Cheese has long been a tasty and nutritious option favoured by many, serving as a source of essential nutrients that include calcium, protein, zinc, phosphorus, magnesium, vitamin A as well as vitamins B2 and B12. However, as consumers take on a healthier approach towards their diet, they are also increasingly wary of the levels of fat and sodium that cheese contains. 

Rising rates of obesity and chronic illnesses have led governments around the world to lobby for reduced fat and low sodium food items. This is evident worldwide, including countries like the US, Australia, New Zealand and the UK. 

According to the Dairy Industry Report by the Association for Packaging and Processing Technologies (PMMI), nearly half (48 percent) of dairy processors in the US are responding to this demand for a healthier lifestyle with options that are low fat, fat-free, lactose-free, organic, with reduced sodium or sugar, or fortified with probiotics, nutrients, calcium and protein.

Despite how straightforward it sounds, applying the above to cheese products is a far more complex issue, especially so when it comes to reducing fat and sodium. With natural cheese comprising just four ingredients—milk, starter cultures, enzymes and salt—both salt and fat play essential roles in developing flavours as well as organoleptic properties. 

MAKING CHEESE

In the cheese making process, starter cultures such as lactic acid bacteria and other adjunct cultures are first added to the milk. The cultures are essential for flavour development, but also serve to facilitate coagulation by lowering the pH. Apart from helping with whey expulsion, the acid produced will also determine the final cheese moisture, flavour and texture. 

An enzyme, rennet, is then added to the cheese milk and the mixture left to curdle. once achieved, curd and whey (mostly water and lactose) are separated. Salt, typically sodium chloride, is then added to the process to finish its transformation into cheese. The three ways of doing this include brine salting, adding salt before pressing, or surface salting after pressing. 

Salt is an important component of cheese that not only acts as a natural preservative, but also heavily impacts the firmness, flavour and safety of the final product. It keeps moisture at bay and slows acid development while keeping spoilage bacteria in check, which are less salt tolerant than the good lactic acid bacteria. It also helps to ripen the cheese and is responsible for the salty flavour found in the eventual product.

With the many functions that it provides—enhancing taste, masking bitter off-notes, reducing water activity and influencing texture—reducing salt can be a real challenge for manufacturers as it heavily impacts flavour, body, texture, consumer acceptance, shelf life and food safety.

A LOW SODIUM SOLUTION

One of the challenges that the industry faces is answering the call for a standardised salt reduction target. This is impossible to achieve as cheese by itself contains varying levels of salt, with some more than others. 

For instance, aged and hard cheeses tend to have more salt while soft cheeses have less of it. As a result, they are softer, contain more moisture, and also have a shorter shelf life. However, in soft cheeses, sodium chloride is crucial for moisture retention and maintaining cheese quality. This highlights the conundrum that manufacturers typically face when it comes to salt reduction due to the nuances involved. 

More than flavour development, salt also plays a functional role and supports the structural development of cheese. Researchers have found that reducing salt content from 0.9 percent to 0.6 percent was enough to alter the balance of volatile compounds and organic acids. It was also found that salt helps to prevent hydrophobic bitter peptides from forming, which meant that reduced levels of the compound would lead to an enhanced bitter after-taste.

Due to salt taking on multiple hats, the industry has been hard-pressed to find a perfect solution. Potassium chloride is about the closest substitute to sodium chloride that is being used in the market as they both share a similar cation. 

AN EQUALLY SALTY ALTERNATIVE

In one particular case, sodium chloride was completely replaced by potassium chloride without any adverse effects on the products functional properties, but the microbiological stability of the product was substantially reduced. Potassium chloride is a substitute suitable for cheese making that helps to lower sodium content without scrimping on saltiness. Studies have shown that it works well in maintaining the functional and microbiological properties of cheese, and also contains the nutritional benefit of reducing blood pressure, which helps to lower the risk of cardiovascular disease. 

However, the compounds Achilles heel lies not in its functional properties, but the fact that it leaves behind a bitter after-taste. This greatly limits the potential use of potassium chloride as consumers are most picky about flavour above everything else. To mask the bitterness, manufacturers tend to a use a mixture of sodium chloride and potassium chloride instead of engaging in a full replacement. 

For instance, researchers have successfully used the combination for cheeses like Cheddar and Haloumi without substantially affecting cheese properties. Potassium chloride could also replac up to 50 percent of sodium chloride in mild flavoured cheeses without leaving a bitter taste. But in harder cheeses like Cheddar for instance, the same substitution percentage resulted in an undesired crumbly texture.

FAT & SALT

Meanwhile, cheese manufacturers who are looking to reduce the amount of fat in their products face a similar challenge. Fat is the main character that contributes to lubrication and a creamy mouth feel. It not only contributes to flavour, but also serves as a vessel for other flavours.  

According to the US Code of Federal Regulations, reduced-fat cheeses must have 25 percent less fat than their full-fat counterparts while low-fat cheeses are defined as having three g of fat or less per serving, which amounts to an 80 percent reduction or more depending on the cheese type.

However, fat is crucial for the formation of processed cheese, much more than it is in natural cheese, as it is responsible for softness and melt characteristics—two of the top traits that consumers look for in such items. Processed cheese is produced by blending together natural cheese, salt, emulsifying salts, and other ingredients and flavourings that are continuously agitated over heat. 

In terms of structural benefits, fat occupies space in the protein matrix to prevent the dense formation of a hard and crumbly cheese. As a result, low fat cheese products (mostly processed cheese slices) tend to have a rubbery texture and require higher moisture to avoid excessive hardness. 

This in turn affects the salt to moisture ratio (S/M) and causes increased moisture in the non-fat components found in cheese, which results in higher acidity levels and lactose retention. High levels of lactose are potentially a bane for manufacturers entering Asian markets as Asians have a higher propensity for lactose intolerance than the average person. 

However, a study conducted by researchers at the Midwest Dairy Foods Research Center discovered that the addition of xylitol could help to improve the functional properties of low-fat processed cheese by significantly decreasing its hardness.

To add on to the challenge, flavour also takes a hit when it comes to low fat cheese. With reduced fat, the bitter tasting fat-soluble hydrophobic peptides that are normally absorbed are now available at higher levels, creating bitterness in the product. 

This then requires the incorporation of certain cultures that have the ability to break down these peptides. Alternatively, fat substitutes such as starch or protein-based beads that imitate fat globules can be used to mitigate the effects of low fat content.

Ultimately, the road towards better health is increasingly paved by consumers and governments as the call to fight against obesity, diabetes and other chronic illnesses heightens. 

Cheese and its derivatives on the other hand, are conventionally perceived as high fat and high sodium products. For the sector to stay competitive, it is imperative that cheese manufacturers review their current offerings and tweak it according to consumer demands for healthier food. 

This is particularly challenging for the cheese sector as fat and salt are two closely-linked components that are crucial to the very essence of what cheese products are supposed to be. Both are huge contributors to the taste, texture and food safety of cheese and the complete exclusion of either will be extremely detrimental. 

When fat is removed from cheese, water has to take its place and in turn, more salt is needed to maintain the ratio. As a result, the key to producing healthier cheese lies in finding the balance between fat and sodium, similar to how it is between taste and nutrition.