Work in progress!
This page is a journal of our maple sugar production. It details some of the decisions behind the upgrades we make throughout the years.
|2021||77L||30+60||RO and gravity lines||Syrup not concentrated enough for many batches.|
|2022||90L||30+105||Electric Evaporator!||Syrup properly concentrated|
When COVID hit Québec, we retreated to the woods. It was the end of winter and the forest was clear. Trees still had no leaves and at least one meter of snow covered the entire forest. This highlighted the bizarre blue tubes which connect the maple trees together. During maple sugar season, we could also see clouds of vapor coming out of the commercial sugar shacks. I was getting curious. How do they do it?
In Québec, everyone knows the basic recipe for maple syrup: collect maple sap and boil until concentrated enough. It seemed simple enough so we naively decided to try it.
To start the first year, we initially tapped 2-3 trees. We had no equipment so I improvised and made a couple of wooden sprouts. They were 5cm wood straws. Made by drilling a hole through a small wood cylinder carved from a branch. Then we drilled a hole in a maple tree and wedged the wood sprout with a hammer. It instantly started to drip and that's the moment when my addiction started.
At the time, we had no idea how much sap was required. It made sense to test using empty yogurt containers as sap buckets. At first we boiled on the electric kitchen stove (don't do that!). Later learned the ratio is insane: around 40L of sap for 1L of syrup.
We ended up buying a few dozen 3 gallon plastic buckets and sprouts later in the season. And boiled on a propane turkey blaster. To insulate the boiler from wind, a small hobo tent was built with tarp.
Someone asked me why it was important to have covers on the buckets. They are required because snow, rain, insects, dirty water dripping from trees and any contaminant should not mix with the sap (even if we filter the sap water later).
If you are interested in beginner instructions for backyard maple sugar production, this guide from University of New Hampshire is a great summary in the form of bullet points.
That year, in 2020, we got around 10L of syrup. Most of it was not concentrated enough but still tasted really good. Much better than store bought syrup. I was really hoping this wasn't just luck.
To prepare for the 2021 season, I read and learned a lot on the best practices of maple sugar production. I really wanted to optimize yield without damaging the trees and without having to spend too much money. Unfortunately, there is not a lot of information online that is scientifically proven. Even research papers are doubtful sometimes, especially when the tree populations is small and only a single site is being used to experiment. Also, there is a lot of misinformation when sources are word to mouth, online forums and blog posts. This is not optimal but at least it makes it more fun because you have to experiment!
With that being said, some techniques make sense and people have proven they work. The techniques selected to optimize our 2021 production aim to produce more syrup, while lowering manual labor and boiling time. The upgrades were major: gravity lines, reverse osmosis system and cardboard sugar shack.
Initially, we only had 30 buckets, which required a daily 45 minute walk for sap collection. We wanted to produce more but with a full time job, it is too much work for me to collect more buckets. That's the main reasons why we setup sap collection lines: they collect sap directly into a reservoir next to the boiler.
Maple sap lines use flexible plastic tubing and there are two main techniques to consider: pump or gravity. The pump method requires a vacuum pump and tubes of diameter 5/16 (sometimes more). The vacuum pump sucks the sap out of the trees. The gravity method chooses a smaller diameter tubing 3/16″ and a longer "tail" for each line of 20-30 taps (sometimes 5/16″ or more if 50+ taps per line). In theory, gravity helps produce a natural vacuum in the tube when it is full of sap. Since we have a limited budget, and we are in a mountain, gravity was chosen.
We setup 3 gravity lines. Each line has 18 to 28 taps. The installation tools cost 250$ and the rest was another 200$ for all tubing, sprouts and adapters. Sprouts are replaced each year (0.30$ each) but the tubes can stay on for 5 to 10 years. In comparison, plastic buckets with cover and sprouts are around 8$ each.
At the end of the season, we had around 90 taps total. This means 90 holes in the trees (the larger trees have up to 3 taps since they have never been tapped before). That is a lot of sap! I estimate 2500L in 2021.
2500L of water takes a lot of energy to evaporate, especially outside, in -10 to 10°C weather. Traditionally, for this quantity of sap, small producers would use larger evaporators. One would cost 4000$ or more and fuel is not included. Instead, I chose to go with a modern technique which extracts water from the maple sap. Reverse osmosis (RO) systems are extremely popular. Millions of homes use them to filter clean water from dirty or hard water wells. Water treatment plants use RO systems to produce clean water.
This happened 1 year before maple sugaring equipment CDL and others started selling small hobby reverse osmosis systems, like CDL's Nano RO which you can see in the following diagram).
Diagram source: CDL Nano RO manual pdf
The RO system applies high pressure to an input solution and forces water molecules to go through a semipermeable membrane. Only water molecules (almost) go through this type of membrane. As seen in the diagram, the outputs of the system are 1) "pure" water (permeate or RO water) and 2) concentrate. The concentrate is the leftover solution which could not go through the membrane and lost water, so it is more concentrated than the input sap. Typically, it is the permeate water output that is kept for residential RO water purification. For maple syrup production, it is actually the concentrate that we care about since it is concentrated maple sap.
Sap coming out of the tree is concentrated sugar at 1% to 4% depending on the tree size, vigor, species (sugar maple or red maple), weather, time in the season and many more variables. Concentration with a small RO system can easily make the sap reach 8% (with 2 or 3 concentrating passes). That might not seem to be a lot but going from 4% to 8% means half of the water content is removed. Which means half less boiling time! When you think about this, it makes a lot more sense to get a RO system before a larger evaporator.
Commercial producers using high end systems to concentrate the sap up to 50% (maple sugar is 66%)! Scientific studies show that concentrating higher than 16% affects the taste (TODO reference paper from Centre Acer). I did my own experiments and no one can notica a taste difference when concentrating to 8%, which is the maximum our system can reach.
I searched how people setup commercial RO, residential RO, and even contacted beverage machine providers to get price lists and catalogs to design my maple RO system. In the end, the cheapest system I came up with was built out of residential RO parts. It was composed of five "400 GPD" membranes, connected in series (which actually puts the membranes in parallel, so each has the same pressure) and a strong booster pump. Then I discovered that an american website sells almost the exact kit I designed, but cheaper than buying individual parts: RO bucket. Paid around 700$ for the kit iirc.
I approximate the system removed approximately 1500L of water in 2021, which reduced the total boiling time (and boiling fuel) in half.
My father built a temporary sugar shack to protect the propane boiler from the wind. Made out of reused commercial refrigerator crates. Strong cardboard walled box, reinforced with flimsy wood pieces. It did the job and kept the heat inside. Probably significantly lowered propane costs boiling time.
In 2021 we made 77L but many batches were significantly not boiled enough. I believe we should have made around 60L that year. The taste is still as good as the first year.