# What determines the rate at which an item will freeze in the given context?

Assume you have two pieces of meat in two rooms and all factors are constant e.g. meat volume, meat temp, room size and so on. The only difference is that the temp in one room is -5c and the other is -20c. Obviously the meat in the -20c room will freeze faster because the air will chill the meat faster. Therefore the rate of freezing in this case is dependant on the temperature of the room.

Now, in the context of a freezer(which is similar to a chilled room) I understand that 'the rate of cooling is determined by how fast the air inside the freezer can extract the heat from the new (warmer) food'. Correct me if I'm wrong, but a freezer does this by pumping out cool air constantly until the set temperature is reached in the freezer. It is the increasingly cool air/or temperature of the air inside the freezer which determines how fast the item is cooling. Therefore besides the fact that the air temp is fluctuating, it is the same as the above example I gave. Am I correct?

1) In other words although using a bigger load, hotter item may take longer, in reality it is the cold air in the freezer(temperature) reached that will determine how fast the item freezes?

Now someone told me that it is not the temperature rather the 'cooler capacity and load' that determines the rate of pull down\freezing.

2) I take it a bigger load means it will bring the temp down/or less cool air will circulate however doesn't this just mean that other factors are being changed which will change the temperature in the freezer to decrease. Even then doesn't this mean it is the new lower temperature that freezes the food and hence the freeze rate or is there another factor I am missing?

3) Now if the freezer cooler capacity says it can freezer 2kg of food in 12 hours what does that mean exactly? Does it mean it will bring the temp of less the 2kg of food to the set temp e.g. -18c in 12 hours? Most freezers have a minimum setting of -18c. Assume we lowered the same freezer to -5c, does this mean it will feeze the food completely up to -5c in 12 hours or sooner? I know at -5c the all water will not freeze as only higher temps can do that.

Really what I am wondering is, imagine you set a freezer to -18c and it took 12 hours to bring that food to -18c and during this time the food(not freezer) only spent 1 hours going from -2c to -5c. If we now lower the temp to -5c would the item get to -5c within an hour(since that what it spends on the higher setting), or would only the temp in the freezer get to -5c in 1 hours and not the food? Would the -5c case cause the food to freeze much slower and take much more time, perhaps hours to get to -5c or would it be as usual. Hope you understand what I am saying.

4) Do you expect that if a 1kg of meat is frozen at -3c it will take a long time to freeze in a freezer which has a capacity of 2kg and 12 hours? Would it take many days to get to that temp?

Ideally I want an answer in layman terms.

Many thanks.

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