Genetic Engineering Has Been Applied to Cheese Making: No Reason to Be Cheesed Off.
Cheese producers were cheesed off. People were just not eating enough veal. Slaughterhouses were running short of calf stomachs and the cheese industry was feeling the pinch. There was not enough rennet to meet the demands of turophiles (that's "cheese lovers" from the Greek “turo” for cheese) around the world.
Rennet, you see, is critical to the cheese making process. At least if you want to indulge in something that is a little more exciting than cottage cheese. Traditionally, it has been made by washing, drying, macerating and brining the lining taken from the fourth stomach of calves. This leads to a product that is a mixture of two enzymes, chymosin and bovine pepsin, both of which can coagulate milk by cleaving proteins in milk and causing them to precipitate. That precipitate is cheese! Why does the stomach lining of mammals contain these enzymes? Because they are needed for proper digestion! If milk did not coagulate to some extent in the stomach, it would flow through the digestive tract too quickly and its proteins would not be sufficiently broken down into absorbable amino acids.
Chymosin is the ideal enzyme for catalyzing this process, but by the 1960s the shortage of rennet was becoming critical. The stomachs of older animals were pressed into service, but the resulting rennet was not really suitable. That’s when researchers discovered that certain fungi, Mucor miehei being a prime example, were capable of producing enzymes that would cleave proteins much like chymosin. This meant that cheese could be produced without using any animal rennet at all. Not only did this address the rennet shortage, it also made possible the production of cheese that met the needs of vegetarians. Such cheese was also kosher because there was no mixing of milk and meat. But purists claim that the taste was not the same. They may well be right. The fungal enzymes have greater proteolytic (protein breaking) activity than chymosin and can give rise to “off” flavors.
