Chilled

I’m going to take ‘chilled’ as temperatures between 0 and 5 degrees centigrade as that is what the UK’s Food Safety Agency recommends. Mind you, it also says you should check your fridge thermometer once a week. Really?

Before fridges and thermometers, however, humanity needed to preserve food for obvious reasons. There were methods using salt, leaving it in the sun and smoking it (as in smoked herring). But the best way was by cooling it.

It would be impossible to talk about the origins of cooling and refrigeration without mentioning the yakhchal which are domed icehouses that not only preserve food but can also generate ice. They were particularly useful in their native Iran, where the climate could very often reach extreme temperatures.

a yakhchal

 Records suggest that yakhchals were first constructed as early as 400 BCE. They have a conical shape. This allows hot air to escape upwards out of the structure. Cool air is allowed in thanks to small entryways at the bottom. The cold air stays firmly trapped within, while hot air escapes. Apparently many people in Iran still use “yakhchal” to refer to modern refrigerators.

To cut a longish story short modern fridges really started in 1851 when James Harrison created a patent for the first practical application of artificial cooling. He started in 1851 by creating an ice-making machine, which he showed off in Geelong, Australia. After tweaking the design slightly, he released the first commercial ice-makers in 1854 and then refrigerators.

Geelong museum with Harrison's portrait

So how does it and subsequent machines work?

Step 1 – The Compressor
The compressor pumps in cold and low pressured refrigerant in a gaseous state. Then, the refrigerant is compressed. This compression heats and pressurises it.

Step 2 – The Condenser
The hot and high pressured refrigerant is then channelled into the condenser. The condenser removes the heat and condenses the gas into a liquid.

Ventilation Fins: The heat that is removed from the refrigerant is then released through cooling fins at the back of the fridge. This is why the back of your fridge can get quite warm, or even hot.

Step 3 – The Expansion Valve
Then, liquid refrigerant is pushed through the expansion valve. Within this chamber, the pressure is suddenly dropped. This sudden drop in pressure causes the liquid to expand, with some of it rapidly turning into vapour. This change of state from liquid to gas has a cooling effect on the surrounding area.

Step 4 – The Evaporator
Afterwards, cold refrigerant in a liquid state leaves the expansion valve and enters the evaporation coils. As it travels through, it absorbs any warm air inside of the fridge. Because refrigerants have low evaporation points, this absorption turns it back into a gas, therefore evaporating. This process has a cooling effect that keeps your fridge cool.

Finally, the cold and low pressure gas from the evaporator travels back into the compressor to begin the cycle again.

Thanks to the Reliant and the Appliance City websites for some of the above information.

I’m going to veer away from fridges for the poem. Straight to Matsuo Bashō (translated by Lucian Stryk).

Lips too chilled
for prattle –
autumn wind

Matsuo Bashō

Thanks for reading, Terry Q.

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Chickens and Eggs: White vs Brown

Growing up in the US, white eggs were all I knew and they demanded mandatory refrigeration. At Easter, I loved colouring them. It was a bit challenging at times making holes in the shell and blowing out the innards, however it was worth the effort as there was great satisfaction dipping these small blank canvases into pots of different coloured food dyes and seeing the surprising creative results.

When I moved to the UK in the latter half of the 1990s there was not one white egg to be found. Also, to my initial horror, I discovered that eggs were not refrigerated. I learnt to accept this and thus far, touch wood, have never been stricken with salmonella.

So why white eggs and refrigeration in the States, and brown eggs stacked on open supermarket shelves in the UK? It all comes down to the types of chickens and processing.

Of the estimated thirty-three billion chickens in the world, there are hundreds of different breeds.

In the US, the most popular chickens for meat are a cross breed between Cornish hens and Plymouth Rocks. Hybrid White Leghorns are the most popular breed for egg laying, producing the bright white eggs that I was so familiar with in my early life.

In the UK, chickens raised for meat in factory farm sheds are typically Cobb 500, Ross 308 and the Hubbard Flex – sadly dubbed the ‘Frankenchickens’ because of so many abnormalities like being so fat their legs can’t support their bodies.

Popular UK breeds producing brown eggs include Bovans Brown, ISA Brown, Lohmann Brown and the Novogen.

Until the 1970s, white eggs were popular in the UK, then fell out of fashion. Preferences are attributed to numerous factors including cultural perceptions, marketing and branding, consumer preferences and production practices to name a few.

As the brown egg has been the norm for decades, consumers were again reintroduced to the whites during the pandemic due to stock shortages. Since then, they have been on the rise with many major British retailers supplying them due to changes in poultry management requirements (i.e. beak treatment) and consideration to sustainability (carbon footprint impact). Some of the white egg producing breeds are now more suitable to raise under new legislation. As in the States, the Leghorn is a popular breed.

Production methods are different between the two countries affecting storage requirements. In the States, eggs are washed stripping them of their natural protective coating, the ‘bloom’ or ‘cuticle’. The eggs become porous and thus, it is important to refrigerate them so bacteria can’t grow and penetrate the vulnerable shell.

Also, the current federal rules do not require vaccination of hens against Salmonella (they do require testing). Major retailers have implemented their own mandates on their suppliers in regards to vaccination, however they do vary.

In the UK and most other countries, the washing of eggs is prohibited. Therefore, the coating remains on the shells and eggs are seen as protected from bacteria.

In addition, since 1998 the British Lion Quality mark (shown above) guarantees that eggs have been laid by British hens vaccinated against Salmonella Enteritidis and Salmonella Typhimurium.

Over 90% of eggs sold in the UK carry this mark. Although refrigerating eggs in this part of the world is not critical, storing in a cool place is recommended.

And now to throw in something completely different and a bit of fun regarding chickens. Several years ago I visited the Rubber Chicken Museum in Seattle. Fun fact: It has the world’s largest and smallest rubber chicken.

The Rubber Chicken Museum

at Archee McPhee

will put a smile on your face
a must see and it’s free

rubber chickens galore
in all shapes and sizes

some smartly dressed
in familiar disguises

like Santa Claus suits
although most of them be

naked as jaybirds
with no modesty

some of them squeak
some are printed on towels

they all tell the tale
of this funny old fowl

yes the Rubber Chicken Museum
at Archee McPhee

will put a smile on your face
a must see and it’s free

Thanks for reading.
Kate J

Sources

Archie McPhee, 2025. Rubber Chicken Museum. https://archiemcpheeseattle.com/rubber-chicken-museum/ Accessed 16 January. 

Egg Info, 2025. British Lion Eggs. https://www.egginfo.co.uk/british-lion-eggs Accessed 12 January. 

Humane League, 2025. How many chickens are in the world and the us. https://thehumaneleague.org/article/how-many-chickens-are-in-the-world Accessed 12 January 

Poultry News, 2025. White turn. https://www.poultrynews.co.uk/production/white-turn.html Accessed 12 January 2025. 

Quora, 2025. Poultry: How did brown eggs become a standard market choice over white ones in the UK? https://www.quora.com/Poultry-How-did-brown-eggs-become-a-standard-market-choice-over-white-ones-in-the-UK Accessed 12 January 2025. 

Statista, 2025. Number of chickens worldwide. https://www.statista.com/statistics/263962/number-of-chickens-worldwide-since-1990/#:~:text=How%20many%20chickens%20are%20in,13.9%20billion%20chickens%20in%202000 Accessed 12 January.

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