What Chemicals Can Be Found in Cheese?

Although you may not think it, there are a number of chemicals found in cheese, including lactose and whey protein.

Aside from a few food additives, the chemicals found in cheese can also be found in milk, but with different compound forms and molecular structures. The modern process of cheesemaking remains fundamentally the same as the methods used for thousands of years, with the main differences being hygiene standards and mass production. 

What is the Chemistry of Cheese?

While there are more than 1,800 varieties of cheese in the world, all different in terms of ingredients and preparation methods, the chemistry of cheese is pretty much the same across the board, with many varieties being chemically similar in terms of basic composition.

In general, the chemicals found in cheese, as well as the minerals and micronutrients, are the same as its source: milk. This makes it rich in:

• Calcium
• Protein
• Phosphorus
• Vitamin B12
• Vitamin A

All cheese varieties are essentially fermented lactose. Lactose is a type of disaccharide found only in milk and its derivative products. It’s composed of galactose and glucose subunits, and has the molecular formula C₁₂H₂₂O₁₁. With the help of lactic acid bacteria, lactose is converted into lactic acid, as shown in this balanced chemical equation:

C₁₂H₂₂O₁₁ + H₂O ⇾ 4CH₃CHOHCOOH

The extra hydrogen and oxygen atoms are derived from the water content of the milk. Once the lactic acid is formed, the proteins in milk start to curdle as their tertiary molecular structures are denatured by the acid.

Most commercially available cheese is made from cow’s milk. The industrial standard is to pasteurise the milk, which involves briefly heating it up to 70°C in order to kill any potentially pathogenic bacteria.

Heating milk above 70°C causes it to prematurely curdle. It’s then cooled down before rennet mixture and starter bacteria is added (usually Streptococci and Lactobacilli). The lactose in the milk is digested by the bacteria for about an hour at the temperature range of 30-40°C.

This fermentation process produces lactic acid, which lowers the pH level of the mixture to 4.6. At this point, the casein protein in the milk will begin to coagulate. The process is sped up by adding an enzyme as catalyst. At the same time, the bacteria also metabolise citric acid, which helps in breaking down the protein. The curds are allowed to set for one to two hours in order to separate the whey liquid.

Chemical Composition of Cheese

Cheese is a milk derived food product that has undergone fermentation. Generally, it is composed of the following chemicals:

• 37% water
• 33% fat
• 23% protein
• 3.5% carbohydrates
• 3.5% minerals and other compounds

The protein casein defines the molecular structure of cheese. Casein micelles aggregate to form a 3D matrix, and calcium serves as the glue that holds the structure together. The molecular formula of casein is C₈₁H₁₂₅N₂₂O₃₉P.

What Chemicals Are in Cheese?

The chemicals found in cheese, particularly the proteins, are derived from milk. The two major types of proteins in milk are casein (which comprises about 80% of milk protein) and whey protein. Saturated fats and minerals are also present in cheese.

In milk, casein molecules are normally wrapped into compact spheres. They’re packed together with calcium and phosphate ions to form microscopic micelles, and are unpacked during fermentation.

In the mass production of cheese, rennet mixture is added. Derived from the stomachs of ruminant animals, this contains the active enzyme chymosin, and is used to speed up the curdling of casein protein. The hardness of the cheese will depend on how much protein coagulates and how much is compacted into a given volume.

Ultimately, the chemicals found in cheese are the product of fermentation, which breaks down the proteins in milk. These chemical compounds are responsible for the flavour, texture, smell, and colour. Adding cultures of molds or bacteria to age the cheese further breaks down its major components

For example, casein breaks down into ammonia, ethanoic acid, aldehydes, and alcohols, amongst other things, while milk fat breaks down into acids and ketones, and lactose breaks down into ethanol and ethanal.

Traces of these chemical compounds are relatively high in aged cheeses, and this is what gives them their strong flavour and smell.

Aside from proteins and breakdown products, cheese also contains fats, vitamin B complex, and other minerals such as iron, magnesium, and zinc.

Proteins and Enzymes

Cheese is basically curd milk that is dried and moulded into shapes. It’s derived from the biochemical action of lactic-acid-producing bacteria that ferments (denatures) the proteins of milk by changing the pH of the milk. 

Casein is the primary protein of cheese, but rennet is the enzyme that allows the casein micelles to aggregate and bind together. This is only possible under specific temperatures. Overheating the milk while it’s being prepared will prevent the enzyme from being activated.

Fats and Lipids

About 33% of cheese is composed of fats and lipids. These are derived from the milk. 

Unlike the proteins and carbohydrates, the fats and lipids in cheese have not undergone any radical transformations.

Common Additives and Preservatives

The oldest cheese was discovered in ancient Egyptian tombs around 3,200 years ago. 

However, cheesemaking itself probably dates back to 10,000 years ago when humans started domesticating sheep. Cheesemaking is a method of preserving food. 

However, cheese also requires preservatives. Salt was probably the first type of preservative and food additive used for flavouring. Other preservatives and additives include bacteriocin, nisin, and potassium sorbate. Modern cheesemaking also uses iysozyme and natamicina as preservatives.

What Chemical Reactions Occur in Cheesemaking?

The fundamental reactions in cheesemaking are complex microbial biochemical breakdowns of lactose and other major components of milk. Mainly, the conversion of lactose into lactic acid is the precursor to the curdling of milk protein (casein) into a solid that’s drained and processed to become cheese. Lactate and citrate are further broken down into other compounds that give cheese its buttery flavour. The breakdown pathway is shown in the illustration below:

Fermentation Process

Milk is fermented into cheese using bacteria that produce lactic acid. The process has several steps. The bacteria eat and metabolise the sugars (carbohydrates) such as lactose in the milk. Among the metabolic waste products of the bacteria is lactic acid. This acid denatures the proteins in the milk.

Acidification and Coagulation

As the lactic acid denatures the proteins, it facilitates the curdling of the milk. The curds are the coagulated proteins that are further processed by cooking and pressing into blocks.

Ageing and Ripening

The ageing and ripening stage of cheese typically lasts for about three weeks. 

After fermenting and curdling the milk it, the curds are cooked and pressed into blocks. The cheese is covered with a cultured mix of salt solution for about two weeks. The blocks are then transferred to a ripening room and allowed to ripen for another three weeks. 

The temperature is maintained between 10 and 12°C at 90% relative humidity. It’s then stored in a cold room, maintaining the temperature between six and 10°C at 70 to 75% relative humidity.

Is Cheese Healthy?

As a direct derivative of milk, virtually all the nutrients of milk can also be found in cheese, including proteins, vitamins and minerals. 

Various cultures and civilisations have independently discovered the process of cheesemaking throughout the ages. It’s not surprising, therefore, that there are many variations of cheese – it’s estimated that there are at least 1,800.

The specific processes and ingredients of the various types of cheese may vary, but cheese generally contains the same basic healthy nutrients found in milk. However, just like in consuming other types of food, cheese should be consumed in moderation to avoid some unhealthy side-effects of over-consumption, such as bloating, inflammation, constipation, and weight gain.

Nutritional Benefits of Cheese

Cheese is a good source of calcium, which helps maintain the health of bones and teeth. It is also a good source of protein, helping the body absorb essential amino acids. It is also an excellent source of vitamin B12, which is needed by the central nervous system and essential in DNA synthesis.

Potential Allergens and Intolerances

If you have an allergic reaction or intolerance to cheese, it’s generally because of the proteins it contains, particularly casein. This may cause typical allergic reactions with one or more of the following symptoms:

• Hives
• Wheezing
• Itching or tingling feeling around the lips
• Swelling of the lips, tongue or throat
• Coughing or shortness of breath due to throat swelling

Conclusion

Cheese is one of the oldest processed foods that humanity has invented. It dates back to prehistoric times, around 10,000 years ago. As a milk derivative, it’s composed of various organic and inorganic chemicals that are also mostly found in milk, such as proteins, calcium, and fats. Cheese is made through the fermentation process of milk and is a healthy food with good nutritional value, as long as it’s consumed in moderation.