Snow remained deep in sugar bushes. Maple syrup producers in southwestern, south central and eastern regions of the province had some of the first significant sap flows early last week on Monday and Tuesday, where daytime temperatures reached thawing conditions over several consecutive days. Thawing conditions occurred again on Friday with a brief sap flow, then a Saturday boil. Early areas reported their second or third boil of the 2014 season. Light and medium colour grades are reported having a slightly stronger quality maple flavour. The long-awaited thaws enabled producers in mid-season areas to continue drilling tap holes and installing taps. Northern late areas remained cold again keeping trees frozen.
This year, the weather in Quebec shows similar delays in tapping due to cold winter conditions extending later than normal. Past records from long-standing maple establishments in Ontario reveal that sap flow was delayed during the mid-1960’s until late March and as late as early April.
The coming week
Cold weather is forecast to continue through the week in northern maple syrup regions. Thawing conditions are predicted in southern areas of the province mid-week and again later in the week. Southwestern regions may experience good sap flows mid-week and again by Friday and Saturday. Sap flow conditions are looking more promising late in the week for eastern regions from Ottawa up to Petawawa and pushing northward up to Huntsville. Cold freezing conditions are predicted for next weekend and will stop sap again.
To predict sap flow events based on long-range weather forecasts, watch for consecutive days of freezing nighttime temperatures near -5 °C followed by thawing daytime temperatures around + 5 °C. These conditions allow maple trees to release sap upon thawing and to recharge trees with new sap upon freezing.
Atmospheric pressure also contributes significantly to the yield of sap during each thaw. Sap flows from high pressure areas inside the tree to low pressure areas outside the tree during a run. Low atmospheric pressure causes sap to flow faster out of the tree. Vacuum tubing creates an artificial low external pressure even when surrounding air pressures are too high for good sap flow, which is the primary advantage of adopting vacuum tube collection. Without vacuum tubing, ideal thawing conditions can sometimes yield little sap where atmospheric pressure remains higher than the internal tree pressure.
Getting started in maple syrup
Photo 1 & 2. In a modern facility (left), a commercial syrup producer may focus primarily on providing bulk syrup or granulated sugar to packers. Producers who prefer farm gate sales, value-added products, pancake houses, sugar bush tours, entertainment activities and demonstrations often invest in museum-quality displays that celebrate the historical values, artistic and past traditions of making maple syrup (right). Promoted by the syrup industry, modern best practices of food safety are expected of commercial producers and packers.
Calibrating a dial thermometer to measure boiling point elevation
Precision dial thermometers are often used by syrup producers to measure the temperature of maple syrup as it reaches a finished density of 66 °Brix. Dial thermometers are placed in the syrup pan near the draw-off valve. The boiling point of a liquid, like water, sap or syrup, will vary as the atmospheric pressure changes with the weather conditions. Dial thermometers are designed to be accurately calibrated prior to each batch of syrup boiled, to be set to the current atmospheric pressure.
Photo 3 & 4. To calibrate a dial thermometer, carefully immerse the stem into boiling water such as a kettle (left), a pot on the stove, or into raw sap nearest the intake valve that has reach a rolling boil. Hot mitts may be needed. While the stem is immersed in boiling water, adjust the lever on the back to rotate and align the graduated face with the pointer to zero. Zero equals the boiling point at the current atmospheric pressure.
Photo 5. The dial thermometer is calibrated to zero and is ready to measure the boiling point elevation of finished syrup. Other value-added products, such as maple butter or maple candy are cooked to temperatures higher than syrup. Make sure you know whether the dial thermometer reads Celsius or Fahrenheit.
Fresh sap boils at 100 °C, similar to water, when it first enters the back sap pan. As the water evaporates away during cooking and the sugars begin to concentrate along the evaporator, the boiling point slowly increases. Syrup that has reached the legal minimum density of 66 °Brix will boil at 104.1 °C. Boiling to 104.2 °C will produce syrup that has a density of 67 °Brix which many producers prefer as having a thicker viscosity and desirable ‘mouth-feel’.
Photo 6. Sugar crystals have begun to form at the bottom of hot-packed syrup. The crystals may be interesting to look at but are not considered good to have in packed syrup. Crystallization can occur where syrup density is above 68 °Brix. Filled containers that sit untouched for long periods of time can form a density gradient inside the container, where the higher density sinks to the bottom and may cause crystallization. On the other hand, these ‘maple gem stones’ might make a unique marketable product?
Ensure safe processing equipment
For a safe start-up, purchase new sap gathering and processing equipment from a reputable maple equipment dealer. If purchasing used equipment for maple syrup production, it is important that all equipment is manufactured using food-grade materials including: sap buckets, sap tanks for gathering and storage, evaporator pans and finishing pans, storage containers for bulk maple syrup and utensils. Food-grade materials include tig welded stainless steel and food-grade plastic. Aluminum sap buckets are common where sap is only stored in the bucket for a short duration.
Avoid old stainless steel pans, tanks, fittings and pipes where seams and joints are joined and held by lead solder. Avoid using terneplate metals, which is steel that is coated with a mixture of lead and tin.
Many commercial maple syrup producers in Ontario have already upgraded their processing equipment and are fully food-safe. Small producers or hobby producers who never attend industry meetings and workshops, or who don’t interact with knowledgable syrup producers are difficult to educate on these risky matters.
Photo 7 & 8 above, 9 below. Producers who are uncertain of their equipment can purchase test kits from equipment dealers to check for the presence of lead. A pink or red result following a swab test means lead is present and the equipment in question should be replaced with new equipment. Lead can seep from soldered joints and plated coatings to contaminate sap and syrup. Tig welded stainless steel components are the proper choices.
Avoid galvanized equipment which consists of steel or iron coated with zinc plating. Galvanized coatings can react with air, water, acid liquids and chlorine cleaners to produce unwanted by-products that can contaminate sap and syrup.
Avoid plastic containers, tanks, sap buckets, and pipes that are not food-grade plastic. Food-grade plastic is a dense, low porous material, unlike common porous plastics. Used equipment made of food-grade plastic should only have been used previously for food production. When in doubt buy new equipment.
Wooden containers and wood utensils are very difficult to sanitize due to the porous nature of wood and are generally not recommended, similar to modern commercial food processing facilities.