G. Larrieu, Instructor, Eng. 160 MW 6:00pm
Research Paper, Draft#1
5, December 2012 The Science of Cheese
There are over 900 types of cheese in existence in the world; about 400 of them come from France. The top cheese exporting countries are France, Germany, Netherlands, Italy, Denmark, and Australia. The top cheese producing countries are the U.S., Germany, France, Italy, and Netherlands (Statisticbrain.com, Table 2). Cheese comes in a wide variety of flavors, textures, and styles; however, the process for making all cheese is basically the same. What is different; however, are the recipes for each cheese. Some cheeses are exposed to higher temperatures, other may need a low pH level (pH value contributes to whether the cheese will be soft or hard, as well as its taste). In addition, the type of animal milk, specific processes, and equipment all contribute to the final flavor and texture.
Discovery and History
Cheese dates back far before recorded history, perhaps as far back as 8,000 B.C.E. Legends say that a nomadic tribe traveling around Asia Minor was carrying milk in animal skin bags, possibly made from the stomach. The nomads were traveling by horse and because of the galloping motion; the enzymes (chymosine and pepsine) contained in the stomach skin, migrated into the milk leading to coagulation of the milk (gelatin curd). This drink (what we would call “whey”) was drained in a woven basket and lightly salted to provide taste. The final product was a nourishing food source of protein for the nomads. Before long, people learned that they could preserve milk for weeks or months by making them into curds and then pressing them together to form cheese.
What is Cheese?
Before modern times there was no cooling method, making the shelf-life of milk very low. As mentioned before, one of the main motivations for inventing cheese was to conserve milk, an important source of protein. Cheese greatly extended the life of milk; it was a nutritious food source high in calcium, minerals, fat and protein, all of which were necessary for survival. Cheese is a general term describing curdled milk, it is made from the components of the milk (protein, butterfat, salt and enzymes) left after separation of the whey from the curds. The fact that cheese could be made from the milk of all different types of mammals was also an advantage and increased its availability. Besides cows, cheese can be made from the milk of sheep, goats, buffalo, reindeer, camels and yaks. The milk goes through a number of different processing stages where its actual molecular structure is changed. There are several steps involved: heating, treating (adding enzymes and bacteria), churning, formation, and aging. The role of the bacteria and enzymes is to act as a catalyst for reactions in cells or organisms and help give flavor. Slight variations in each step produce vastly different flavors and textures.
Cheese can have different flavors, ranging from sour to bitter. Lucius Slyke, a dairy chemist, has observed that whenever the cheese has a sour taste; it happened because “the sourness of the cheese comes from the acidity of the cheese. The cause of excessive acidity may be caused by the presence of too much moisture in the cheese…” (Price and Slyke, 223-224). Thus, when the cheese has too much moisture a chemical reaction happens between the water and milk, making it sour or bitter, and changing the pH levels (a measure of acidity or alkalinity). Defective flavors may be result: acidic flavor (too much moisture, a chemical reaction changing the pH levels of the milk), bitter flavor (caused by adding too much rennet, extract of animal organs such as the stomach), Cowy flavor (odor of the cow barn, resulting