Nutrition Meets Food Science

Wonders Beneath the Shell

Eggs always remind me that “you really don’t know what lies beneath the shell of someone that you know”. If we go in history of eggs – we will come to know that eggs are part of food system since creation of mankind providing us with best quality protein &many other important nutrients. Be it a main ingredient or a side one it gives a different texture as well as flavour to all food items.

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India is one of the largest egg producers in the world. Although eggs of all birds are eaten, eggs of chicken are the most consumed one than any other bird. Just like a skin, the brittle, glossy outer shell protects the inner content of an egg.

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Moving on to what’s inside the shell?

  1. Shell a membrane – that prevents the entry of microorganisms inside egg & reduces excessive evaporation of the inner content.
  2. Egg white – It has maximal water but contain 8-12% protein with trace amount of carbohydrate & fats. Some egg white proteins are ovalalbumin, conalbumin, ovamucoid, ovamucin, lysozyme, avidin, ovoglobulin & ovoinhibitor.
  3. Egg yolk – The egg yolk comprises around 25-33% fat & 15-17% protein & water. Lecithin present in yolk gives egg an excellent emulsifying property which is required for making cakes, muffins, mayonnaise, etc.

Looking from nutrition point of view, eggs are rich source of energy, proteins, fat, minerals & vitamins except vitC.

Nutrient Amount Nutrient Amount
Energy Kcal 173.0 Retinol µg 420
Protein g 13.3 Thiamine mg 0.1
Fat g 13.3 Riboflavin mg 0.4
Calcium mg 60.0 Niacin mg 0.1
Phosphorus mg 220.0 Folic acid µg 78.3
Iron mg 2.1 Vitamin B12 µg 0.2

Nutritive value of egg as per 100gms (Source: Food Science, B Srilakshmi)

Safety measures to keep in mind while Buying, Handling & Cooking Egg:

  1. Do not buy the broken one as there is a chance of microorganism invading in it.
  2. Outer surface may be dirty and contaminated so it may be better to wash the eggs with soap if not clean.
  3. Refrigerate eggs at low temperature for longer shelf life.
  4. Purchase only that much needed for a week or two, do not buy in bulk & store, the freshness will anyway gets reduce.
  5. Cook atleast till the white portion solidifies to ensure killing germs if incase present.
  6. Floating test to evaluate the quality of egg :
    Dip the egg in 12 % salt water if the egg sinks it is considered as good in quality whereas floating eggs are poor one due to the fact that it floats because of increase in air cells & loss of moisture the longer it is stored.

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Vegetarian eggs are unfertilised (without fusion of sperm) eggs of hen. The leghorns which are chosen for egg production lay only unfertilised eggs as they are not allowed to mate with cocks whereas country breed lays fertilised eggs which are commonly sold in India.(You get unfertilised eggs also very commonly now in India. These are bigger, mostly white and have very little flavour when cooked whereas country breed has smaller eggs which are mostly brownish and have very nice typical flavour).

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Role in Cookery

People all over the world eat eggs as in varieties of delicious, mouth watering cuisines such as egg curry, egg garlic rice, egg biryani, stuffed eggs, egg crescents& breakfast recipes such as omelette, fried egg, frankies, poached eggs, scrambled & boiled eggs.

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Omelette is the most common cuisine made by beating egg & frying it in little amount of oil or butter. Any combination of veggies, herbs, spices, meat, chicken, garlic, mushrooms, etc can be added as filling; hence omelette is the most variant recipe out of all the other.

Scrambled egg is prepared by beating egg yolk & egg white with or without addition of milk& then cooking &stirring gently for few minutes as it coagulates.

Poached eggs are commonly eaten in the traditional American breakfast. It is made by breaking & directly putting egg in boiling water. The egg is left in hot water until the white portion becomes like soft jelly & the yolk is semi liquid covered by white portion of egg.

Egg curry (also known as Anda curry) is a typical Indian quick & tasty recipe in which egg is simmered in spicy masala curry made with blending vegetables, coconut milk &various spices.

Street side Egg franky/ Egg roll: A fast food which is healthier at the same time? Yes! Egg franky is one of it, it can fulfil your cravings for junk with spicy tangy sauces, loaded with veggies &egg rolls folded with layer of Roti/paratha made up of cereals/ millets.

Foaming of egg

The foaming property of egg white makes it quite necessary ingredient in confectionary industries for making cakes, pastries, custards & other bakery goods. Foaming occurs in egg because of formation of collide of air bubbles surrounded by egg protein- albumin. As we beat egg, the albumin gets denatured (lose its structure) & some of them becomes insoluble that results in stiffening & stabilising foam.

Eggs are used as thickening agent in soups, stirred & baked custards, puddings, etc

It can be used as an emulsifying agent especially for ice-creams, candies & mayonnaise.

Role in making cakes & other bakery products:

It helps in binding all ingredients together adding good structure & strength to the cake.

It adds flavour, colour, moisture & texture to the baked goods.

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Egg whites are whipped to make a smooth foam and can be used in leavening of bakery goods.

The more egg added to the cake more tender, soft & eggy it will taste that an egg lover may like to eat.

Eggs & Cardiovascular risks:

People living with cardiovascular disease cut off eggs from their daily diet because of the fear that it might increase their blood cholesterol level. Although eggs contain some amount of cholesterol in it eating one egg a day will cause no rise in the cholesterol level. Consuming egg with other snacks or breakfast which is already having a bulk of fats may lead to rise in cholesterol or eating with high fat red meats.

American Heart Association (AHA) says “Eggs Fit in Heart Healthy Diet Patterns”

  • Healthy individual can include upto a whole egg in heart-healthy diet pattern

According to the Australian Heart Foundation (AHF), there is no evidence of egg directly affecting heart health for people to limit egg consumption.


Studies on relationship between eggs & dietary cholesterol continues to grow as science advances. From over all data it is clear that eggs are excellent source of essential nutrients precisely Vit A (retinol), proteins & carbs. This Nutrient-dense property of egg makes it healthier amongst other animal source foods. It is always a great option with less cooking time & more palatable whether you have it with whole wheat bread, parathas, egg salad, roll or franky with a dip.

Abir Ansari

Jr. Nutritionist, PFNDAI

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