Many of you Vegetarians have probably consumed numerous Hungry Jacks (Australian Burger King) Veggie Burgers, as did i many years ago when i first went vegetarian. What many people don’t know is that these burgers contain a product called Rennet which is in fact an animal product. Rennet is made from rennin, an enzyme which is secreted in the fourth stomach of calves, lambs, and goats. It is most often derived from the dried and ground stomachs of unweaned calves and is used in making many types of cheese.
(screenshot taken directly from Hungry Jacks website http://hungryjacks.com.au/images/pdf/Allergens.pdf)
Natural calf rennet is extracted from the inner mucosa of the fourth stomach chamber (the abomasum) of slaughtered young, unweaned calves. These stomachs are a by-product of veal production. If rennet is extracted from older calves (grass-fed or grain-fed) the rennet contains less or no chymosin but a high level of pepsin and can only be used for special types of milk and cheeses. As each ruminant produces a special kind of rennet to digest the milk of its own species, there are milk-specific rennets available, such as kid goat rennet for goat's milk and lamb rennet for sheep's milk.
FYI for UK, USA and Canadian citizens, according to http://veg.ca/content/view/67/107/ Burger King veggie burgers in Canada and UK are vegan and the USA Burger King veggie burger is vegetarian but contains egg products so is not vegan.
More Cheese Info for Vegetarians
Most true vegetarians do not eat many types of cheese because they contain this animal rennet which is a by-product of slaughter. There are numerous cheese manufacturers now who use vegetable rennet or microbial rennet (from fungus).
click here for a list of Australian cheeses which are animal free
click here for a list of American cheeses which are animal free
there are many other vegetarian cheeses all over the world. use google to find them!
Information sourced from the following: