2017 Maple and Black Walnut Syrup

Back in January I mentioned that we tapped our black walnut trees this year along with our maples. I've put off posting about the results because we ended up using it for Sunshine's science fair project. The research for her project yielded some interesting info that ran counter to what I'd heard in the past.

Sunshine's exhibit at the science fair last week

the jars are samples of syrup from this year and last

I'd always heard that sugar maples had the highest sugar content and all other trees had less, but that's not actually true. Black walnuts have a similar sugar content to sugar maples and other maples have about half that. Birch trees are commonly tapped in Alaska, but have quite a low sugar content.

It takes about 40 gallons of sap from a black walnut or sugar maple to get 1 gallon of syrup; it takes about 80 gallons of sap from a red or silver maple to get 1 gallon of syrup; and it takes about 100 gallons of birch sap to get 1 gallon of syrup.

maple sap (raw), early walnut sap (boiled down a lot), late walnut sap (boiled down somewhat)

walnut sap darkens as the season progresses

People haven't been tapping black walnuts for very long, so there's not a lot of research available. But what research has been done shows that while black walnut sap has the same sugar content as sugar maple sap, black walnuts produce a third less sap. So black walnuts are a good tapping option, but you need more of them to produce the same amount of syrup. Black walnut syrup has a similar flavor to maple syrup, so it can easily be substituted for maple, or combined with maple to stretch it.

Black walnut sap is also high in pectin (that stuff that helps jams and jellies set up), which becomes evident as you boil the sap and filter it. I kept clogging my filters, and I couldn't figure out where the "crud" was coming from. Now that I know about the pectin, it makes complete sense. So that's an added inconvenience when making black walnut syrup. Not that it will keep us from tapping our black walnuts again- it's just good to know what we're dealing with.

This winter was very mild, so we never got the cold weather we really need to get the sap flowing. As a result, we only collected a very small amount of maple sap. Oddly enough, we collected a decent amount of walnut sap.

Ocean insisted on helping Sunshine with the wheeled bucket as we gathered up the collection buckets and spiles (he's pushing the bucket as Sunshine pulls it).

We're not sure why the black walnut sap was flowing but the maples weren't. Our research also showed that sap flows when the atmospheric pressure inside the maples is greater than the atmospheric pressure outside the tree. The change in pressure is caused by the fluctuation in temperature between nighttime and daytime.

This article about climate changes and their effects on sap quality and quantity doesn't really address the question of why black walnut sap was flowing and maple sap wasn't, but it was still interesting.

2017 syrup
maple:             10 cups of sap boiled down to .09 cups syrup
black walnut:   54.5 cups of sap boiled down to .33 cups syrup
                         23 cups of sap boiled down to .19 cups syrup
            totals:  .09 cup maple syrup and .52 cup black walnut syrup

There should have been more syrup, but we cooked it down too much. Next year we'll be a lot more careful about watching the thermometer and not overcooking our syrups.

2016 syrup
2015 syrup