The decades old debate about the human health effects of dietary milk fat continues, and the Dairy industry has responded by creating low fat versions of many dairy products, including cheese. But fat has important functionalities in cheese.

1. Importance of Fat in Cheese

• Contributes lubrication and creamy mouth feel. Think about the texture of triple crème cheese.
• Contributes flavour and acts as a reservoir for other flavours. Let’s remember that many flavours in ripened cheese are derived from the metabolism of fat by (specially) secondary cultures during ripening.
• Fat globules disperse light and suppress translucence, making the cheese appear darker.
• Fat globules occupy space in the protein matrix and prevents the formation of a dense matrix, which produces a hard, corky cheese.

Therefore, it is not hard to predict that reducing the amount of fat has important implications for cheese quality and special technological considerations have to be made to create a product with appropriate sensorial characteristics.  In addition, most jurisdictions have composition standards for many cheese varieties, so reduced fat may have regulatory/marketing challenges.

2. Current Status of Low-Fat Cheese

• Low-fat process cheese slices have been well established in the marketplace for decades.
• One third reduced fat Cheddar (20% fat vs 31% full fat) is available in most supermarkets. In 2018 the global low–fat cheese market size was valued at USD 93.9 billion, and this market is expected to keep growing at a compound annual growth rate of 3.8% from 2019 to 2025.
• Low-fat Cheddar with more than two thirds fat reduction (10% fat vs 31% full fat) requires fat substitutes. The most successful substitutes to date are microparticulated whey proteins. These are designed to replace and imitate the functionality of fat globules. Fat globules soften or shorten cheese because their physical size  prevents formation of a tight protein matrix. However, they are otherwise non-interactive with proteins. Similarly, microparticulated proteins act as fillers which are chemically inert but create physical disruption of the casein matrix.

3. Effects of Reduced Fat on Cheese Composition

• To maintain yield and avoid hardness, low-fat cheese requires higher moisture.
  • Typical target moisture for low fat Cheddar ranges from 42 – 48%.
  • Lower moisture (near 42%) can achieve 6 – 9 month aging and may have some typical medium Cheddar flavour, but texture is hard.
  • Higher moisture (towards 48%) gives softer body, but causes gumminess and shorter shelf life.
• More moisture means increased moisture in the non-fat substance (MNFS) and reduced salt in moisture (SM). To achieve SM for curing (SM > 3.6%), salt content may need to exceed 2%, which gives too much salty flavour.
• More moisture also means more lactose retention, which causes higher acidity.
• Some manufacturers have used a washing step to leach out the excess lactose, but washing causes a coarser texture and bland flavour.

4. Defects

• Rubbery and flaky due to lack of lubricity and the tight protein matrix.
• Gummy and chewy.
• Bitterness caused by hydrophobic (fat soluble) peptides (protein fragments) which result from curing. The amount, or at least the perceived amounts of these peptides, is increased in low-fat cheese, perhaps because these hydrophobic peptides are normally absorbed by the fat and are more available for tasting in low-fat cheese. Certain cultures have the ability to further break down these peptides and reduce bitterness so that bitterness in low-fat cheese often peaks after a few weeks and then decreases with further ripening.
• Astringency is common in low-fat cheese. It is distinct from bitterness, but often confused with bitterness. It is not detected by the taste buds, but, rather is a textural/physical perception at the back of the mouth. The perception may be related to interaction of saliva with cheese components, probably certain peptides.
• Meaty/brothy flavour is typical of low-fat cheese. This is related to interaction of amino acids (from protein breakdown) with alpha-dicarbonyls.
• Unclean flavours related to non-starter bacteria are more pronounced in low-fat cheese. They can be reduced by microfiltration to remove most bacteria before cheese manufacture.
• Gas formation, probably due to non-starter bacteria encouraged by low SM, causes slits. Again, this can be controlled by microfiltration of the milk.

5. Low-Fat Cheddar Make Schedule

When developing a low-fat cheddar cheese, adjustment of the make schedule needs to be tried to outcome the effects of the reduced fat. These changes include:

General Principles

• Adjust each stage to include more moisture.
• Keep pH higher at each stage relative to normal Cheddar.
• Reduce nonstarter bacteria to a minimum and use highly active non-bitter cultures.

Standardization

• Standardize to obtain about 35% FDM or about 20% fat in the cheese assuming 45% moisture

Pasteurization

• Normal HTST (72.5°C, 16 s) is recommended.
• There may be some advantage in higher temperature to denature whey proteins and increase moisture retention.
• Microfiltration can also be used to further reduce microflora in the milk

Culture

• Use normal levels of highly active, non-bitter mesophilic LAB.
• Culture adjuncts such as Lactobacillus bulgaricus or attenuated LAB cultures may be used to enhance ripening.

Calcium Chloride 

• Recommended, especially if higher pasteurization temperatures are used. 

Cutting

• Low fat cheese tends to retain more moisture. This is helpful because moisture softens the cheese, but it may also encourage growth of unwanted bacteria. If more moisture is desired, one way to achieve that is to cut the curd after renneting into large than normal particles.

Cooking Temperature

• Lower than normal, 37°C versus 39°C.

Draining

• High pH, near 6.4.
• Shorter cooking time

Stirring Out

• Once or none.

Washing

• May be necessary for high moisture cheese to reduce lactose content.

Salting

• Normal, about 2.5% of expected yield.

Curing

• Normal temperatures (5 – 10°C).
• Shorter time, especially for high moisture.