It's supposed to help with cooking the albumen in such a way that it doesn't get all feathery at the edges.
I have no idea what the actual chemical reaction is, though.
I've also heard of people adding a pickle to the poaching liquid instead of vinegar directly.
Vinegar and salt both help the proteins (albumin) to denature (unwind) more quickly and link up to form a network of proteins, thus setting the egg. The quicker the proteins denature the less feathering there will be around the edges and the nicer looking the egg.
Egg whites need to be heated up to a certain temperature in order to coagulate ("set").
Lowering the pH (increasing the acidity) of the cooking liquid is one way to lower the temperature required for coagulation of the egg whites. So, in a way, this does prevent "feathering" of the eggs, but not because of any direct reaction; rather, the reason the eggs feather less is because they have less time to feather, because they don't need to get as hot.
Any acidic liquid will have a similar effect. White vinegar is probably the most effective, but you could also add lemon juice or wine to the poaching liquid. In fact, eggs poached in red wine sauce ("Oeufs en Meurette") is quite a popular preparation method.
For reference, the coagulation temperature is also proportional to the salinity (add salt to lower the coagulation temperature, add sugar to raise it), and inversely proportional to the number of eggs used (more eggs = lower coagulation temperature).
I read this question - What is the effect of poaching fish in milk? and was surprise that one can poach fish using milk. However, I was wondering if the milk will be spoil if it is continuous being cooked? And also would it be better if milk powder is used instead of just fresh milk?
I'm sometimes making my own béarnaise sauce, and it tastes great and has perfect thickness the first day after making it. But whenever I leave leftovers in the fridge over night, the béarnaise gets really thick (like when whipping cream to much). I'm trying to keep from overcooking my egg yolks, so I don't think that's whats wrong. I follow a pretty classic recipe with taragon, black peppercorns, white wine vinegar, shallots, egg yolks and clarified butter. Is there a way to keep it from thickening like this when left in the fridge over night?
1.What is the difference between poaching and slow cooking? I believe in poaching you are meant to remove chicken 20 minutes after boiling so the meat doesn't dry out while In slow cooking I believe you leave it for longer so that the meat becomes more tender? Is the temperature for both between 140F-180F? Are there any other differences between the two when it comes to cooking soup e.g.... of cooking. Anyway which is correct, does slow cooking actually affect salt water absorbtion to the point that the chicken in a soup will absorb more salt? Will poaching chicken soup cause salt water
I experiment some with pie crusts and have seen recipes that include vinegar as well as eggs. What does the vinegar do and what does the egg do. I have heard the vinegar promotes tenderness but have read on one of the posts here that it speeds gluten formation.
Possible Duplicate: How should I poach an egg? How do you make a poached egg without it getting all messy when you break the egg into a pot of boiling water? I find that it is hard to get the egg to coagulate cleanly and evenly when making poached eggs. Someone suggested using balsamic vinegar which helps a little bit but the vinegar is messy in itself. I have also tried putting the egg into a special poached egg pod, but it is hard to get the egg out.
When I poach eggs, an off-white foam/scum forms on the surface of the water and sometimes attaches itself to the egg. Does anybody know what causes it, and how I can avoid it? EDIT: I use malt vinegar rather than white vinegar, which I think discolours the foam/scum and makes it look more unpleasant, so I think I'll change to white vinegar.
I have a recipe that calls for Wanjashan naturally brewed organic rice vinegar and I do not have this ingredient. Is there another vinegar I can used instead? I have white vinegar, red wine vinegar, and malt vinegar. The recipe is for sweet and sour pork ribs with honey.
I have seen recipes for easter egg dyes that call for 1/4 cup vinegar per cup of water and others that call for 2 teaspoons per cup of water. That's a pretty wide range--what practical effect does the amount of vinegar have? More generally, what is the role of vinegar in dye recipes? What would happen differently if it were left out?
Some recipes call for red wine vinegar in steak marinades. Is the Red wine vinegar used as means to break down the meat tissue or is it just there as a flavor agent?