If you live at a high altitude, you're likely familiar with changes you need to make when baking bread and cake. The difference in air pressure means baking times, temperatures, and sometimes even ingredient ratios need to be tweaked to get the best outcome. But did you know that you might also need to adjust your candy-making to compensate for high altitudes?
When you don't make changes to your candy recipes or procedures, you will most likely end up with overcooked candy. This is because water boils at lower temperatures at higher altitudes, so you do not need to cook your candy as long or to as high a temperature as you would at sea level.
So what adjustments are necessary for high-altitude candy making? The good news is there are two ways of doing it, and both are really easy fixes involving only a candy thermometer.
The Boiling Water Test
The adjustments you need to make are dependent on your actual altitude. The easiest and most reliable way to determine what temperature conversions are required is to perform the boiling water test with your candy thermometer. You simply submerge the thermometer in boiling water and note the temperature five minutes after the water comes to a boil.
At sea level, water boils at 212 degrees Fahrenheit (100 degrees Celsius), but it boils lower temperatures at higher altitudes. If, during your test, the water boils at 205 F, subtract the seven-degree difference from your candy recipe. For example, if the recipe calls for a maximum temperature of 270 F, bring the candy to 263 F.
This is the best method since it accounts for your exact altitude and any irregularities or inaccuracies with your specific candy thermometer.
Make Some Calculations
If you do not have time to test your thermometer, or if you just want a general idea of how to adjust candy temperature recipes, here is a handy rule of thumb: Subtract 2 degrees Fahrenheit from a stated temperature for every 1,000 feet you are above sea level.
For instance, if you live at 2,000 feet above sea level, your approximate conversion would be 4 degrees less than the stated candy temperature. If you were making a recipe that called for the candy to be brought to 240 F, you would only cook it to 236 F.
Another example: If you live at 6,500 feet above sea level, your conversion factor is 13 degrees (2 x 6 [thousand feet] + 1 degree for that extra 500 feet). If your recipe called for 280 F, you would only cook your candy to 267 F.
As you can see, the higher the altitude, the more important it is to do this conversion. Even a few degrees can make a tremendous difference in the successful outcome of the candy. Also, remember that this is just an approximation. For a more accurate conversion formula, you should do the boiling water test on a regular basis.