Nisin as a cleaner label shelf life solution to clotted cream

The production process of Clotted cream consists of the following main steps:

1. Selection and handling of milk sources

Milk source: Selection of high quality whole milk, usually from unpasteurised fresh milk, which gives a better texture to the cream.

Pre-treatment: The milk source may be pre-treated, including filtration and homogenisation, to remove impurities and ensure the consistency of the cream.

2. Heating and Cooling

Heating: The milk is heated to about 80-85°C (175-185°F) and kept at this temperature for about 1-2 hours. This process helps to separate the fat from the milk and encourages the proteins in the milk to coagulate.

Cooling: The heated cream is quickly cooled to about 50°F (10°C), usually under refrigeration. During cooling, the milk fat floats to the surface of the milk, forming a thick layer of cream.

3. Separation and Handling

Separation: After cooling, the cream layer formed on the surface is carefully removed. This process can be carried out manually or mechanically.

Processing: The removed cream is further whisked to ensure a uniform texture. A small amount of lactic acid bacteria or other cultural bacteria may be added during the mixing process to improve the flavour and texture.

4. Packaging and Storage

Packaging: Pack the processed clotted cream in clean containers and seal them tightly.

STORAGE: Store under refrigeration, ensuring that the temperature remains below 4°C (39°F) to extend shelf life and maintain product freshness. Shelf life status: Clotted cream can be stored in an airtight container in the refrigerator for up to two weeks. Once opened, it will keep for approximately 4 days, depending on the method of refrigeration. Unopened clotted cream can be kept longer, up to 14 days.

5. Quality control

Testing: Various quality tests, including microbiological tests, organoleptic evaluations (taste, odour, texture, etc.), and physico-chemical tests are performed during the production process and on the final product to ensure that the product meets standards.

Key points in the production process

Temperature control: Temperature control during the heating and cooling process is essential to ensure that the milk and fat are separated effectively and that the cream has the correct texture and flavour.

Hygiene: Strict hygiene standards need to be maintained throughout the production process to prevent contamination and microbiological growth.

The shorter shelf life of Clotted Cream is mainly related to the following factors:

1. High fat content

Fat oxidises easily: Clotted cream is high in fat, which oxidises easily during storage, leading to flavour deterioration and quality loss.

Separation of cream: High fat content also makes the cream easy to separate, affecting its texture and consistency.

2. Low temperature storage

Refrigeration requirements: Clotted cream needs to be stored at low temperatures (usually below 4°C or 39°F), and even under proper refrigeration conditions, the shelf life of the product is still short.

Microbiological Growth: Although cold temperatures can slow the growth of microorganisms, they cannot completely inhibit them. Bacteria and moulds may still multiply during storage, affecting the safety and flavour of the product.

3. Natural ingredients

No preservatives: Traditional clotted creams are usually free of chemical preservatives and rely on natural ingredients for their preservative effect, which gives them a relatively short shelf life.

Natural flavour: While natural ingredients and production processes can provide superior flavour, they may also make the product more susceptible to external environmental influences.

4. Product structure and texture

Emulsification instability: The texture of clotted cream consists of milk fat and emulsion. This emulsified structure may be unstable during storage, leading to changes in texture and mouthfeel.

Dehydration and caking: Over time, the cream may become dehydrated or caked, affecting its experience.

5. Microbiological contamination

Storage time: Even under good storage conditions, the slow growth of microorganisms can lead to product spoilage. As storage time increases, the product becomes more susceptible to contamination and spoilage.

Cross-contamination: Poor hygiene during production and handling may lead to cross-contamination of microorganisms, which can shorten shelf life.

6. Packaging

Sealing: Incomplete sealing of the packaging or inappropriate materials may also result in the cream coming into contact with air, leading to oxidation and spoilage.

Suggestions for Extending Shelf Life

Refrigeration: Maintain at a suitably low temperature and avoid high ambient temperatures.

Seal packages: Use well-sealed packages to reduce air and microbial exposure.

Proper handling: avoid frequent opening of packages to reduce the risk of contamination and oxidation.

Quick Consumption: Try to consume the product within a short period of time after purchase to ensure freshness and safety.

Natural bacteriostatic ingredients: natural bacteriostatic agents that are permitted to be used can be selected to extend the shelf life appropriately

The following types of microbiological contamination may occur during storage of clotted cream:

1. Bacterial contamination

Lactic Acid Bacteria (LAB): Although most lactic acid bacteria are beneficial to dairy products, in excessive numbers they may cause changes in the flavour and texture of the product.

Pathogenic Bacteria:

Listeria monocytogenes: this bacterium can still grow under refrigeration and is especially dangerous to people with weakened immune systems.

Salmonella spp.: can cause food poisoning and affect gastrointestinal health.

Escherichia coli (E. coli): some strains can cause serious foodborne illness.

2. Moulds

Penicillium spp.: This mould may grow on the surface of cream, producing mouldy spots and unpleasant odours.

Aspergillus spp.: Certain species of Aspergillus may also contaminate dairy products when stored improperly.

3. Yeast

Yeasts (Yeasts): such as red yeast (Rhodotorula spp.) may cause acidity, spoilage or bubbling of the product.

4. Fungi

Moulds and yeasts: These fungi not only affect the appearance and taste of the product, but may also produce harmful toxins (e.g. mycotoxins).

5. Spoilage bacteria

Spoilage bacteria: e.g. Klebsiella spp. and Clostridium spp. which may multiply under inappropriate storage conditions and cause cream to spoil.

6. Dairy-specific bacteria

Lipolytic bacteria: Certain bacteria can break down milk fats, resulting in changes in the taste and odour of cream.

Nisin is a natural antimicrobial agent, usually produced by Lactococcus lactis, which is used as a preservative in the food industry, especially in some dairy products. Here are more details about how nisin helps preserve clotted cream:

1. Antimicrobial action

Mechanism: Nisin is able to inhibit the growth of a wide range of bacteria, particularly gram-positive bacteria, including some that contribute to the deterioration of dairy products. It acts by disrupting bacterial cell membranes.

Broad-spectrum: Nisin is effective against many bacteria and some harmful microorganisms, and can therefore help to extend the shelf life of dairy products.

2. Application to dairy products

Preservative effect: Nisin is often used in some dairy products, such as processed cheeses, cheese analogues, etc., to prevent bacterial growth and thus extend the shelf life of the product.

Suitability: Its use is usually safe in food formulations and is subject to strict regulatory approval.

3. Use in clotted cream

Preservative: The addition of nisin to clotted cream may help to extend its shelf-life and reduce bacterial growth, thereby delaying spoilage.

Impact: Whilst nisin can be an effective inhibitor of bacteria, its suitability for use in clotted creams is dependent on the manufacturer's needs and formulation, and is currently permitted in Europe, the USA and most regions.

4. Precautions for use

Dosage: Nisin should be used in accordance with appropriate regulations and standards to ensure safe concentrations in food.

Formulation suitability: Addition of nisin may require adjustment of the formulation to ensure that it is optimal and does not affect the taste and texture of the final product.

5.Shelf life status

Clotted cream can be kept in an airtight container in the fridge for up to two weeks. Once opened, it will keep for about 4 days, depending on how it is refrigerated. Unopened clotted cream can be kept longer, up to 14 days.

The use of nisin at a dosage of 10mg/kg (pure) can at least double the shelf life by 10 to 15 days under refrigeration, which is the maximum dosage in Europe. Conversion to 1000IU is 400mg/kg, before packing and after cooling.