Unsafe to Can Tree Sap at Home

Sugar maple, state tree of Wisconsin

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.

Typical aseptic packing.

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, maple 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, maple sap should be discarded.

Resources for tapping maple trees to produce sap or syrup are available:

Stay well and food-safe!

Authored by: Barb Ingham