The Art Of Cheese: Time To Maturity

The time it takes for cheese to mature depends on the type of cheese being made. Fresh cheeses are often unaged, soft cheeses are usually aged between two weeks and two months, and hard cheeses are aged for several months to two years or more. The aging process, also known as ripening or maturing, allows time for microbes and enzymes to break down proteins and fats into acids that influence the texture, taste, and aroma of the cheese. A longer aging time results in a firmer, more intense cheese, while a shorter aging time yields a milder taste and softer texture.

Freshness of milk impacts taste

The freshness of milk is a key factor that influences the taste of cheese. The quality of milk used in cheesemaking directly affects the quality of the final product. Using fresh milk directly from the farm can result in superior cheese quality.

Milk is mainly composed of water, but its other components, such as fat, protein (casein), lactose, and minerals, play a crucial role in the cheesemaking process. The fat content of the milk, for instance, contributes to the richness and creaminess of the cheese. The proteins in milk, particularly casein, are essential for curd formation. They coagulate to form a network that traps fat and water, creating the curd that will eventually become cheese.

The lactose in milk is also important. During fermentation, it is transformed into lactic acid, which influences the cheese's acidity level. This acidity plays a crucial role in the cheesemaking process as it affects the coagulation of proteins and the development of the cheese's flavor and texture.

The quality of milk can be affected by various factors, such as freshness, age, and handling. The diet of the animal producing the milk can also have an impact. For example, milk from cows that graze on fresh pasture often produces cheese with more complex flavors than milk from grain-fed cows.

In addition, the odor and taste of milk can provide clues about its quality. A noticeable odor or a change in taste from what is considered normal could indicate issues with animal health, milking equipment, sanitation, nutrition, or ventilation. For instance, a "barny" odor may be due to poor ventilation, while a "cowy" or acetone smell may indicate a metabolic disorder. A rancid taste, characterized by a soapy, bitter, or blue cheese flavor, could be caused by a breakdown of the milkfat into fatty acids due to various factors such as air leaks in pipelines, inadequate cleaning, or deficiencies in the cow's diet.

Therefore, the freshness and quality of milk are critical factors that influence the taste and overall quality of cheese. By paying attention to the odor, taste, and appearance of milk, cheesemakers can detect potential issues and make adjustments to ensure the best possible final product.

Acidifying milk: direct vs. indirect

The acidification of milk is a fundamental step in the manufacture of dairy products like cheese, and it can be achieved through direct or indirect methods.

Direct acidification involves the addition of organic or inorganic acids to milk, such as hydrochloric, sulfuric, or phosphoric acid. This method is often used for cheese varieties like Mozzarella, Feta, and Cottage cheese. It results in a quick decrease in pH, leading to the formation of compact casein aggregates. These aggregates require subsequent homogenisation to prevent powderiness or sedimentation.

On the other hand, indirect acidification utilises biological processes to lower the pH of milk. This is done by inoculating milk with lactic acid-producing bacteria, such as Lactococcus lactis subsp. lactis or cremoris. These bacteria convert lactose in the milk to lactic acid over an incubation period of around 16-18 hours at 30°C. This method is the most commonly employed in New Zealand and is used for cheese varieties that are cooked to less than 40°C.

Both methods have their advantages and are chosen based on the desired characteristics of the final product. Direct acidification provides more control over the pH and can be achieved more rapidly. Indirect acidification, on the other hand, produces a more viscous product with a soured flavour due to the bacterial activity.

The choice between direct and indirect acidification depends on the specific requirements of the cheese variety being produced, and both methods play a crucial role in the overall cheese manufacturing process.

Rennet and other coagulants

Rennet is an essential food processing aid in the cheese-making process. It is a functional enzyme that induces milk curd formation. The term rennet is usually dedicated to a preparation that starts with natural rennet from the abomasal mucosa of ruminants. The enzyme is found in the stomach of young ruminants that have not been weaned from their mother's milk. Rennet is used to convert milk sugars (lactose) into lactic acid, which then acts on the milk's proteins, causing them to clump together as solids (curds) and separate from the remaining liquid (whey). Animal coagulant, typically in the form of calf rennet, is the most common type of coagulant used in cheesemaking. However, there are also vegetarian alternatives to animal rennet, including commercial vegetable rennet and coagulants made from common plants.

Commercial vegetable rennet is made from an enzyme produced by the fermentation of a fungus, Rhizomucor miehei. This type of rennet is available in liquid and tablet form and works well for home cheesemaking. While vegetable rennets can effectively coagulate cheese curds, animal rennet is generally preferred for aged cheeses as vegetable rennet may develop an off flavour after a long ageing period.

There are also several common plants that can be used as coagulants, such as nettle, yarrow, thistle, and mallow. These plant-based coagulants can be made at home and used in cheesemaking. However, according to a 2017 study by Jaros and Rohm, except for the coagulant extracted from Cynara cardunculus L., none of the plant-derived coagulants have significant commercial importance in cheese making.

In addition to animal and vegetable rennet, there are also commercial acid coagulants available for cheesemaking, such as citric acid and tartaric acid. These coagulants are used for making some soft cheeses and provide more consistent acidity levels compared to household vinegar or lemon juice.

Overall, rennet and other coagulants play a crucial role in the cheese-making process by aiding in the formation of milk curds and separating them from the whey. The type of coagulant used can vary depending on the specific cheese being made and the desired ageing process.

Stirring, cooking, and washing curds

Stirring Curds

Stirring curds is an essential step in the cheese-making process. After cutting the curds, it is important to let them rest and firm up for about 5 minutes before stirring or draining. When stirring, it is important to maintain a consistent temperature of around 96°F (35.5°C). Stirring helps to prevent the curds from clumping together and also reduces their size. The curds will continue to shrink as more whey is released during the stirring process.

Cooking Curds

Cooking the curds involves slowly heating them to a higher temperature. This process can be done in a few different ways, depending on the type of cheese being made. For simple cheeses like kefir cheese and yogurt cheese, the curds are drained right away. For other cheeses, the curds are cooked after draining the whey, resulting in hard, rubbery cheeses like Cheddar, Parmesan, and Emmental.

During the cooking process, it is important to stir the curds gently every 5 minutes to prevent clumping. The cooking time will depend on the desired dryness of the cheese, typically ranging from 30 to 60 minutes. After cooking, the curds are drained and hung to remove any remaining whey.

Washing Curds

Washing curds is a traditional cheese-making technique that shapes the flavour, texture, and aroma of many cheeses. This method involves rinsing the curds with warm water, typically heated to around 50–55°C (122–131°F). Washing curds reduces the lactose content, resulting in milder, sweeter, and softer cheeses.

To wash the curds, first cut the coagulated milk into small, even pieces to increase the surface area and allow for efficient whey drainage. Then, remove a portion of the whey and replace it with warm water. Gently stir the curds in the warm water for 10 to 20 minutes, maintaining a consistent temperature. This process may be repeated for certain cheeses, such as Gouda, to further adjust lactose levels and acidity. Finally, drain the curds and prepare them for pressing and further processing.

Aging and storing cheese

You can age cheese in a regular refrigerator, but it is not ideal. A standard refrigerator is 10-15 degrees cooler than a cheese cave and tends to remove moisture from the air, causing unprotected cheese to dry out. The lower temperature also causes the aging process to slow down. If you are using a regular refrigerator, place the cheese in an airtight container in the warmest part. The container should be around 40% cheese and 60% empty space. The humidity in the container is usually maintained by the moisture within the cheese, but you can add humidity by using a wet paper towel placed in a corner of the container.

A better way to age cheese at home is to convert a regular or dorm-sized refrigerator. You can easily control the temperature with a regulator, setting it to 52-55°F. You can increase the humidity by using a shallow pan of water with a sterilized sponge or butter muslin to help the moisture evaporate. If you need to increase the humidity, spray the inside walls with sterile water.

A cool space in the cellar, where the cheese can be protected in a cabinet or covered plastic box, is also a great choice for aging. Cellars usually have consistently cool temperatures, but controlling the humidity can be challenging. To regulate humidity, place the cheese into a plastic box with a lid. To elevate the humidity, place a damp sponge or paper towel in the corner of the container, not touching the cheese. The goal is to add moisture to the air, not the cheese. The air should be damp, not the cheese.

When using a plastic box or container for aging cheese, do not let too much moisture build up. If condensation is dripping onto the cheese, open the container slightly to let some moisture escape. Wipe away any moisture that collects in the bottom of the container when turning the cheese. Do not let a wet surface develop, as mold growth can become a problem.

When aging soft ripened and high-moisture cheese, pay close attention to moisture buildup. Use cheese mats to keep the cheese slightly elevated, allowing it to breathe and preventing the bottom from becoming too moist. Open the boxes frequently to exchange the gases from the ripening cheese with fresh air, especially with higher-moisture young cheese.

Frequently asked questions