Patrick Oconnell
Cheese is a milk product that likely dates back to the Neolithic period. It is believed that cheese-making began over 6,000 years ago, with some of the earliest known cheeses being gorgonzola, roquefort, and cheddar. Today, there are over 1,000 types of cheese, each with its own unique flavour and texture, often achieved through the use of bacteria. Bacteria play a crucial role in the cheese-making process, with specific types of bacteria being used to give cheese its distinct taste and texture. Lactic acid bacteria, for example, are often used as starter cultures, converting milk sugar (lactose) into lactic acid, creating an environment inhospitable to spoilage organisms. Other bacteria, such as Propionibacterium freundenreichii, contribute to the formation of holes in Swiss cheeses, while Brevibacterium linens gives washed-rind cheeses their distinctive colour and aroma.
Characteristics and Values of Bacteria Used in Cheese
| Characteristics | Values |
|---|---|
| Bacteria Type | Lactic Acid Bacteria (LAB) |
| Bacteria Families | Lactococci, Lactobacilli, Streptococci |
| Bacteria Species | Lactobacillus helveticus, Streptococcus thermophilus, Lactobacillus rhamnosus, Weissella confusa |
| Function | Conversion of lactose to lactic acid, lowering pH and inhibiting spoilage |
| Role in Cheese | Cheese starter culture, flavour and texture development, preservation |
| Cheese Types | Cheddar, Mozzarella, Emmental, Gruyere, Grana Padana, Roquefort, Stilton, Danish Blue |
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What You'll Learn
Bacteria and fungi are used in cheese production
Cheese is a fermented milk product that likely dates back to Neolithic times. It is believed that cheese-making began over 6,000 years ago, with some of the earliest known cheeses being gorgonzola, roquefort, and cheddar. Today, there are over 1,000 types of cheeses globally, each with its own unique flavour and texture. This variety is made possible by the diverse range of bacteria and fungi used in the cheese-making process.
Lactic acid bacteria (LAB) play a crucial role in converting the milk sugar lactose into lactic acid, which lowers the pH of the cheese and inhibits the growth of spoilage organisms. This process is essential for preserving the cheese and developing its unique flavour and texture. Different types of LAB can be used as starter cultures, including Streptococcus thermophilus, Lactobacillus helveticus, Weissella confusa, and Lactobacillus rhamnosus. These bacteria produce enzymes and metabolic by-products that contribute to the distinct flavour and texture of the cheese.
In addition to bacteria, fungi such as moulds also play a key role in cheese production. White moulds, for example, are used in soft-ripened cheeses like Brie and Camembert. These moulds produce enzymes that break down milk proteins, creating a ripened layer surrounding a firm interior. Other types of mould, such as Penicillium roqueforti, are essential for producing blue-veined cheeses like Roquefort, Stilton, and Danish Blue.
The combination of bacteria and fungi in cheese production results in a diverse range of flavours and textures. For example, the orange-pigmented bacterium Brevibacterium linens contributes to the distinctive colour and aroma of washed-rind cheeses. Similarly, Propionibacterium freudenreichii is responsible for the holes in Swiss cheeses, while also adding to their sharp flavour.
Overall, the use of bacteria and fungi in cheese production is a complex and fascinating process that has evolved over thousands of years. By utilising different combinations of microorganisms, cheesemakers can create an incredible variety of cheeses, each with its own unique characteristics.
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Lactic acid bacteria are used as a starter culture
Lactic acid bacteria (LAB) are used as a starter culture in cheese production. They are often called "starter cultures" because they play a crucial role in converting the basic milk sugar, lactose, into lactic acid, which lowers the pH of the cheese and inhibits the growth of spoilage organisms. This conversion is a critical step in the cheese-making process, as it creates an environment that is unfavourable for the growth of harmful microorganisms.
Lactic acid bacteria are cultured under artificial conditions and can be isolated from cheese for this purpose. Some common types of LAB used as starter cultures include Streptococcus thermophilus, Lactobacillus helveticus, Weissella confusa, and Lactobacillus rhamnosus. These bacteria are chosen for their ability to release proteases, lipases, or β-galactosidases, which contribute to the formation of unique tastes, aromas, and textures in the final cheese product.
During cheese fermentation, LAB perform several important functions. Firstly, they convert lactose in milk into monosaccharides, galactose, and glucose, which promote the development of cheese flavour. Secondly, they degrade proteins into peptides and free amino acids (FAAs), and thirdly, they decompose lipids into fatty acids. These processes are facilitated by proteases, key enzymes that hydrolyse proteins during cheese fermentation. Importantly, aspartic protease, a specific type of protease, improves the taste, flavour, and functional properties of cheese by digesting κ-casein and promoting milk coagulation.
The use of LAB as starter cultures also offers health benefits to the cheese. They can produce enzymes and metabolic by-products that give the cheese distinct flavour profiles. Additionally, they contribute to vitamin production and aid in gut health. Overall, the inclusion of LAB as starter cultures in cheese production is essential for developing the desired sensory attributes and nutritional characteristics of the final cheese product.
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Bacteria gives cheese its unique taste and texture
Cheese is a fermented milk product that likely dates back to Neolithic times. It is believed that cheese-making began over 6,000 years ago, with some of the earliest known cheeses being gorgonzola, roquefort, and cheddar. Today, there are over 1,000 types of cheese, each with its own unique texture and flavour.
The unique taste and texture of cheese are largely due to bacteria. Bacteria are a group of one-celled organisms that are microscopic in size. While some bacteria can cause illness, others are harmless to humans and can even provide benefits, especially in cheese production. The type of bacteria used is what gives each type of cheese its unique taste and texture.
Lactic acid bacteria, often called "starter cultures", play a critical role in converting the basic milk sugar, lactose, into lactic acid. This lowers the pH of the cheese, making it inhospitable to many spoilage organisms. Some of the starter bacteria used to make cheese come from the genus Lactobacillus, such as Lactococcus lactis subsp. lactis or Lactobacillus helveticus.
During cheese fermentation, lactic acid bacteria perform three important functions: they convert lactose in milk into small molecular monosaccharides, galactose, and glucose, which promote the formation of cheese flavour; they degrade proteins into peptides and free amino acids (FAAs); and they decompose lipids into fatty acids. The release of proteases, lipases, and β-galactosidases by lactic acid bacteria forms a unique taste, aroma, and texture.
In addition to lactic acid bacteria, other microorganisms such as fungi and moulds also play a role in cheese production and flavour development. White moulds, for example, are found on the outside of soft-ripened cheeses and produce enzymes that break down milk proteins, resulting in a characteristic ripened layer.
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Yeasts and moulds are used in cheese production
Cheese is a milk product that has been around for thousands of years. The process of making cheese involves transforming milk into a product with a diverse flavour and consistency. The goal of cheesemaking is to control the spoiling of milk into cheese. Bacteria play a crucial role in this transformation, and different types of bacteria are used to give each cheese its unique taste and texture.
Yeasts and moulds are also used in cheese production to create distinct flavours and textures. For example, yeasts like Saccharomyces cerevisiae are used alongside lactic acid bacteria in artisan or probiotic cheeses to enrich the product's texture, flavour, and nutritional profile. Debaryomyces hansenii and Geotrichum candidum are yeasts used in brined and surface-ripened cheeses like feta, Saint-Nectaire, and Brie, contributing to their flavour, rind development, and creamy texture.
Moulds, such as Penicillium roqueforti in blue cheese and Penicillium camemberti in Camembert, also play a significant role in cheese production. These moulds add unique flavours and textures through their enzymatic actions on proteins and fats. Surface-ripened cheeses like Camembert and Brie are ripened by moulds, while others like Stilton are ripened internally by piercing the cheese to admit air and promote mould spore germination and growth.
While yeasts and moulds can enhance cheese, they can also cause spoilage if not carefully managed. Yeast contamination can lead to off-flavours, gas production, and changes in texture. Therefore, rigorous hygiene practices, temperature control, and continuous monitoring are crucial to maintaining cheese quality and preventing spoilage.
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Bacteria is cultured and allowed to ripen with rennet
Bacteria plays a crucial role in the production of cheese, a fermented milk product that dates back thousands of years. While not all cheeses use bacteria in their production, many rely on specific bacteria to impart their distinct taste and texture.
During cheese production, lactic acid bacteria from the lactose in milk are cultured under artificial conditions. These bacteria, such as Lactococcus lactis subsp. lactis or Lactobacillus helveticus, are essential in converting lactose into monosaccharides like galactose and glucose, contributing to the development of cheese flavour.
Once the bacteria are cultured, they are allowed to ripen with the addition of rennet. Rennet is a complex set of enzymes traditionally derived from the stomachs of ruminant mammals, including young calves. It is used to separate milk into solid curds and liquid whey, with the curds being the solid portion of the cheese. The key component of rennet is chymosin, a protease enzyme that curdles the casein, the main protein in milk.
The use of animal rennet has decreased over time, with less than 5% of cheese in the United States still employing it. This shift is due to the demand for non-animal alternatives and the limited availability of mammalian stomachs. As a result, microbial rennets have gained popularity, with about one-third of cheese worldwide being produced using these substitutes.
Microbial rennets are derived from various microorganisms, including bacteria, fungi, and yeasts. Through genetic engineering, rennet genes can be introduced into these microorganisms to produce recombinant chymosin during fermentation. This process yields fermentation-produced chymosin (FPC), which is identical to calf chymosin but lacks pepsin, resulting in a different impact on the aging process.
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Frequently asked questions
Bacteria used in cheese include Streptococcus thermophilus B8, Lactobacillus helveticus B6, Weissella confusa B14, Lactobacillus rhamnosus B10, and Propionibacterium freudenreichii.
Bacteria are used to give cheese its particular taste and texture. They can release proteases, lipases, or β-galactosidases to form a unique taste, aroma, and texture. They also convert lactose in milk into small molecular monosaccharides, which promote the formation of cheese flavour.
Bacteria can break down proteins into peptides and free amino acids (FAAs) in cheese, and decompose lipids into fatty acids, which contribute to the texture of cheese.
Bacteria are used in cheese-making because they act as a preservative, preventing the growth of spoilage organisms, and creating a more neutral environment. They also contribute to the taste, texture, and health benefits of cheese.
