Ask the Dietitian
By Althea Zanecosky, MS, RD, LDN
Mid-Atlantic Dairy Association
April 2010
Q: I no longer eat meat but still enjoy cheese as a major protein source. I’ve heard cheese-making requires an enzyme from calves. Is this true?
A: Cheese is an ideal food for vegetarians. It contains protein, vitamins (A, B and E), minerals (calcium, phosphorus, sodium, potassium, magnesium) and trace elements (zinc, iron, manganese).
Many cheeses, especially hard cheeses, are traditionally made from milk coagulated with an enzyme-rich substance called rennet that is obtained from the lining of the fourth stomach of calves. The most important enzyme in rennet is called chymosin or rennin, and it inactivates a milk protein called kappa casein that would otherwise keep the other forms of casein in milk in liquid form. The proteins then break out in clumps and combine with milk fat and water, forming the familiar curds.
But there are cheeses made without rennet, using a source that did not come from an animal. “Vegetarian” rennet is becoming increasingly popular and recent developments in its production from non meat sources means that this trend is likely to continue. Vegetarian rennet is derived from plants, funguses or bacteria, or with genetically engineered rennet that never saw a calf. Vegetarian rennet, also known as synthetic rennet, is becoming popular with cheese makers because the quality is consistent and the cost is low.
Certain cheeses can be coagulated by lactic acid bacteria rather than rennet. They include cream cheese, cottage cheese, ricotta and some mozzarella, but check the label or contact the manufacturer to find out if rennet is added.
One of the issues with buying loose vegetarian cheese, or buying food that contains cheese, is that vegetarian cheese looks exactly the same as the non-vegetarian alternative. This means that it is not simply a case of being able to look at a piece of cheese to tell if it is vegetarian; information needs to be provided with it. Labeling does not always make it clear which cheeses are made with which kinds of rennet. Specialty health food, vegetarian, or cheese stores can often offer good advice about the different types of cheese available for vegetarians. In the supermarket it is necessary to carefully read cheese labels and to look for the source of rennet. It is useful to make a note of different kinds of vegetarian rennet before shopping as this will help to make the identification of vegetarian safe cheese easier. Cheeses that contain 'vegetarian rennet' or 'microbial enzymes' will be suitable for vegetarians.