Frederic Melton
Cheese is a beloved food for many, but some people wonder if it is made from expired milk. While it is true that bacteria in milk grow rapidly when it gets old and cause it to curdle, the process of making cheese involves a lot more processing than simply letting milk go bad.
| Characteristics | Values |
|---|---|
| Is cheese made from expired milk? | No, cheese is not made from rotten or expired milk. It is made from clean milk that is deliberately infected with specific cultures that cause the milk to coagulate. |
| What is expired milk? | Milk that has soured or turned "cheesy" due to bacteria growing rapidly. |
| What is cheese? | Cheese is the human-administered spoilage of milk, resulting in a less perishable, more delicious form of concentrated fat and protein. |
| How is cheese made? | After milk is poured into big vats, a “starter culture” of bacteria is added to convert the lactose into lactic acid. Then an enzyme called rennet is added to curdle the milk. Once the casein has curdled, the whey protein is left behind as a thin, watery liquid. The whey is removed, salt is added, and the curds are cut into smaller pieces and heated to release more whey. The curds are then pressed into molds and left to age (dry) for various periods of time. |
Explore related products
What You'll Learn
Cheese is not made from rotten milk
It is a common misconception that cheese is made from rotten milk. While it is true that cheese is the result of controlled spoilage of milk, it is not made from rotten milk. Rotten milk is the result of an uncontrolled process of bacteria, moulds, and other microorganisms acting on milk, causing it to spoil. On the other hand, cheese is made by deliberately introducing specific cultures of bacteria to clean milk, causing it to coagulate and form curds. This process is carefully controlled to produce the desired texture, taste, and flavour of the cheese.
Cheese is created through a complex and highly controlled process. It starts with plain milk, to which a starter culture of bacteria is added to convert lactose into lactic acid. Then, an enzyme called rennet is added to curdle the milk. This rennet is usually obtained from the stomachs of young cows, but modern cheesemakers use bacteria and yeast that have been genetically modified to produce the enzyme. Once the milk has curdled, it separates into curds (milk solids) and whey (liquid). The whey is then drained off, leaving clumps of casein, which are pressed into moulds and left to age.
The type of bacteria used, the temperature, the amount of time they are allowed to act, and the amount of water drained from the curdling milk all play a crucial role in determining the final product's texture, taste, and flavour. This careful control over the cheese-making process ensures that the desired characteristics of the cheese are achieved and distinguishes it from the uncontrolled spoilage of milk.
While it is true that expired milk can undergo a rudimentary form of the cheese-making process, it is not the same as the carefully crafted process used to create the various cheeses we know and love. The bacteria in expired milk grow rapidly, causing it to curdle and separate, but this does not result in the same level of control over the taste, texture, and flavour as the traditional cheese-making process.
In summary, cheese is not made from rotten milk. Cheese is a carefully crafted product of controlled milk spoilage, utilising specific cultures of bacteria to produce a delicious, less perishable form of concentrated fat and protein.
The Birthplace of Stilton Blue Cheese: A Tasty Tour
You may want to see also
Bacteria in expired milk
Milk is 80 to 90 percent water, depending on the animal it comes from, and also contains fat, protein, sugar, and minerals. Bacteria in expired milk can cause it to spoil, or go bad. Spoilage is evidenced by curdling, a rancid odour, and an acidic pH. The acidity in the milk increases due to the production of lactic acid from lactose, which is caused by spoilage microorganisms. As the acidity increases, groups of casein proteins lose their negative charges and their ability to repel each other, causing them to bond and resulting in the curdling of the milk.
There are many types of bacteria that can cause milk to spoil, including spore-forming bacteria such as Paenibacillus, which can cause off-flavours in a variety of foods and curdling in dairy products. Other types of bacteria that can cause spoilage include Pseudomonas fluorescens biovar I, Ps. fragi, Ps. lundensis, and Ps. fluorescens biovar III.
To prevent spoilage, milk often undergoes heat treatment or pasteurization to kill off microbes that can cause food spoilage and disease. However, certain bacterial strains can survive this heat shock as spores and cause milk to curdle in storage. In addition, improper pasteurization or post-contamination due to unsanitary practices can contribute to early milk spoilage.
Cheese, on the other hand, is not made from "rotten" or expired milk. Instead, it is the product of controlled spoilage or the highly controlled action of bacteria that produce acids that coagulate the casein in the milk. The type of bacteria, temperature, amount of time they are allowed to act, and the amount of water drained from the curdling milk all contribute to the final texture, taste, and flavour of the cheese.
Babybel Cheese: A Comprehensive Guide to Its Making
You may want to see also
Processing milk into cheese
Cheese is not made from rotten or expired milk. Instead, it is made from clean milk that is deliberately infected with specific cultures that cause the milk to coagulate. This process of controlled spoilage of milk results in a less perishable, more delicious form of concentrated fat and protein.
The first step in processing milk into cheese is pasteurization or heat treatment. This step is done to kill any pathogens present in the milk and improve the environment for the starter cultures to grow. The milk is then cooled to 90°F (32°C) to bring it to the temperature needed for the starter bacteria to grow. The starter cultures and any non-starter adjunct bacteria are added to the milk and held at this temperature for 30 minutes to ripen. The bacteria are then allowed to grow and begin fermentation, which lowers the pH and develops the flavour of the cheese.
The next step is to add rennet, an enzyme that acts on milk proteins to form the curd. The curd is allowed to form for approximately 30 minutes without being disturbed so that a firm coagulum forms. The curd is then cut into small pieces and heated to 100°F (38°C) to separate the whey from the curd. The whey is drained, and the curd forms a mat. The curd mats are then cut into sections, piled on top of each other, and flipped periodically in a step called cheddaring, which helps to expel more whey and continue fermentation.
The process varies slightly depending on the style of cheese desired. For example, if a high-moisture cheese like Brie is being made, the curd will be kept very loose and wet, and the cheesemaker may gently hand-ladle the curds into forms. The type of coagulant used also depends on the type of cheese desired. Acid cheeses, such as cream cheese or queso fresco, are made by adding acid to the milk to cause the proteins to coagulate. Most types of cheese, such as cheddar or Swiss, use rennet in addition to starter cultures to coagulate the milk.
Cheese Puffs: A Crunchy, Cheesy Snack Explained
You may want to see also
Explore related products
Pasteurization
The pasteurization process involves heating milk to a specific temperature for a defined period, typically ranging from a few seconds to several minutes, depending on the specific method employed. There are two primary methods of pasteurization: High-Temperature Short Time (HTST) pasteurization and Ultra-High Temperature (UHT) pasteurization.
HTST pasteurization, also known as batch pasteurization, heats milk to a temperature of at least 72°C (161°F) for at least 15 seconds. This method is commonly used in the dairy industry and is effective in killing harmful bacteria while preserving the quality and sensory characteristics of the milk. After heating, the milk is rapidly cooled and stored, ensuring its safety and maintaining its nutritional value.
On the other hand, UHT pasteurization, or ultra-heat treatment, involves heating milk to a much higher temperature, typically above 135°C (275°F), for a shorter period. This method is employed for milk intended for extended shelf life or as a base for products like powdered milk. UHT treatment results in an almost sterile product, ensuring the milk's stability and safety without the need for refrigeration over an extended period.
The primary goal of pasteurization is to destroy pathogenic bacteria and protect consumers from foodborne illnesses associated with consuming contaminated milk. Before pasteurization became widespread, milk was often a source of dangerous bacteria such as Salmonella, E. coli, and Listeria, which can cause severe gastrointestinal infections with potential complications including dehydration, kidney failure, and even death, especially in vulnerable populations.
In addition to food safety, pasteurization offers other benefits. It extends the shelf life of milk by reducing spoilage, improving distribution efficiency and reducing food waste. Pasteurization also enhances the keeping quality of milk, preventing curdling and off-flavours during storage and transportation.
Cheesy, Gravy-licious Fries: Ultimate Comfort Food Creations
You may want to see also
Different types of cheese
Cheese is an ancient food, with origins that predate recorded history. There are more than 2,000 varieties of cheese produced around the world, with some estimates suggesting there are over 700 types of British and Polish cheeses alone. The type of milk used, as well as factors like temperature, humidity, and bacterial cultures, can greatly impact the final product's flavour, texture, and appearance.
Blue Cheese
Blue cheese is made from edible mould spores of Penicillium roqueforti, using fresh goat or ewe's milk. It is matured in air tunnels for up to six months, with young cheese having a firm and crumbly texture, and matured cheese having a creamy texture. It is one of the tangiest cheeses with an intense flavour.
Mozzarella
Mozzarella is a universally known type of cheese, typically found in most homes. It is processed from cow or water buffalo milk with rennet added as a coagulant. The curds are kept in whey and stretched out, undergoing a process called Pasta Filata, which gives mozzarella its unique smooth texture. It is known for its gooey texture and mild flavour, making it ideal for pizza and pasta dishes.
Brie
Brie is a rich, buttery, and creamy cheese with an edible rind and a soft middle. It is typically made with cow's milk and cream, which is added during the production process. It is often served chilled, but baked brie topped with honey and herbs is also popular.
Cheddar
Cheddar is a popular variety of cheese, especially in the United States. Young cheddars are mild and creamy, while aged cheddars have a stronger flavour and a crumbly texture. The curds undergo a unique "cheddaring" process after being separated from the whey.
Colby
Colby is similar to cheddar but has a softer texture and less tangy taste. It is sometimes blended with other cheeses, such as Monterey Jack, to make Colby Jack. It melts well, making it suitable for grilled sandwiches, cooked vegetables, and warm dishes.
Other Varieties
There are numerous other types of cheese, including fresh cheeses like cottage cheese, cream cheese, and mascarpone, as well as semi-hard and semi-soft varieties. Some cheeses are processed or blended, like American cheese, which is a blend of natural cheeses like cheddar and Colby. Each type of cheese has unique characteristics, making it suitable for different dishes and culinary applications.
The Origin Story of Philadelphia Cheese
You may want to see also
Frequently asked questions
No, cheese is not made from "rotten" milk. Rotting is an uncontrolled process in which bacteria, moulds, and other life forms consume the milk, release waste into it, and eventually die. On the other hand, cheese is the product of a highly controlled process in which specific bacteria are used to deliberately infect clean milk, causing it to coagulate.
The process of making cheese involves first adding a “starter culture” of bacteria to fresh milk, which converts the lactose into lactic acid. Then, an enzyme called rennet is added to curdle the milk. Once the casein has curdled, the whey protein is separated from the milk solids, or curds, through a combination of cutting, stirring, heating, and draining. The curds are then cut into smaller pieces, salted, and heated again to release more whey. After the additional whey is drained off, the remaining casein clumps are pressed into moulds and left to age (dry) for various periods of time.
Yes, it is possible to make a rudimentary form of cheese with expired milk at home. However, it is important to note that the taste and quality may not be as desirable as that of cheese made with fresh milk. One simple method involves bringing the expired milk to a near boil, removing it from the heat, and stirring in lemon juice or vinegar. The milk will begin to curdle immediately, and after letting it sit for about 10 minutes, you can strain the curds through a jelly bag or cheesecloth.
Cheese has an expiry date primarily for stock rotation, product recalls, and insurance purposes. Additionally, expiry dates help retailers and consumers determine when to discard or return the product. However, it is worth noting that properly stored cheese can often last significantly longer than its expiry date.
