I regularly make syrup from herbs (mint, lemon leaf, basil, etc.), usually with the following recipe: 1l water, 500g sugar, boil, let it cool to 70°C, add herbs, let it seep a day, strain it, add lemonic acid + some preservative, boil again and bottle.

What is the role of sugar in this syrup? (I know syrup is sugar + water by definition.) Does it have any role here besides making the liquid sweet? (e.g. flavor extraction, preservation, etc.)

Why I'm asking: I'd like to make a diabetic variant, without sweeteners (can cause digestion problems). Would it work without sugar?

  • Why not just try it? Commented Sep 29, 2022 at 17:57

3 Answers 3


As you said, syrup is sugar with some water and some flavorings, in your case herbs. It is frequently used as a concentrate for flavored drinks.

If you instead boil herbs in water, you are not making syrup, you are making simple herbal tea. So, the consequences will be

  • taste. People enjoy drinking sugared water, and they are OK with a bit of herbal taste in it. If you instead give them diluted tea, they will likely not enjoy it. Tea is much tastier when consumed at full strength. So, you won't have a concentrate, you will have a drink-it-straight liquid.
  • conservation. You will have to find an entirely new recipe, one which is engineered around conserving tea, as opposed to one which is engineered around conserving syrup. And what you do is so unusual, that I highly doubt that such a recipe has been developed. So you will have to can it using unsafe methods.

An exception to the safety problem would be if you acidify it sufficiently to do a water bath canning, but then people will no longer want to chug it from the bottle. They might, or might not, enjoy it after dilution - but it will be a sour drink, unmoderated by sugar, which runs counter to the taste of most people in our culture.

And in the end, the question is why you would go to all that trouble. Tea is easy enough to make on the spot, and tastes better fresh. Why bottle it at all?

  • 9
    The other solution (pun intended) is to add enough alcohol to kill anything. or, even better, distil the herbs with alcohol
    – MD-Tech
    Commented Sep 15, 2022 at 16:15
  • @MD-Tech Another "solution" is oil, although the botulism scare is always an issue for food meant to be consumed cold. Commented Sep 15, 2022 at 19:47
  • Osmotic pressure from sugar water might also be a factor, extracting stuff from the herbs. Not sure how big.
    – Deleted
    Commented Sep 16, 2022 at 18:24
  • It seems intuitive that lowering water activity would make a solution a slightly more non-polar solvent. There is less highly mobile water to go around interfering with dissolution of flavors into the solution.
    – Confused
    Commented Sep 18, 2022 at 7:11

‘Sugar free’ syrups exist, but they usually have some sort of artificial sweetener as a replacement.

Typically they’re sold for flavoring coffee or snow cones.

Besides the sweetness, the sugar gives the liquid viscosity that may be necessary for some applications, and that’s usually replaced with gums or similar. And sugar in sufficiently large amounts is a preservative, as reduces ‘water availability’ for microbial growth.

If you’re not adding a sweetener to your mix, I would probably call it an ‘herbal infusion’ or a ‘tincture’. I suspect that you would need to increase the acidity or make other changes for preservation purposes, but I’ll have to leave that for people with more expertise in the matter. You might also want to use smaller bottles so it’s less likely to spoil before being used up.

  • 3
    Snow cones I think you mean. (Too small an edit for a suggested edit.) Commented Sep 16, 2022 at 1:11

Sugar traditionally is an essential part of sweetener syrup, the reason being that pre-dissolving the sucrose as an aqueous solution makes it much easier to mix into fluids where solid sucrose doesn't as easily dissolve - ie. cold beverages, whipped egg whites and cream, etc. The added flavourings are the optional component.

For food safety, the free water in solution is bound to the sucrose molecules. More sucrose per mass of water means less available water for pathogen metabolism (see chart below for ratios) - a 'water activity' value of 0.92 is generally recognized as inhibiting C. botulinum, and 0.85 for shelf stability where pathogens and most spoilage yeasts and moulds will not grow. These values are for just the effect of water activity, as added acid will also provide inhibitory effects.

Diabetic-friendly sweeteners would not have the same effect on water activity as their usage masses are much lower due to their sweetening powers being significantly, often magnitudes, greater than sucrose - very little sweetener is used with most of the bulk as solubilising aids and anti-caking agents.

Steeping the aromatics in just water alone will yield the equivalent of making a tea with those ingredients.

For mint, lemon leaf, and basil specifically, the aroma compounds are more soluble in an oil or alcohol-based carrier and are usually sold as such. The issue for your scenario would be resolubilizing the compounds in water-based beverages. Some manufacturers will have water-soluble formulations, ie. Amoretti's basil extract: https://amoretti.com/products/basil-extract-ws

Water Activity of Sucrose and NaCl Solutions Water Activity of Sucrose and NaCl Solutions. From: https://ucfoodsafety.ucdavis.edu/sites/g/files/dgvnsk7366/files/inline-files/133655.pdf

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.