Are chemical ice packs as efficient as regular ice?

Question

I live in a moderately temporary climate and our fridge freezer does not have an built-in ice maker.

I want to rapidly chill food after cooking it sous vide. Would cold water from the tap supplemented with 2 or 3 plastic ice packs (the type used in cool boxes etc.) suffice or must I use a 50/50 mix of ice and water?

I will not be chilling thick cuts of meat (e.g. roasts), mainly just chicken breasts or steaks etc.

Answer 1

Those ice packs are full mainly full of water, with dye and some sort of preservative. You can tell they're water because the liquid expands on freezing and only water does that.

A given quantity (weight) of ice will take the same amount of heat to melt whether it's in plastic or not. So, apart from a small error from the weight of the plastic, ice packs will be as capable of cooling as the same weight of ice.

Ice packs won't, however, cool a water batg quite as quickly as ice cubes, for two reasons

• the plastic shell acts as an insulator
• they have less surface area (one big lump compared to lots of little ones)

The latter point also means they won't cool the bath as evenly.

But having said that, they'll be fine if you're sensible:

• use fairly small containers with gaps between them (that's important with vacuum sealing as you can't stir the food) . This is a good idea anyway
• use more, smaller ice packs to increase the surface area
• stir the chilled water bath, or move the food around in it.
• seal the containers well (of course you're doing this) as any leakage will contaminate the outside of the ice packs rather than going down the drain.

In practice, for fairly small quantities, even cold tap water chills small portions fast enough to go in the fridge with plenty of time for them to finish cooling within safety guidelines; ice can provide convenient speed but isn't absolutely necessary except for thick pieces.

Answer 2

If I interpret your question right you want to cool food rapidly after cooking for storing. What you want is something that's going to make the food cold as quickly as possible.

There are actually 3 choices here:

1. Ice packs: these are usually rigid plastic containers filled with water. The plastic shell is going to inhibit heat flow, so they won't cool the water as quickly
2. Gel ice packs: these have silica gel in them which allows them to be flexible even when partially frozen. They also freeze at a lower temperature than ice, so they come out colder, which is an advantage, however they are designed to give longer lasting cold, used in a cooler or on an injury, so not necessarily the best for your application
3. Ice: either in cubes or small-medium sized blocks ice will give you the fastest cooling as there's a lot of surface area

So ice is definitely the best choice, however if all you want to do is cool some sous vide steaks down packs may do okay. If it was me I would pour water in lockable plastic containers and cram them any way they'll go in the freezer, then pop out the ice when needed.