Initial questions are:
1. How does Lipase work in adding flavor?
2. Why will it not work for fresh cheeses but is required for cow or sheep's milk Feta, is it because Feta can be eaten fresh but is better after aging 2-4 weeks which presumably gives time for the Lipase to do it's work?
3. Should you add it directly to milk or to water first and let stand for 20 minutes before adding to milk (I've seen it both ways) and why?
4. When should you add it in the cheese making process, ie when add starter culture or when add rennet?
5. When to use different types of Lipase?
6. Any other advice/information/rules-of-thumb appreciated, especially if it's in more laymans terms?
Thanks in advance . . . John.
Some hopefully brief comments that may explain or confuse,
1. Fats, such as butterfat, consist of three fatty acid molecules (long tails) attached to a glycerol molecule (the head). They are not soluble in water and they are very stable. So they tend to stick together (like all good families should) and are of mild demeanor (slight flavor). But if you take the molecules of fat apart by cutting the tails away from the head they are a different animal. Now the tails are soluble in water and many types are not stable. And they can have distinct flavors. But they can also become rancid. And they can become soaps.
Lipase's job in the business world of nature is to cut the tails off of fats. As a rule lipases are quite stable and not very fussy about their working conditions, but that is only a rule. Some are very fussy and will only cut a particular tail when it is in a particular position in the original fat molecule. Some will only work in a certain temperature range. Some will not live very long in water. Some will work only at a certain pH. And some are very promiscuous and long lived.
The sources of lipases are many. They are found in raw milk and cream. Some probably survive pasteurization. Lactobacillus produce them, as well as Bifidobacterium, P. camembertii, and P. roquefortii. In other words, you are gaining lipases when you culture your milk and when you affinage or age your cheeses. And they are found in the digestive glands of milk eating animals.
2. They should work very well in fresh cheeses. Lipases are added in minute quantities to clothes washing detergents. Of course these are specially chosen enzymes, but they are extremely active in hot wash water and even though they may be deactivated well before the wash cycle has ended they remove enormous quantities of fats from the cloth by breaking them into water soluble fatty acids. There lies one of the fine points. If you break the fats down too early in the process many fatty acids will leave with the whey. In some cheeses that may be a desired effect, in others the opposite. Sorry I'm not a master cheesemaker...
3. In my experience, with lipases not cheeses, I would say add dry lipases to a small quantity of water just before using. The primary reason is to see that you have the solids well dissolved or dispersed before adding it to the culture. There is no reason to hold them for twenty minutes and it may be detrimental to the activity. Liquid preparations should be able to be added to the culture straightaway.
4. My gut feeling
would be to add them just before the rennet.
5. This I can't comment on with any authority as I'm not familiar with the preparations commonly used in cheese making. If I were to guess I would say calf lipase is tailored to the fatty acid profile of cow's milk, kid to goat's milk and lamb to sheep's. Without a little research I don't know if there are any significant differences in the fat profiles of these different species, so it may be unimportant from that standpoint. They may be more specific for certain phospolipids, but that's a different beast altogether.
6. In absence of contrary instructions I would store dry lipases in a very well sealed vapor impermeable bag or jar in the freezer. When you use them you should remove them from the freezer, quickly withdraw the amount you need, reseal the container and immediately replace the bag in the freezer. The two things you are trying to avoid here are a freeze/thaw cycle for the bulk package and the entry of warm humid air into the package. Treated carefully they should have a storage life measured in years. For the liquids, store in the refrigerator unless freezing is specified. I might look into this a little more if anyone is interested, as I can't remember off the top of my head if it would be a good idea to have a small bag of silica gel or activated calcium chloride in the outer container or not. It's been a few years.
Sorry, I guess that wasn't very short and is probably pretty confused (ing).