Fan oven temperature conversion and biology/chemistry
Many recipes call for a lower temperature in a fan oven (usually by 20°C), which makes sense as these ovens transfer heat more effectively. However there would appear to be exceptions:
When the conventional oven temperature is only just high enough for browning – the Maillard reaction needs ⪆ 140°C while caramelisation of most pure sugars needs ⪆ 160°C. A recipe reducing from 160°C to 140°C would therefore seem to result in much less browning when equally cooked through. But keeping the non-fan temperature would result in overcooking.
Sterilising jam jars in the oven (common/official advice for hot-packing jams, chutneys etc.) relies on the surface getting hot enough to kill anything that could be living on them.
I'm sure there are others.
How can we identify and deal with such cases? Is there a good rule of thumb for when to lower the temperature and when not to?
Best Answer
I think that the feature that you would use to identify the ones that might require the same or higher temperature in fan assisted ovens is removal of water.
In the case of a fan oven, the water is more efficiently removed from the food surface by elimination/reduction of the boundary layer through circulation of air in the enclosed space. The boundary layer is a diffusion rate-limiting layer of still air that limits diffusion away from any surface (e.g. Washed clothes dry faster on a windy day than on a still one when hung outside). In conventional ovens, the boundary layer is larger as the air is largely still and the environment is isothermal.
In most recipes the cooking involves removal of water from the items being cooked, however the Maillard reaction and sterilization of (dry) glassware both rely on heat alone.
Pictures about "Fan oven temperature conversion and biology/chemistry"
What is the temperature difference between fan oven and conventional oven?
Fan-forced ovens therefore cook faster. Cooking temperatures for fan-forced ovens are roughly 20C lower than those for conventional ovens but with the same cooking time. At lower temperatures this difference is less, 110C/100C fan.What is 180 degrees for a fan oven?
Oven Temperatures Conversion TableGas\xb0FFan \xb0C33251504350160537517064001805 more rowsWhat is oven fan temperature?
Final Words Fan in baking is simply referring to a convection oven with the fan turned on. Fan baking ensures that the heat is evenly distributed at a rapid pace thanks to the inclusion of a fan inside of the oven. It's great for many recipes but not the best choice for very delicate recipes.Why are fan oven temperatures lower?
Why are fan oven temperatures lower? Fan oven cooking temperatures are typically around 20\xb0C less than conventional ovens. This is because the fan circulates hot air around the inside of the oven and into the food, ensuring a more even temperature and food that's cooked more quickly.Celsius to Fahrenheit to Kelvin Formula Conversions - Temperature Units C to F to K
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Max Vakhtbovych, Maksim Romashkin, Max Vakhtbovych, Max Vakhtbovych