How to Cook Sugar Syrup

Swan made of caramel


hat is so special about sugar syrup? Not unusual ingredients for sure, since, in most cases, it contains only sugar and water. So what is so difficult in mixing some sugar and water?

Why would anyone want to cook sugar syrup?

I still clearly remember my first pastry lesson taught by my, at the same time adored and terrifying, chef Julie. She explained in detail how to cook sugar syrup, and we were soaking every word, with our eyes and jaws wide open, especially when she piped a caramel swan in front of us! Wow, that was breathtaking! And all that effort just to decorate a “simple fruit salad”!

Types of Sugar Syrup

Sugar syrup is a solution of sugar in water. The ratio of sugar and water can vary, so light syrup contains more water by weight than sugar while heavy syrup contains more sugar than water. Simple syrup is a solution of equal amounts of sugar and water by weight.

Sugar syrup

This photo shows the first stage of boiling; liquid is still translucent, and there are large bubbles on the surface. As it continues to boil, the bubbles are getting smaller because the water content gets reduced.

Sugar syrup

Why Would Anyone Want to Cook Sugar Syrup?

Well, in pâtisserie we use sugar syrup for various purposes. We use light or simple syrup to imbibe sponge cakes, to sweeten fruit salads or for soaking baba pastries. Heavy syrups are usually boiled off until they reach a certain temperature, and then used in making various pastry elements like Italian meringue, pâte à bombe, candy, and caramel making. Since it is important to cook the syrup to a certain temperature, it is handy to use a thermometer.

You want to have a sweet life? Sugarcoat it yourself!Pastry-Maestra-button-tweet-this

What Type of Thermometer to Use?

There are many types of kitchen thermometers, but only a few can endure extremely high temperatures, and can be used when making sugar syrup.

The first one is a liquid-filled thermometer that can measure from 38°C (100°F) to 200°C (400°F). It is called a candy thermometer, and it is also used in deep frying. This type of thermometer usually has a clip, and you can attach it to a pan very easily. It should be submerged into the liquid approximately 5cm (2″), and it needs 1-2 minutes to get a reading.

Infrared thermometer is a non-contact measuring device, which is a very convenient feature, since you don’t have to be near the heat source, and it reads temperatures in only 0,5 seconds. It is very easy to use, but there is also a downside – this type of thermometer reads only the temperature of the surface. So – although it can measure temperatures in a range from -50°C (-58°F) to 390°C (735°F), it is not designed for measuring sugar syrup. If you happen to have one of those, do not point the laser beam towards the eyes directly, because it may cause permanent damage to the retina.

Kitchen thermometer-infrared and digital

Finally, digital thermometer with a probe, which is my favorite. It is very accurate, measures the temperature in a few seconds and its measuring range is from 0°C (32°F) to 200°C (400°F). As it is using advanced technology, the temperatures are programmable. You can set it to your desired temperature, and the beeping sound will alert you once that temperature is reached.

Sugar syrup boiling - thermometer

How the heck do I do that exactly? Am I going to put my hand in a boiling sugar??

However, if you don’t have a thermometer, there is another way to determine the stage of the syrup: take some of the boiling syrup and put it in very cold water. You are probably wondering now: “How the heck do I do that exactly? Am I going to put my hand in a boiling sugar syrup??” In fact – yes! But, wait, not just yet! You have to prepare everything first. Prepare your pan with sugar and water. Fill one bowl with cold water halfway, and put some ice cubes inside. When your syrup boils, wait for a few minutes. Then, put your hand in cold water and keep it inside for 5-10 seconds. When you stop feeling your hand (just kidding!), QUICKLY (like 110 of a second quickly) grab some of the boiling syrup with your fingers and put that hand IMMEDIATELY back into the cold water. This whole process shouldn’t take more then a second! When you feel that the syrup is cold, you can take your hand out and check the stage of the syrup. Depending on the firmness of the cooled syrup, it is possible to define in what stage the syrup is. If you don’t feel confident of doing this technique, don’t worry, you can just use the spoon. Grab some of the syrup with your spoon and submerge it into your cold water. Once when you are sure that the spoon is cold, check the firmness of the syrup inside the spoon. Now that can’t be that difficult, right?

Sugar syrup-warning

The Sugar Syrup Stages

Here are several stages of sugar syrup which are important for making different pastry elements:

Sugar syrup stages

  • Thread stage is at 107°C (225°F). When you put some syrup between your fingers and separate them, the syrup will form a thin thread. This stage is used for cooking jams and sauces.
  • Soft ball stage appears at temperatures between 116°C (240°F) and 118°C (245°F). At this stage, you can form the cooled syrup into a soft, malleable ball. We use syrup cooked to soft ball stage to make Italian meringue, Pâte à bombe, fudge and fondant icing.
  • Firm ball occurs when sugar syrup is cooked to 118°C (245°F) – 121°C (250°F). It is used for making caramel candy, fruit jams, and Italian meringue.
  • Soft crack is a stage of cooking when syrup reaches 135°C (275°F) – 140°C (285°F).
  • Hard crack is a stage of sugar syrup at temperature of 145°C (293°F) – 155°C (311°F). It is used for making bonbons, nougat, sugar decorations of pulled and blown sugar.
  • Caramel is the final stage of cooking sugar syrup. It begins at 165°C (330°F). At this stage, there is no more water in the syrup, and sugar starts to break down to many complex compounds. At the same time, it changes color from light golden to deep brown. Caramel is used to make bonbons, nougatine, crème caramel, as a flavoring various creams and custards or caramel decorations.


In these two photos, you can see how boiling caramel looks like. In the first photo, you can see light caramel, and in the lower one there is dark caramel. Be very careful when working with caramel, as it can cause severe burns!

Sugar syrup-light caramel
Sugar syrup-dark caramel

Sugar Syrup Troubleshooting

When cooking sugar syrup, in the beginning you have to stir the mixture so that the sugar can dissolve easier. Unfortunately, because of that, almost certainly some sugar crystals will remain on the sides of the pan. We don’t want that! If those crystals get into the syrup, they will start a chain reaction of undesirable re-crystallization. How to prevent that?

  • Brush the sides of the pan with cold water. The water will wash down the crystals.
  • When syrup starts boiling, you can put the lid on a pan, and after few minutes the steam will wash off all the crystals.
  • Add some glucose syrup (see the photo bellow) or corn syrup to your sugar syrup – that will prevent crystallization.

Sugar syrup-adding glucose

  • Instead of glucose, you can use an acid, such as cream of tartar or lemon juice.
  • When the syrup boils, stop stirring.
  • If you are cooking syrup to caramel stage and you want to add something, like cream or nuts, make sure that you warm them first. If you add something cold to caramel, it causes temperature shock which can result in re-crystallization of caramel.

How to Cook Sugar Syrup at High Altitudes?

At sea level water boils at 100°C (212°F). However, when you start climbing, the atmospheric pressure starts to drop, and that directly impacts the boiling point of water and other liquids. If you are not sure at what altitude you are, put some water into a saucepan, and insert a probe of your digital candy thermometer inside. When it starts boiling, look at the temperature. The science says that for every 300 meters (approximately 1000 feet) above the sea level you should subtract the temperature of cooking for 1°C (2°F). So, if you are (like me) living at sea level, the temperature of sugar syrup for – lets say – making Italian meringue is 118°C (245°F). If you, however, live in La Rinconada, Peru, which is, according to National Geographic Magazine, the highest city in the world (5,130 meters/ 16,830 feet) to make Italian meringue you will need to cook your sugar syrup to 101°C (213°F). Interesting, ha?

Sugar syrup boiling, Pastry Maestr