Coffee Syrups: How to Make Vanilla, Brown Sugar, Cinnamon and Caramel Syrup

A coffee syrup is sugar dissolved in water — usually equal parts of each — with a flavour such as vanilla, cinnamon, brown sugar or caramel. To make one, warm 200 g of sugar with 200 ml of water until it dissolves, add the flavouring, let it cool, then bottle it and keep it in the fridge. A tablespoon sweetens a latte.

Cafés use syrups because they are quick and consistent. At home they are worth making for a simpler reason: they let you sweeten cold drinks properly, and they cost a fraction of the bottled kind.

Why syrup instead of sugar

Granulated sugar dissolves slowly in cold liquid, which is why a spoonful stirred into iced coffee ends up as a gritty layer at the bottom of the glass. A syrup is already dissolved, so it mixes straight in. Japan settled the question long ago: the little pots of liquid sweetener served with iced coffee there are called gum syrup, although they are ordinary simple syrup with none of the gum arabic that old recipes used.

Syrup also makes flavouring easy. Vanilla, spices and caramel all give up their flavour readily to hot sugar water, and once infused the syrup carries them into any drink.

The base: 1:1 or rich 2:1

Standard syrup is one part sugar to one part water. By weight, that makes it 50% sugar; a tablespoon, which weighs around 18–20 g, carries roughly 8–9 g of sugar. For comparison, Torani's vanilla syrup lists 20 g of sugar in a two-tablespoon serving, or 10 g a tablespoon.

Rich syrup is two parts sugar to one part water. It is about two-thirds sugar, so a tablespoon carries about half as much sugar again as standard syrup, and it keeps longer. Use about two-thirds as much in any recipe written for 1:1.

Rich syrup has one drawback, and the numbers explain it. Sucrose dissolves at about 2.01 g per millilitre of water at 20 °C, and less as it gets colder. Made 2:1 by weight — 200 g of sugar in 100 ml of water — a rich syrup sits right at that limit at room temperature, so in the fridge it holds more sugar than the water can keep in solution, and crystals start to form, especially if a stray crystal or speck gives them somewhere to start. Made 2:1 by volume — a cup of sugar, about 200 g, to half a cup of water, about 120 ml — it holds around 1.7 g per millilitre, comfortably below the limit.

Candy makers have another trick: a little acid, such as cream of tartar or lemon juice, heated with the sugar, splits some of the sucrose into glucose and fructose. That mixture, invert sugar, crystallises less easily than sucrose alone. For coffee syrups it is rarely needed; making rich syrup by volume is simpler. If a bottle does crystallise, warm it gently and the crystals will redissolve.

Flavoured syrups

Each of these starts from 200 g of sugar and 200 ml of water.

Vanilla is the café standard. The method above follows Starbucks' own home recipe, which simmers the sugar, water and split pod for five minutes and, if using extract, stirs it in once the syrup has cooled.

Caramel syrup is the one that needs care. Heat the dry sugar in a heavy pan until it melts and turns a deep amber, then pour in the water — hot, and a little at a time, standing back, because it will spit and steam violently — and stir over low heat until the hardened caramel redissolves. True caramelization of table sugar starts at about 170 °C, which is why the flavour here is so much deeper than in a quick brown-sugar syrup: no water-based syrup ever gets that hot while it simmers.

Nut and other flavours — hazelnut, almond, lavender — can be made by steeping toasted nuts or dried flowers in the hot syrup for 20–30 minutes and straining, or simply by adding a few drops of extract to plain syrup.

How long homemade syrup keeps

Sugar preserves by tying up water. Microbes need water they can use, measured as water activity: most moulds stop growing below about 0.80, and almost nothing grows below 0.60. Honey, which is about 82% sugar and 17% water by weight, sits at roughly 0.5–0.7, which is why it keeps for years in a cupboard. A 1:1 syrup is half water, so it gives microbes far more to work with.

The practical effect is large. In an informal test, the drinks writer Camper English made syrups of each strength and watched them in the fridge until they turned cloudy, the first sign of spoilage. Standard 1:1 syrup lasted about one month; rich 2:1 syrup lasted about six months. Adding a tablespoon of vodka stretched the 1:1 syrup to about three months.

To get the most from a batch:

• Bottle it clean. Rinse the bottle or jar with boiling water first.
• Keep it cold, and pour rather than dipping a spoon in.
• Strain out fresh ingredients. Bits of fruit, ginger or nuts left in the bottle give microbes more to feed on.
• Throw it out if it turns cloudy, smells off or shows mould.

Bottled syrups last far longer because of what is on the label. Torani's vanilla syrup, for example, lists cane sugar, water, natural flavours, citric acid, and potassium sorbate and sodium benzoate "to preserve freshness". Homemade syrup has none of those, which is why it belongs in the fridge.

How much to use

A tablespoon of 1:1 syrup in a 240–350 ml latte is a sensible starting point: about 8–9 g of sugar, roughly two teaspoons. Iced drinks need a little more to taste equally sweet, because cold dulls sweetness — the iced latte guide explains why. The World Health Organization suggests that keeping free sugars below about 25 g a day brings extra health benefits, so two or three syrupy drinks can use up most of that. The caramel macchiato guide works through the sugar in one of the sweetest café drinks.

Syrups go into most of the café drinks in this library: the latte, the iced latte, the caramel macchiato and the mocha, among others.