Storing fish in ice box without melting wet

Quoted from fishingKaki forum

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Dry Ice: how to use it to keep your catch fresher.
We fishos typically use iceboxes to store our catches. But by the time we get home, all our fishes had turned pale from being soaked in water because the ice had melted.

Don't you wish there's a better way to keep your fishes cold and yet dry ?
Yes, there is, and dry ice is probably your obvious choice.
However, a lot of fishos are not sure of how they should make use of dry ice properly.

They probably think they can just plonk their fishes into an icebox filled with dry ice, and they would all be nicely frozen.
Wrong.
Heard of "freezer burns" ? That's what will happen to your prized catches.
When defrosted, the fishes will turn soggy and tasteless.
So the 1st lesson to remember is: never super-freeze your fishes by direct contact with dry ice.

The effective cold area of dry ice is about 3 cm only.
If I put a can of beer on dry ice, it will freeze solid.
But put a beer 5cm away, it will remain nice and warm !
Lesson 2: the cooling distance of dry ice is VERY LIMITED.

Dry ice property is such that it will super-freeze anything it touches.
Anything else not in direct contact, it has practically no effect on them.
There is no in-between temperature range.

Well, how about putting a few layers of newspaper between the dry ice and the fishes ? No direct contact, so no chance of freezer burns, right ?
Right. But your fishes will all be warm and rotten by the time you take them home. Newspaper is a heat insulator. No heat transfer = no cooling effect.

"Oh wait a minute!" one of you might say.
"According to my long-ago school day physics theory on Conservation of Energy , as long as we keep the icebox air tight, the fishes will eventually get chilled as the heat energy from the fish will flow to the dry ice although there is no contact between them."


Yes, true. But for that to work, the icebox has to be a perfect hermetically-sealed chamber, where there is no heat gain from outside source.

A normal icebox is not air tight, nor is its thermal insulation efficient. Heat from the outside will leak in.
That's why an icebox packed full with fish and ice chips will still eventually end up being soaked in cold water. Outside heat had leaked in.

It is a good practice to put a layer of newspaper to cover the top of your ice before you close the box lid down. It helps to seal off outside heat from entering.


So, how should you make use of dry ice to keep your catches fresh ?


This is how I'd done it.

1) Put plenty of dry ice at bottom of icebox.
2) Put a thick layer of ice cubes/ice chips to cover dry ice.
3) Put in layer of fishes.
4) Put in thin layer of ice cubes/ ice chips.
5) Repeat 3) and 4) until icebox is full.
6) Put a layer of newspaper on top. It helps to seal off heat from outside that leaks in thru the lid.
7) Close the lid.

This is what happens inside the icebox.
1) Ice melts slowly, water trickles downwards.
2) Water contacts dry ice, freezes immly.
3) No water puddle, no soggy fishes. Temperature always below 0 degree.
4) Fishes not in direct contact with dry ice, so no freezer burns.

This process will remain status quo until the dry ice runs out.
What's keeping the fishes fresh is not the dry ice. It's the humble ice cubes.
What the dry ice is doing is sarcrifice itself by absorbing heat from water and evaporates away as CO2 gas.

improved method:
- newspaper
- ice cubes
- fish
- ice cubes
- fish
- ice cubes
- newspaper
- dry ice
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Contact Thomas or Linda,
HP: 90663443,96733721
Tel: 64745519
Price: $2.50/kgs(minumum 10kgs), cheaper if regular customer
Free delivery with minimum orders. Kian Seng Hup Kee supermart
Stirling Rd, Blk 170 #01-1137
64745777 Linda.
$2 per kg. Order in advance.

www.dryice.com.sg
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