How to can maple syrup

In this brief guide, we will answer the question “how to can maple syrup?” with an in-depth analysis of the proper canning process of maple syrup. Moreover, we will also discuss the signs of spoiled maple syrup.

How to can maple syrup?

Traditionally, maple syrup is typically canned at a temperature within the range of 99°C to 103°C. This temperature is achieved by either directly using the evaporator or the finishing pan.

Alternatively, if the syrup has been stored before canning, it is reheated to a minimum temperature of 82°C prior to immediate canning.

After being filled, the containers of maple syrup naturally cool down. To ensure that the headspace and closure are sterilized, the container is either inverted or laid on its side. (1)

Conventional canning refers to a widely used food preservation method that involves placing food in tightly sealed containers and subjecting it to heat to eliminate microorganisms. 

The primary goal of applying heat is to destroy harmful pathogens and prevent the growth of spoilage microorganisms, while the sealed container acts as a barrier against new microbial contamination.

While metal containers are commonly used in this process, there are also alternative options available, including glass jars, plastic cans, and retort pouches. 

The intensity of heat applied to a particular food depends on various factors such as the acidity level of the processed food, its density, composition, heat transfer resistance and the heat resistance of target microorganisms. 

Initial microbial load, type of container, heating medium, equipment, and processing techniques, among others are also important factors.(2)

What is the canning equipment?

Conventional canning utilizes various types of sterilizers, including both batch and continuous systems. In batch retorts, cans are loaded into crates and placed inside the retort for heat treatment before being unloaded.

On the other hand, continuous retorts involve the automated and continuous movement of filled and sealed containers from ambient conditions to a pressurized steam environment. 

They remain in the pressurized environment for the required process time and are then transferred back to ambient conditions for further handling.

In terms of syrup production, it’s worth noting that batch boiling tends to result in darker and more robust syrup compared to continuous flow boiling. 

If your intention is to produce lighter and more delicately flavored syrup, a continuous flow method may be preferable for you to consider. (1, 2)

How to store maple syrup?

For optimal storage of unopened maple syrup, it is recommended to keep the bottle in a dry, dark, and cool area, away from heat sources like sunlight and stovetops. While refrigeration is not mandatory, it is advisable to refrigerate unopened syrup to enhance its preservation.

Once opened, it is essential to seal the bottle tightly and refrigerate it at all times. Unlike certain commercial syrups, natural maple syrup does not contain added preservatives, necessitating refrigeration to maintain its freshness.

If you intend to prolong the shelf life of maple syrup, freezing can be an effective method of preservation.  (1)

Is it safe to consume expired maple syrup?

No, consuming expired maple syrup can indeed result in food poisoning and present various health risks. 

Symptoms of food poisoning may manifest as headaches, vomiting, stomachaches, diarrhea, loss of appetite, and feelings of nausea. 

Typically, these symptoms subside within a day or two. However, if they persist beyond this timeframe, seeking medical attention is crucial.

To safeguard your health, it is vital to be vigilant for any signs of spoilage, such as an unusual smell or discoloration, as they indicate that the syrup has degraded and should not be consumed. 

If you observe mold growth in the maple syrup, it is advisable to promptly dispose of it to prevent potential health hazards.(3, 4)

How long does maple syrup remain good once opened?

According to the experts, maple syrup remains good for up to 1 year once opened. But make sure that you stored it correctly. 

Moreover, if you store it at room temperature then automatically its shelf becomes shorter. (5)

What are the signs of maple syrup spoilage?

The primary indicators of maple syrup spoilage include the presence of mold growth, an off odor, and an off taste.

Mold growth on the surface of maple syrup is a clear indication of product defect. While mold spores are resilient to heat, the extensive evaporation process during syrup production generally eliminates fungal contaminants effectively. 

Therefore, the presence of any mold in maple syrup is likely due to improper sanitation, low bottle filling temperature, or inadequate adherence to good manufacturing practices.

Assessing the freshness of maple syrup can be done by giving it a sniff. If you notice an unpleasant aroma, such as a sour or yeasty smell, it is advisable to discard the syrup to maintain its quality.

If the maple syrup does not taste as it should, it is best to discard it for quality reasons. Unpleasant or off flavors may indicate spoilage or degradation of the syrup.

By being vigilant about mold growth, paying attention to odor, and evaluating the taste, you can ensure that the maple syrup you consume is of high quality and enjoyable.

Spoilage can result from physical contaminants like minerals, wood chips, dust, or ash, as well as microbial factors such as yeast and fungi. It’s important to note that maple syrup does not have a specific expiration date.

Contamination, whether from physical or microbial sources, can lead to various forms of defective sap, resulting in lower quality syrup. Fungi can contaminate syrup regardless of its sugar content.

Failure to properly sterilize containers can also lead to bacterial or fungal contamination, which can impact the syrup’s chemistry, resulting in changes to its color and/or flavor.(1, 6)

Other FAQs about Maple Syrup that you may be interested in.

How to store maple syrup

Substituting maple syrup for honey

Can maple syrup go in the fridge?


In this brief guide, we answered the question “how to can maple syrup ?” with an in-depth analysis of the proper canning process of maple syrup. Moreover, we discussed the signs of spoiled maple syrup.


  1. Mary Lynn Whalen and Maria Franca Morselli. Fungi Associated with Pure Maple Syrup Packed at the Minimum Recommended Reheating Temperature. Journal of Food Protection,47, 688-689, 1984.
  2. Vergara-Balderas, F. T. Canning: Process of Canning. Encyclopedia of Food and Health, 628–632. 2016.
  3. BM Lund, SJ O’Brien, Public Health Measures: Food Safety in Hospitals and Other Healthcare Settings, Encyclopedia of Food Safety, Academic Press, 2014, 140-148.
  4. Food Safety
  5. U.S. Department of Agriculture. Website. Washington, DC. How long can you keep maple syrup?.
  6. Perry Jennifer J. A Comprehensive Review of Maple Sap Microbiota and Its Effect on Maple Syrup Quality. Food Reviews International 38, 2022.