Can syrup turn into alcohol?

Syrup is a thick, viscous liquid that is made by dissolving sugar in water. It is commonly used as a sweetener or flavoring agent. Some common types of syrup include maple syrup, corn syrup, golden syrup, and molasses. Syrup is high in sugar content, which makes it a potential source for alcohol fermentation under the right conditions. However, the process of turning syrup into alcohol is not straightforward. There are several factors that determine whether syrup can successfully ferment into alcohol.

What is Alcohol Fermentation?

Alcohol fermentation is the process by which sugars are converted into alcohol and carbon dioxide by yeast. For fermentation to occur, yeast needs access to sugars, water, and a low-oxygen environment. Yeast feeds on the sugars and metabolizes them into ethanol and CO2. Ethanol is the intoxicating agent in alcoholic beverages that provides the “buzz”.

For syrup to ferment into alcohol, the right type of yeast must be present. Brewers and vintners use Saccharomyces species of yeast to convert sugars into alcohol. Saccharomyces cerevisiae (ale yeast) and Saccharomyces bayanus (wine yeast) are among the most common yeasts used. The yeast needs to be active and alive to facilitate the chemical conversion.

Sugar Content

One of the most important factors determining whether syrup can turn into alcohol is its sugar content. Yeast requires sugar to live and carry out fermentation.

Most syrups have a very high sugar concentration. For example:

  • Maple syrup is about 66% sugar by weight
  • Honey is around 82% sugar
  • Molasses contains 55-75% sugar

This high sugar content makes syrups a viable starting point for fermentation.

However, extremely thick and viscous syrups may contain too much sugar for yeast to effectively ferment. Very high concentrations of sugars cause high osmotic pressure, which can dehydrate and kill yeast cells before they can turn the sugars into alcohol.

The best syrup candidates for fermentation have a high but not excessive sugar content along with a low enough viscosity to allow active yeast growth. Thinner, free-flowing syrups provide the ideal conditions.

Water Content

Water is crucial for yeast growth and fermentation. Yeast requires water to reproduce, thrive, and metabolize sugars into alcohol.

Most syrups contain relatively low water content since they are concentrated sources of sugar. Maple syrup, for example, is about 34% water. Molasses contains around 31% water.

The low water content makes the syrup environment hypertonic, drawing water out of yeast cells through osmosis. This can limit the yeast’s ability to grow and ferment unless additional water is added.

Before using syrup as a sugar source for fermentation, it is often necessary to dilute it with extra water. The ideal water concentration depends on the type of yeast, but a 1:1 syrup to water ratio provides a good starting point in most cases.


The acidity level of syrup can also impact the ease of fermentation. Yeast prefers a pH between 4-6, with the optimal pH around 5. At very low pH values, yeast growth and fermentation is hindered.

Many syrups fall within yeast’s preferred pH range:

  • Maple syrup has a pH of around 6.4
  • Corn syrup pH is around 5.5
  • Molasses pH ranges from 5.5-6.0

These pH levels allow productive fermentation by brewer’s and wine yeast. However, some syrups are too acidic. For example, sorghum syrup has a pH of 3.5-4.0, below the optimal yeast range. Diluting sorghum syrup with water can raise the pH to make it more fermentable.

Presence of Yeast Inhibitors

Some syrups contain compounds that can inhibit yeast growth and fermentation. For instance, maple syrup contains abscisic acid and phenolic compounds that can slow or stop yeast activity at high concentrations.

Molasses and sorghum syrup also contain small amounts of yeast growth inhibitors. These syrups may require dilution and optimum yeast pitching rates to overcome the inhibitors.

On the other hand, corn syrup does not contain significant yeast inhibitors and is readily fermented. Identifying potential inhibitors in the starting syrup can help troubleshoot suboptimal fermentation outcomes.

Presence of Other Microbes

Since syrups are derived from plants and concentrated by evaporation, they harbor populations of bacteria and wild yeast naturally present in the plant source. These resident microbes can compete with the fermenting yeast, lowering alcohol yields.

Heating and acidifying syrup prior to fermentation can help kill off unwanted microorganisms. Maintaining good sanitation and limiting oxygen exposure also gives the fermenting yeast a competitive advantage.

With proper sanitation and yeast pitching practices, the fermenting yeast can usually outcompete bacterial contaminants. But when first starting with an unpasteurized syrup, the presence of other microbes introduces more unpredictability.

Types of Yeast

As mentioned earlier, the choice of yeast strain impacts syrup fermentation. Not all yeast can adequately ferment syrups, especially extremely high sugar and acidic syrups.

Yeast strains used for brewing, wine-making, and distilling ethanol are the best bets for fermenting syrup to alcohol. Some examples include:

  • Champagne yeast: Saccharomyces bayanus
  • Distiller’s yeast: Saccharomyces cerevisiae
  • Wine yeast: Saccharomyces cerevisiae
  • Ale yeast: Saccharomyces cerevisiae

Within these species, individual strains will have slightly different alcohol tolerances and byproduct profiles that can be paired with the desired syrup. Proper yeast selection and pitching rate helps ensure efficient fermentation.

Fermentation Process

If the syrup has suitable sugar content, pH, water activity, and limited inhibitors, the actual fermentation process is similar to other sugar-based ferments. Here is an overview:

  1. Dilute the syrup in water to reach a desired sugar concentration, such as 10-15% sugar by weight. The dilution also helps achieve a favorable pH and minimize osmotic stress on the yeast.
  2. Boil the diluted syrup to sterilize it and drive off any volatile inhibitors.
  3. Cool the syrup and aerate it to introduce oxygen into the solution.
  4. Pitch the selected yeast strain into the cooled syrup. Ale and wine yeast typically need higher pitching rates than bakery yeast.
  5. Maintain the fermentation temperature within the yeast’s preferred range, usually 60-75°F.
  6. As fermentation proceeds, the yeast will convert sugar into CO2 and alcohol. Avoid excessive temperatures, oxygen exposure, and contamination.
  7. Monitor the specific gravity to track the depletion of sugars. Fermentation is complete when the gravity stabilizes.
  8. When done, separate the yeast and allow the fermented syrup “wash” to clarify.
  9. The clarified syrup alcohol can be bottled directly or distilled to concentration the ethanol.

This general process can produce alcoholic ciders and wines from syrups. Taking the additional step of distillation concentrates the alcohol into higher proof spirits.

Results from Syrup Fermentation

Assuming proper conditions, yeast can convert syrups into a range of alcohol concentrations:

  • Fermenting diluted maple syrup can yield 5-8% ABV cider or wine.
  • Molasses can be fermented into 6-12% ABV alcohol depending on sugar content.
  • Corn syrup ferments easily into 10-15% ABV ethanol solutions.

The residual flavors from the source syrup come through in the final fermented alcohol. For example, maple wine has subtle maple notes while molasses spirits have a rum-like flavor.

Distilling the wash to 40% ABV or higher results in a neutral spirit without much flavor carryover. The concentrated alcohol preserves the most volatile aromatic compounds.

Besides ethanol, fermenting syrup also produces other alcohols like propanol, butanol, and amyl alcohol. The yeast strain and fermentation temperature help determine the ratio of different alcohols produced. These give each syrup spirit its own unique characteristics.

Challenges of Syrup Fermentation

While syrups can successfully ferment into alcohol, the process comes with some challenges:

  • The high viscosity and sugar concentration makes dilution essential.
  • Acidity and fermentation inhibitors may need to be controlled.
  • Sanitation is critical given the rich nutritional medium.
  • Fermentation progress needs close monitoring.
  • Distilling is required to obtain high alcohol concentrations.

Additionally, syrup sources vary each season, so their fermentability can change from year to year. Recipes may need adjustment to account for different sugar content, pH, microbiota, etc.

Advantages of Using Syrup

Despite the challenges, there are some advantages to fermenting syrup instead of other sugar sources:

  • No need to add supplementary yeast nutrients
  • Natural flavors carry through into the finished alcohol
  • High yields of alcohol are possible from the dense sugars
  • Variety of syrups allows different taste profiles

Syrup-based ferments are also generally less expensive than grain- or fruit-based alcohols. The process allows creative usage of local syrups.

Legal Considerations

Home fermentation and distillation of syrup for personal use is typically legal in most jurisdictions. However, there are some regulations to keep in mind:

  • Production limits – home distilling usually limited to 100 gallons per year
  • Sale and distribution prohibitions – alcohol requires licensing to sell
  • Taxation – spirits may incur additional taxes when sold commercially
  • Legal drinking age -21 years in the U.S.

It’s advisable to check regional laws before fermenting or distilling syrups to sell as alcoholic beverages. Quality control and safety regulations will apply.


Syrup is a viable starting material for fermenting alcohol at home or commercially. The high innate sugar content of syrups gives yeast ample nutrients to produce ethanol and other alcohols through fermentation. However, syrups need sufficient dilution and proper conditions to allow efficient yeast metabolism. Using brewer’s, wine, or champagne yeasts can yield 5-15% ABV fermented syrup solutions. Distillation can further concentrate the alcohol content. While syrup fermentation comes with some challenges, the resulting maple, corn, or molasses-flavored spirits can be worth the effort.

Leave a Comment