Syrups for Coffee: Sugar, Honey, Glycerine and Gum

Sugar dissolves slowly and incompletely in iced coffee, and honey sinks to the bottom of it, so anything cold is sweetened with a syrup. Below are the syrups by weight, how much goes in a cup, and how long each keeps. Then comes a question from my own bar: I put glycerine in my simple syrup to give it body. Does that belong in a coffee syrup, and how is it different from gum arabic, which bartenders used for the same purpose a hundred and fifty years ago?

The short answer: at the amount I use, the measured evidence says the glycerine is probably too little to feel once the syrup is in the drink. Gum arabic is a different kind of ingredient and does more per gram, but it is slow, cloudy and expensive, and in a large coffee it is thinned out as well.

The syrups, by weight

Make them on a scale. A cup of sugar weighs less than a cup of water, so “one to one” by cups is a weaker syrup than one to one by weight. The last two columns give the sweetness of two teaspoons of sugar in an 8 oz cup and three in a 12 oz cup: a place to start.

Syrup	Recipe, by weight	How to make it	8 oz cup	12 oz cup	Keeps
Simple syrup	1 sugar : 1 water	Stir into hot water until clear; cool	16 g	24 g	About a month, cold
Rich syrup	2 sugar : 1 water	Heat gently to dissolve; cool	12 g	18 g	Longer than simple; still cold
Demerara or brown sugar	1 : 1 or 2 : 1	As above, with raw or brown sugar	16 g / 12 g	24 g / 18 g	As above
Vanilla	Simple syrup plus vanilla extract to taste	Add the extract after the syrup has cooled	16 g	24 g	About a month, cold
Honey syrup, 3 : 1	3 honey : 1 water	Weigh into a squeeze bottle with warm water (about 100 °F); shake. Do not boil.	13 g	20 g	At home: cold, from a few days to four weeks (sources differ). At a stall: mix on the day
Honey syrup, 2 : 1	2 honey : 1 water	As above	15 g	22 g	As above
Maple syrup	Straight	Nothing to make	12 g	18 g	Refrigerate once open
Monk fruit and erythritol blend	1 blend : 1 water	Dissolve warm	16 g	24 g	Cold, a few days
Allulose	1 allulose : 1 water	Dissolve warm	23 g	34 g	Cold, a few days

What each tastes of, and which coffee it suits, is on the printable card: Syrups and Sweeteners: Recipes by Weight (PDF). Honey has a page of its own, Honey in Coffee, because it behaves differently from sugar. The vanilla can be home-made extract.

Rich syrup keeps better than simple because more of its water is tied up by sugar. Neither is shelf-stable. Both live in the refrigerator, or in the cooler at a stall.

The honey figures are two different rules. At home, the National Honey Board gives four weeks refrigerated and a bar reference gives a few days; neither publishes a test (Honey in Coffee has both). At a licensed market stall the answer is set by law, not by spoilage: a syrup mixed at home is home-prepared food, so it is mixed at the booth on the day.

Pumps. A standard café syrup pump of the kind sold for Torani’s 750 mL bottles gives ¼ oz a pump, about 7.4 mL, which in a 1 : 1 syrup is about 9 g. So the 12 oz column above is two pumps, and the 8 oz column a little under two. A 1 : 1 syrup is roughly half sugar by weight, so two pumps carry about 9 g of sugar: at a dollar a pound for sugar, about two cents a drink. What the rest of a cup costs is on Prices and Customers.

Flavored syrups beyond vanilla are steeped the same way: a spice or a bean simmered in the syrup and strained out. Brown sugar with a cinnamon stick, maple with cinnamon, and a caramel syrup (sugar cooked to amber, then loosened with hot water, never cold, because the caramel is far above boiling) are the common ones. The recipes, and the seasonal drinks they go into, are on Flavored and Seasonal Drinks. Commercial syrups keep on a shelf because they add preservatives, most often potassium sorbate and citric acid; a home syrup has neither, which is why the “Keeps” column says cold.

My simple syrup, and what is in it

My simple syrup is not quite the one in the table. It is 237 g of water, 200 g of sugar and 19 g of food-grade vegetable glycerine: one cup, one cup and one tablespoon, put on a scale. I add the glycerine for mouthfeel.

In numbers, that syrup is 44% sugar, 52% water and 4.2% glycerine. A 20 g dose, about what a 12 oz iced coffee takes, carries 8.8 g of sugar and 0.83 g of glycerine.

Glycerine: what it is

Glycerine, glycerin and glycerol are three names for one substance. It is a small molecule, a sugar alcohol, made by splitting fats and oils. The European Food Safety Authority describes it as “a clear, colourless, hygroscopic syrupy liquid.” The bottle of pure glycerine is very thick: about 1,400 times the viscosity of water.

• It is legal and ordinary. In the United States it is on the list of substances “generally recognized as safe when used in accordance with good manufacturing practice” (21 CFR 182.1320), with no numeric limit. In Europe it is additive E 422.
• It is sweet, somewhat less than sugar, and it has calories: makers’ data sheets give about 4 per gram. It counts as carbohydrate on a label, not as sugar.
• “Vegetable” matters to some customers. Glycerine can be made from animal fat as well as from plant oils, so it is vegan or kosher only when the bottle says so.

Can anyone feel 4% glycerine in a drink?

The thick liquid in the bottle is not what reaches the mouth. It is diluted twice: once into the syrup, and again into the drink.

What is measured. The only careful threshold in print comes from wine, where glycerol is a natural part of the drink and tasters have argued about it for decades. In 1984 Ann Noble and G. F. Bursick had trained tasters compare a dry white wine with and without added glycerol. Their abstract gives two numbers:

• Tasters could detect added sweetness at 5.2 grams per litre.
• To feel added thickness took 25.8 grams per litre. Below that, “glycerol does not produce a detectable increase in perceived viscosity.”

Later wine studies mostly agree. One found glycerol’s contribution to perceived body “nominal” next to sugar and alcohol. Two found a small effect at 5 to 10 grams per litre in some wines. A third, by the same group, found none. Nobody reports an effect below 5.

What my syrup delivers. Here is the glycerol in the finished drink, for a light and a heavy hand:

Drink	Syrup added	Glycerol in the drink	Against the 25.8 g/L thickness threshold
A 3 oz stirred cocktail	10 g	4.2 g/L	6 times below
The same	20 g	7.6 g/L	3.4 times below
An 8 oz hot coffee	10 g	1.7 g/L	15 times below
The same	20 g	3.2 g/L	8 times below
A 12 oz iced coffee	10 g	1.2 g/L	22 times below
The same	20 g	2.3 g/L	11 times below

Every line is well under the threshold. In coffee it is not close.

Glycerine thickens water no more than sugar does. A classic set of measurements puts a 10% glycerol solution at 1.31 centipoise at room temperature; a 10% sugar solution is 1.34. Water is 1.0. Gram for gram they are the same. So the 19 g of glycerine in my syrup thickens it about as much as 19 g more sugar would. The body I notice in the bottle is real, but most of it is the sugar’s.

Heat thins all of it. Water is less than half as viscous at 140 °F as at room temperature, and syrups follow. Whatever body a syrup adds, a hot coffee shows less of it than an iced one.

The honest limits of that conclusion. The thresholds were measured in white wine, at room temperature, not in coffee or a cocktail. No sensory test of glycerine in either has been published. And a spirit-forward drink is a different thing from a wine: it may be that glycerine softens the burn of alcohol in a way that is not thickness at all. So I am not throwing my recipe out. I am going to test it, and the test is easy: make two bottles, one with and one without, and run the triangle game from the tasting page on a few friends. If nobody can pick the odd glass, the glycerine goes.

Should glycerine go in a coffee syrup?

Reasons it does no harm:

• The dose is tiny. A 20 g serving of my syrup has 0.83 g of glycerine. The British warning about glycerol is for children’s slush drinks, where one 350 mL cup can hold about 17 g, twenty times as much.
• It is cheap. The glycerine in a 750 mL bottle of syrup costs about 35 cents at one seller’s quart price.
• It mixes instantly and stays clear.

Reasons to leave it out:

• It probably cannot be felt in a cup of coffee, by the numbers above.
• It does not preserve the syrup. Water activity is a measure of how much of the water in a food is free for microbes to use, from 0 (none) to 1 (pure water). Worked out from published sugar tables, 4% glycerine lowers the water activity of a one-to-one syrup from about 0.95 to about 0.93. Mould and yeast are comfortable at both. A rich two-to-one syrup, at about 0.86, does far more with no additive at all.
• It is one more thing on the label, and one more question from a customer. A bottled syrup has to list it: it is over 2% and it is there for a purpose.
• A market stall cannot sell bottled syrup from a home kitchen at all. Michigan’s cottage food list says, in so many words, “No simple syrups.” Syrup for the drinks is mixed at the booth under the food licence (the rules page).

What the commercial syrups do. The ingredient lists on the makers’ own pages show it. Torani’s vanilla and caramel syrups have none. Monin’s plain cane syrup has none. Monin’s vanilla syrup in the glass bottle lists vegetable glycerine third, after sugar and water, and the same flavor in the plastic litre does not. Monin does not say why. One possibility is that it carries the flavoring rather than adding body; nothing Monin publishes settles it.

My answer: for a coffee syrup, no. Sugar and water do the work, and a rich syrup gives more body than a simple one with nothing added. In the cocktail syrup I will keep it until the triangle test tells me otherwise.

Gum arabic: a different kind of thing

Gum arabic is the dried sap of acacia trees: in the words of the federal regulation, “the dried gummy exudate from stems and branches of trees of various species of the genus Acacia.” Syrup made with it is gomme, or gum syrup, and it is what nineteenth-century bars sweetened with. The 1862 bar manual bound with Jerry Thomas’s How to Mix Drinks gives a recipe by the barrel: “20 lbs. of best clear white gum arabic dissolved in 4 gallons of water, nearly boiling hot; take 60 lbs. of sugar, melt and clarify it with 1 gallon of water … add the gum solution, and boil for 2 minutes.” That works out to a syrup that is about 16% gum. My own gomme syrup is a modern, lighter version.

Where glycerine is one small molecule, gum arabic is a tangle of very large ones: branched chains of sugars with a little protein attached, thousands of times heavier than a glycerine molecule. That difference is the whole comparison.

	Glycerine	Gum arabic
What it is	One small molecule, a sugar alcohol	A mix of very large sugar-and-protein molecules; a soluble fibre
Sweet?	Yes, a little less than sugar	No
Thickening, gram for gram	About the same as sugar	Several times more than sugar or glycerine
Holds flavor oils in suspension	No	Yes. This is its main job in soft drinks.
Clarity	Clear and colourless	A straw-yellow syrup with a foamy head; needs a day to settle
Making it	Pour and stir	Slow. The powder clumps, and wants hours or an overnight soak.
In a hot drink	Stable	Stable in heat and in acid, but its proteins are damaged by long hot storage
Keeping	Does not spoil; does not preserve the syrup	The gum itself is broken down by bacteria over time; keep it cold
US rule	”Good manufacturing practice”; no number	A percentage limit in the finished food: 2% in soft drinks, 1% in most other foods
Cautions	Large amounts in small children	Wind, at 30 g a day; the dry powder is an allergen for people who work with it
Cost per 750 mL of syrup	About $0.35	About $16 at a small-jar price, for a syrup that is 10% gum

Why gum works where glycerine does not. Thickening comes from the size of the molecule. A 1% solution of gum arabic is about 23% thicker than water, by one published measurement; 1% of sugar or glycerine adds about 3%. And the gum’s small protein fraction lets it coat droplets of oil, which is why a gomme-sweetened drink is said to feel “silky” and to hold together.

Is it felt in coffee? The wine threshold is a weight of glycerol, so it has to be turned into a thickness before gum can be compared with it. 25.8 g/L is about 2.6% glycerol, and at about 3% more viscosity per 1%, that is a drink roughly 8% thicker than water. On the same footing, gum at about 23% per 1%:

Drink, with a 10%-gum syrup	Gum in the drink	Thicker than water by about	Against the ~8% threshold
A 3 oz stirred cocktail	about 1%	23%	Well over
An 8 oz coffee	0.4%	9%	At it
A 12 oz iced coffee	0.3%	7%	At it

So gomme plausibly earns its trouble in a three-ounce drink. In a coffee it lands right at the edge of what wine tasters could feel, which is too close to call either way. This is weak evidence: an estimate across two papers, a threshold measured in white wine, and a straight-line scaling of viscosity that is only roughly true at these strengths. No one has tasted it.

The rule to know. The federal regulation limits gum arabic to a percentage of the food “as served.” Soft drinks get 2%. Coffee and syrups are not named, and on a plain reading fall under “all other food categories,” at 1%. The 1862 recipe, used with a heavy hand in a small drink, would go over that. A modern 10% gomme in a cup of coffee would not come near it. No regulator has said which row applies to a coffee drink, so the 1% row is a plain reading, not a ruling.

Side by side: which to use where

For	Use	Why
Iced coffee, cold brew, a flash-brewed pour-over	Simple or rich syrup, nothing added	Sugar is doing the work. Neither additive can be felt at this dilution.
A honey coffee	Honey syrup, mixed on the day	Honey is the point, and it brings its own body
A small, strong drink: a cocktail, or a phin coffee served short	Gomme, if you want to feel it	Enough gum reaches the mouth to register
A spirit-forward cocktail, quickly	Glycerine syrup, pending the triangle test	Ten seconds’ work; the evidence for it is thin
Anything sold in a bottle	Sugar and water only	The shortest label, and no cottage food route exists for syrups anyway

Where these go: the add-ins they sit beside are on Additions; iced coffee and cold brew on Iced Coffee and Ice; the stall’s menu on The Drinks.

What is not known

• Any tasting study of glycerine or gum arabic in coffee, in cocktails or in soft drinks. Every threshold here is from white wine.
• A measured shelf life for a syrup with glycerine in it. The water-activity figures are calculated.
• Why Monin puts glycerine in some syrups and not others.
• Which row of the federal gum arabic limit covers a coffee drink.
• Anything published on what either does to espresso crema or milk foam.

Sources

• European Food Safety Authority, re-evaluation of glycerol (E 422), 2017, and of acacia gum (E 414), 2017; its 2026 opinion on glycerol in beverages.
• 21 CFR 182.1320 (glycerin) and 21 CFR 184.1330 (acacia), 2024 edition; 21 CFR 101.4 on listing ingredients.
• Noble and Bursick, “The Contribution of Glycerol to Perceived Viscosity and Sweetness in White Wine,” American Journal of Enology and Viticulture, 1984; Nurgel and Pickering, Journal of Texture Studies, 2005; Gawel, Van Sluyter and Waters, Australian Journal of Grape and Wine Research, 2007.
• Segur and Oberstar, “Viscosity of Glycerol and Its Aqueous Solutions,” Industrial and Engineering Chemistry, 1951; Nordzucker, The Functional Properties of Sugar, 2020, for sugar’s viscosity and water activity.
• UK government, “Glycerol in slush ice drinks,” July 2025.
• Sanchez and others, Food Hydrocolloids, 2002, for the viscosity of acacia gum.
• Christian Schultz’s manual in Jerry Thomas, How to Mix Drinks, 1862; Difford’s Guide on gomme.
• Michigan Department of Agriculture and Rural Development, cottage food list.
• Monin’s and Torani’s own product pages for the ingredient lists, and two sellers’ pages for prices, read 2 October 2026; Barista Underground’s Torani pump listing for the pump volume.
• The dilution tables and the cost and water-activity figures are worked out from those sources.