Supermarket Refrigeration To Milk Pasteurisation
You might not notice it, but refrigeration impacts so many parts of our day to day lives.
Think about it.
The food you eat. How you keep cool. The roads you walk and drive on. Advances in technology in the world you live in.
is part of so many aspects of daily life.
And with Howden compressors at the heart of many of these refrigeration solutions, there is a good chance that Howden is keeping your world, and the world around you, cool.
Due to refrigerations main association to food and food preservation we want to explore some of the processes where refrigeration plays a vital part in the food we consume each and every day.
Refrigeration And The Food You Eat
What do you have for breakfast? A bowl of cereal? A hot cup of coffee? Maybe you prefer a full fry up or cheese on toast?
Well, as you know, refrigeration plays a huge and very critical part in our food industry including:
- Cold and freeze storage in retail
- Refrigeration in the farming sector
- Refrigeration in dairies.
Refrigeration underpins every part of the food supply chain from large industrial refrigeration plants to the chilled fridges in your supermarket and home.
The main aim of all food preservation methods is to slow down processes that cause deterioration of the food in terms of quality and safety.
Howden compressors are the heart of the refrigeration system.
Commercial Cold Storage & Refrigeration
From picking out your favourite sandwich in the chilled section, to choosing tonight's dinner from the deli, and grabbing a bag of ice from the freezer.
Your supermarket is going to have a vast range of different commercial chillers, freezers, and coolers. These are not just for display on the shop floor, but are also used keep the products fresh while waiting in storage.
Without cold storage, most produce won’t stay fresh for more than a few days - regardless of whether it has been produced, picked or farmed.
All food deteriorates in quality over time, and refrigeration or freezing can reduce the speed at which this occurs. Helping preserve food and store it for longer periods.
Refrigerators, simply put, are insulated cabinets that use an electric compressor to move liquid (refrigerant) around cooling bars to drop the temperature of the air inside the unit, therefore keeping the products inside continuously cool.
Keeping products in a temperature-controlled environment maintains the freshness without damaging the quality of the food.
The low temperature prevents the growth of bacterial pathogens and minimises the growth of spoilage microbes.
Chilling also has beneficial effects on quality - minimising moisture transport and maintaining flavour, colour, and texture.
- Chilling food at 0°C to 4°C can yield a shelf life of two to seven days
- Deep chilling food at -2°C to -4°C can extend its shelf life by up to four weeks
- Blast freezing products at -32°C to -40°C can keep food fresh for extended periods of time
All while preserving the quality, safety and nutritional content of the food at a level close to its initial values.
On the shop floor of a supermarket, you will often see refrigerated display cases and chilled counters.
These refrigerators allow the products to be showcased, but more importantly perform the essential role of keeping the contents cool and preserving their freshness and quality whilst waiting to be purchased.
Note that all of these products should have a display-by date and will be disposed of when they go past this.
Walk-in cold stores and chilled production areas are often used for the storage of longer life products. These are often found in the warehouse of the store.
The cold stores are designed to complement the flow process of holding and loading the food.
Refrigeration solutions such as cold rooms, chilled shelves, blast chillers and blast freezers all play their part in locking in the freshness of produce regardless of whether you are working with fish or seafood, meat or poultry, or fruit and vegetables, or dairy.
Refrigeration in Farming
Meat, like any other form of produce, is subject to deterioration over time caused by microorganism growth. Unlike other produce, meat has other things to deal with as well.
Meat is subject to an endogenic enzymatic activity which causes muscle tissue to mature, become tender, and develop in taste. Not only this, but meat also loses weight through surface evaporation and is very sensitive to oxidation.
Therefore, to prevent or reduce these processes, it is essential to be in control of the temperature as well as the environment in which the meat is stored and processed.
This is done in a cold chamber.
Within the cold chamber, rapid cooling of the meat takes place.
This not only slows and nearly stops the development of surface microorganisms but it also reduces weight loss and discolouration from oxidation.
The air temperature must be in the region of 0°C, with no decrease below -1°C, which could freeze the meat surface and affect its appearance.
The humidity during the chilling operation should be kept fairly high to prevent excessive weight loss, and the primary chilling is complete when the warmest point of the carcass has reached a temperature of about 7°C.
On occasion, the meat will be aged.
Ageing is done to increase tenderness and develop taste through the activity of the meat enzymes.
This is also controlled by temperature and can be accelerated by increasing it but the recommended temperature is 4°C.
When chilled meat is stored for long periods a lower temperature, without the risk of freezing should be used - normally 0°C.
When meat is to be stored for longer periods freezing must be used to minimize any physical, biochemical and microbiological changes affecting quality in storage.
A product can be considered frozen when its centre has a temperature of -12°C or less.
Freezing is performed in tunnels or in chambers with intense air circulation called blast chambers.
Air temperatures should be in the range of -30° to -35°C.
Refrigeration in Dairies
Did you know that refrigeration is used during the pasteurisation process of milk?
Pasteurisation involves heating the raw milk to 71.7°C, and depending on the pasteurisation type holding it for a certain length of time, and then cooling it very quickly to less than 3°C.
The heat treatment of the milk is done to destroy any lethal microorganisms that are found in raw milk eg tubercle bacillus (TB). Milk also contains other substances and microorganisms that can spoil the taste and shorten the shelf life and these are also destroyed as much as possible by the heat treatment.
This is done without markedly affecting the physical and chemical properties of the milk, and works best when the heat treatment is applied as quickly as possible after the milk has arrived at the dairy.
As the milk is only pasteurised rather than sterilised there is still the opportunity for microorganisms to develop after the heat treatment. Therefore the milk is very quickly cooled and kept at a low temperature to inhibit this development.
The pasteurisation process
The most common pasteurisation process is High-Temperature Short Time (HTST).
Chilled milk is heated from around 4 °C to a pasteurisation temperature of 72-75 °C, held at that temperature for 15-20 seconds and then chilled to 4 °C again.
A hot water circuit is commonly used as the heating medium.
Then the next incoming cold milk is pre-heated by the outgoing hot milk that was just pasteurised, which is simultaneously pre-cooled.
This process takes place in a heat exchanger and is called regenerative heat exchange or, more commonly, heat recovery.
The pre-cooled milk is then further cooled to the desired temperature with a refrigerated cool water circuit.
The pasteurisation process ensures that the milk is safe to drink by killing any harmful bacteria that may be present in raw milk, and keeps it fresh for longer by inhibiting any enzymes or bacteria that can cause reduced quality and shelf life.
So there you have it, refrigeration is a lot more than just the fridge in your kitchen. Refrigeration is vital in so many industrial processes from farming to retail, to medical and leisure, and so much more.
Whether you have questions about which compressor is right for you. Or if you’re ready to improve your operations then please Get In Touch.
And don't forget to leave us a comment below!