• It is believed that cheese was discovered by accident in early civilizations when milk was stored in a pouch made from the stomach of animals. Rennet, an enzyme found in the stomach of ruminant animals, would cause the milk to coagulate and separate into curds and whey.¹
• Cheddar cheese is not naturally yellow. All cheese is white, like the milk it is made from. Yellow cheeses have had a coloring added to them.²
• Pickling vegetables can improve their flavor and make them more nutritious and easier to digest. During fermentation, bacteria produce vitamins as they digest vegetable matter.³

There is a lot of science to explore in the foods we eat every day. This lesson focuses on the science that takes place between the harvest of raw commodities from the farm, to the product that ends up on grocery store shelves. Science plays a role in processing wheat into bread, milk into a variety of dairy products, cucumbers into pickles, and much more.

Most people initially think of processed food as being less healthy than whole foods, especially when considering highly processed foods like premade meals. These convenience foods are often high in refined sugars, sodium, and fats. However, the USDA (United States Department of Agriculture) defines a processed food as one that "has undergone any changes to its natural state—any raw agricultural commodity subjected to washing, cleaning, milling, cutting, chopping, heating, pasteurizing, blanching, cooking, canning, freezing, drying, dehydrating, mixing, and packaging."⁴ Each of these food preparation practices are known as "processing," but don't necessarily decrease the nutritive value of the food. Some even increase the concentration of nutrients. For example, milk can be processed into cheese, this is an old, some may say ancient, food process. After processing, some cheeses have more protein per serving than the milk used to create it. Cheese also has a longer shelf life than milk and adds variety and flavor to our diet. Milk can also be processed into yogurt which has beneficial bacterial cultures that aid in digestion. 

Food packaging science and technology has improved the shelf life of fresh fruits and vegetables. Fresh produce has a lot of value in a healthy diet, but there are inherant challenges for distribution. Many meats, fish, fruits, vegetables, and dairy products stay fresh for only a few days before they begin to spoil. The secret is in the packaging. Modified atmosphere packaging (MAP) fills a food package with a gas or gas mixture other than oxygen. In most cases nitrogen and carbon dioxide. Oxygen promotes spoilage and the growth of aerobic microorganisms. Food products packaged with MAP stay fresh significantly longer.⁷ 

Science and technology can also be used to overcome challenges in our food system. In 2020 approximately 13.25 billion pounds of cheese were produced. The most common enzyme used to transform milk into cheese is Rennet. Rennet causes the milk to coagulate and is used to make hard cheeses.⁵ It helps the milk mixture separate the forming curds from the whey. Rennet splits off the hydrophilic portion of the casein micelles so it will no longer stay suspended in the aqueous solution of milk. Instead, the casein aggregates together to form the curds, while the whey (or liquid portion) separates.⁶  Rennet is found naturally in the stomach lining of a young ruminant animal such as a calf, goat, or sheep. Rennet helps young ruminants digest milk by curdling it. Rennet is not a primary product of raising ruminant livestock, but can be collected as a by-product. Calves raised for veal are the most common source of animal rennet in the United States. As demand for cheese grew in the late 20th century, scientists began searching for alternatives to calf rennet. The veal industry in the United States was (and is) too small to support the entire cheese industry. Fermentation Produced Chymosin (FPC) is the most technologically advanced form of rennet used in cheesemaking. It was approved for use by the FDA in 1990.⁸ FPC is useful because the enzymes in the formulations can be altered and closely controlled to produce desirable flavors in the final aged cheese. FPC comes from cultured yeast cells that have been introduced with genetic information that allows them to produce enzymes such as chymosin, pepsin, and lipases that are identical to those found in animal rennet. FPC is suitable for consumption by vegetarians and it can be produced in quantities that match the market demand.