· and age of fowl. · In the 1970s

·       In
the 1970s the American heart association recommended that people limit their
daily cholesterol consumption and egg intake to reduce the risk of CHD.

·       Egg
is cholesterol enriched and contributes to the risk of CHD.

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·       Cholesterol
metabolism is complicated in the human system and the human diet is not the
sole factor that decides the level of cholesterol in the blood.

·       Healthy
daily cholesterol intake of less than 300 mg/ day.

·       Cholesterol
content in a typical large egg is 213 mg of cholesterol per yolk; in this way,
the daily consumption of one yolk should technically meet the AHA guideline.

·        If the egg yolk cholesterol content could be
reduced to 50% the consumption of two eggs per day will meet the AHA.

 

 

 

 

GENETIC SELECTION:

·       From a
genetic point of view egg cholesterol content is affected by several factors
such as species of bird breed, or strain and age of fowl.

·       In the
1970s several genetic selection studies aiming to decreases egg yolk
cholesterol were carried out.

·       Reduction
in cholesterol by genetic selection is fairly small (9 to 10mg) and is not
significant if an average daily intake of cholesterol is about 250 mg.

·       However,
there is a lower limit to egg yolk cholesterol, due to its role in developing
the embryo.

·       Disadvantage
is that genetic selection for low cholesterol eggs results in smaller yolks and
smaller egg size.

·       However
limited changes in yolk cholesterol concentration (5to 7% reduction) can be achieved
by genetic selection.

 

 

 

 

EFFECTS ON
CHOLESTEROL OF DIETARY CHANGE:

Effect of fat:

·       Dietary
cholesterol supplementation can increase the concentration of cholesterol in
eggs.

·       Dietary
omega-3 fatty acids are another factor affecting yolk cholesterol content.

·       Feeding of
birds with menhaden fish oil and flaxseed results in yolk cholesterol
reduction.

 

 

 

 

 

·      
Flaxseed

               

 

Effect of natural products:

·       Some
natural products have been shown to have the ability to reduce cholesterol
level in humans and animals.

·       Garlic has
been reported to be the most effective agents in reducing the cholesterol level
in yolk and plasma.

 

               

·       Egg yolk
cholesterol was significantly decreased by feeding alfalfa meal, oats,
sunflower meal; rice mill feed r wood shaving to laying hens when compares to
yolk cholesterol of hens fed the basal diet.

·       Greatest
reduction in egg yolk cholesterol was found by feeding either oats or wood
shavings.

oats

         

Wood shavings        

                

 

Effect of Phyto sterols:

·      
Phyto sterols (also called plant sterols), which are
structurally and functionally similar to cholesterol in vertebrate animals.

·      
Feeding plant sterols decreases cholesterol
concentration in plasma and egg.

Effects of minerals and vitamins:

·       Dietary micro
minerals (copper, zinc, vanadium, chromium, and iodine) and minerals or dietary
vitamins (vitamin A, ascorbic acid, and niacin) change the yolk cholesterol
level.

·       However,
the role of vitamins and minerals has not been proved yet beyond doubt.

 

Effects of fibre:

·       Dietary
fibre is a group of ingredients portion of plant of foods that can be resistant
to the human or animal gastrointestinal system, absorbing water and easing
defecation.

·       It is
thought that fibres could affect cholesterol metabolism through bile acid
binding and stimulate faecal sterol excretion.

·       Regardless
of the dietary source, feeding fibre to laying hens dilutes the available
energy content of a diet and, as a result, may limit energy intake and
potentially reduce hepatic cholesterol production especially if prior energy
intake had been excessive.

PHARMACOLOGICAL
METHOD:

·       Certain
drugs have been successful in lowering egg cholesterol by as much as 50%.

·       Drugs lower
cholesterol in the egg by either inhibiting the synthesis of cholesterol in the
hen or by inhibiting the transfer of cholesterol from the blood to the
developing yolk on the ovary.

·       Today, the
drugs which have shown promise in lowering cholesterol are not yet approved by
the FDA for commercial use.

·       Chromium
supplementation to laying hen diets at concentrations of less than 1 ppm have
been shown to lower egg cholesterol and also improve egg interior quality.

·       Supplementing
a layer ration with chromium picolinate alters lipid profiles in the serum and
the lower cholesterol content f the yolk.

·       Even though
genetic selection alternative nutrition and pharmaceutical techniques are an
effective strategy in modifying egg cholesterol content, there is a certain
limit possible for the reduction of cholesterol levels.

·       Liver and
the ovary are the primary sites of cholesterol biosynthesis in the laying bird.
(Popjak and tietz,1953;husbands and brown, 1965;weiss et al., 1967a).

·       Most of the
cholesterol found in the yolk is synthesized in the liver of the hen,
transported by the blood in the form of lipoprotein, and deposited in
developing follicles; the concentration of plasma cholesterol is not closely
associated with the concentration of yolk cholesterol.
(weiss et al 1967c; Sutton et al.,1984)

·       Lovastatin,
which is an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase , the
rate limiting enzyme in the cholesterol biosynthesis pathway(rodwell et
al.,1976).

 A method for preparing a low
cholesterol egg product resembling a Sunnyside
up egg product comprising:

·       providing a mold having
yolk cavity and a white cavity;

·       supplying to the yolk
cavity, a simulated yolk portion having a water to dry ingredient ratio of from
about 0.8 to about 1.2, and comprising, based on the weight of dry ingredients,
from about 20% to about 45% of dry egg white, from about 5% to about 35% of an
oil having a P/S of greater than about 0.6, from about 10% to about 15% of a
dry milk protein source, from about 0.5% to about 7% of vegetable gum, and flavouring,
colouring and emulsifiers in an amount sufficient to maintain uniformity in the
yolk portion;

·       Supplying to the white
cavity on top of the yolk portion, a white portion consisting essentially of
liquid egg white;

·       Freezing the yolk and
white portions;

·       Removing the frozen egg
product from the mold; and

·       Frying the egg product
over low heat to obtain a cooked, natural appearing Sunnyside up egg product.

 

 

 

 

 

 

 

REFERENCE:

Ø Modifying
egg yolk cholesterol in the domestic fowl – a review  P.STEWART HARGIS.

Ø Low-cholesterol egg product and
process US 3941892 A

Ø Reduction of the cholesterol
content of eggs by the oral administration of lovastatin to laying hens ;
Robert G.elkin and John C. Rogler