Why do eggs become hard on boiling??!


Question: Why do eggs become hard on boiling!?!?
Answers:
When you heat an egg, the heat causes the amino acid bonds in the proteins to collapse and rebuild stronger bonds!. As this process takes place, the bonds grow stronger and tighter (via energy from the heat) and force out the water that made them liquid!. Thus, the equation for an egg is the more you heat it, the more water is forced out during the protein bonding and thus the egg becomes harder!.Www@FoodAQ@Com

Cooking, or packing in alcohol, vinegar, salt, some clays or lime, all will make an egg go hard!.!.!.!. eg pickled eggs, Chinese thousand year eggs, etc!.!.!.
all are great to eat, just boiling is a little boring

All these processes congeal the proteins

for a more scientific answer :-
An important function of proteins in food systems is gelation!. This phenomenon involves the formation of a three-dimensional matrix mainly through inter-protein hydrogen bonding and allows the immobilization of water within the gel structure!. The coagulation or gelation of proteins—in particular, the irreversible, heat-induced coagulation or gelation of egg proteins—often controls the success of certain cooked food products!. It is of interest to the food scientist to be able to quantitatively monitor the gelation process to better predict end-product characteristics, as well as understand the mechanism of network formation!. A better understanding of the gelation process will permit manipulation of variables to obtain a gel of desired textural characteristics and functional properties!.

Although the coagulation, i!.e!., denaturation of proteins can be brought about by heat, high pressure, salts, acids, alkalies, alcohols, or denaturing agents such as urea (Mirsky and Pauling 1936)!.!.Www@FoodAQ@Com

Egg contain 67 per cent proteins (in egg white) and 33 per cent fats and proteins (in egg yolk)!. Egg white protein is mostly albumin (ovalbumin and Conalbumin) All proteins have primary,secondary and tertiary structures!.

Tertiary structure of egg white protein is due to hydrophobic interactions and hydrogen bonding!. They also contain Cysteine amino acid, which has sulfhydryl group (SH)!.

These sulfhydryl groups form covalent disulfide bonds and hold 2 distant sections of proteins in close proximity!. Disruption of the tertiary structure (or 3 dimensional structure) due to heat, chemicals or acidity is called "denaturation"!.

When we heat an egg, the, heat breaks the intermolecular forces and the tertiary structure gets broken!. The proteins unfold from their nature folded structure and precipitate forming a white solid mass!.Www@FoodAQ@Com

because cooking makes the liquid become a solidWww@FoodAQ@Com

b/c meat doesnt melt i guess!? deep down it's just chicken (and goo - ew i know)Www@FoodAQ@Com

HeatWww@FoodAQ@Com

Ummm - because they cook!.Www@FoodAQ@Com





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