Hey everyone, just a question about cooking in general, not necessarily sous vide.
Let’s say I’m cooking a big batch of stuff (to split into meals over a week), and I’m using Tupperware-type containers. If I want to freeze some portions to preserve their freshness and nutrients, should I freeze immediately after cooking, or let the food cool to room temperature before freezing? If I were to let it cool naturally, should I do it with the airtight lid on or off? What’s the reason for either approach? I read something about anaerobic bacteria, but I’m not fully sure. I know that I’ve thrown vacuum bags into the fridge straight out of the water bath, and there’s been no adverse outcome both in terms of the food and my health.
Best practice says shock chill before you freeze. Being submerged in water with ice and perhaps salt, will reduce the product’s temperature more quickly than throwing it into the freezer. Firstly, water is a better conductor of heat than air. It works both ways. Water will conduct heat away from the product in the same way as it will conduct heat into it in sous vide processing. Another reasons is that it will not put an extra load on your freezer, which is not designed to deal with high temperatures. The introduction of an above ambient temperature item will increase stress on your freezer’s cooling system and put other items in your freezer at risk.
KL, big batches of food can be challenging to the home cook without proper equipment or techniques.
Follow Ember’s suggestions. And please don’t use the Tupperware-like containers, airtight lids or not. The problem is you are freezing items in contact with air in those containers and that’s going to allow nutrients to oxidize. Whether or not you cook SV, it’s better to freeze in meal-sized vacuum packed bags. They will chill quicker and will be less likely to dessicate in your freezer. Be sure to date and label every item.
And where did you get that idea of cooling food in a covered container?
Frozen food processors certainly don’t leave their products sitting out at room temperature after cooking. The cooked food goes directly through a liquid nitrogen tunnel that feeds directly into their storage freezer. After cooking some will package hot and tumble in a ice bath first to hasten the process. You can get close to that rapid drop in temperature at home just using an ice bath and spreading the food packages around your freezer, the lower the better.
Here’s the reasons you requested:
bacteria growth is minimized through rapid and thorough chilling. Your thought of leaving food sitting out at room temperature is reckless.
it ought to be evident that covered food, particularly when insulated by surrounding air, isn’t going to cool as quickly as uncovered.
the slow cooling of food, even in your freezer, is detremental to product quality. Please accept that rapid chilling is a fundamental of producing quality frozen food in spite of your experience.
If you still want to use the tupperware containers, leave a little head space to allow for expansion when frozen. You can lay a piece of plastic wrap directly on top of the cooled food, then apply the Tupperware seal.
The object of the game is food safety when cooling your food. If you have a large batch of something like soup,or stew, freeze a few 2 liter bottles of water ahead of time then add them directly into the liquid contents, all the while having your pot in ice water as explained above. Get your food cooled as quickly as possible, then freeze. Split your haul into smaller batches, if possible.
Gigi and Scott, both of you are mostly correct.
Of course once food is frozen it will not expand.
Gigi is mostly correct too because as food with a high water content undergoes a change of state from semi-liquid or liquid above the freezing point to a solid mass below the freezing point (frozen) the space between its water molecules expand. Naturally food retains that expanded shape until thawed. You can best observe this from the peaks that forms on the surfaces of frozen liquids in round containers.
If you follow Gigi’s less than optimum technique of adding frozen water to a cooked batch as it chills, be sure to adjust the water content of your formula before cooking to allow for it. The water where i live is tasteless so i prefer to use stock, reduced wine, or other liquid flavour enhancements in my cooking.
I’ve had the most success and longest safe storage life by packaging food immediately after cooking and then rapidly chilling it. I’ve used both blast chillers and ice water baths and found ice water best particularly when the products are tumbled in the ice bath. For large batches i use many bags to allow for rapid chilling in an ice bath. Smaller bags also allows faster tempering.
My practical research with the support of a Microbiologist indicated it’s best not to exceed 2-inches of thickness for the most rapid chilling of food in large batches. Over that thickness chilling slows considerably.
Hi kl005,
Go with ember and chatnoir’s advice!
Here is a practical example.
I cook large batches of spagetti sauce. When ready, I turn off the stove then prepare my vacuum bags for the volume of sauce,(never less than 15 bags), the sauce ‘cools’ while I’m preping bags. When the bags are ready, I fill the sink with water, ice, & about 1 ½ cups salt, then mix. Now, I fill the bags with 2 ½ cups of the still hot (about 150-160 degrees F) sauce, vac seal the bag with the filling in the bottom hanging over the counter edge so liquid won’t get to the seal area. When sealed, I flatten the sauce bag out so that the sauce occupies the whole bag and is about 1inch thick. Now the bag goes into the sink of ice water, mix after each bag, add more ice as necessary. (Collect lots of ice cubes during the week before the cook.). When all of the bags are cold, take them out, dry off, put them into the freezer.
The whole purpose of the ‘shock’ cooling is to get your food from hot to cold as rapidly as possible. This is to pass through the temperature zone where bacteria, yeast, and moulds live & breed as fast as possible so that you get no bacterial growth in your food.
Sorry I wasn’t clear with my reply. I wasn’t advocating adding ice to the cooked batch. I meant to freeze water in 2 liter bottles that had been capped, thereby making an encapsulated “icicle” that will cool off the interior of the batch while it also sits in the ice bath. So sorry for the confusion!
I am not sure you Understood Gigi’s advise re: the frozen jugs. She stated that she would drop the frozen jugs (WHILE STILL ‘JUGGED’) into the soup or whatnot.
This does not introduce water to the recipe, but does cool it quickly via ‘non-liquid-emitting ice cubes’.
I appreciate and agree with your point re: adding water during your cook, and taking account for it if you try to cool your recipe his way.
