Introduction: Cheese and Mould
Cheese is a popular dairy product that is enjoyed by people all around the world. It is made by coagulating milk and separating the curd from the whey, which is then processed into different types of cheese. While cheese is mostly known for its delicious taste and creamy texture, it is also prone to developing mould. This begs the question: would the process of cheese developing mould be considered a physical change?
Defining Physical Changes in Science
In science, physical changes are defined as changes that alter the physical properties of a substance without changing its chemical composition. Examples of physical changes include changes in shape, size, and state of matter. These changes can be reversible or irreversible, but they do not alter the chemical composition of the substance. Physical changes are different from chemical changes, which involve a change in the chemical composition of a substance and are often irreversible. The question of whether cheese developing mould is a physical change or a chemical change is dependent on the underlying processes that are occurring during mould development.
The Process of Cheese Development
Cheese development is a complex process that involves a series of physical and chemical changes. It is mostly carried out by bacteria and fungi, which play a crucial role in the cheese-making process. Cheese-making involves coagulating milk to form curds, which are then separated from the whey. The curds are then processed in various ways to form different types of cheese, such as cheddar, mozzarella, and brie. However, during this process, the cheese is exposed to various environmental factors that can influence its texture, flavor, and appearance. One such factor is mould, which can develop on the surface of the cheese or within the cheese itself.
The Role of Bacteria in Cheese Making
Bacteria play a crucial role in cheese-making, as they help to acidify the milk and form the curds. Different types of bacteria are used depending on the type of cheese being made. For example, lactic acid bacteria are commonly used to make cheddar and Swiss cheese, while propionic acid bacteria are used to make Swiss cheese. These bacteria feed on lactose in the milk, which produces lactic acid, lowering the pH of the milk. This is important because it causes the milk proteins to denature and clump together, forming curds.
Mould and Cheese: A Natural Occurrence
Mould is a common occurrence in cheese-making, and most cheeses are intentionally inoculated with mould to give them their unique flavor and texture. However, mould can also develop unintentionally, either on the surface of the cheese or within the cheese itself. This can occur as a result of the cheese being exposed to air, as mould spores are present in the environment. Different types of moulds can grow on cheese, including penicillium, geotrichum, and mucor. These moulds can have different effects on the cheese, depending on the type of cheese and the strain of mould.
The Chemical Reactions Behind Cheese Mould
Mould growth on cheese is a result of chemical reactions between the mould and the cheese. Mould requires a food source to grow, and cheese provides an ideal substrate for mould growth. The mould secretes enzymes that break down the protein and fat in the cheese, which releases amino acids and fatty acids. These compounds can then react with other compounds in the cheese, such as calcium, to produce new compounds. This can lead to changes in the texture, flavor, and appearance of the cheese.
Physical Changes vs Chemical Changes in Cheese
Determining whether cheese developing mould is a physical change or a chemical change is not straightforward. While the growth of mould on cheese does alter its physical properties, such as its appearance and texture, it also involves chemical reactions between the mould and the cheese. The mould secretes enzymes that break down the cheese’s protein and fat, which is a chemical change. However, the overall composition of the cheese does not change, as the basic components of the cheese, such as its proteins and fats, remain intact. Therefore, cheese developing mould could be considered both a physical and a chemical change.
The Effect of Mould on Cheese Texture and Flavor
The effect of mould on cheese texture and flavor depends on the type of mould and the type of cheese. Some moulds, such as penicillium, can impart a desirable flavor and texture to the cheese. For example, blue cheese is made by intentionally inoculating the cheese with penicillium, which gives it its characteristic blue veins. Other types of mould, such as mucor, can cause the cheese to become slimy and unpleasant to eat. The texture of the cheese can also be affected by the growth of mould, as the mould can break down the cheese’s proteins and fats, making it softer or more crumbly.
Cheese Preservation Techniques and Mould Growth
Cheese preservation techniques can help to minimize the growth of mould on cheese. One common technique is to coat the cheese in wax or plastic, which creates a barrier between the cheese and the environment. This prevents the cheese from being exposed to air, which can reduce the growth of mould. Another technique is to age the cheese in a controlled environment, such as a cheese cave, which can regulate the temperature and humidity, reducing the growth of mould.
The Impact of Temperature and Humidity on Mould
Temperature and humidity can have a significant impact on the growth of mould on cheese. Mould grows best at temperatures between 55-70°F and high humidity levels. Therefore, storing cheese in a cool, dry place can help to reduce the growth of mould. However, it is important to note that some types of cheese, such as soft cheeses, are more prone to mould growth and should be consumed quickly.
Conclusion: Cheese Mould and Physical Changes
In conclusion, cheese developing mould can be considered both a physical and a chemical change. While the growth of mould alters the physical properties of the cheese, such as its appearance and texture, it also involves chemical reactions between the mould and the cheese. The effect of mould on cheese texture and flavor depends on the type of mould and the type of cheese. Cheese preservation techniques can help to minimize the growth of mould on cheese, and temperature and humidity play a significant role in mould growth.
References and Further Reading
- Cheese.com. (2021). Cheese making process. https://www.cheese.com/cheese-making-process/
- Khan, M. A., & Kang, H. J. (2018). Cheese: An overview of composition, types and health benefits. In Nutrients in dairy and their implications on health and disease (pp. 1-15). Academic Press. https://doi.org/https://doi.org/10.1016/B978-0-12-809762-5.00001-9
- McGee, H. (2019). On food and cooking: The science and lore of the kitchen. Scribner.
- University of Guelph. (n.d.). Food science basics: Physical and chemical changes. https://www.uoguelph.ca/foodscience/book/export/html/136
- Varnam, A. H., & Sutherland, J. P. (1994). Cheese and fermented milk foods. Elsevier Applied Science. https://doi.org/10.1007/978-94-011-1283-9
