When making confectionery such as fudge, toffee or Turkish delight, a sugar thermometer is a valuable tool. Perhaps you have a sugar thermometer, have often seen 'small crack' or 'soft ball' printed on it and wondered what these terms mean. But what if you don't have one?
You can still make perfectly good sweets if your thermometer is lost or broken, or if you just didn't have one to begin with, by using a method known as the cold water test - indeed, professional sugar boilers will often pride themselves on their ability to do without a thermometer.
The Cold Water Test
The most common process in the manufacture of sweets is to boil a syrup made of sugar, water and glucose syrup to a specific temperature. As the syrup boils, water is driven off as steam, the sugar concentration increases and the temperature of the syrup rises to well beyond the boiling point of water. The final temperature and water content reached by the syrup, determines its properties when it has cooled down: how hard the finished sweet will be and what kinds of sweet can be made with it.
All you need for the test is a teaspoon and a small container of iced water. A bowl, dish, or jug, which will hold about a litre and which you can easily get both hands into is ideal.
A small amount of the syrup - about a teaspoonful - is dropped into the water and how it behaves indicates its temperature. Some finger manipulation of the syrup is necessary, so be aware that the temperatures we're dealing with here are well above that of boiling water, and sugar syrup is very, very sticky. Take great care when using this method and wait for a few seconds after the syrup has been dropped into the water before you touch it.
The Stages (at Sea Level)
|Cold water test||Temperature (°F)1||Description||Type of sweet made|
|Thread||220-230||When dropped into cold water the syrup makes a thread which will not ball up||Syrup for fruit sauces|
|Pearl||231-239||The thread begins to form a ball||Turkish delight and fruit jellies|
|Soft ball||240-243||The syrup forms a ball which will not hold its shape||Fondant creams|
|Firm ball||244-249||The syrup forms a ball which yields to slight pressure||Mint cake|
|Hard ball||250-260||The ball is much firmer||Nougat|
|Soft (small) crack||270-284||The syrup forms hard strands which will bend but not break||Toffee|
|Hard crack||285-299||The syrup forms strands which are hard and brittle||Rock, boiled sweets|
|Caramel||300-320||The syrup takes on a light straw colour in the cooking vessel||Butterscotch, honeycomb|
As you can see, each stage falls within a range of temperatures, giving you some leeway over how hard or soft you can make each type of sweet. This is another advantage of the cold water test over a thermometer - you can feel with your fingers exactly how firm your syrup has become and make allowance for having miscalculated the measures for any of the ingredients.
Following on from that particular advantage, one more reason why the cold water test is more accurate for making sweets is altitude. As altitude increases, atmospheric pressure drops and the boiling point of water occurs at progressively lower temperatures2. If you boiled the sugar to the same temperature at say, 10,000' (about 3,000 metres) as you would at sea level, the sweets would be overcooked. The cold water test will give the same results regardless of altitude, and help you to turn out perfect sweets every time.
High Altitude Guide for Cooking Sweets (in °F)
What Happens to the Syrup Above 320°F?
Once the syrup has passed hard crack, the cold water test won't show anything other than hard, brittle strands of sugar when dropped into water, and there are few uses for sugar syrup which has been boiled this high other than as a dessert decoration or a colouring additive to foods which need to be coloured brown such as gravy or treacle toffee. At this point there is little or no water left in the syrup, and the sugar begins to break down, creating rich flavours as the sugar caramelises, but which gradually become more bitter as it burns.
|320°-340°||Caramel - clear liquid||The syrup is a light amber colour and translucent|
|340°-350°||Caramel - brown liquid||The syrup turns dark brown and opaque|
|350° and above||Burnt sugar||The syrup is black|
Getting Started with the Cold Water Test
To begin with you're going to have little or no idea of how hot the sugar syrup is at any one time, and you won't know precisely when to use the test to determine which stage it has reached, which is why you need to start off by using it in conjunction with a sugar thermometer. Over time you will recognise how the syrup bubbles at different temperatures, you will see how it thickens as it gets hotter, and you will notice colour changes as the temperature of the syrup rises.
With practice, the cold water test will not only work as well as a thermometer, but will in many circumstances it will be more accurate. It's a method that's well worth learning if you plan to make sweets on a regular basis.