Most cheeses aren't vegetarian. Are there any types of cheeses which are?
I'm not asking for specific products, but general information on when cheese is not considered vegetarian (e.g. removing some enzymes, or specific techniques/processes which can isolates animal's milk).
Which ingredients or processes in cheese-making can be eliminated for the cheese to be considered vegetarian?
All traditional cheese is non-vegetarian, but some kinds can be made vegetarian.
Rennet is a combination of a bunch of enzymes, made in the stomach of ruminants such as cows. It's used in cheese-making to help separate the curds from the whey. It's most often sourced from slaughtering juvenile cows.
However, rennet can also be sourced from GMO micro-organisms and certain fungi/bacteria, and thus can be vegetarian/vegan. Most cheeses can substitute traditional rennet for this vegan kind.
But some cheeses, for example Parmesan (in the EU at least), have to use animal rennet. This is because for a cheese to be called Parmesan, it has be made using a traditional method that uses animal rennet. This particular example only applies within the EU, but I'm certain there are other cases I don't know about.
I have been unable to find a list for which cheeses need animal rennet though.
TL;DR: only buy cheese that says it is vegan/vegetarian and doesn't contain animal rennet.
Also, cottage cheese, cream cheese, and other soft cheeses often don't need rennet. They may contain gelatin though, but you'll have to check the label.
Edit: As Will helpfully pointed out in the comments (that I just now saw, sorry about that), http://cheese.joyousliving.com/ has a nice list of veg*n cheeses.
The standard non-vegetarian ingredient in cheese is animal-derived rennet. Non-animal rennet may be used to produce a vegetarian cheese.
Sadly it's not yet mandatory in all countries to declare what type of rennet is used in a product. Some shops may be able to help with lists of products, and some manufacturers do label their cheeses accordingly
A example from Switzerland is the list of the supermarket chain Migros. And on the website from Switzerland Cheese Marketing AG is a search for Swiss cheese whit a filter "Mikrobielles Lab" available (not implemented in the english site yet). It lists about 50 vegetarian cheeses.
However, a retailer's list may be unreliable since the manufacturer may sometimes change the rennet without prior notice.
A related point is that to produce milk the animals need to get pregnant at least once. And as only females produce milk, at least the male babies are usually killed in dairy industries.
