Clarifying the differences between oils and butters

Recipe terminology can be baffling for those learning to cook. I have received questions about the differences among butter, oils and shortening — fats that are frequent items in many recipes.

Let's address some of those questions:

Some recipes call for butter and some unsalted butter. Are they interchangeable? What is the difference?

This question comes up frequently. The general consensus is that unsalted butter is preferred in recipes so that the cook will have more control over salt in the recipe. Salt content in butter varies from brand to brand. That sounds logical, but I have not found there is that much flavor difference.

In a cooking class with Master Chef Jacques Pepin, I heard a very different answer to this question and I concur with his thinking. He explained that salt is actually a preservative and, when added to butter, it retards the growth of bacteria. Thus, salted butter will keep longer before becoming rancid.

Unsalted butter is fresher because it does not have the salt; so if you want to use a really fresh product, use unsalted butter.

French recipes generally call for unsalted butter. However, when I was in France, I was surprised when two French chefs used salted butter. When I asked them about it, the response was, "It tastes better!"

I prefer unsalted when baking because it contains slightly less water content. However, the temperature of butter is more important in baking than the salt issue. If you are making pastry, the butter must be chilled to create a flaky texture. However, if you are making a cake, the butter must be room temperature so it will easily incorporate the sugar and eggs.

If you have unsalted butter that you do not plan to use within a week or so, it is best to freeze it. Drop it into a freezer storage bag, express excess air and freeze. It will keep up to four months.

I make a salad dressing that calls for vegetable oil. Can I substitute olive oil and, if so, will I use the same amount?

You certainly may substitute olive oil but it will change the flavor of the salad dressing. Usually the amount of oil would stay the same when you are substituting one for another.

Highly flavored oils, such as dark sesame seed oil, would not be a viable substitute as the flavor would overpower the food. Those oils are used for seasoning and flavor enhancements.

What exactly is vegetable shortening and is there another name for it?

Vegetable shortening is a generic term for vegetable oil that has gone through a hydrogenation process that transforms the liquid oil into a solid. Traditionally, shortening is an ingredient favored for baking pie pastry and cakes. Most supermarkets carry national brands, such as Crisco, and perhaps a store brand as well.