Backsweetening – When Dry Won’t Do

The beauty of yeast is that they typically are very good at what they do. Give a yeast some sugar and hospitable conditions for growth and they will turn that sugar into booze… ALL of it. This is fine and dandy as booze is our desired endpoint and too much sugar is bad for us anyway 😉

Brown sugar, white sugar and honey

What happens when you want a bit of sweetness left in your product? Not everyone enjoys a dry wine and many meads explode with flavour when a bit of residual sweetness remains. The main criticisms of many of my meads is that they are too dry. I’ve been known to add a little honey or agave syrup (it dissolves MUCH easier than honey) to the glass of my most critical friends. It’s true, a little sweetness really does open up the flavour, especially in mead containing fruit or spices.

While this method works, it is poor science and an extra step before consumption. This trick will also not win you any awards at brewing competitions. Enter backsweetening: the process of adding additional sugars once fermentation is complete, just before bottling.

The trick here is to ensure that no further yeast activity is possible or you will end up with “cork bullets” or “bottle bombs.” This can be dangerous and it’s a terrible waste of good alcohol. The addition of potassium metabisulphite will kill most of the yeast and therefore stop fermentation. There is a huge literature on the amount of sulphite to use but in general I shoot for 50mg/L before backsweetening. When mixing in the sulphite try not to introduce air as the sulphite will be inactivated by oxygen.

It is important to note some that live yeast may still be present after sulphite addition. Sorbate is typically used in concert with sodium metabisulphite to ensure that any yeast cells that remain are not able to reproduce. Adding potassium sorbate to water results in sorbic acid which inhibits yeast reproduction. Sorbate can effectively prevent yeast reproduction at a concentration as low as 0.01-0.2%, depending on other conditions such as pH, temperature and the presence of oxygen. It is typically recommended to use potassium sorbate at 0.2g/L.

After adding these inhibitors, wait a day for them to do their job, then additional sugar can be safely added. Popular choices for sweetner include granulated sugar, corn sugar (dextrose), brown sugar (for that rich molasses flavour), fruit juices and honey. Of course the AMOUNT to add is according to personal preference.

It is a useful experiment to create a concentrated solution of whatever sugar you intend to use and then make a serial dilution with water. These sugar solutions can then be tasted (in order of increasing sugar) and notes can be made on sweetness which can then be applied to backsweetening.

Backsweetening - White Sugar

PreparationSugar ConcentrationTaste
25g sugar made up to 250mL water100g/LI think my teeth are melting!
100mL of 100g/L + 100mL water50g/LCare for a glass of diabetes? This will be too much for most people, I but I won't judge...
100mL of 50g/L + 100mL water25g/LThis results in a definite "sweet" product, there's no mistaking it but it's not offensive.
100mL of 25g/L + 100mL water12.5g/LDefinitely sweet, but not overpowering. This is my go-to concentration for mead.
100mL of 12.5g/L + 100mL water6.25g/LBarley perceptible sweetness - just enough to take the edge off.

Simply multiply the desired concentration by the volume of brew to be sweetened and add it. Although the other flavours present will have an effect on the perception of the sweetness, your experimental taste should be pretty close.

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