We talked the other day about how proteins are very long molecules that often come entangled together in a ball which is basically inedible and to be able to digest them we need to unfold (denature) them. Very often this process changes the appearance of food, for example in the case of fish and egg whites they become opaque, and we associate this change with the fact that they have been cooked.

While I was writing that post I read that, although the most common way to denature proteins is by heating them, there are other ways such us using vinegar or salt. This is why we think of food that has been preserved in salt or vinegar as cooked, even though they have never been exposed to high temperatures. Some examples are: anchovies in salt, pickles, Serrano ham, cured salmon, carpaccio, salted beef, etc. I did a couple of experiments to test in a small scale how this works.

In the first one I tested how vinegar can unfold proteins with an egg. I put a raw egg in a glass (this time without the shell 🙂 ) and covered it with vinegar. After a couple of hours I could already see how the white had become a bit opaque and also it stayed together rather than spreading and mixing with the vinegar:

Raw egg in vinegar.

Raw egg in vinegar.

Raw egg in vinegar after 2 hours.

Raw egg in vinegar after 2 hours.

Even though I changed the vinegar and waited until the next day, there was no further change in colour, probably because the vinegar cannot penetrate further in the egg. This explains the trick that I had heard of pouring a bit of vinegar in the water while boiling eggs to prevent the whites spreading everywhere in the pot in case an egg cracks. Of course one has to be careful with the amount of vinegar in this case not to alter the taste of the eggs.

The second experiment I did was on raw fish (in this case salmon). With just a thin layer of salt you can see (and feel when you try to tear it up with your hands) after an hours the change in colour and texture:

Raw salmon

Raw salmon

Salmon sprinkled with salt after 1 hour.

Salmon sprinkled with salt.

Difference in colour between raw salmon and salmon cured with salt.

Difference in colour between raw salmon and salmon cured with salt.

If you want to cure salmon at home with the purpose of eating it you should use a mixture of 50% salt and 50% sugar. The sugar is necessary because it feeds a type of bacteria which accelerates the process which breaks down the enzymes normally responsible to causing food to spoil. You can use this mixture to cure other kinds of fish or even meat. The length of time will depend on how thick is your slice. For a thin slice one hour is enough but if you want to do the whole salmon at once you will need 12-18 hours.

This is a small detour in the series of posts on phase transitions due to a technical problem (the thermometer I need for my next experiment run out of battery :().

Fortunately yesterday I spent the day in a cooking-related activity and have some pictures to show you.

The Edinburgh School of Food & Wine organizes one-day courses on Saturdays where you learn how to prepare a given menu and then enjoy it as a late lunch with matching wines. I received for my birthday a voucher to attend one of these courses and I chose to attend the Scottish cuisine one (they also have Spanish food, Italian food, etc).

The techniques we used were fairly basic but they gave us lots of little tricks and tips to use in the kitchen and especially the opportunity to see a real chef working life in front of you for a day, which you don’t have every day. This together with the fact that all the staff there were extremely nice and helpful made a very enjoyable day that I recommend to any amateur cook.

The menu we prepared yesterday was the following. The entrée was cured salmon salad where we cured the salmon ourselves with a mix of equal parts of salt and sugar. This usually takes over 18 hours if you want to cure the whole fish, but if you slice it think enough it takes under an hour. This was my salad:

Cured salmon salad

Cured salmon salad

The main course was Pan fried duo of pheasant and pigeon with rumbledethump potatoes (which is a fancy word for potato mash with cabbage). What I enjoyed most of this recipe was to learn how to make a whisky sauce which here in Scotland very often accompanies meat and the number-one Scottish dish: haggis. Here is my main:

Duo of pheasant and pigeon with rumbledethump potatoes.

Duo of pheasant and pigeon with rumbledethump potatoes.

For dessert we had a Scottish classic: Cranachan (aka Cream Crowdie). This consists of a mix of whisked cream with toasted oatmeal and Drambuie layered with raspberries (which have also been macerated with Drambuie). we accompanied it with shortbread and a not so traditional but lovely piece of dark chocolate. I was very surprised to see how easy it actually is to make shortbread and I will certainly be doing that again. Here is the result:

Cranachan with shortbread.

Cranachan with shortbread.

They told me they were thinking about doing a one-day course on tempering chocolate. If they do, I’ll be the first to come since this is a technique that I have been wanting to learn for a while. Hopefully I will have some more pictures to show you soon then :).

Note: the fun fact of the day was a group of cows peacefully walking around which came to me when I arrived and stared at me for a couple of minutes which I found really intriguing. The staring cows are now the new header of the blog.

UPDATE: The Edinburgh School of Food & Wine will organize their first Chocolate Master class on August 8th. If you happen to be in Edinburgh that day I am sure it would be an excellent way to spend a Saturday morning.