Rennet extract is an important commercial enzyme preparation which is indispensable to the cheese making industry, The term "rennet" is used to denote the enzyme system extracted from the fourth stomach (abomasum) of a suckling calf. Most of the enzymatic material in the extract is rennin. It also contains a small amount of pepsin and some other proteolytic enzymes. The amount of pepsin in rennet extract appears to depend upon the age of the calves at the time of slaughter. It has been suggested that some proteolytic enzymes from higher plants might be useful in cheese manufacture. Krishnaswamy et al. reported that Cheddar cheese made with ficin quickly developed a bitter flavor which decreased in intensity during curing. Cheddar cheese made with an extract from the flower petals of Cynara cardunculus developed extreme bitterness and a pasty body during 30 days curing at 10 C. An extract from the fruit of Withania coagulans was used by Kothavalla and Khubchandani as a coagulating agent in the manufacture of Surati and Cheddar cheese. No unusual flavors were reported, but they experienced rather high fat losses.