Hey
Here's what I found so far:
I can also say I have read that egg whites amount to the purest form of protein and therefore (albumin) is used as a standard from which to measure other proteins efficiencies.
Safest yet - no more than 2 - 3 yolks per day for most (except allergics) and egg whites have no limit, except that too much protein will cause hyperacidity and that in itself is not good (1 - 1.5 g protein per day more than enough).
<div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">EGGS
NUTRITIONAL CONTENT, COMMERCIAL
ASPECTS AND DIETARY LEGISLATION
Source : Zafferano, Volume No.4 April,2000
Mirella Giuberti - Nutritionist - Teacher By State Hotel Institute "Orio Vergani in Ferrara"
In April of last year the Research Institute CIRM conducted a survey on common nutritional stereotypes. From this survey of doctors gastronomic experts foods industry managers specialist journalists and junior school students, it emerged that certain prejudices old and new regarding Italian dining habits are still very much alive it seems that a large number of Italian consumers have an exaggerated idea of the nutritional value of eggs.
And accordingly this article aims to shed a little light on the subject.
COMPOSITION
An egg weight on average 60g and consists of three parts; the shell (approx. 6g) is made of calcium and magnesium carbonates calcium and magnesium phosphates and other organic substances the albumen also called the white weight approx 20g is made of water and protein and coagulates readily when heated the yolk is positioned and held in the center by elastic band-like structures (a thickening of the albumen) known as the chalaza, and constitutes the most nutritionally valuable part of the egg.
It is rich in proteins of high biological value (linked to iron and phosphorous) as well as fats vitamins and minerals.
The white is surrounded by a shell, which in turn is made up of two layers. In the wider portion of the shell these layers tend to come unstuck generating a space full of air called the air space which is important in determining the freshness of the egg.
NUTRITIONAL VALUE
The egg is not a complete food as it lacks sugars and vitamin C, but it is rich in other valuable nutrients 100g of whole egg (2 eggs weighing 50g net each) contains 12.4% proteins 8.7% fats, a good amount of vitamin B1,B2,PP, A and D, and a good quantity of iron phosphorous, sulphur and potassium up an energy value of 128kcal (food composition tables National Institute ed 1997).
Proteins have considerable nutritional value; they contain amino acids that the human organism has difficulty producing therefore they must be introduced through diet to ensure growth and reconstruction of tissues proteins contained in the white and the yolk of an egg are the best source of protein for man albeit certain proteins in the white can cause allergic reaction in individuals with particular sensitivity.
Fats; Eggs contain a modest quantity of fats (compared to 16-47% found in cheese and 35% in salami and sausage products) with various chemical structures; eggs contain triglycerides rich in saturated fat phospholipids and cholesterol Note that eggs now contain one forth less cholesterol than in the past at 371mg/100g. for this reason Indications on weekly consumption of egg given to hypercholesterolemia sufferers are now less restrictive but there is still a ban on packaged products with a high yolk content e.g. mayonnaise custards certain desserts (typically tiramisu) or pasta dishes containing which is also rich in cholesterol.
Phospholipids are highly unsaturated lipid molecules of which lecithin is the most important; lecithin abounds in the yolk and contains choline which is indispensable to cell nuclei and particularly to nerve cells.
These compounds are useful for contrasting hypercholesterolemia and are necessary for the metabolism of the liver.
DIGESTIBILITY
The digestibility of a food is calculated by measuring the time between ingestion and passage from the stomach to the intestine Research has shown that egg remains in the stomach for a relatively brief period that varies according to how the egg is cooked .
Two soft-boiled eggs remain in the stomach for less than two hours while two fried eggs pass to the intestine after approximately three hours.
Raw white of egg is difficult to digest as the gastric juices find it difficult to break down and cooking the white also has the effect of deactivating an antivitamin factor.
As for the yolk the fats are rendered more digestible by minimal cooking albeit a greater heat would help digestion of the proteins.
Accordingly soft-boiled eggs are the most beneficial.
The main effect of cooking an egg is that the proteins coagulate turning from fluid become solid and thermolabile vitamins are lost to a significant degree.
COMMERCIAL ASPECTS
There are various commercial aspects connected with the different characterizing features of an egg. The WEIGHT can vary from more than 75g to less than 45g and must be identified by law. The colour of the shell white or speckled is strictly connected to the breed and has nothing to do with the nutritional value of the egg itself. The colour of the yolk can vary from light yellow to dark orange and depend mainly on the presence of vegetal pigments (carotenoids) that may be present in the feed but can also vary according to the breed of anima. The taste generally fine delicate and pleasant can also vary according to the type of feed given to the laying hens. Odour in general is nit present although the porosity of the shell can allows smells from adjacent products to permeate into the egg.
LEGISLATION
Statutorily the single word egg defines a hen’s egg If the egg is not produced by a hen then the word must be accompanied by the species of fowl (pheasant duck goose etc.) Both Italian law and EU regulations impose exact specification on eggs destined for the commercial distribution. Among the numerous aspects involved, producers must observe instructions on the obligation to identify freshness and weight.
Freshness. Is evaluated by determining the depth of the air space, which is inversely proportional to the freshness of the product.
Egg are classified in various categories indicated by the letters A,B and C allowing the customer to select the desired product; A EXTRA-egg with air space less than 4mm; A-egg with air space less than 6mm; B-egg with air space Between 6 and 9mm; C-egg with air space more than 9mm Category C eggs are not retailed but used in the food industry; category B egg are divided into three subgroups according to the storage technique used.
The weight is shown using weight intervals/categories or by a number varying from 1 (heaviest) to 7 (lightest)
After classification at the packaging center the eggs are distributed for sale in containers showing the quality and weight the week or date of packaging and the name of the packaging company Retailers must purchase eggs from the packaging centers where the product is sealed with labels provided by the relative government department.
Egg can also be sold by the producer direct to the consumer but in this case the eggs do not have to carry indication relative to quality.
STORAGE
An egg gathered in accordance with recommended health and hygiene conditions and put straight into refrigeration will remain fresh for at least a month As cracks in the shell and compression of the air space are to be avoided it is advisable to place the egg with the narrow end downwards.
Ageing gradually denatures the membrane around the yolk, which will appear less compact and when the shell is cracked open Laceration of the air space leads to rapid decomposition with hydrolysis of the proteins and an increasing level of ammonia in the yolk.
DIETARY ASPECTS
The yolk is introduced early into a child’s diet due to its considerable nutritional properties Given the possibility of an allergic reaction the white is usually introduced later towards the end of the first year of life.
The inclusion of eggs in the diet of young people adults and the elderly provides fundamental nutrients and the elderly provides fundamental nutrients for growth and maintenance of body structures.
The egg also improves the nutritional value of other food sources as they can be used in a very versatile way in numerous dishes; in egg pasta for example the lack of protein and low mineral and vitamin content of wheat is compensated for by the egg.
The absence of uric acid precursors make the egg an indispensable source of protein for gout sufferers
whose consumption of meat must be strictly limited.
The presence of choline stimulates liver function. Eggs are not contraindicated in the prevention or cure of arteriosclerosis.
From a dietary point of view accordingly the whole egg with no added fat is tolerated well by everybody except individuals with diseases of the gall bladder.
In the case of gallstones eggs can cause contraction of the gall bladder wall resulting in colic pains.</div>
