We're working on the most sour hard candy on earth. Here's the basic recipe: 2 cups sugar, 1/2 cup of water, 1/4 cup corn syrup, 3.2ml flavor (one small Lorann drum). Once the composition gets to 300F we take it of the stove, transfer into a cold container, quickly mix in 1-3 teaspoon of citric acid and pour it over a plastic mold.

The problem we're having is that the more citric acid we add to it will make it softer. Is there a way to compensate for the additional citric acid by mixing in something else? (more sugar, corn syrup perhaps?).

It'd appreciate if somebody can explain the chemistry behind the binding of sugar and citric acid.

  • 1
    I think there is a reason why sour candy is made into gummies.
    – Escoce
    Feb 15, 2016 at 15:05

2 Answers 2


You are breaking the sugar into fructose and glucose, getting invert syrup

I'd suggest making the sugar base and then adding fine powder or dissolved acid with rapid cooling to stop the hydrolysis.

Or use a paste of fine citric acid with some oil to slow down dissolving of the acid.

You can also try to use mechanical mixing like extruder screw or rolls to keep the water contents lower and better control heating.

Also note that your candies can turn soft and sticky over time.

  • For the citric acid paste, do you mean mixing citric acid powder with say canola oil? Would I add the mix after it reaches the hard crack temperature point (300F) as it cools down?
    – Fabian
    Feb 15, 2016 at 20:41
  • Hit Enter too soon. Will adding more sugar or corn syrup compensate for the citric acid addition? Thanks Eugene!
    – Fabian
    Feb 15, 2016 at 20:42
  • Yes, to cover citric acid crystals with hydrophobic coating. When adding - the colder the better, less acid will dissolve. Feb 15, 2016 at 21:35
  • Starch may help to some extent, but it's prone to acid hydrolysis too, it just goes slower due to lower solubility and longer chain of monosaccharides. And it gives maltose and gluscose, which are less sweet than fructose and sugar. Feb 15, 2016 at 21:43
  • And would monocrystalline citric acid be the most sour hard candy on earth? (Without any additions, just recrystallise, calibrate and pack it) Feb 15, 2016 at 21:50

I have noticed that candy makers add citric acid after the syrup is poured onto the cooling table and it's cooled somewhat. I know of one person who will combine citric acid with sugar crystals and sprinkle that on the outside of her candy apple. But, most hard candy has citric acid added. I am guessing that it is added as it is cooled and being creamed or stretched. For liquid syrups being poured into molds, I don't know when to add it. Help!!!

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