Tapping activities

A number of maple syrup producers in southern regions took advantage of the thawing weather conditions last week to begin tapping trees.  Several large producers have completed tapping their trees.  Northern and north eastern regions remained too cold with trunks frozen where producers did not tap trees yet.

Photo 1.  Snow remains very deep this year in many sugar bushes hampering work.  Mainlines normally chest height or higher are inches above or buried under snow in this Haliburton sugar bush.

In southern areas, sap was flowing during drilling and tap installation February 19, 20 and 21, where sunny temperatures were around 5 °C.  Larger producers in southwestern areas report they did not get enough sap to make a batch of syrup, particularly where reverse osmosis is used to concentrate sap prior to boiling.  Most commercial producers used the first sap flow to rinse collection tubing systems, then sap was discarded.  The first seepage of sap from maple trees can sometimes be off-flavour anyway for making syrup.

Several smaller producers and hobby producers not having RO concentrators report they boiled a small batch of syrup on February 21 or 22, Friday or Saturday, and produced light syrup.  Sap sugar concentration was below 2 °Brix as often occurs in the first flow of sap. By the week-end February 23, temperatures dropped to well below 0 °C to freeze trunks again and stop sap flow.

Many southern area producers east to Ottawa made significant progress tapping their sugar bushes and are prepared to activate their vacuum tubing systems when thawing conditions return.  With modern closed vacuum tube collection systems, new tap holes are not as susceptible to premature drying out since dry winter air is excluded from tap holes.  Tests with Leader check valve spouts have also shown to prevent drying out of tap holes.  Taps having open spouts with bucket collection can encounter problems with premature drying of tap holes due to access of dry cold air into the exposed sapwood.  Therefore, producers using open spouts on buckets can delay drilling tap holes until thawing temperatures return in a week or so.

Long range weather forecast

Temperatures are predicted to remain far too cold and sap flow is not expected for the next week.  There is some concern that the sap collection season may be shortened this year due to the very low freezing temperatures forecast.  We can confidently say that it is impossible to predict the duration of the maple syrup season or the yield until it is over.

To predict sap flow events, watch for several consecutive days of thawing daytime temperatures with freezing nighttime temperatures of – 5 to – 8 °C.  Daily freeze thaw cycles are necessary to make sap flow and recharge the maple trees for consecutive release of sap.  Watch extended weather forecasts to predict sap flow conditions.

Filtering maple syrup

Maple syrup requires filtering of sediment, known as niter or sugar sand, after it leaves the evaporator.  Sometimes fresh maple syrup can be loaded with large quantities of niter and can be difficult to filter clear, while other batches of syrup have little sediment and are easy to filter.

Filtering requirements can vary from season to season within the same bush.   Several types of filters are available, ranging from simple flat filters, fabric cone filters, to pressurized cylinder and plate filters.  Cloth and cone filters can be washed in hot water between use and hung to dry in an open area out of sunlight.  Never use soaps or detergents to wash cloth filters since the flavour of soap will show up in finished syrup.

Photo 2 & 3.  Pressurized plate filters of standard aluminum frames or new poly-carbonate frames (shown left) are commonly used.  These filters are pre-loaded with powdered filter aid (right), which helps filter sugar sand or niter from hot syrup.

Mouldy smelling cloth filters will also impart off-flavour in finished syrup.  If in doubt, purchase new cloth filters each year.  Equipment dealers can show you how to operate each type of syrup filter to make clear syrup.

 Photo 4 & 5.  A cloth cone filter with several cone pre-filters (left) clears hot syrup  straight off the evaporator.   Several layers of cloth flat filters (right) filter sugar sand from hot syrup from the evaporator.

Reverse Osmosis

Syrup producers continue to adopt reverse osmosis as a means to significantly reduce the amount of fuel required to process sap into syrup.  Labour costs are reduced by more than 50% due to shorter cooking times.  Producers who are at full capacity of their current evaporator can significantly increase the capacity, number of taps and syrup production by adopting RO.    RO’s can quickly remove 75 – 80% of the water from sap prior to boiling.   Ensure the RO membrane is properly cleaned and rinsed with potable water at the manufacturers recommended times during use.

Photo 6 & 7.  Small reverse osmosis units (left) are available for operations up to 500 taps.  Large capacity RO’s (right) are available for big operations having thousands of taps and can be easily expanded by adding more membranes and pumps.

Researchers recommend that sap sugar concentrations can be increased to a maximum of 15 – 18 °Brix sugar concentration from the raw 2 °Brix concentration without affecting the quality and flavour of finished maple syrup.   Sap sugar concentrations taken higher than recommended maximums can lead to poor flavour development, light colour grades due to insufficient cooking duration and reduced syrup quality.  

Some producers only increase sap sugar up to 8 – 10 °Brix through their RO and are confident that the duration of the cooking time is most important to develop the full flavours and rich colour of maple syrup through heating reactions of caramelization of sucrose and Maillard reaction of invert sugars and amino acids.