I was hoping someone could advise the food safety limits in cooling for frozen dessert. Currently we freeze to -18C within 6 hours but im not sure where this limit comes from. Also it is not always practical to be able to measure the temperature at the 6 hours period. I was hoping that we could record temperature after 2 hours and show an achieved temperature.
Would some please advice where the 6 hours to reach -18oC would come from.
I suspect yr "rule" comes from outside UK. Here are two UK comments -
While it is advised that food should be cooled from 60°C to 10°C in less than 4 hours, and then stored under refrigeration at 5°C or cooler, it is widely accepted good practice that rapid cooling from 60°C to 10°C in less than 90 minutes is preferable.
For cook-chill production there are specific requirements for the cooking, cooling, storage, transport and reheating of products. A specific HACCP system would need to be developed and implemented to cover the temperature requirements for this type of food production. Food that has been cooked and is going to be chilled down and then reheated must be:
cooked thoroughly to a core temperature of 75°C (for 30 seconds) to destroy pathogens
cool rapidly to 5°C (within 90 minutes) to prevent the germination of bacterial spores and subsequent bacterial growth – using blast chiller or ice baths/cold running water
store food between 0°C and 5°C
It is possible yr "rule" is (vaguely) ex-USDA, eg -
(60degC) >>[time a]>> (21.1degC) >>[time b]>>> (<=5degC)
a = <2hrs, b = <4 hrs