Prior research indicated that high blood cholesterol was associated with heart disease. Further research pointed out an emerging role of dietary fat and cholesterol and their effect on blood cholesterol levels, which led to recommendations to restrict dietary cholesterol to 300 mg/day. As eggs were a source of dietary cholesterol and were eaten frequently solely as eggs or in various food products, it was recommended that egg intake should be restricted to 3 eggs/week. Epidemiologic and population studies conducted with consideration of other dietary constituents, caloric intake, physical exercise and healthy behavior found no difference in heart disease risk between individuals eating 3 eggs/week or those that ate more than 3 eggs/week. With the growing acknowledgement of the fact that health derives from an overall pattern of diet rather than from the avoidance of a specific food, the focus has shifted from avoidance of particular foods to more holistic healthy eating patterns. As information about public health and nutrition science progresses and is disseminated in the general population it will affect consumers' attitudes towards food and diet and this attitude will influence the food industry and change the direction of food product development.

Cheese making takes advantage of the coagulation of milk to give curd, which is processed into cheese. Curd can be obtained using various salts, acids, and enzymes, however their use can lead to different tasting cheese. The use of enzymes is frequently the preferred method of obtaining curd. Enzyme coagulants are produced from animal, vegetable, bacterial and fungal sources. Traditionally the natural animal enzyme "rennet" obtained from the stomach of a mammal (calf, lamb, buffalo, pig, etc.) was used to make cheese. Calf rennet is regarded as the most important rennet for cheese making and is considered the gold standard against which other rennet is assessed. The enzyme chymosin specifically cleaves the milk protein "kappa-casein" and thus leads to curd formation from milk.

Rennet can also be obtained from microbes and fungi. A few of the microorganisms used as a source of coagulants are Bacillus polymyxa, Mucor miehei, Mucor pusillus and E. parasitica. Improved purification procedures are used to remove unwanted material from these coagulants. In addition to microbial rennet, vegetables can also be used to obtain rennet. Earlier vegetable enzyme rennet was obtained from fig trees, paw paw, pineapple, and castor oil seeds. Plants that coagulate milk through non-enzyme means are marjoram, mint, and rosemary.

Advances in genetic engineering have made it possible to transfer the gene for expression of prochymosin from the calf stomach to a range of host microorganisms, allowing vast quantities of chymosin to be produced through fermentation. The recombinant enzyme is purified to a high level and is then used for cheese making. This recombinant enzyme has been found to be as efficient and reliable as the calf rennet and is an important alternative to calf rennet. The structure of the recombinant enzyme has also been found to be almost identical to calf rennet and can be used in all types of cheese manufacture. In addition, the shortage of calf rennet is overcome through the availability of the recombinant enzyme chymosin, which is available in the market, is not objectionable for vegetarians, and can be used in accordance with religious dietary regulations.