DESIGNER’S EGGS/ DIET EGGS OR VALUE ADDITION TO POULTRY EGGS ( PRE-OVIPOSITION OR PRE HARVEST TECHNOLOGY) IN INDIA- FUTURE PROSPECTS
People are becoming more health cautious and became choosy for their daily routine meals. Consumers demand products which are safe, healthy, fresh, tasty and nutritious with a desired aroma and colour. People demand eggs which are safe and also promote their health, free from drug/ pesticide residues and other harmful components but rich in special health promoting components like n-3 fatty acids, anti-oxidants, extra vitamins, minerals and non-nutrient components and pay a premium price for such eggs. Among the various nutrients contained in the egg, protein content is least changeable. The changeable nutrients are fats (fatty acid profile, minerals and vitamins), herbal active principles like Alicin, Betaine; Lutein, antioxidants. In order to reap the growing demand of health conscious consumers, the far seeking people industry started modifying the composition of the eggs. The poultry industry in particular has been seeking newer technologies to exploit products beyond their traditional food value. One such technology is DESIGNER FOOD (MEAT/EGGS), which can be defined as a nutritionally modified functional or designer food, which retains its functional, nutritional and sensory qualities but has a significantly altered lipid profile.
Cholesterol scare————-
Egg is a cholesterol rich food. A large egg contains about 210 mg of cholesterol. Assumptions like egg consumption will increase the serum cholesterol levels directly, many have reduced the egg consumption. This “cholesterol phobia” has scared the people in developed countries until 1990 and still continued to do so in developing countries including India due to ignorance; leading to low egg consumption. Even though the nutritional superiority of the egg has been proved beyond doubt, the egg consumption in India is very low due to vegetarianism as well as cholesterol scare. Although the nutritionists and cardiologists have established that there is only an insignificant correlation between dietary and serum cholesterol levels; the consumers are still scared of consuming cholesterol rich foods, hence there is an urgent need to reduce the egg yolk cholesterol levels as well as to incorporate several other health promoting components in the egg. The industry is presently geared in production of speciality eggs that have higher or enriched levels of certain nutrients already present in the eggs or lower the levels of other nutrients, which are considered undesirable for some reasons. Such eggs are called “designer eggs“, “functional eggs”, “diet eggs”, ” “omega-3 fatty acid enriched eggs”, which are capable of safeguarding the health of the consumers. The designer egg will be produced with rich health promoting components like omega-3 fatty acids and vitamin E along with incorporation of some more additional health promoting components, like anti-oxidants, carotenoid pigments, certain vitamins and minerals; besides reducing the yolk cholesterol levels. In general, omega-3 fatty acids reduced the LDL-Cholesterol (Bad cholesterol) levels in serum, thereby reducing the risk of cardiovascular diseases. Furhter they scavenge the free radicals and act as immunomodulators in the persons, consuming such eggs regularly.
DESIGNER EGGS———–
One of the ways to market a new product is to change the old product. The contents of the chicken egg can be changed in such ways as to be more healthful and appealing to a segment of our consumers who are willing to pay for those changes in the egg. “Designer eggs” are those in which the content has been modified from the standard egg.
Designer eggs contain higher concentrations of several vitamins, high omega 3 fatty acids pigments, minerals etc. The egg contents are modified keeping in mind the consumer demand with respect to safety, healthfulness, freshness, taste, colour, etc. The nutritional strategy is the choice of dietary ingredients. Functional feed for functional food is the first step for the production of designer egg by incorporating the substances in the layer feed for producing nutritionally enriched eggs.
In case of poultry products, there are two types of value addition. One is, value addition before the product is produced, i.e.”pre-slaughter or pre-oviposition value addition”. Products like, organic / designer / functional eggs and meat will come under this category. The other category is “post-slaughter or post-oviposition value addition”, which is usually referred as “post harvest technology”.
The health conscious consumers are in need of safe poultry products, which are free from drug / pesticide residues and other harmful components. Moreover, the consumers are ready to pay a premium price for such products, which are safe and also promote their health; due to the presence of special health promoting components like n-3 fatty acids, anti-oxidants, extra vitamins, minerals and non-nutrient components. These types of value addition will be done mostly by combination of manage mental and nutritional manipulations, such value addition in eggs is otherwise also called Designer eggs.
Designer eggs-Significance——————-
In general, eggs are regarded as highly nutritious food. The egg is considered as nature’s most complete food containing high quality proteins, a 2 to 1 ratio of unsaturated fats to saturated fats an excellent source of iron, phosphorus and other minerals and all vitamins with the exception of vitamin C. Multifunctional attributes of eggs have contributed to their continuing use as ingredient in many food items. The antibacterial components in the egg and their contribution to food safety is an acknowledged fact.
Pre-Oviposition Value Added Eggs—–
Organic and cage-free eggs are the earliest pre-oviposition value added eggs. According to the American Egg Board (AEB), organic eggs are those obtained from hens fed rations having ingredients that were grown without pesticides, fungicides, herbicides or commercial fertilizers. Moreover, these hens are reared free from cages and fed organic feeds free from any performance enhancers like antibiotics, antimicrobials, coccidiostats and other drugs. The organic foods are usually free from residues of pesticides, drugs and other harmful chemicals. The chemical composition of cage reared and free-range hens’ eggs are reported in Table 1.
Egg is the best vehicle to incorporate several health-promoting components in it. As early as 1934, Cruickshank has reported that the fatty acid composition of egg yolk could be modified by dietary manipulation. However, this technique was not utilized for more than 50 years. Dyerberg and Bang (1979) reported that n-3 fatty acids would protect the heart from Cardiovascular Diseases (CVD). In the late 80s, Sim, Jiang and their associates in the University of Alberta, Canada, have blended these ideas together and developed a Designer Egg, rich in n-3 fatty acids and antioxidants. They have patented this egg as Professor Sim’sDesigner Egg. They have incorporated the n-3 PUFA in the egg yolk at the expense of saturated fatty acids, by feeding hens with diets having flax seeds. Since n-3 PUFA is highly unsaturated and unstable, the yolk fat will undergo rancidity quickly; leading to off odours. To overcome this problem, they have incorporated natural antioxidants like vitamin E, selenium and carotenoid pigments.
Later in Australia, Farell (1998) enriched the eggs with folic acid and iron; which are good for anemic patients. In Canada, Leeson (2004) produced lutein-enriched eggs; which will act as a retinal tonic, by preventing Macular Degeneration and Retinitis Pigmentosa. In India, Narahari (2004) has developed Herbal Enriched Designer Eggs (HEDE), which are not only rich in n-3 PUFA, vitamin E, selenium, carotenoids, certain B complex vitamins and trace minerals; but also rich in herbal active principles like, Allicin, Betaine, Euginol, Lumiflavin, Lutein, Sulforaphane, Taurine and many more active principles of the herbs, depending upon the herbs fed to the hens (Table-2). Moreover, these eggs had about 25 % lesser cholesterol in their yolks, compared to ordinary eggs. Feeding such HEDE to human volunteers has resulted in significant reduction in their Triglycerides (TG) levels, increased the good HDL cholesterol (Table 4), improved immunity and haematocrit.
Table – Active principles present in herbs/ herbal enriched functional eggs and their role in human health
Active principles Source Effect on human health
Allicin, Allylic sulfide Garlic, onion and their leaves Lower L.D.L. cholesterol and anticarcinogenic
Betaine Sugar beet, grape pulp Reduces plasma homocysteine, which damages arterial walls
Carotenoid pigments Spirulina, marigold petals, alfalfa, red pepper Antioxidant, anticarcinogenic
Eugenol, eugenic acid Basil leaves Immunomodulators
Flavonoid compounds Turmeric powder Antimicrobial, antioxidant
Lutein Bay (curry) leaves, Marigold petals Antioxidants, Improves vision
Lycopene Tomato pomace, grape pulp Lowers LDL (bad) cholesterol, antioxidant, anticarcinogenic
Nirangenin Citrus pulp Reduces LDL cholesterol
O-3 PUFA Flax seed, canola, fish, oils insects, worms Reduces LDL cholesterol, hypertension, angina, atherosclerosis
Phytosterols Seeds, weeds, legumes fenugreek Increases HDL (good) cholesterol, reduces blood sugar
Quercitin, Luteolin, Diosgenin, citogenin Fenugreek, spices Stimulates insulin secretion, antimicrobial, tonic
Statin Brewery waste, yeast, fermented products Lowers LDL cholesterol
Sulphoraphane Brocoli, cauliflower, cabbage, radish leaves, waste Anticarcinogenic and antioxidant
Taurine Milk, eggs and meat products Prevents atherosclerotic plaque formation
Tocotrienols Brans Lower LDL cholesterol
DIFFERENT TYPES OF DESIGNER’S EGGS————-
Dietary manipulation is the major step in producing the pre-oviposition/pre-slaughter value addedpoultry products. Various nutritional manipulations to the chicken diet will be done to produce different types of value added products.
Omega 3 poly unsaturated fatty acids enriched egg———-
Poly unsaturated fatty acids (PUFA) are classified into two groups/families: Omega-3 and Omega – 6 PUFA, depending on the position of the first double bond from methyl end of the carbon chain. PUFA with the first double bond on the third carbon atom from the methyl end are called Omega-3 fatty acids. Linolenic acid (C18:3 n-3), eicosapentenoic acid (EPA, C20:5 n-3), and docosahexaenoic acid (DHA, C22:6 n-3) are the main Omega -3 fatty acids. The dietary sources of w-3 fatty acids are linolenic acid from flaxseed, canola and soybean oils or docosahexanoic acid (DHA) or eicosapentaenoic acid (EPA) from marine algae or fish oil. Linoleic (C18:2 n-6) and arachidonic acids (C20:4 n-6) are the major Omega -6 fatty acids. Dietary sources of linoleic acid are corn oil, safflower oil and sunflower oils and that of arachidonic acid are meat, eggs and brain. Dietary fat concentration has little effect on the total fat content of the egg yolk. But its fatty acid profile (or the ratios of the different types of fatty acids) can be modified simply by changing the type of fat used in the diet. Hens fed diets high in omega-3 fatty acids produce eggs with high omega-3 fatty acid content in the yolk.
Omega-3 polyunsaturated fatty acid (PUFA) and lutein are important value-added ingredients incorporated from diet and deposited to egg yolk in layers. Due to the anti-nutritive factors associated with flax, the incorporation of omega-3 PUFA in diet reduces the transfer of lutein to the yolk. This can be taken care by feeding the omega 3-fatty acid and lutein rich diets on alternate days. Another strategy to improve incorporation into the yolk includes modifying delivery of ingredients, or modifying the ingredients themselves like extrusion of flax seed. The energetic efficient birds are also more efficient in nutrient absorption due to longer and wider villi with higher villus length to crypt depth ratio and greater surface area in the duodenal area. There is a time course to the egg enrichment process reaching a plateau state. Laying hens due to their ability to turn over stored body lipids in 6-7 days usually reaches a stable enrichment contents approximately after seven days when fed enrichment diet.
Vitamin enriched egg———–
The vitamin content of the egg is quite variable depending upon their concentrations in the diet. Efficiency of the hen for the transfer of different vitamins into the egg varies from 5-80% (Naber, 1993). Therefore the vitamin contents of normal egg can be modified by dietary manipulations. Two vitamins, A and E, are gaining worldwide interest of the nutritionists. The hens are fed to produce eggs with more vitamin E than ordinary eggs. The results of a study conducted by Leeson and Caston (2003) to increase the egg vitamin levels by increasing the dietary concentration of vitamins by 3-10 times in the hen’s diet indicated that only five vitamin E, 25%; vitamin K, 108%; biotin, 60%; pantothenic acid 24% and vitamin B12, 139% were deposited in the egg in sufficient quantities.
Mineral enriched egg——————-
Most of the minerals are present in the egg shell with very minute quantity present in the albumen and yolk. There has been very little success in changing the calcium and phosphorus content of the albumen and yolk. It is possible however to increase the content of selenium, iodine and chromium. Selenium may be added to laying hen diets either as selenite, selenate (inorganic forms) or as selenomethionine (organic form). Selenium content of the egg can be increased by supplementing with 0.4 ppm selenium as seleno- methionine in hen enrichment feed. In the iodine deficient areas of the iodine enriched eggs can be a good source of iodine. Today, the selenium content of eggs can be easily modified by the supplementation of organic selenium rich feed to the hens. Selenium enriched eggs were first time developed in the Scottish Agriculture College in 1998 (Surai, 2000) by the use of supplementation of organic selenium in the form of Se-enriched yeast into hen diets. The selenium exist in the eggs mainly in the form of selanomethionin (Se-met).
Anti-oxidants enriched eggs————-
Egg is a rich source of natural antioxidants which protect the fat-soluble vitamins and other yolk lipids from oxidative rancidity. However, their normal levels in the yolk are not sufficient to protect the designer eggs rich in omega-3 PUFA. Hence it is essential to increase the anti-oxidant levels in the designer eggs. The designer egg not only contain high levels of the above antioxidants; but also contain synthetic anti-oxidants like ethoxyquin and anti-oxidants of herbal origin such as lycopene, curcumin, sulforaphene, carnosine, quercetin, depending upon the herbs used in hens’ diet. Supplementation of these anti-oxidants in hens’ diet increases their levels in the egg. For designer egg production, vitamin E and organic selenium are added as anti-oxidants at levels of 200-400 mg/kg and 0.1-0.3 ppm, respectively.
Pigment enriched eggs—————
Yolk colour is the index of pigments present in it. In India people prefer dark coloured yolk eggs as they consider these eggs to be Desi and more nutritious and pay premium for these eggs. Dietary concentrations of any particular pigment govern the types and the concentrations of pigment in the egg. Poultry nutritionists increasingly recognize that carotenoids though act as a precursor for vitamin A yet these pigments have the ability to scavenge free radicals and to affect innate, humoral and cell mediated immune response. Egg yolk carotenes are classified as xanthophils (Lutein 0.1%, zeaxanthin 0.2% and cryptoxanthin 0.03%) and carotenes (traces of a-carotene and 0.03% b-carotene). Canthaxanthin (carotenoid) is deposited in the yolk at a level that is linearly related to the level in the diet (Grashorn and Steinberg, 2002). Other carotenoids that have been considered for inclusion in eggs include lycopene (Kang et al.., 2003).
Among xanthophylls lutein and zeaxanthin are most abundant (Handel man et al.., 1999). These pigments are effective against macular degeneration, a major cause of blindness in the elderly. Lutein, zeaxanthin and Vitamin E protect eyes against macular degeneration. Of the estimated 600 naturally occurring carotenoids, only lutein and zeaxanthin are selectively incorporated into the macula. These carotenoids absorb blue light (responsible for damaging retinal membranes. Lutein and zeaxanthin as antioxidants take care of free radicals induced by oxidative stress. Xanthophylls also act as anticarcinogenic agents. Some of the pigments posses’ vitamin A activity.
Antibodies enriched egg-——————–
Chicken egg is abundant in antibodies like “IgY”; which can be used to treat human rotavirus, E.coli, Streptococcus, Pseudomonas, Staphylococcus and Salmonella infections. A hen has the ability to produce about 298 mg of specific antibodies within 6 weeks. The lysozyme (G1- globulin), G2 and G3 globulins, ovomacroglobulin, antibody – “IgY” and other natural antimicrobials and immunostimulants are present in the egg.
Pharmaceuticals————-
Biotechnology tools are being used to develop genetically modified chickens that produce compounds that can be harvested from the eggs. These compounds include insulin for the treatment of diabetes. Hen produces antibodies when exposed to viruses, bacteria, etc. The antibodies circulating in the hen’s body are transferred to the eggs. Now specific antigens are being selected and injected to the hens to develop antibodies against them. Designer eggs in near future may be produced that result in a range of antibodies for treatment against snake venom, to counter microorganisms which cause tooth decay.
SPECIALITY EGGS
Eggs which have a special attribute which makes them attractive to a niche market are known as “speciality” eggs. A number of these eggs are available in stores. The packaging used, however, can often be misleading. Alternative choices to consumers with special needs and preferences. • Nutrient content of an egg can be changed only by altering the hen’s feed. • Nutrient content cannot be altered by changing environmental conditions. • Due to higher production costs, specialty eggs are usually more expensive than generic shell eggs.
Types of Specialty Eggs –
Organic Eggs
Vegetarian Eggs
Aracauna Eggs
Pasteurized Shell Eggs
Fertile Eggs
Cage-Free Alternatives
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
Image-Courtesy-Google
Reference-On Request.
