oils into the final food (the same advice is broadly applicable to fish oils as well): ●
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Add the oil as late as possible in the production process. Minimize thermal exposure and air incorporation as much as possible. Where possible, produce in a closed system using a suitably modified atmosphere. Ensure the oil is homogenously distributed into the food matrix. Usually it is advisable to prepare a premix concentrate of oil in another suitable component of the formulation.
It is important that the other ingredients should be free of pro-oxidants, such as metals (Cu, Fe, and Zn), oxidized oils and fats, and photosensitisers (e.g., riboflavin in milks). Where possible, a suitable antioxidant cocktail should be added. While synthetic forms are usually the most efficacious, usually the natural forms are preferred for regulatory and labeling reasons. Commonly used antioxidants include mixed tocopherols, ascorbic acid, rosemary extract (carnosic acid), green tea extracts, and ascorbyl palmitate. Once production is complete, the choice of packaging is also important. Where possible, this should be impermeable to both oxygen and light and encourage single-serve use. Storage conditions of the final food should be also ideally in dark, cool conditions. The actual dose of algal oil in food usually reflects local nutritional labeling requirements. It is more difficult to achieve good tasting, long shelf life foods if higher doses are used.
6.7 Delivering omega-3 fatty acids into food products: Stable algal oil forms and their use in the production environment Native algal oil will have the highest concentration of EPA and DHA and thus have the optimum cost in use. However, it will be very susceptible to oxidation and hence require more restrictions in terms of handling and storage. If this is a problem, then powder or emulsion forms may provide a solution.
6.7.1 Microencapsulation In general, food systems offer a challenging environment for omega-3 fatty acid. Those foods with long shelf lives (e.g., cereals) pose a particular problem, because even if the highest quality of oil is used, oxidation will begin eventually. With this in mind, it is not surprising that food technologists have concentrated on fortifying shorter shelf life products such as dairy or bakery items (Moghadasian, 2008). However, even here it is inevitable that the complex food matrix will contain components that will initiate or
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catalyze the oxidation process of the algal oil. In addition, the complex environment will reduce the efficacy of antioxidants and chelating agent added with the intention of delaying the initiation process. So one technique that can be used in these systems is microencapsulation, which effectively provides an impermeable barrier between the oil and food matrix. The technique of microencapsulation was pioneered by the pharmaceutical industry where it was used to protect sensitive ingredients. The process involves protecting the core with a protective encapsulating matrix. The microencapsulation process must have the following properties if it to be viable for the use of omega-3 fatty acids (as listed by Taneja and Singh, 2012): ●
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The stability of algal oils must be improved (before it is added to the food matrix). It has to provide an effective barrier to oxidation and be compatible with the food matrix. It must not have an effect on organoleptic properties or the shelf life.
The use of encapsulated omega-3 fatty acid powders greatly extends the range of possible applications they can be used in, but by definition the cost has to be greater and the content of active EPA/DHA will be much less. We shall consider the main encapsulating systems applicable to algal oils (Barrow et al., 2013).
6.7.2 Oil in water emulsion systems Emulsifying agents such as lecithin, gum arabic, and octenyl succinate starches produce an emulsion with a negative charge on the surface of the droplet, which attracts pro-oxidant metal ions (Taneja and Singh, 2012). This can be overcome using proteins, typically those derived from milk or soya. Once a stable emulsion of the algal oil has been produced, the next step is usually to dehydrate it and form a powder, typically using spray drying. For extra protection, the resulting powder can be atomized and coated with a secondary layer, typically a high melting fat or starch. A major drawback of this type of microencapsulation is that the barrier matrix has to be water-soluble and hence tends not to be an effective barrier to oxygen. The level of loading of the algal oil is limited. Levels above 50% are difficult to achieve without making the encapsulate too fragile for operational use.
6.7.3 Complex coacervation These systems usually contain two colloids with opposite charges. The process typically starts with the formation of an emulsion with a positively charged polymer (e.g., gelatin (type A) or chitosan). This emulsion is then mixed with a second emulsion containing negatively charged polymers such as gum arabic, alginates, carboxy methylcellulose, or gelatin (type B). The pH of the mixture is carefully adjusted until a coacervate results with the polymers precipitating on the core. The resulting microparticles can then be agglomerated by a process of gentle cooling with agitation. The agglomerates can then be stabilized by cross-linking reactions (e.g., the use of the enzyme transglutaminase in the case of gelatins). They are then spray dried to form a powder. Though the process is complex, it has the advantage of enabling higher oil
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loadings with minimal surface oil content (typically 0.2%, compared with up to 1% for simple emulsion systems) (Wang et al., 2014). Ideally, marine omega-3 powders should be stored at 4 °C and should not be frozen as the coating may be ruptured as the oil expands. As with the native oil, the powder, once opened, should be used entirely. Any remainder should be sealed, ideally nitrogen flushed and used within a week.
6.7.4 Alginate microspheres Alginates are ionic biopolymers that can be used to produce microbeads containing the oil. Typically, alginates form a gel when in contact with calcium ions at an optimal pH.
6.7.5 Omega-3 oil emulsions Omega-3 emulsions can be added directly to aqueous systems and are ideal for use in the production of beverages, but there are limitations. As with powders, emulsions are most expensive to use and have less EPA and DHA potency. Although making an emulsion of omega-3 oil reduces the risk of oxidation, they are still much more liable to oxidize than powders and require special handling. Omega-3 emulsions will still cause turbidity, so they should not be used with clear beverages. It is possible to produce an ultrafine nanoemulsion that overcomes this problem. However, the nanotechnology used can fall afoul of regulatory restrictions; hence, such emulsion cannot be sold in the European Union at the present time. Where omega-3 emulsions are added to low juice beverages (i.e., less than 50%), it is necessary to add a stabilizing system (e.g., pectin and or xanthan gum) and carefully emulsify the whole batch.
6.7.6 Food applications for algal oils Proven applications for algal omega-3 oils include fresh and ultra heat treated (UHT) milks (skimmed, semiskimmed, and full fat types), yogurts, processed cheeses, ice cream, frozen confections, chocolate confections, cooking oils, margarines/spreads, soft candy gums (gummies), salad dressings, processed meat, and bakery items. Some applications that are not suitable for omega-3 fortification include tea bags, instant chocolate beverages, high boiling sweets (candies), and chewing gum.
6.8 Regulatory approval of algal oil for use in foods and supplements DSM’s algal oil DHASCO® has been approved for use in infant formula in the European Union under Commission Directive 2006/141/EC. This regulation states that addition is optional but when it is added, 1% of the total fat content should consist of n-3 LC-PUFAs and 2% of the fat content should be n-6 LC-PUFAs of which 1% is
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arachidonic acid (ARA). DHASCO® is also considered as a food in the EU (e.g., not a novel food) based on its “significant degree of use” prior to 1997. DSM’s Life’s DHA™-S algal oil is approved for use as a novel food ingredient in specific food categories and dietary supplements under the European Novel Food Regulation (EC) 258/97 (OJ L 209/55, 16.7.2014; OJL 144/13, 12.6.2003; OJL 278/56, 23.10.2009). The same applies to DSM’s Life’s Omega™ algal oil which typically contains a ratio of about 2:1 DHA:EPA. This was authorized in July 2012 (see http://ec.europa.eu/food/food/biotechnology/novelfood/dha_o_authorisation_ letter_06072012_en.pdf). Both algal oils must be labeled “DHA rich oil from the microalga Schizochytrium sp.” under these regulations. Algal oils from other producers have also received novel foods approval on the basis of their “substantial equivalence” to DSM’s Life’s DHA™-S algal oil. With regard to health claims, the following article 14 claims have been authorized and published in the Official Journal of the European Union (Commission Regulation (EU) No 440/2011 of May 6, 2011). ●
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DHA intake contributes to the normal visual development of infants up to 12 months of age. DHA maternal intake contributes to the normal development of the eye of the foetus and breastfed infants. DHA maternal intake contributes to the normal brain development of the foetus and breastfed infants.
With regard to article 13.1 claims, the final approved claims appeared in the Official Journal of the European Union 25.2.12, Commission regulation (EU) 432/2012 of May 16, 2012. In this case, the following claims appear for DHA alone: “Maintenance of normal brain function” and “Maintenance of normal vision,” while for EPA and DHA, a claim of “maintenance of normal cardiac function” appears. The accompanying conditions of use for all three claims include a recommended total daily intake of 250 mg per day for the general population. In April 2014, The U.S. Food and Drug Administration (FDA) published a final rule prohibiting certain nutrient content claims for foods that contain omega-3 fatty acids (USDA, 2014). The final rule prohibits label statements that claim the products are “high in” DHA or EPA, and synonyms such as “rich in” and “excellent source of.” Any existing claim will not be permitted beyond January 1, 2016. This is likely to affect food manufacturers who were limited to their inclusion rate and could previously claim an “excellent source of omega-3” with just the addition of 32 mg per serving. Structure/function claims for dietary supplements that are based upon clinical science will still be able to be made, but the dose should be in alignment with the levels used in the relevant studies.
6.9 Future trends The use of algal oils in foods and supplements will continue to grow as demand for EPA/DHA increases. The use of algal oils remains a proven, sustainable alternative to fish oils and will form an increasingly large proportion of the EPA/DHA market because of the limitations on fish oil production. The range of algal oils will expand.
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New technology will further enhance the yields of algal oil from open pond algae fermentation and we can expect to see further growth of production plants in sun-blessed areas where the land is unsuitable for agricultural use. The scientific understanding of the health benefits of marine omega-3 fatty acids continues to grow exponentially; hence, they are likely to be recommended for both prevention and treatment of a much wider range of clinical conditions as well as health benefits. The continuing development of marine omega-3 ingredients forms with improved oxidative stability will enable their incorporation into an ever-widening range of food products.
6.10 Sources of further information and advice NUTRI-FACTS, a website that is a useful source of scientific information on essential micronutrients. www.nutri-facts.org. DHA/EPA Omega-3 Institute. Scientific material written by Dr. Bruce Holub of the University of Guelph in Canada. www.dhaomega3.org. Fats of Life. A science-based website about the health effects of PUFAs. www. fatsoflife.com. GOED omega-3, the Global Organization for EPA and DHA Omega-3. 1075 Hollywood Avenue, Salt Lake City, UT 84105, USA. Tel.: +1-801-746-1413. www. goedomega3.com. ISSFAL, International Society for the Study of Fatty Acids. www.issfal.org. National Algae Association, 4747 Research Forest Dr., Suite 180, The Woodlands, TX 77381, USA. Tel.: +1-936-321-1125. www.nationalalgaeassociation.com. “Oils and Fats – Production Properties and Uses” training course, held annually at the Leatherhead Food Research (see www.leatherheadfood.com for details). Omega-3 Centre. Australian-based organization promoting omega 3 fatty acids. www.omega-3centre.com.
Acknowledgments A special thank you is due to my longtime colleague, Dr. Ruben Abril, whose long experience of incorporating marine omega-3 oils in food products has been richly drawn upon in the writing of this chapter. I would also like to thank my colleagues John Dobson and Milly Rooijakkers for their information and support.
References Armenta, R.E., Valentine, M.C., 2013. Single cell oils as a source of omega-3 fatty acids: an overview of recent advances. J. Am. Oil Chem. Soc. 90, 167–182. Barclay, W., Weaver, C., Metz, J., Hansen, J., 2010. Development of a docosahexaenoic acid production technology using Schizochytrium: historical perspective and update. In: Cohen, Z., Ratledge, C. (Eds.), Single Cell Oils, Microbial and Algal Oils, second ed. AOCS Press, Urbana, pp. 75–96.
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Barrow, C.J., Wang, B., Adhikari, B., Liu, H., 2013. Spray drying and encapsulation of omega-3 oils. In: Food Enrichment with Omega-3 Fatty Acids. Woodhead Publishing Series in Food Science, Technology and Nutrition, Woodhead Publishing, Sawston, UK (chapter 6). Carr, M., 2014. Meeting Global Omega 3 Demand with Algae, SupplySide® Omega 3 Insights, July 2014. Virgo Publishing LLC, Phoenix, AZ. Commission Implementing Decision of 14 July 2014 on authorising the placing on the market of oil from the micro-algae Schizochytrium sp. as a novel food ingredient under Regulation (EC) No 258/97 of the European Parliament and of the Council and repealing Decisions 2003/427/EC and 2009/778/EC (notified under document C(2014) 4670), OJ L 209, 16.7.2014, pp. 55–58. European Food Safety Authority (EFSA), 2014. Scientific Opinion on application (EFSAGMO-UK-2009-76) for the placing on the market of soybean MON 87769 genetically modified to contain stearidonic acid for food and feed uses, import and processing under regulation (EC) No 1829/2003 from Monsanto. EFSA J. 12 (5), 3644. Farmers Guardian, 2014. http://www.farmersguardian.com/arable-farming/news/defra-givesgreen-light-for-gm-omega-3-plants-trials/63769.article. Kitessa, M.S., Abeywardena, M., Wijesundera, C., Nichols, P.D., 2014. DHA-containing oilseed: a timely solution for the sustainability issues surrounding fish oil sources of the health-benefitting long-chain omega-3 oils. Nutrients 6, 2035–2058. http://dx.doi. org/10.3390/nu605035. Milledge, J.J., 2012. Microalgae-commercial potential for fuel, food and feed. Food Sci. Technol. 26 (1), 28–30. Moghadasian, M., 2008. Advances in dietary enrichment with n-3 fatty acids. Crit. Rev. Food Sci. Nutr. 48, 402–410. Ruiz-Lopez, N., Haslam, R.P., Napier, J.A., Sayanova, O., 2014. Successful high-level accumulation of fish oil omega-3 long-chain polyunsaturated fatty acids in a transgenic oilseed crop. Plant J. 77 (2), 198–208. Shultz, H., 2014. ADM enters into omega-3 market with partnership on algal DHA ingredient, May 21, 2014, Nutra ingredients-USA.com. Taneja, A., Singh, H., 2012. Challenges for the delivery of long-chain n-3 fatty acids in functional foods. Annu. Rev. Food Sci. Technol. 3, 105–123. USDA, 2014. Federal Register Vol. 79, No. 81/Monday, April 28, 2014/Rules and Regulations 23273, USA. Wang, B., Adkihari, B., Barrow, B.J., 2014. Optimisation of the microencapsulation of tuna-oil in gelatin-sodium hexametaphosphate using complex coacervation. Food Chem. 158, 358– 365. http://dx.doi.org/10.1016/j.foodchem.2014.02.135. Winwood, R.J., 2013a. Algal oil as a source of omega-3 fatty acids. In: Jacobsen, C., et al. (Eds.), Food Enrichment with Omega-3 Fatty Acids. Woodhead Publishing Series in Food Science, Technology and Nutrition, Woodhead Publishing, Sawston, UK (chapter 14). Winwood, R.J., 2013b. Recent developments in the commercial production of DHA and EPA rich oils from micro-algae. OCL 20 (6), D604. Zeller, S., 2006. Safety evaluation of SCOs and the regulatory requirements for use as food ingredients. In: Cohen, Z., Ratledge, C. (Eds.), Single Cell Oils. American Oil Chemists’ Society, Champaign, IL.
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R.J. Winwood DSM Nutritional Products (UK) Ltd., Heanor, Derbyshire, UK
6.1 Introduction The global market for omega-3 fatty acids for human consumption was worth about US$25 billion in 2011 and is expected to grow to US$37.7 billion by 2016, mainly due to increased consumption in India and China (Carr, 2014). Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the key omega-3 fatty acids found in fish oil. The health benefits of EPA and DHA are widely recognized by scientists and regulatory bodies around the world, including authorized health claims issued by the European Food Safety Authority (EFSA). In recent years, intake recommendations for EPA and DHA for health maintenance have risen sharply and it is evident that most of the world’s population is in a state of insufficiency. However, current fish oil production is many fold insufficient to supply this and there is competition for its use from the aquaculture industry. Matters are complicated by the fact that fish catches suitable for fish feed/fish oil production have leveled off at 25–30 million tons per annum. Around 4.5 kg of wet fish is required to generate 1 kg of fish meal and fish oil (Kitessa et al., 2014). The source of EPA and DHA in fish oils is the marine microalgae that the fish consume. The microalgae can be grown in contained fermenters. Oil can then be extracted from the ruptured algal cells. The downstream processing of the algal oil from this stage is very similar to fish oil. The resulting algal oil has no contact with the marine environment at any time during its production. It is of high purity and organoleptic quality and can generally be used to fortify foods in the same way that fish oil is used, but is suitable for vegetarian diets. The story of development of algal oils and how they are processed has been described previously (Barclay et al., 2010; Winwood, 2013a,b—two publications). This chapter will concentrate on the practical aspects of incorporating algal oils into fortified foods and exploring the market demand.
6.2 Enriching foods with marine omega-3 fatty acids The main source in the human diet of EPA and DHA is oily fish. Many diets around the world, including the westernized diet, have minimal consumption of oily fish and are awash with omega-6 fatty acids derived from vegetable oils. The problem is Specialty Oils and Fats in Food and Nutrition. http://dx.doi.org/10.1016/B978-1-78242-376-8.00006-5 © 2015 Elsevier Ltd. All rights reserved.
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e xasperated by the fact that incorporation of fish by-products in animal feeds has declined very significantly, meaning that erstwhile sources such as organ meats and most eggs can no longer contribute nutritionally useful amounts of EPA and DHA to the diet. As an example, the combined EPA and DHA content of farmed Atlantic salmon from Tasmania was around 1750 mg/100 g wet weight with a fish oil diet in winter 2002, but had fallen to around 1050 mg/100 g in autumn 2013 as increasing amounts of chicken fat were added to the fish oil feed (Kitessa et al., 2014). While supplements containing fish oil provide an excellent way of meeting our nutritional requirements for EPA and DHA, sadly those people that need them most are either unable, or unwilling, to buy them. Even among purchasers of fish oil capsules, the level of compliance to achieve recommended intake levels is poor. Food fortification remains the most practical way of increasing EPA and DHA intake across the whole population. While a key aim of fortification is to increase levels of the long-chain marine omega-3 fatty acids EPA and DHA, additional intake will also help reduce the fatty acid ratio n6:n3 to healthy levels.
6.3 Strategies for developing omega-3 enriched functional foods Incorporation of either fish or linseed (flax)/rape seed (canola) oils in the feed of livestock results in higher concentrations of omega-3 in food products based on poultry, eggs, meat, or milk. Transgenic technology can be utilized to produce plants and animals (pigs, beef, poultry) with higher levels of omega-3 fatty acids. While many consumers are suspicious of genetically modified (GM) technology, the development of GM oil seed crops with high levels of EPA and DHA has continued. In 2012, a transgenic version of the oilseed plant Arabidopsis thaliana yielded an oil containing 15% DHA (Kitessa et al., 2014). In 2014, approval was given by the U.K. government body DEFRA to the Rothampsted Research Centre at Harpenden for a trial to grow the oil seed crop Camelina sativa, which had been genetically modified with genes from marine algae to produce high levels of EPA and DHA (Farmers Guardian, 2014). The seed contains 35–45% oil of which levels as high as 30% EPA or 14% DHA/12% EPA combined are possible, depending on the variant. Camelina is of particular interest as a crop as it can be grown on marginal agricultural land and can withstand cool and wet conditions and yet still produce an oil yield of some 800 kg/ha. A full account of the development of the crop has been written by Ruiz-Lopez et al. (2014). Another approach has been taken by Monsanto with their transgenic soybean MON 87769. This GM soybean produces an oil rich in stearidonic acid, which is a significant precursor of EPA, though the onward conversion to DHA is very limited in humans. The EFSA Panel on Genetically Modified Organisms has recently delivered a positive opinion with regard to an application to place the soybean MON 87769 on the European market for use in food and feed (European Food Safety Authority (EFSA), 2014). In Europe, most algal omega-3 oils are covered by the Novel Foods legislation. This specifies the food applications in which the oil may be used and defines a maximum addition level per 100 g of product that must not be exceeded. As an example, the algal
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Table 6.1 Maximum use levels of algal oil derived from Schizochytrium for various food categories in the European Union as of July 2014 (Commission Information Decision, 2014) Food category
Maximum use level of DHA
Dairy products except milk-based drinks
200 mg/100 g or for cheese products 600 mg/100 g 200 mg/100 g or for analogs to cheese products 600 mg/100 g 600 mg/100 g 500 mg/100 g 250 mg DHA per day as recommended by the manufacturer for normal population 450 mg DHA per day as recommended by the manufacturer for pregnant and lactating women 250 mg per meal replacement
Dairy analogs except drinks Spreadable fat and dressings Breakfast cereals Food supplements
Foods intended for use in energy-restricted diets for weight reduction as defined in Directive 96/8/EC Other foods for particular nutritional uses as defined in Directive 2009/39/EC excluding infant and follow-on formulae Dietary foods for special medical purposes
Bakery products (breads and rolls), sweet biscuits Cereal bars Cooking fats Nonalcoholic beverages (including dairy analog and milk-based drinks)
200 mg/100 g
In accordance with the particular nutritional requirements of the persons for whom the products are intended 200 mg/100 g 500 mg/100 g 360 mg/100 g 80 mg/100 ml
DHA oil Life’s DHA™-S is now allowed in the following applications following a recent revision (July 2014) of the approval. The allowed categories and maximum use levels from this algal oil derived from the microalgae Schizochytrium are shown in Table 6.1. Practical advice for the food technologist as regards how to practically incorporate such algal oils into food products is given in Section 6.6.1.
6.4 What are the benefits of using microalgae to produce food ingredients? Microalgae have a higher growth rate and higher biomass density in comparison to land-based crops. They are a source of rare, key bioactive nutrients normally only found in the marine environment and provide an alternative to extraction from fish.
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The fermentation substrates used for microalgal fermentation are widely available and derived from renewable resources. (Glucose syrup is a popular choice as the major constituent and is usually obtained by enzymic degradation of starch.) Microalgal fermenters can be used to fix carbon dioxide. Numerous phototrophic algae are able to adapt their metabolism to heterotrophic conditions; indeed, that is the only way they can function when the sun’s rays are not available! San Francisco-based Solazyme Inc. is a good example of a company making full use of heterotrophic algal fermentation to make a wide range of products aimed at the fuel, green chemistry, nutrition, and the lubricants sector (www.Solazyme.com). They have existing algal oil plants in the United States at Peoria, IL, and Clinton, IA, currently producing 2000 MT and 20,000 MT, respectively. However, a much larger plant, capable of producing 100,000 MT of algal oil per year using massive 625,000 L fermenters started production in Brazil on May 29, 2014, in a joint venture with Bunge Global Innovation LLC. Microalgae such as Chlorella and Spirulina have been grown for many years in open ponds for use as nutritious food ingredients. They can also be a useful, commercial source of natural pigments; for example, carotenoids from Dunaliella, Astaxanthin from Haematococcus, and Lina Blue from Spirulina (Milledge, 2012). The use of open pond systems has been challenging in the past mainly due to economic and contamination issues, but new technology has been developed to overcome these problems and it is reported that yields of up to 5000 US gallons of algal oil per acre are now possible (Carr, 2014).
6.5 Selecting EPA and DHA producing microalgae Currently, the most commonly used microalgae for the production of DHA-rich algal oil and biomass are from the marine members of the families Thraustochytriacea and Crythecodiniacea. The Thraustochytrids include the genera Schizochytrium and Ulkenia, whereas Crypthecodinium is a genus of the family Crypthecodiniaceae. Members of these genera are widely dispersed in the oceans of the world. The selection of suitable heterotrophic microalgae depends on their ability to inexpensively produce large quantities of DHA from glucose in large stainless steel vessels (i.e., absence of light). Autotrophic algae require a source of light, using the light of the sun to drive their metabolism. This seriously limits the design of the fermenter, particularly the size, which in turn limits the yield. Open pond systems, on the other hand, are optimally suited for growing autotrophic algae. Thraustochytrids are heterotrophs with a high oil content (typically 50–77% on a dry weight basis). The oil is >90% triacylglyceride, rich in DHA, and has a low cholesterol content. The precise taxonomy of Thraustochytrids remains a matter of some debate. They are found in the kingdom Chromista and phylum Labyrinthulomycota. In fact, they are often found in association with decomposing plants/algal matter and their nutrition is primarily saprotrophic (Armenta and Valentine, 2013).
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In practice, the strains of microalgae in use today in the production of DHA- and EPA-rich oils are the results of intensive collection, isolation, and screening procedures. The most successful strains shared the following properties (Barclay et al., 2010): ●
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High growth rates High lipid contents Growth unaffected by low salinity conditions High proportion of DHA and EPA as percentage of total lipids in elevated temperature fermentation (30 °C).
All strains in commercial use have undergone extensive toxicological investigation as part of their conditions for regulatory approval. A useful review of the safety and toxicological aspects of producing single cell oils has been written about by Zeller (2006). DSM Nutritional Products use the microalgae Crypthecodinium cohnii (see Figures 6.1 and 6.2) to make their DHASCO™ oil for the infant formula market. This oil has a DHA content of 40–45% w/w, and virtually no EPA. DSM also produce an algal oil for the food, beverage, and supplement industries called Life’s DHA™—S oil. This is made using microalgae Schizochytrium (see Figure 6.3) and is standardized at 35% or 40% DHA, and also contains low levels of EPA (<2%). DSM uses a different strain of Schizochytrium to produce an algal oil with a DHA:EPA ratio of 2:1 to match the ratio found in certain high-quality fish oils. The product targeted at the food fortification market called Life’s Omega™ 45, contains a minimum of 40% total DHA and EPA, and is specified as having minimum levels of 24% DHA and 12% EPA (w/w); while the product targeted at the supplements market, particularly for high potency capsules, is called Life’s Omega™ 60, and contains minimum levels of 30% DHA and 15% EPA (w/w).
Figure 6.1 Photomicrograph of the microalgae Crypthecodinium cohnii. Courtesy of Casey Lippmeier of DSM Nutritional Products. ©DSM Nutritional Products.
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Figure 6.2 Photomicrograph of the microalgae Crypthecodinium cohnii. Courtesy of David L. Spector of Cold Spring Harbor Laboratory, Laurel Hollow, NY, USA. ©DSM Nutritional Products.
Figure 6.3 Photomicrograph of the microalgae Schizochytrium. Courtesy of Casey Lippmeier, DSM Nutritional Products ©DSM Nutritional Products.
There are other producers of DHA-rich algal oils in China and India. In May 2014, the U.S. agri-giant Archer Daniels Midland Company announced its intention to produce a DHA-rich oil from heterotrophic algae (Shultz, 2014) through a partnership with Synthetic Genomics Incorporated (SGI). Until recently, the production of EPA-rich algal oil has been largely restricted to the laboratory scale. According to Milledge (2012), algal oils rich in EPA have been produced from the microalgae Phaedodactylum tricornutum, Nannochloropsis
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Figure 6.4 Photomicrograph of the microalgae Nannochloropsis. Courtesy of Aurora Algae Inc. ©Aurora Algae Inc.
and the diatom, Nitzchia. These organisms have predominantly an autotrophic metabolism. Aurora Algae Inc. cultivate proprietary strains of Nannochloropsis microalgae (see Figure 6.4) in large seawater open ponds, in geographic locations with high solar radiation. They use proprietary techniques to select for strains with high oil yield, high proportion of EPA, and substantially no DHA. Aurora Algae has commercialized a high EPA content (> 65%) oil under the product name A2 EPA Pure™, targeted for use in the supplements and pharmaceuticals sector. EPA-rich algal oils, again with minimal DHA content, are also produced in the southwestern United States by Qualitas Health (www.qualitas-health.com) using shallow, open, and closed pond fermentation systems. Here, a saltwater strain of Nannochlopropsis oculta has been selected to provide optimum yields in the prevailing climatic conditions.
6.6 The difficulties of utilizing omega-3 fatty acids in new food product development Very long-chain polyunsaturated fatty acids (PUFAs) such as EPA and DHA are extremely liable to oxidation. Once the process of oxidation has begun, it is self- propagating and cannot be stopped. The result of this process is highly rancid foods with strong fishy odor and flavors. Fish oil is a by-product of fish protein production, and hence requires extensive refining and purification to remove the odors and tastes associated with its source. This process of oxidation can also lead to a loss of nutritional value of the food in which it is incorporated through co-oxidation of other nutrients.
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A reluctance to use a fish-originated oil can be overcome by using algal oil. The specially selected strains of microalgae are grown in contained fermenters under controlled conditions. However, while algal oil can have superior organoleptic characteristics, the key component omega-3 fatty acids (EPA & DHA) are just as likely to oxidize as those found in fish oil once incorporated in food products—so the same precautions to prevent oxidation are required. The main causes of LC-PUFA oxidation in food products are: ●
●
●
●
Exposure to oxygen; High temperatures (time dependent); Trace metals (e.g., Fe, Cu, Zn); and Light.
The key techniques available to food technologists for preventing oxidation of LCPUFA during the production and shelf life of food products are as follows: ●
●
●
●
●
●
●
Limiting exposure to air (i.e., oxygen); Nitrogen blanketing; Preventing air incorporation (e.g., reducing turbulent flow, filling tanks from bottom); Ensuring that on the production line all transportation systems are kept clean and free from components containing ferrous metal, copper, or zinc; Avoiding rework; Ensuring the thermal processing should be for the minimum time possible. High temperature short time (HTST) processing is preferred; and Use deionized water wherever possible.
Selection of suitable raw materials can help prevent oxidation problems: ●
●
●
Good starting quality ingredients should be used at all times; All other ingredients should be low in Fe, Cu, and Zn; and Vegetable oils should be low in oxidative parameters (i.e., low peroxide values (PV), anisidine values (AV), totox values (TV), and long Rancimat oxidative stability values).
Finally, care must be taken with the final product in terms of packaging and storage. ●
●
●
Packaging should be selected that has good barrier properties to oxygen and UV light. Where possible, the package should be sealed immediately after a nitrogen surge. A realistic shelf life should be decided on in accordance with the prevailing storage conditions.
6.6.1 Algal oil handling and incorporation into foods Algal oils are best stored frozen at −20 °C, or kept chilled at 4 °C if freezing is not possible. Frozen oil should be subjected to a minimal number of freeze–thaw cycles—an absolute maximum of twice. Algal oil may be thawed at room temperature (15–30 °C) overnight. If the oil is not completely thawed, it may be heated in a water bath at 50 °C for a maximum of 60 min. Whenever possible, the entire amount of thawed oil should be used during the day’s production, but where this is not possible, the remainder should be flushed with nitrogen and frozen again as soon as possible. The exception to
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this rule is where a further production is to be made within 1 week. In this case, the oil should be kept covered, flushed with nitrogen, and chilled at 4 °C prior to use. During the production process itself, it is important that the other ingredients should be fresh and high quality. The following advice will be useful for the incorporation of algal oils into the final food (the same advice is broadly applicable to fish oils as well): ●
●
●
●
Add the oil as late as possible in the production process. Minimize thermal exposure and air incorporation as much as possible. Where possible, produce in a closed system using a suitably modified atmosphere. Ensure the oil is homogenously distributed into the food matrix. Usually it is advisable to prepare a premix concentrate of oil in another suitable component of the formulation.
It is important that the other ingredients should be free of pro-oxidants, such as metals (Cu, Fe, and Zn), oxidized oils and fats, and photosensitisers (e.g., riboflavin in milks). Where possible, a suitable antioxidant cocktail should be added. While synthetic forms are usually the most efficacious, usually the natural forms are preferred for regulatory and labeling reasons. Commonly used antioxidants include mixed tocopherols, ascorbic acid, rosemary extract (carnosic acid), green tea extracts, and ascorbyl palmitate. Once production is complete, the choice of packaging is also important. Where possible, this should be impermeable to both oxygen and light and encourage single-serve use. Storage conditions of the final food should be also ideally in dark, cool conditions. The actual dose of algal oil in food usually reflects local nutritional labeling requirements. It is more difficult to achieve good tasting, long shelf life foods if higher doses are used.
6.7 Delivering omega-3 fatty acids into food products: Stable algal oil forms and their use in the production environment Native algal oil will have the highest concentration of EPA and DHA and thus have the optimum cost in use. However, it will be very susceptible to oxidation and hence require more restrictions in terms of handling and storage. If this is a problem, then powder or emulsion forms may provide a solution.
6.7.1 Microencapsulation In general, food systems offer a challenging environment for omega-3 fatty acid. Those foods with long shelf lives (e.g., cereals) pose a particular problem, because even if the highest quality of oil is used, oxidation will begin eventually. With this in mind, it is not surprising that food technologists have concentrated on fortifying shorter shelf life products such as dairy or bakery items (Moghadasian, 2008). However, even here it is inevitable that the complex food matrix will contain components that will initiate or
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catalyze the oxidation process of the algal oil. In addition, the complex environment will reduce the efficacy of antioxidants and chelating agent added with the intention of delaying the initiation process. So one technique that can be used in these systems is microencapsulation, which effectively provides an impermeable barrier between the oil and food matrix. The technique of microencapsulation was pioneered by the pharmaceutical industry where it was used to protect sensitive ingredients. The process involves protecting the core with a protective encapsulating matrix. The microencapsulation process must have the following properties if it to be viable for the use of omega-3 fatty acids (as listed by Taneja and Singh, 2012): ●
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The stability of algal oils must be improved (before it is added to the food matrix). It has to provide an effective barrier to oxidation and be compatible with the food matrix. It must not have an effect on organoleptic properties or the shelf life.
The use of encapsulated omega-3 fatty acid powders greatly extends the range of possible applications they can be used in, but by definition the cost has to be greater and the content of active EPA/DHA will be much less. We shall consider the main encapsulating systems applicable to algal oils (Barrow et al., 2013).
6.7.2 Oil in water emulsion systems Emulsifying agents such as lecithin, gum arabic, and octenyl succinate starches produce an emulsion with a negative charge on the surface of the droplet, which attracts pro-oxidant metal ions (Taneja and Singh, 2012). This can be overcome using proteins, typically those derived from milk or soya. Once a stable emulsion of the algal oil has been produced, the next step is usually to dehydrate it and form a powder, typically using spray drying. For extra protection, the resulting powder can be atomized and coated with a secondary layer, typically a high melting fat or starch. A major drawback of this type of microencapsulation is that the barrier matrix has to be water-soluble and hence tends not to be an effective barrier to oxygen. The level of loading of the algal oil is limited. Levels above 50% are difficult to achieve without making the encapsulate too fragile for operational use.
6.7.3 Complex coacervation These systems usually contain two colloids with opposite charges. The process typically starts with the formation of an emulsion with a positively charged polymer (e.g., gelatin (type A) or chitosan). This emulsion is then mixed with a second emulsion containing negatively charged polymers such as gum arabic, alginates, carboxy methylcellulose, or gelatin (type B). The pH of the mixture is carefully adjusted until a coacervate results with the polymers precipitating on the core. The resulting microparticles can then be agglomerated by a process of gentle cooling with agitation. The agglomerates can then be stabilized by cross-linking reactions (e.g., the use of the enzyme transglutaminase in the case of gelatins). They are then spray dried to form a powder. Though the process is complex, it has the advantage of enabling higher oil
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loadings with minimal surface oil content (typically 0.2%, compared with up to 1% for simple emulsion systems) (Wang et al., 2014). Ideally, marine omega-3 powders should be stored at 4 °C and should not be frozen as the coating may be ruptured as the oil expands. As with the native oil, the powder, once opened, should be used entirely. Any remainder should be sealed, ideally nitrogen flushed and used within a week.
6.7.4 Alginate microspheres Alginates are ionic biopolymers that can be used to produce microbeads containing the oil. Typically, alginates form a gel when in contact with calcium ions at an optimal pH.
6.7.5 Omega-3 oil emulsions Omega-3 emulsions can be added directly to aqueous systems and are ideal for use in the production of beverages, but there are limitations. As with powders, emulsions are most expensive to use and have less EPA and DHA potency. Although making an emulsion of omega-3 oil reduces the risk of oxidation, they are still much more liable to oxidize than powders and require special handling. Omega-3 emulsions will still cause turbidity, so they should not be used with clear beverages. It is possible to produce an ultrafine nanoemulsion that overcomes this problem. However, the nanotechnology used can fall afoul of regulatory restrictions; hence, such emulsion cannot be sold in the European Union at the present time. Where omega-3 emulsions are added to low juice beverages (i.e., less than 50%), it is necessary to add a stabilizing system (e.g., pectin and or xanthan gum) and carefully emulsify the whole batch.
6.7.6 Food applications for algal oils Proven applications for algal omega-3 oils include fresh and ultra heat treated (UHT) milks (skimmed, semiskimmed, and full fat types), yogurts, processed cheeses, ice cream, frozen confections, chocolate confections, cooking oils, margarines/spreads, soft candy gums (gummies), salad dressings, processed meat, and bakery items. Some applications that are not suitable for omega-3 fortification include tea bags, instant chocolate beverages, high boiling sweets (candies), and chewing gum.
6.8 Regulatory approval of algal oil for use in foods and supplements DSM’s algal oil DHASCO® has been approved for use in infant formula in the European Union under Commission Directive 2006/141/EC. This regulation states that addition is optional but when it is added, 1% of the total fat content should consist of n-3 LC-PUFAs and 2% of the fat content should be n-6 LC-PUFAs of which 1% is
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arachidonic acid (ARA). DHASCO® is also considered as a food in the EU (e.g., not a novel food) based on its “significant degree of use” prior to 1997. DSM’s Life’s DHA™-S algal oil is approved for use as a novel food ingredient in specific food categories and dietary supplements under the European Novel Food Regulation (EC) 258/97 (OJ L 209/55, 16.7.2014; OJL 144/13, 12.6.2003; OJL 278/56, 23.10.2009). The same applies to DSM’s Life’s Omega™ algal oil which typically contains a ratio of about 2:1 DHA:EPA. This was authorized in July 2012 (see http://ec.europa.eu/food/food/biotechnology/novelfood/dha_o_authorisation_ letter_06072012_en.pdf). Both algal oils must be labeled “DHA rich oil from the microalga Schizochytrium sp.” under these regulations. Algal oils from other producers have also received novel foods approval on the basis of their “substantial equivalence” to DSM’s Life’s DHA™-S algal oil. With regard to health claims, the following article 14 claims have been authorized and published in the Official Journal of the European Union (Commission Regulation (EU) No 440/2011 of May 6, 2011). ●
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DHA intake contributes to the normal visual development of infants up to 12 months of age. DHA maternal intake contributes to the normal development of the eye of the foetus and breastfed infants. DHA maternal intake contributes to the normal brain development of the foetus and breastfed infants.
With regard to article 13.1 claims, the final approved claims appeared in the Official Journal of the European Union 25.2.12, Commission regulation (EU) 432/2012 of May 16, 2012. In this case, the following claims appear for DHA alone: “Maintenance of normal brain function” and “Maintenance of normal vision,” while for EPA and DHA, a claim of “maintenance of normal cardiac function” appears. The accompanying conditions of use for all three claims include a recommended total daily intake of 250 mg per day for the general population. In April 2014, The U.S. Food and Drug Administration (FDA) published a final rule prohibiting certain nutrient content claims for foods that contain omega-3 fatty acids (USDA, 2014). The final rule prohibits label statements that claim the products are “high in” DHA or EPA, and synonyms such as “rich in” and “excellent source of.” Any existing claim will not be permitted beyond January 1, 2016. This is likely to affect food manufacturers who were limited to their inclusion rate and could previously claim an “excellent source of omega-3” with just the addition of 32 mg per serving. Structure/function claims for dietary supplements that are based upon clinical science will still be able to be made, but the dose should be in alignment with the levels used in the relevant studies.
6.9 Future trends The use of algal oils in foods and supplements will continue to grow as demand for EPA/DHA increases. The use of algal oils remains a proven, sustainable alternative to fish oils and will form an increasingly large proportion of the EPA/DHA market because of the limitations on fish oil production. The range of algal oils will expand.
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New technology will further enhance the yields of algal oil from open pond algae fermentation and we can expect to see further growth of production plants in sun-blessed areas where the land is unsuitable for agricultural use. The scientific understanding of the health benefits of marine omega-3 fatty acids continues to grow exponentially; hence, they are likely to be recommended for both prevention and treatment of a much wider range of clinical conditions as well as health benefits. The continuing development of marine omega-3 ingredients forms with improved oxidative stability will enable their incorporation into an ever-widening range of food products.
6.10 Sources of further information and advice NUTRI-FACTS, a website that is a useful source of scientific information on essential micronutrients. www.nutri-facts.org. DHA/EPA Omega-3 Institute. Scientific material written by Dr. Bruce Holub of the University of Guelph in Canada. www.dhaomega3.org. Fats of Life. A science-based website about the health effects of PUFAs. www. fatsoflife.com. GOED omega-3, the Global Organization for EPA and DHA Omega-3. 1075 Hollywood Avenue, Salt Lake City, UT 84105, USA. Tel.: +1-801-746-1413. www. goedomega3.com. ISSFAL, International Society for the Study of Fatty Acids. www.issfal.org. National Algae Association, 4747 Research Forest Dr., Suite 180, The Woodlands, TX 77381, USA. Tel.: +1-936-321-1125. www.nationalalgaeassociation.com. “Oils and Fats – Production Properties and Uses” training course, held annually at the Leatherhead Food Research (see www.leatherheadfood.com for details). Omega-3 Centre. Australian-based organization promoting omega 3 fatty acids. www.omega-3centre.com.
Acknowledgments A special thank you is due to my longtime colleague, Dr. Ruben Abril, whose long experience of incorporating marine omega-3 oils in food products has been richly drawn upon in the writing of this chapter. I would also like to thank my colleagues John Dobson and Milly Rooijakkers for their information and support.
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