When a sugar syrup is cooked, water boils away to yield a high-temperature sugar concentrate. As the temperature rises, so does the concentration of sugar in the solution. The highest temperature it reaches indicates its properties once cooled to room temperature. It is practical at sea level to use a candy thermometer for evaluating the sugar syrup—however other techniques exist such as the cold water test and the thread/string test used in Indian cooking.
Cold Water Test edit
Each test is completed by dropping a dollop of the hot candy solution in cold water, and then extracting and evaluating the candy formed. Be sure to allow for a moment for the candy to cool before handling it to avoid getting burnt.
Thread Test edit
The thread or string test is commonly used in Indian cooking to assess the stage of a sugar syrup. To do it, allow a few drops of the sugar syrup to cool. Place the syrup between the thumb and forefinger, and gently separate the fingers. Observe the number of unbroken threads formed.
Stages of Cooked Sugar edit
Note that the following temperatures are listed at sea level, as they are listed in most cookbooks. The temperatures will differ at higher elevations due to the decrease in atmospheric pressure—because of this, the cold water or thread tests can be a more reliable gauge at elevation.
- Temperature range: 230°F-235°F
- Sugar concentration: approximately 80%
- Cold water test: when cooled in water it will create a liquid thread that cannot be easily collected.
- Thread test: a single unbroken thread will form between the fingers.
- Uses: This stage is proper for making syrup such as Chocolate Syrup but is not technically a candy.
Soft Ball edit
At this point, the candy cannot easily support itself and will begin to run if left out.
- Temperature range: 235°F-240°F
- Sugar concentration: approximately 85%
- Cold water test: syrup can be formed into a soft and flexible ball.
- Thread test: two single unbroken threads will form between the fingers.
- Uses: This stage is proper for making items such as Fudge.
Firm Ball edit
- Temperature range: 245°F-250°F
- Sugar concentration: approximately 87%
- Cold water test: syrup will create a firm chewy ball that can support its own weight and will remain chewy.
- Thread test: two unbroken threads will form between the fingers.
- Uses: This stage is appropriate for making candies such as Caramel, but please note this in not the same thing as Caramelizing.
Hard Ball edit
- Temperature range: 250°F-255°F
- Sugar concentration: approximately 92%
- Cold water test: syrup will form thick ropy threads, and a hard ball will form with a larger quantity of syrup.
- Thread test: three unbroken threads will form between the fingers.
- Uses: This temperature is best suited for recipes such as Rock Candy.
Soft Crack edit
When the solution reaches this stage the bubbles will become obviously smaller and more concentrated. The candy at this stage has a low moisture point.
- Temperature range: 270°F-290°F
- Sugar concentration: approximately 95%
- Cold water test: syrup will create small flexible threads.
- Thread test: n/a
- Uses: This stage is optimal for recipes such as Honey Taffy or salt water taffy.
Hard Crack edit
At this point the moisture levels are nearly non-existent. It is also the highest recipe that will be used in a standard candy recipe—after this point you enter the region of caramelizing.
- Temperature range: 300°F-310°F
- Sugar concentration: approximately 99%
- Cold water test: syrup will form brittle threads and easily break when bent or dropped.
- Thread test: n/a
- Uses: Toffee and Hard Candy.
At this stage the sugar will begin to caramelize and take on an amber color. Once this stage is reached, the sugar can quickly progress to burnt, and it is necessary to watch it closely. This stage can also be reached by heating sugar without water until it melts and caramelizes, but it can be tricky to ensure even heating and caramelization with this method.
- Temperature range:
- Cold water test: n/a
- Thread test: n/a
- Uses: caramel sauce, caramel shards