The Science of Cheese: How does cheese age and develop flavour?

November 2, 2023

The Basics of Cheese-Making

Cheese is essentially the result of milk undergoing a complex series of transformations, primarily due to the action of microbes and enzymes. Here’s a simplified breakdown of the cheese-making process:

Coagulation:Milk is curdled using enzymes such as rennet or acid. This coagulation causes the separation of curds (solids) from whey (liquid).

Draining:The curds are separated from the whey, and the curds are often cut and gently stirred to facilitate whey drainage.

Salting:Salt is added to the curds, which not only seasons the cheese but also helps control moisture levels and slows down bacterial activity.

Aging:The cheese is aged under controlled conditions, which is where the magic truly happens.

The Role of Microbes

Microbes, including bacteria and moulds, play a pivotal role in cheese aging. These microorganisms convert the simple flavours of fresh curd into the complex and distinctive flavours that we associate with various cheese varieties. Here’s how they do it:

Lactic Acid Bacteria:These bacteria are responsible for converting lactose (milk sugar) into lactic acid. This acidification process contributes to the tangy taste of cheese and also helps preserve the cheese by creating an environment less favourable to spoilage microorganisms.

Surface Bacteria and Molds:Many cheese varieties are covered with specific strains of surface bacteria or moulds. These organisms, including Brevibacterium linens, Geotrichum candidum, or Penicillium, contribute unique aromas, textures, and flavours to the cheese. They break down proteins and fats, transforming the cheese’s structure and taste.

The Aging Process

Cheese aging is akin to fine wine aging; it gets better with time. As cheese ages, a series of chemical reactions occur that result in flavour development and texture changes. Some of the essential factors in this process include:

Proteolysis:Enzymes, both natural and those introduced during the cheese-making process, break down proteins into smaller peptides and amino acids. This process softens the cheese’s texture and contributes to its flavour complexity.

Lipolysis:Enzymatic breakdown of fats occurs, leading to the development of distinct fatty acid profiles. These fatty acids play a significant role in the cheese’s flavour and texture.

Evaporation:As cheese ages, moisture content decreases. This concentration of flavours and the transformation of texture are vital to the development of a cheese’s character.

Oxygen Exposure:Controlled oxygen exposure, especially for cheese with mould rinds, facilitates the development of unique flavours and aromas. Oxygen interacts with the surface bacteria and moulds, creating a wide range of possible outcomes.

The Impact of Time and Conditions

Different cheese types require various aging conditions in terms of temperature, humidity, and time. For example, fresh cheeses like mozzarella are typically consumed shortly after production, while hard cheeses like Parmigiano-Reggiano may age for several years, resulting in a complex and crystalline texture with rich, nutty flavours.


The science of cheese is a testament to the marvels of microbial activity and enzymatic transformations. From the coagulation of milk to the intricate aging process, cheese undergoes a fascinating journey that results in a myriad of flavours and textures. The next time you savour a piece of cheese, take a moment to appreciate the intricate science behind its aging and the dedication of cheesemakers who craft these edible works of art. Cheese truly is a testament to the marriage of nature and human ingenuity.