Making maple syrup is a time-honored tradition in many parts of Wisconsin, and it is as much of an art as a science. Even though sap does run in other trees such as birch and elm in early spring, maples produce more and sweeter sap than any other tree.
Collection. Once trees are tapped, a collecting container is placed at the site to catch the sap as it flows. A major goal in maple production is to gather and process the sap as quickly as possible. To minimize microbial growth, particularly during warm periods, sap should normally spend no more than a few hours in the collecting container. Sap is collected in special metal buckets or, increasingly, via a plastic tubing system.
Evaporation. Once the sap is collected, it is boiled to remove water and concentrate the syrup. During the evaporation process, sap is concentrated to the desired density and flavor, and color develops as a result of chemical reactions that occur during heating. The extent and character of the color and flavor are determined, in part, by the length of time the sap is boiled. The longer the sap is boiled, the darker it becomes and the stronger the flavor. Making light-colored syrup requires a short evaporation time. Anything that slows the evaporation process (uneven fire, weak fire, excessive sap depth in evaporator, etc.) will produce darker, usually stronger-flavored syrup. It may take 43 or more gallons of sap to produce one gallon of syrup! There is an International Grading System for Pure Maple Syrup; check it out as your guide to buying maple syrup anywhere in the world.
Bottling. Once maple sap has been processed into maple syrup and the correct density is obtained, the syrup is ready for filtering and packing. Syrup is best filtered while it is still hot (185° to 190°F) for rapid removal of sediment. To prevent contamination of finished syrup by yeast or mold growth, finished syrup should be hot packed. Syrup can be hot-packed into large drums or cans, or into retail/ home-sized containers. Regardless of the type of container, syrup should be packed into cleaned and sanitized containers. Small containers can be sanitized by boiling for 10 minutes in water. Because filling into any kind of container, sterilized or not, may cause contamination, containers hot-filled with syrup should be inverted immediately for 1-2 minutes after being hot-filled and sealed. Turn filled containers right-side-up to cool.
Storage. Pure maple syrup should be kept in a cool, dark place; for a quality product, be sure to use within 2 years. Refrigerate after opening. If excess water is present or if containers are not clean when filled, there may be the growth of bacteria, yeast or mold during storage. If spoilage develops, discard the product. For maximum flavor, bring maple syrup to room temperature or warm it before serving.
The North American Maple Syrup Producers Manual is available for purchase from Ohio State University. Other resources:
- How to Tap Maple Trees and Make Maple Syrup (University of Maine)
- Maple Syrup Best Management Practices (University of Massachusetts)
- Focus on Food Safety When Making Maple Syrup (handout)
- International Grade Standards for Maple Syrup (handout)
Enjoy! And stay food-safe. Barb
Published on April 14, 2021
If you have been scrolling the internet of late you might have noticed that some companies are touting the reported health benefits of drinking tree sap. Some ads suggest that drinking tree sap or ‘tree water’ is a natural way to hydrate. Regardless of whether drinking tree sap is a ‘natural way to hydrate’, canning tree sap or tree water at home is decidedly unsafe.
Tree sap is not naturally acidic. Whether tree sap is sourced from sugar maple (the most popular source) or other tree species, the pH of tree sap may be over 5.0. This means that canning tree sap at home may create a risk of botulism poisoning. Botulism toxin may develop in a low-acid food (pH over 4.6) that is canned using a boiling water canner or an atmospheric stream canner, heat processing steps that are commonly used by home canners processing maple syrup.
Why is maple syrup different from maple sap? Many people know that maple syrup comes from the sap of the sugar maple tree, collected and boiled down each spring to make it denser. The ‘rule of thumb’ is that it takes 43 gallons of sap (with 2 percent sugar content) boiled down to make a gallon of maple syrup. Since sugar content of the sap can vary by tree, and previous season growing conditions, it may require from 40 to 50 gallons, or more, for a gallon of syrup.
From a food safety standpoint, the key difference between maple sap and maple syrup is the sugar content. As maple sap is boiled and concentrated, water is removed and the natural sugars are concentrated in the final product. Maple syrup is 65% sugar content, or higher. The high sugar content provides a measure of safety and ensures that the spores of Clostridium botulinum will not grow in the product as it sits on the shelf.
How is it possible for a beverage company to sell packaged map sap? While there are no safe, research-tested recipes for consumers who might wish to can maple sap at home, large manufacturers have access to special equipment that may allow these companies to safely manufacture tree sap for sale.
Beverage manufacturers increasingly use aseptic processing and packaging to manufacture shelf-stable, low-acid products. Aseptic processes typically heat beverages to 280 degrees F for a few seconds, followed by rapid cooling and packaging. In addition to maple sap, other beverages that may be heated and packaged using aseptic technology are shelf-stable milks, sports beverages, and coffee beverages.
Is there any way to safely preserve maple sap at home? Consumers who wish to preserve maple sap to enjoy at home should consider freezing. Freezing is an often overlooked method of home food preservation that will keep foods and drinks safe almost indefinitely.
To freeze maple sap for later use, package in food-safe freezer bags or containers, removing as much air as possible to protect flavor and quality. Freeze no more than 2 to 3 gallons of maple sap at any one time. Alternately, freeze maple sap in ice cube trays. Once frozen, remove sap ‘cubes’ from trays and store in freezer bags, using the empty trays to freeze more product.
Kept refrigerated, map sap should last for 2 to 3 weeks without spoiling. If signs of spoilage such as mold or yeast growth, bubbling or changes in color are noticed, map sap should be discarded.
Resources for tapping maple trees to produce sap or syrup are available.
- Maple Syrup Production for the Beginners (Penn State)
- Maple Sugaring Tips for Beginners and Backyard Maple Sugar Producers (Univ of New Hampshire)
Stay well and food-safe, Barb