Generally speaking, butter spreads have a water component to them. That's what the emulsifier is for, as it keeps the fat and water from separating.
The problem is that you can't fry/cook with it. If you place it in a pan it will separate, and sizzle in a very unpleasant manner. If I remember correctly, it actaully smells quite awful in the process.
As for baking, I think it'll be fine anywhere there needs to be fat as fat. Wherever you need fat as something to hold the structure, you had probably best not use it. Caveat emptor, as I don't bake very much at all.
Let it be aid, however, that margarine as opposed to butter spread, can be used anywhere that butter is used. It isn't as tasty, and has trans-fats. On the other hand, it has less cholesterol.
You are asking not just to substitute for butter, but to reduce the total amount of fat in cookies.
All of the most common butter substitutes are going to be oils, margarine or other fats since they will perform similarly in the chemistry of the cookie. This makes it difficult to offer a simple substitution.
Instead, I recommend taking the approach of making cookies that are naturally lower in fat such as:
- Meringues - zero fat
- Macaroons - little fat, just in the coconut
- Macrons (french style) - little fat, without the filling -- just from the nut powder
or using recipes designed specifically to have lower fat content. If you google "reduced fat cookie recipe" you will find a wealth of results.
One site that looks promising, although I cannot vouch for it as I haven't tried the recipes is:
Good housekeeping's reduced fat cookie recipes
Another source for lower calorie recipes that are often pretty good, although not targeted specifically at reducing fat is:
Cooking light
Since fat contributes a lot of calories, you may have luck with their recipes.
The benefit of using recipes designed for less fat is that they are (from reputable sources) tested and likely to give you a better outcome than simply trying to substitute in a traditional recipe.
Also, you can try simply reducing the amount of fat in the cookie. This is going to be tricky as it will modify the chemistry, but you may be able to get away with a 1/4 to 1/3 reduction before you get completely unpalatable results, but this will require testing on a recipe by recipe basis. It also will not work well for cookies based on the creaming method, as the fat medium is part of the leavening (the purpose of the creaming method is to create a solid fat/air foam).
One final thought: some people say you can substitute apple sauce. You might try this on a recipe by recipe basis, but it will completely change the cookie. I think you will get better results with recipes created from the ground up to use less fat.
Best Answer
What is enzyme-modifed butterfat?
According to the United States Food and Drug Administration:
https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1287
That probably doesn't offer much that you don't already know. It says that enzymne-modified butterfat is made from butterfat or milkfat and enzymes, which are themselves derived from dairy products.
What is an enzyme?
An enzyme is a protein that acts as a catalyst, accelerating chemical reactions.
https://www.ncbi.nlm.nih.gov/books/NBK9921/
Like all catalysts, they are not consumed or changed by the reaction they facilitate.
Should there be enzymes in my food?
Yes! As stated above, cells contain thousands of enzymes, so there's no avoiding them. But most of those enzymes are not doing anything interesting in your food. However, sometimes we need specific enzymes to make the food we eat. For instance, in order to make cheese, we need to add rennet. Rennet is a group of enzymes, including, most importantly, chymosin, which is the enzyme that causes the milk to curdle. Some cheese also relies on the enzyme lipase, which causes fat to break down and release fatty acids. These fatty acids are partly responsible for the flavor (and texture) of most blue cheeses, feta cheese and others.
How do enzymes enhance flavor?
To avoid a long discussion of what flavor is, let's just say that it has to do with your nose and mouth reacting to certain compounds in a food. As discussed above, enzymes can catalyze the reactions that produce flavorful compounds. They can also produce compounds that make already present flavors more noticeable (like how adding salt to food not only makes it taste salty, but also brings out the other flavors).
Examples
DuPont, an American chemicals company, makes a variety of enzymes that can be used to improve cheese flavor and make it easier to produce. For example, KM450 Lipase is supposed to reduce bitterness, reduce ripening time and modify the flavor intensity of mature goat cheese. Savorase® ARP is meant to improve the flavor of Swiss or Italian-type enzyme modified cheese, while Savorase® CHC is to be used for Cheddar flavor enzyme modified cheese.
https://www.dupontnutritionandbiosciences.com/products/natural-flavor-enzymes.html