Tuesday, February 19, 2013

Eating Valley Oak Acorns

Valley Oak A-corn Bread
Spread upon a large cookie sheet, the Valley Oak (Quercus lobata) acorns that I collected last month are a constant temptation. The acorns are just so big! Even though I usually dry my acorns completely before shelling them, I wanted to share the process with some college friends that were visiting, so we shelled a pint that were not yet dry, and cooked up my first batch of Valley Oak acorn bread.

This (left) Valley Oak acorn split itself open as it sprouted
Valley Oak acorns sprout in the late fall and if given the chance, will rapidly send a tap root deep into the ground. Most of the acorns I collected last month had just started to sprout, and several of the shells were split along their entire length from the vital force of the growing nutmeat. A few acorns even escaped their shells completely! Late season harvesting has advantages since only healthy (weevil free) acorns will sprout, and expansion-fractured shells are a cinch to remove by hand. However, on low mast years, all the late season acorns might already be cached by the squirrels.

Partially dried Valley Oak acorns
Acorns that haven’t hatched themselves out of their shell can still be easily processed if the nuts are completely dry. Acorn nutmeat shrinks by up to about 10 percent as it dries, and the shells become brittle, allowing them to crack easily. If you shake an acorn that is sufficiently dry, you should be able to feel the nutmeat rattle inside of the shell. Hurried by temptation, I struggled to remove the shells from the acorns that were still fresh, but hadn’t split themselves open. Using a nutcracker was like trying to crack open a gummy bear, because both shell and nutmeat were still soft, so I finally resorted to slicing open the shells with a paring knife. The nutmeat came out of the shell free from the bitter brown seed coat, which clings to other species such as Black Oak (Quercus kelloggii).

Shelled acorns ready to blend into flour
Some species of acorns (like Garry Oak) oxidize rapidly when shelled fresh, but my Valley Oak acorns appeared to be amazingly stable. I put 2 cups of shelled acorns into a Vita-mix with 2 cups of water, and blended them into a fine flour batter. Then I poured the batter into a gallon sized mason jar and filled it with water, which I changed every day for several days (for more information about this process, see How to Eat an Acorn). After 3 days the batter was only slightly astringent, and after 5 days, it was almost completely free of all bitter/astringent constituents. Katrina used the batter to make her a-corn bread recipe, which turned out amazingly delicious- almost like a butterscotch brownie! Of all the cold-leached acorns I have tried, they are among my favorite, perhaps second only to Garry Oak acorns. Valley Oak acorns are actually less bitter than Garry Oak acorns, but also slightly less flavorful.

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Sunday, February 3, 2013

Bigleaf Maple Syrup

Home-made Bigleaf Maple syrup
When I was nine years old I ravenously read the Laura Ingles Wilder books and was quickly enamored by the pioneer lifestyle of the Ingles family, especially the stories about Laura’s early life in the Wisconsin woods, and Almanzo’s life in the forests of New York. One day, after reading about how Almanzo helped his father collect and boil maple sap to make maple sugar and maple syrup, I decided to try and make some of my own. We had a large wooded lot next to our house and I knew that there were several Vine Maples (Acer circinatum). The Vine maples were memorable because we used to climb up the trees until they bent down to the ground; like giant springs, the bent Vine Maple stems amplified our jumps, and launched us 10 feet or more off the ground. Without any instructions beyond Wilder’s anecdotes, I improvised my own sap collection system from an empty tin can nailed to a tree. To try and induce sap flow, I cut a small “V” in the bark above the pail. The days that followed were filled with anticipation, and ultimately disappointment, as my tap didn’t even yield a drop.

It wasn’t until I moved to Wisconsin for college, almost 10 years later, that I actually talked with someone who made maple syrup. Sugar Maple (Acer saccharum) and Red Maple (Acer rubrum) are most commonly tapped, but several other species of maple as well as birch, walnut, and hickory can also be used. I learned that my Vine Maple experiment failed because I improperly tapped the tree, at the wrong time of the year. Rather than cutting a “V” in the bark, I should have drilled a small hole 1-2 inches into the sap wood (xylem). Sap runs when the trees are leafless and the temperature swings above freezing during the day and below freezing at night. My major professor and best friend both had small sugar bush operations, but the timing never worked out for me to help them out and experience the process first hand.

When I moved to Victoria for my master’s degree, I started hearing about a festival and network of hobbyists and businesses on Vancouver Island that were focused on producing sap from our native Bigleaf Maple (Acer macrophyllum). Once again, a busy student schedule made it impossible to attend their events, but Katrina ordered a wonderful book on the subject called “Bigleaf Sugaring: Tapping the Western Maple” by two of the core members, Gary and Katherine Backlund. Here in Washington, Dr. Terry Maresca is also promoting Bigleaf Maple tapping; last summer, with school behind me, I made a point of attending her workshop at the Northwest Indian College Traditional Food Conference on Bainbridge Island.

Armed with good literature and hands-on instructions, I wasn’t about to let this winter pass without tapping a few Bigleaf Maples, so I ordered a dozen stainless steel taps, purchased some food grade plastic tubing, and started hording large empty water jugs from the neighbors' recycling.

Bigleaf Maple taps at Dad's house
In early December, I tapped a few stems on a large clustered Bigleaf Maple next to Dad’s house. Using a 5/16” drill bit, I bored 2 inch long holes at a slightly upward sloping angle into trees about 2 feet from the ground. My taps taper to an outside diameter of 5/16, so when I gently pounded them in, they fit snugly. To each tap I connected plastic tubing that allowed the sap to flow downwards to a "T" fitting, and then into a large receptacle at the base of the tree.

3 gallons of Bigleaf Maple sap
Theoretically, when the temperature and barometric pressure are adequate, sap flows up from the roots through long hollow xylem cells, to the branches and developing buds. Like a pin prick on a finger, the xylem cells, bisected by the drill, bleed sap until those living tissues heal, at which point a new hole must be drilled. Throughout December, our taps yielded only a few cups per week but during a stretch of cold nights and warm sunny days in mid January, sap production increased dramatically peaking with about 13 gallons of sap produced from 3 trees in about 3 days. According to the Backlunds, Bigleaf Maples in the Pacific Northwest can produce sap for 5 months from November until February, which is much longer than the 6 week season that is common for maples in the Northeastern woodlands.

Testing the specific gravity of Bigleaf Maple sap
The time had finally come to figure out how I was going to boil the sap down into syrup. Bigleaf Maple sap is only about 2-4% sugar with the remaining 98-96% being water. In order to produce syrup, the water must be evaporated off until the sugar concentration is about 66%. Small batches can be evaporated on a stove top, but high energy costs quickly make this method impractical.

The solution is to burn wood, which is practically free for the taking for anyone living in the Pacific Northwest that has a strong back and a little forest land. Traditionally, a large cast iron cauldron is suspended over a fire and sap is added as it is collected until the season ends and the syrup is “finished.” Open fires are notoriously inefficient and impart (for better or worse) a smoky flavor on the sap. Today, most people that make syrup use an evaporator that is made up of a steel firebox, and a stainless steel evaporating tray with a maze of chambers that allows for a continuous feed of sap in one end, and finished (or nearly finished) syrup out the other end. New to this enterprise, my evaporator is somewhere in between. I employed the same old rusty stove—salvaged from a sunken ship—that Katrina uses for making salt and simmered my sap in a 5 gallon pot placed on top of the stove.

My small sugar shack
Here in the Pacific Northwest where our winters are pretty soggy I needed to make sure that my open pot wouldn’t fill up with rainwater faster than I could evaporate it off, so Dad and I built the world’s smallest sugar shack (3’x4’) out of salvaged roofing and scrap lumber. With stove inside the sugar shack, I managed to reduce 5 gallons of sap into syrup, but it took an entire day. Commercial units boast evaporation rates an order of magnitude faster, so I set out to make some improvements.

Trying to evaporate sap on a stove
The problem with my stove is that the surface that is supposed to be conducting heat into my pan is ¼" steel, and the walls, which are supposed to be insulating the heat and forcing it upwards into my pan, are thin, rusted, and riddled with holes. A roaring fire wasn’t even sufficient to keep the sap boiling, so my sap evaporated leisurely, like a warm bath. To mitigate for the shortcomings of my stove, I replaced my large kettle with a stainless steel steam table tray (like the trays used at buffets), which has a larger surface area on the bottom, and when only filled partially with sap, managed to produce a gentle simmer. 

The improved evaporator
A nice boil
Still not satisfied, I decided it was time to modify the stove itself. My friend Ric helped me cut away a square section of the stove top with his oxy-acetylene torch to allow the steam tray table to nest inside the stove and come into direct contact with fire. The new setup is vastly superior; I can easily maintain a vigorous boil and I have increased my evaporation time three-fold.


Filtering warm sap that is ready to be finished
One of the tips that Terry shared with me was to reduce the sap to about 50% sugar in small batches as you collect it, and then store it in the freezer until you have several quarts. Terry likes to finish her syrup in larger batches, because the finishing process demands constant attention to ensure that you don’t drive off too much water and scorch the syrup. After three days reducing 4-5 gallons each day, I was eager to taste some syrup and decided I had enough condensed sap to finish.

Finishing the sap on an electric range
There are several ways to finish syrup, but as far as I can tell, the most important thing is that you have the ability to take your syrup off the heat source once the sugar concentration is 66-68%. Syrup above that concentration will crystallize into sugar, and below that, it is prone to molding. I finished my syrup in a large saucepan on our electric stove-top and monitored the sugar concentration with a thermometer. The boiling temperature of finished sap at sea level is about 219° F, and after about an hour of constant monitoring my syrup was finished. I poured it immediately into sterilized mason jars and screwed the lids on tightly.

My 13 gallons of Bigleaf Maple sap yielded about 1.75 quarts of syrup, which is a little better than a 30 to 1 ratio of syrup to sap (and means that sugar concentration in my sap was a little above 3%). While this doesn’t sound like a lot, it is on par with sap from Sugar Maples. The taste of my maple syrup is superb. Too bad it took me 24 years to figure out how to make it!
My first batch of Bigleaf Maple syrup

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