How are omega 3 fortified eggs produced and what effect does fortification have on the eggs
chemical and molecular structure, as well as consumer acceptance?
Christopher Evans
March 22, 2012
Introduction
Functional foods, such as the designer egg, have risen in popularity in industrialized
nations over the years. A designer egg is classified as such due to the fact that it has been
fortified with vitamin E, lutein, (classified as a xanthophyll that gives the yolk its yellow
pigment) and omega-3 fatty acids (1 text). The vitamin E present in the egg yolk aids as an
antioxidant, scavenging free radicals that would otherwise expedite the oxidation of the fatty
acids present in the egg yolk, including the omega-3 fatty acids. The lutein, also has healthful
benefits associated with its presence. While these vitamins and phytochemicals are important, the
main focus of these designer eggs as a functional food is the presence of the omega-3 fatty acid
chains.
Omega-3 fatty acids are considered an essential fatty acid, because the human body
cannot produce fatty acids with the double bond before the ninth carbon-carbon bond from the
omega end (2 the nutrition of science text). The omega-3 fatty acid alpha-linoleic is the fatty acid
commonly used in the fortification of designer eggs. This is an 18 carbon molecule containing
three double bonds that can be found in foods such as flax seed and chicory root. This fatty acid
chain can be converted by the human body to two other essential fatty acids, EPA
(eiscosapentanoic acid), and DHA (docosahexanoic acid). The human body’s conversion of
alpha-linolenic fatty acid to EPA and DHA is inefficient at best, so producers of designer eggs
have sought sources of EPA and DHA to fortify their products with, such as certain fish oils and
algae, which will be discussed later. This mode of fortification offers a different set of problems
that scientists continue to grapple with.
This research paper will discuss the advantages and drawbacks of fortification. The food
science aspects of fortification will be discussed such as the materials and methods involved, and
how the egg is chemically and molecularly modified through the process of fortification. Finally,
this paper will delve into the dietetic implications and considerations for this particular
functional food.
Advantages and drawbacks of fortification
There are several advantages to the fortification of eggs with different vitamins, minerals,
and omerga-3 fatty acids. Consumer reports have shown that designer eggs have become a
desired alternative to fish oil, due to the presence of omega-3 fatty acids. (3). This modification
is important to those following ovo or lacto-ovo vegetarian diets which allow the consumption of
eggs. An egg yolk is about 30% lipid, with the majority of that being unsaturated. Recent
research has been conducted linking certain dietary lipids to the development of coronary heart
disease and certain forms of cancer (4). Replacing these dietary lipids with omega-3 fatty acids
can reduce inflammation and oxidation in the body, two major contributors to many forms and
cancer and coronary heart disease. In addition, the fortification of designer eggs with omega-3
fatty acids, carotenoids, vitamin E, and selenium provide the eggs polyunsaturated fatty acids
(PUFA) with better stability during storage and cooking, high availability of vitamin E and
carotenoids and an improved status of n-3 and antioxidants in individuals who consume the
product (5,6).
While there are many advantages to fortification, there are also drawbacks. The addition
of higher amounts of mono and polyunsaturated fats can reduce the shelf life of the designer
eggs. Unsaturated fatty acids, such as omega-3 fatty acids, are more unstable bonds on the
molecular level due to the presence of one or more double bonds (6). This higher level of
instability can lead to an increased risk of oxidation, which in turn decreases shelf life. That is
one of the reasons why designer eggs are fortified with vitamin E as well. Vitamin E is a free
radical scavenger and helps diminish lipid oxidation (6).
Another drawback associated with the fortification of the designer eggs is concerned with
taste. A hen’s feed can be supplemented with flaxseed, which contains the alpha-linoleic or with
marine animal oils/algae. The advantage to the fish oil/algae is that the human body does not
have to convert these fatty acids to EPA or DHA. However, studies have shown that fortifying
the hens diet with too high an amount of the fish oil/algae can lead to a product that possesses a
“fishy” or “off” flavor (7). The same off- flavor can be seen with the over supplementation of
flaxseed in the hen’s diet.
Fortification process and egg modification
In the case of non ruminants such as the chicken, the fortification of n-3 is fairly
straightforward. The transfer of n-3 from the diet to the blood does not need to be protected
because the fatty acids are absorbed unchanged (8). The main means of fortification is
accomplished through the laying hens’ diet. Many types of feed are utilized to procure the
desired effect. The materials used in an altered diet are extensive. Some examples of feed include
grass, grass silage, red clover (autumn and spring) and white clover varieties. Different seeds
used include linseed, rapeseed, flaxseed, soy and sunflower seeds. Some marine sources used in
fortification include fish oil, the marine algae Schiochytrium sp., and Nannochloropsis oculata
(8). Lists of “novel” sources that are not generally used include hemp, chia, lupin, naked oats and
camenilla seed. Which type of feed used in fortification is decided by different factors. Cost and
availability is taken into consideration, both in the U.S and globally, the impact of the fat or oil
form, consumer and retailer acceptance and demand, and finally animal feed restrictions
involving the use of fortified supplements (8).
A study conducted by Yannakopoulos and colleagues included 16,000 hens divided into
two treatment groups. The hens were housed into cages, with four hens in a cage, and ranged in
age from 30 to 50 weeks (4). The birds were kept in a three floor battery, and were randomly
interspersed. The control group ingested a standard diet, and the other group received extra
vitamins such as vitamin E and folic acid, selenium, flaxseed and what was described as an
herbal mix. The herbal mix contained starch, sugar, fat, cellulose, sodium chloride, calcium,
phosphorous, magnesium, potassium, sodium, iron, copper, manganese and zinc. Factors such as
feed consumption, and weight of the eggs were measured daily. The hens fed the enriched diet
ate a slightly higher amount, (107.8 g to 106.5 g) but for the purposes of the study, the results
were insignificant. However, the egg production of the hens fed the enriched diet was listed at
over 90% over eight weeks. The eggs produced were also slightly larger by those hens fed the
enriched diet (64.84 vs. 65.92) (4).
Of more importance, was the makeup of the eggs produced by the hens ingesting the
altered diet. The eggs contained less saturated fatty acids and more PUFA. Each egg also
contained around 120 mg of DHA, which is not found in flaxseed or any other components of the
diet. This could be attributed to the desaturase and elongase enzymes present needed to convert
alpha-linoleic to DHA. The herbal mix was thought to have played a role in the more efficient
conversion of alpha-linoleic to DHA (4).
Another study conducted by Garcia-Rebollar and colleagues chose to utilize marine oils
in conjunction with linseed oil (9). Ten diets were set up factorially using different amounts of
marine fish oil, or MFO (15g, 17g/kg) along with five different amounts of linseed oil (1,2,3,4
and 5g/kg). This study was conducted to determine the yolk composition as well as the sensory
qualities of the eggs in question. 160 44 week old ISA brown laying hens were housed in cages
sized (33 x 41cm). The birds received the same pre-experimental diet for 21 days. The trial lasted
56 days with the hens receiving the ten different diets. The hens were kept at a controlled
temperature (21 degrees C) and received 15 hours of light/day during the experiment (9).
Three eggs were saved from each group for chemical and statistical analysis. The
treatments did not affect feed intake, laying rate, egg weight, yolk weight, Haugh units or shell
thickness. In addition, the n-3 FA supplements in the diet did not affect the ratio of total FA in
the yolk and the dietary fat, or the yolk fat content. The differing diets had a small affect on the
total saturated FA and monounsaturated FA in the yolk. The only real significance was the
amount of n-3 and n-6 fatty acids present in the yolk (9).
A study conducted by Scheideler and colleagues focused on the fortification of eggs with
either flaxseed oil or menhaden fish oil in conjunction with vitamin E (3). The study examined
factors such as consumer acceptance, oxidative products and yolk color of fresh and stored eggs.
In this study, the method used to measure the stability of foods during storage is known as
thiobarbituric acid reactive substances or TBARS. This measurement reflects the amount of
oxidation undergone in the yolk over a period of time. In the process of lipid oxidation, lipids
oxidize and produce hyperperoxides that react with thiobarbituric acid resulting in a pink
substance that can be measured (3).
Two trials were used in this particular study. In the first study, eight diets were
determined; (control, 1.5% menhaden fish oil, 5, 10, and 15% of whole or ground flaxseed) were
administered to four pens with three hens each. The experimental diets were mixed once during
the start of the study, were stored at 21 degrees C and were feed the diet 8 weeks. Samples were
procured from each of the studies after 6 weeks. The eggs were then analyzed for stability of the
yolk fatty acids and for sensory evaluation (3).
In the second trial, a 2x2x2x2 arrangement was used with 16 dietary treatments. This trial
analyzed brown versus golden flaxseed, ground versus whole varying temperatures (4, 21
degrees C), and two levels of vitamin E supplementation (27 vs. 50 IU). The diet was feed to
slightly younger hens (24 vs. 43 week old hens) with four identical pens of five hens each. The
samples were taken at the 6 week mark and analyzed for yolk stability and sensory evaluation. In
both trials eggs were stored for 2, 4 and 6 weeks under refrigeration and analyzed for stability
and sensory evaluation (3).
The results of flaxseed supplementation in the first trial showed a linear relationship
between amount of the flaxseed in the diet and the amount of n-3 fatty acid in the yolk. Diet was
also shown to affect levels of oxidation. In general throughout the study the eggs from the hens
fed the control diet had lower TBARS scores than those fed the diets supplemented with fish oil
or flaxseed. However, the TBARS scores did decrease after 6 weeks of storage. The study was
not conclusive as to why this happened. It may have indicated the loss of active carbonyls due to
reactions with other components, such as proteins (3). Another factor may have been the
antioxidant reactions taking place during storage. Further studies would need to be conducted to
determine the true effect. The study also showed a linear relationship between higher amounts of
supplemented flaxseed, and higher TBARS scores. This is likely due to the fact that the higher
level of n-3 fatty acids found in the yolk promoted higher levels of oxidation. The decrease of the
TBARS score was seen in each diet over time. The overall affects of ground versus whole
flaxseed supplementation were not very consistent, showing only slight affects at the two week
mark (3).
The results of trial 2 indicate that TBARS was not affected at 0 or 8 weeks of storage.
TBARS over time did reduce, in a similar fashion as the first trial. However, there was a notable
interaction effect between varieties of flaxseed and amount of vitamin E supplemented. A
vitamin E supplementation of 50 IU lowered the TBARS score at week 0 for the golden variety
and at week 8 for the brown flaxseed variety. The results were consistent for varying vitamin E
supplementation for both golden and brown varieties of flaxseed. The color of the yolk was also
affected by the variety of flaxseed used in fortification. The golden variety had a lighter color
yolk, while the brown variety had a darker yolk (3).
Overall this particular study settled upon a few different conclusions. The enriched eggs
with levels of 1.5% menhaden fish oil and up to 5% flaxseed supplementation had no
significantly discernible effect on consumer acceptance. However, levels of 10 to 15%
supplementation of flaxseed did produce negative effects on appearance and consumer
acceptance in comparison to the non-enriched eggs (3).
Consumer acceptance
From a functional foods standpoint, eggs are a popular food source because they are rich
in fatty acids and the associated fat soluble compounds (10). Omega-3 fatty acids in particular
are highlighted for their anti-inflammatory abilities and uses in certain disease preventative
measures. Products such as the Columbus egg, created by Belovo, first appeared in Belgium in
1997 (10). They later appeared in the Netherlands, India, U.K, South Africa and Japan, with
production exceeding 50 million/year in Europe alone. Similar eggs can be found in the U.S. as
well (10). Consumer acceptance is greatly influence by taste and appearance. As mentioned
previously, both of these factors can be altered by type and amount of fortification (1, 4, 11). The
addition of marine fish oils or flaxseed exceeding 5 to 10% negatively affects taste in sensory
evaluations (11)
Dietetic implications
The designer egg as a functional food has significant dietetic implications. One such
implication is the perception of the ever increasing role of omega-3 fatty acids and it’s relation to
reduced inflammation (12). It’s importance has lead to research being conducted to effectively
and accurately measure intake on a case by case basis (13). Many studies have shown the link
between heightened inflammation and its role in the increased risk of cardiovascular diseases and
many forms of cancer (11). Omega-3 fatty acids such as EPA and DHA have anti-inflammatory
properties that aid in lowering levels of inflammation and thus the risk of diseases associated
with higher levels of inflammation. The type of omega-3 fatty acids present is also an issue. As
mentioned previously, the body does have the ability to alter alpha-linoleic to EPA and DHA,
but the process is inefficient (2). For practicing RD’s it is important to know what type of fatty
acid is present, in what amount, and if the amount is a suitable substitute for fish high in omega-3
FA such as salmon and trout or other products such as algae or flaxseed high in omega-3 FA.
Another aspect of designer eggs to consider is cost. For those of lower socio-economic
status, the designer egg may not be a viable option. It is important for RD’s to be able to
determine on a case by case basis which form of omega-3 supplementation is most effective and
desirable when considering cost, lifestyle choices and functionality.
The role of omega-3 fatty acids, particularly DHA, has begun to receive attention for the
role it plays in early childhood development. Between the ages of 6 and 12 months the blood
levels of DHA tend to decrease breast fed infants due to exhausted stores of maternal DHA and
the introduction of foods that are inadequate sources of DHA as primary sources of nutrition
(14). Hoffman and colleagues conducted a randomized, clinical trial format to examine how the
supplemental DHA in the form of egg yolks would affect sweep-visual evoked potential or VEP,
which measures retina and visual cortex development. The control group received no DHA,
while the experimental group receiving 113g of baby food containing 115mg DHA/100g of food.
Blood levels of DHA increased in the experimental group, and as a result their VEP levels
improved as well, indicating heightened visual development. DHA is known to play a role in
neural development as well (11, 14). For those mothers choosing to formula feed, DHA
supplementation is not quite the issue it is for breastfeeding mothers as most formulas on the
market are supplemented with DHA. However, it is important for practicing RD’s to have a firm
grasp of the scientific literature that is available and how it affects expectant mothers, mothers
who are breastfeeding, and the children themselves in the case of omega-3 fatty acids, in
particular DHA.
Reshaping of the food supply has changed consumer needs and expectations, especially
in regards to functional foods (15). People are living longer than ever before and as a result
health care costs are increasing. In addition, there is rising amount of scientific evidence that a
healthy diet can sometimes prevent the proliferation and progression of disease. As the amount
of professional and consumer knowledge rises, so do regulations on food production. All of these
factors add up to a higher demand for functional foods such as the omega-3 enriched designer
egg (15). It is in the best interest for health care professionals and their clientele that there is no
knowledge gap that may detrimentally affect the consumer.
References
1. McWilliams M. Foods Experimental Perspectives. 7th ed. Upper Saddle River, NJ:
Prentice Hall; 2012.
2. Thompson JL, Manore MM, Vaughan LA. The Science of Nutrition. 2nd ed. San
Fransisco, CA: Pearson Benjamin Cummings; 2011.
3. Scheideler SE, Froning G, Cuppett S. Studies of consumer acceptance of high omega-3
fatty acid-enriched eggs. J. Appl. Poultry Res. 1997;6:137-146.
4. Yannakopoulous A, Tserveni-Gousi A, Christaki E. Enhanced egg production in practice:
the case of bio-omega-3 egg. Int. J. Poult. Sci. 2005;4(8):531-535.
5. Surai PF, Sparks NHC. Designer eggs: from improvement of egg composition to
functional food. Trends Food Sci Technol. 2001;12(1):7-16.
6. Meluzzi A, Sirri F, Manfreda G, et al. Effects of dietary Vitamin E on the quality of table
eggs enriched with n-3 long-chain fatty acids. Poult Sci. 2000;79(4):539-545.
7. Cachaldora P, Garcia-Rebollar P, Alvarez C, Mendez J, De Blas JC. Double enrichment
of conjugated linoleic acid and n-3 fatty acids through dietary fat supplementation. Anim.
Feed Sci. Technol. 2008;3-4(144):315-326.
8. Woods VB, Fearon AM. Dietary sources of unsaturated fatty acids and their transfer into
meat, milk and eggs: a review. Livest Sci. 2009;1-3(126):1-20.
9. Garcia-Rebollar P, Cachaldora P, Alvarez C, De Blas JC, Mendez J. Effect of the
combined supplementation of diets with the increase of fish and linseed oils on yolk fat
and composition and sensorial quality of eggs in laying hens. Anim. Feed Sci. Technol.
2008;3-4(140):337-348.
10. Siro I, Kapolna E, Kapolna B, Lugasi A. Functional food: Product development,
marketing and consumer acceptance-a review. Appetite. 2008;3(51):456-467.
11. Raes K, Huyghebaert G, De Smet S, Nollet L, Arnouts S, Demeyer D. The deposition of
conjugated lineoleic acid in eggs of laying hens fed diets varying in fat level and fatty
acid profile. J Nutr. 2002;132(2):182-9.
12. Bovet P, Faeh D, Madeleine G, Viswanathan B, Paccaud F. Decrease in blood
triglycerides associated with the consumption of eggs of hens fed with food
supplemented with fish oil. Nutr Metab Cardivasc Dis. 2007;4(17):280-287.
13. Sullivan BL, Williams PG, Meyer BJ. Biomarker validation of a long-chain omega-3
polyunsaturated fatty acid food frequency questionnaire. Lipids. 2006;41(9):845-850.
14. Hoffman DR, Theuer RC, Castaneda YS, Wheaton DH, Bosworth RG, O’Connor AR,
Morale SE, Wiedemann LE, Birch EE. Maturation of visual acuity is accelerated in breast
feed term infants fed baby food containing DHA-enriched egg yolk 1,2. J Nutr
2004;134(9):2307-2313.
15. Position of the American Dietetic Association: Functional foods. J Am Diet Assoc
1999;10(99):1278-1285.