Tracking Sugar Content of a Cider

Most homemade ciders, unless specially handled, ferment out completely and contain very little residual sugars. This is because apple juice mainly contains fermentable sugars (fructose, sucrose, and glucose), and smaller amounts of non-digestible carbohydrate (e.g., pectin), organic acids, especially malic acid, amino acids, and minerals. This is very different from wort that contains a significant amount of dextrins; while dextrins are not fermentable by yeast, they are digestible by humans and contribute carbohydrate calories to beer. It is the lack of non-fermentable sugars that make dry ciders attractive to carbohydrate watchers.

Sweet commercial ciders are different in this regard because they do contain residual sugars. This can be accomplished by arresting fermentation with the addition of sulfite or sorbate, or by pasteurization. It is tempting to stop fermentation through chilling, but this usually does not work and the cider continues fermenting to completion. Other cidermakers allow their cider to fully ferment, stabilize with sulfite or sorbate, and then add sugar or fresh juice; this practice is called back-sweetening.

Measuring the specific gravity of fermented cider, beer, or wine does not provide enough information, even when the specific gravity is less than 1.000, to know if there is residual sugar because there are more than two parts to these solutions. The rule of thumb used by winemakers is to be cautious about bottling wines with a specific gravity greater than ~0.995 because there may be residual sugars that will re-ferment in the bottle. There are colorimetric tests, like the now discontinued Clinitest® urine test kit, that provide more accuracy than hydrometers. For your purpose, however, it is reasonable to consider ciders with final gravities less than 1.000 to be dry and to contain very little, if any, residual, digestible carbohydrates.

I specifically mentioned the Clinitest® test kit because there are many references in the home winemaking literature about this specific kit. There is a replacement kit on the market called the AimTab®. Although these test kits are designed to measure reducing sugars, such as glucose, lactose, fructose, galactose, and pentoses, that may be excreted in urine, a particular concern related to diabetes, the kits are also very handy to run tests on wine and cider. If you are interested in learning more about this method, there is quite a lot of information out on the web.

Dry ciders are becoming more popular as farmhouse cider operations are taking hold throughout apple-producing parts of the U.S. Many of the ciders being produced by the newer operations are more traditional in their approach where arrested fermentation, back-sweetening, and pasteurization methods are less common. The use of bacteria that convert malic acid to lactic acid, in a process known to winemakers as malolactic fermentation or MLF, such as Oenococcus oeni (formerly Leuconostoc oenos) and some Lactobacilli, other yeasts, like Brettanomyces, and barrel-aging in both wine and Bourbon barrels, is adding a whole new dimension to ciders. The dry ciders you want to make are really ideal for these aged types that oftentimes are more similar to white wines than most of the ciders that are served in pubs.

Response by Ashton Lewis.