Egg white powder in Italian Buttercream

I used it a few times and I wasn't very happy with the taste or smell.  I can also tell when its has been used to replace regular egg whites, If you have ever smelled "aged" egg whites you will know what I mean. Its kind of a clam shell like smell.  I do like Meringue Powder a bit better if I have to use a powdered egg product.

I am guessing you want to use eggwhite powder because your concerned about salmonella , and making Italian butter cream only gets the egg white up to about 130f or so, not quite the 160f needed to kill off the possible bad stuff. Personally I don't worry about getting salmonella from eggs, chances are very small, I do make a exception if I am making something specifically for small children or elderly people I will just use pasteurized eggs.

Alice Medrich in her book "Chocolate and the Art of Low-Fat Desserts"  shows you how to cook egg whites to 160f.

http://www.ochef.com/728.htm

If you making Italian Buttercream and useing her egg white method just take some of the sugar from the syrup part and use it for the heating the egg white part. (for every 2 egg whites its 4 Tbsp sugar). So if your Italian Buttercream recipe calls for 5 egg whites you would take 10 Tbsp of sugar from your sugar syrup amount.

I did have that issue with more yolks or whites for a while, both of them actually freeze very well, You just use a ice cube tray and put 2 yolks or 1 white per cube, then after there rock hard you put the cubes in a bigger freezer bag, (Yolks & whites in separate bags).

I would suggest since your already making cakes to save up your yolks to make ice cream with them, you can find ice cream makers for cheap at garage sales or thrifty stores. You can find fresh fruit all year round at stores now or IQF (instant quick frozen) fruits. They are actually better than fresh fruits most of the time because they are harvested at there peak freshness and quick frozen the same day there picked. Not to mention they are pasteurized in the process so free from harmful bacteria.

I use yolks up making mousse, Pastry cream, ice cream, Banana cream for pie, Crème Anglaise, Hollandaise, Mayo, Béarnaise, Caesar Salad dressing..... Or I just toss extra yolks I have in what ever cake batter / muffins I am making, 1 or 2  wont muck up the batter to bad.  

Opps almost forgot, you can always just mix it up and make French Butter cream instead of the Swiss or Italian versions, French Butter cream uses the yolks instead of the whites.  Joe Pastry's site is great for learning how to bake stuff you would have never tried before. And you will find endless ways to use up all thoughs extra egg parts.

http://www.joepastry.com/category/pastry-components/buttercream/french-buttercream/

Pasturized egg whites, frozen or refrigerated, work well for Butter Creams.

No wasted yolks

 Frozen or refrigerated pasteurized egg whites, do work great. But you do have to remember to give them a stir or two before you use them. They kind of separate into 2 parts, a watery part and a unset jello like part. (Thats my experience with them and the brand I used, they could have been sitting around for a few days, I dont know how long they were in the fridge).    

Its pretty easy to calculate the amount you need if you use grams, one egg white is about 33 grams. So its what ever number of egg white times 33 to get the gram amount.

If you still use measuring cups Chris its pretty easy.

One egg has about 2 tbsp of egg whites
2 tbsp = 1 fluid ounce (so 1 fluid ounce per egg)
8 fluid ounces = one cup
so there are 8 egg whites in one measuring cup and 4 egg whites in a 1/2 a cup, 2 egg white in a 1/4 cup.  
 

I like to lightly wisk both of them and add a drop or 2 of water for the yolk. Dont try to incorporate to much air into them though. Not sure about the salt .  

I cant really say about the heat and traveling with them. Eggs are a great petri dish for growing bacteria and with out the shell covering them its best not to push your luck.  

Swiss and Italian butter cream are pretty much the same thing except you cook the Swiss egg whites to 160F so no salmonella issues to worry about. I am not sure why more people do the Italian butter cream More than the swiss one.