The Art Of Fermenting Cheese: Timing And Techniques

Fermentation is a crucial step in the process of making cheese. The duration of the fermentation process depends on the type of cheese being made. For instance, fresh cheeses like ricotta or cottage cheese may only require a few hours of fermentation, while aged cheeses like cheddar or gouda may need several months to develop their desired flavours and textures. The fermentation process for cheese typically involves several key steps: acidification, coagulation, draining and pressing, and ripening. During fermentation, microorganisms break down the lactose in the milk, producing lactic acid and other compounds that give cheese its unique flavour and texture.

The ripening of cheese

For example, AOC Camembert, by law, cannot be sold before 21 days and is considered to be at its peak of maturity between 3 and 4 weeks of age. However, some people may prefer to leave their Camembert for 4 to 5 weeks to develop a stronger flavour, thicker rind, and runnier interior. White mould cheeses, such as Camembert, can be ripened in a kitchen refrigerator for up to 7 weeks.

The ripening process involves additional microbial and enzymatic activity, which further transforms the cheese. During this time, enzymes and bacteria continue to modify proteins, fats, and sugars in the cheese. The flavour of the cheese will become stronger with age, and the texture will change. A young, firm cheese of 1 to 2 weeks old is best for cooking, as it has a milder flavour. An over-ripe cheese may smell strongly of ammonia, be very loose around the edges, and be very soft to the touch.

The length of the ripening process depends on the style of cheese. For instance, Monterey Jack is usually ready after one month of ageing, while Parmesan-style cheese requires at least 9 to 12 months. Bries and Camemberts are typically aged for about 6 weeks, while Blue Cheese may take from 3 to 5 months. Cheddar cheese can be aged for up to 12 months or longer, depending on the desired style.

The role of bacteria in fermentation

The fermentation of cheese is a metabolic process that consumes sugar in the absence of oxygen. This process is carried out by microbes, which include bacteria, yeast, and moulds. The role of bacteria in this process is critical, as they initiate the fermentation process and contribute to flavour development.

Lactic Acid Bacteria (LAB) are the microbes (bacteria) added to milk early in the cheese-making process to induce fermentation. They get their name from converting lactose to lactic acid, acidifying the milk. LAB are often referred to as "starter cultures". Examples include Lactococci, Streptococci, and Lactobacilli.

Adjuncts are microbes added to encourage flavour development, such as Lactobacillus helveticus, which is often added to aged Gouda to give it a sweet flavour. Non-Starter Lactic Acid Bacteria (NSLAB) are lactic acid bacteria that grow as cheese ripens and are not added for milk acidification. Their exact role in cheese flavour development is still being understood.

Bacteria also play a role in eye (hole) formation in Swiss cheese and Gouda. In Swiss cheese, Propionibacterium freudenreichii converts lactic acid into carbon dioxide, propionic acid, and acetic acid. The carbon dioxide creates the holes, and the other products give Swiss cheese its characteristic flavours. In Gouda, bacteria like Leuconostoc mesenteroides and Lactococcus lactis ssp. lactis biovar. diacetylactis convert citric acid to carbon dioxide and diacetyl, creating a buttery flavour.

Additionally, bacteria can be responsible for the distinctive aromas and textures of white mould cheeses like Brie and Camembert. Geotrichum candidum, a yeast that exhibits mould-like tendencies, is known for its contribution to sulphur flavour and the thickness of the rind.

The role of bacteria in cheese fermentation is diverse and essential to developing the unique characteristics of different cheese varieties.

The time taken to ferment different types of cheese

For example, Monterey Jack is usually ready after one month of ageing, whereas a Parmesan-style cheese requires at least 9 to 12 months. Bries and Camemberts are typically perfect after about 6 weeks of ageing, and blue cheese may take from 3 to 5 months.

The French measure the ripeness of Camembert in quarters, with each quarter representing a week. AOC Camembert cannot be sold before it is 21 days old, and it reaches its peak of maturity somewhere between 3 and 4 weeks. However, you can enjoy your cheese at any stage depending on your tastes. A young, firm cheese of 1-2 weeks old is best for cooking, and those who prefer a milder flavour. If you prefer a stronger flavour, thicker rind, and runnier interior, you may prefer to leave the cheeses for 4-5 weeks before eating them. If you are maturing your white mould cheese in a kitchen refrigerator, allow up to 7 weeks for it to ripen.

The time taken to ferment cheese at home may be just one hour, or it may take 6 to 8 hours. In some cases, the process may take more than a day, depending on the type of cheese being made.

The process of coagulation

During coagulation, the curds have a soft and gel-like texture due to the presence of water and solids. As the curds are heated, liquids in the form of whey are gradually released, and the curds continue to condense until cheese is formed. The rate of coagulation can be controlled by adjusting the temperature, with higher temperatures resulting in faster coagulation. Additionally, the type of milk used can impact the taste and texture of the final product. For instance, raw milk can produce cheese with a rich flavor, while ultra-pasteurized or homogenized milk may be preferred for food safety reasons.

The coagulation process also involves the use of starter cultures, which are specific strains of bacteria and yeast added to the milk to initiate fermentation. These starter cultures play a crucial role in converting lactose into lactic acid, contributing to the sharp, fresh flavor of the curd. Common starter cultures include mesophilic and thermophilic bacteria strains such as Lactococcus lactis, Lactobacillus helveticus, and Streptococcus thermophilus.

After coagulation, the curds are separated from the whey and may be pressed into molds to further remove moisture and shape the cheese. This step is known as draining and pressing, and it helps to expel more whey and condense the curds. The curds are then salted and allowed to age, during which time additional microbial and enzymatic activity occurs, further transforming the cheese and developing its unique flavor and texture.

The influence of the environment on the fermentation process

The environment in which cheese ferments has a significant influence on the process and the final product. The temperature, humidity, and surrounding microbial life all play a role in shaping the cheese's flavour, texture, and overall character.

Temperature is a critical factor in cheese fermentation. Different cheeses require different temperatures for optimal fermentation. For example, English cheeses like Cheddar, Stilton, Leicester, and Wensleydale ferment best at temperatures between 29-31°C. In contrast, cheeses like Emmental and Parmesan require higher incubation temperatures, provided by thermophilic starter cultures. The Kaltbach Cave in Switzerland, where Kaltbach Le Gruyere is aged, maintains a constant temperature of 50-53°F, contributing to the unique characteristics of the cheese.

Humidity is another important environmental factor. The Kaltbach Cave, for instance, has a humidity level of 96%, which impacts the cheese's texture and flavour development.

The microbial life present in the environment also influences cheese fermentation. Traditional Fermentation relies on naturally occurring bacteria and yeast in the environment, resulting in less control over the final product but potentially yielding more complex flavours. On the other hand, Starter Culture Fermentation introduces specific strains of bacteria and yeast to the milk, allowing for more precise control over the cheese's flavour and texture.

The duration of fermentation varies depending on the type of cheese being made. Fresh cheeses like ricotta or cottage cheese may require just a few hours, while aged varieties like cheddar or gouda can need several months to develop their desired characteristics.

The ripening or ageing process further enhances the influence of the environment on the final product. During ripening, the cheese is exposed to specific temperature and humidity conditions, allowing microbial and enzymatic activity to transform its flavour, texture, and aroma. The length of the ripening process depends on the desired style of the cheese. For instance, Monterey Jack is typically ready after one month of ageing, while Parmesan requires at least 9-12 months.

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