The evaporator is an enormous stainless steel vat in which the maple sap undergoes a condensation process, resulting in a series of reactions that partially determine the colour an d flavour of the future syrup. The maple sap is boiled for many hours, until enough of the water has evaporated. It takes 40 litres of maple sap to make 1 litre of syrup with the specified density of 66o to 67o Brix.
Modern Martinette’s evaporator (also called boiler) using oil
Old Martinette’s evaporator ( also called boiler) using wood
The Brix value corresponds to the percentage of sucrose by weight. For example, 66 Brix degrees is equivalent to 66 g of sucrose per 100 g of solution. When this figure is reached, we have genuine maple syrup!
Other reactions also take place in the evaporator, the main one being the caramelisation of certain sugars, which gives the syrup its colour. The more the sugars caramelise, the darker the syrup.
Caramelisation must be controlled or avoided, because it produces a caramel taste that masks the subtle, authentic flavour of maple syrup so maple syrup has to cook fast on a high intense and regular fire.
The osmosis units
The osmosis unit utilises th phenomenon of reverse osmosis, by which water can be seperated from sugar. Primarily a technique for sea-water desalination, reverse osmosis has been adapted for use in concentrating maple sap. Although not all maple syrup producers use this technique, it does save firewood and time.
The method works by exerting mechanical pressure on the sap (2% to 3% sugar), forcing a certain volume of pure water to pass through a semi-permeable membrane which blocks the passage of larger molecules such as sugar and other dissolved components. At the cylinder outflow, there are two phases: the distilled water thus extracted and the maple sap, concentrated so that its sugar and mineral content may be as high as 8%.
The concentrated maple sap is then heated in the evaporator.
The electronic thermometer
the thermometer is fixed at the end of the boiler. It’s calibrated depending of the barometric pressure of the air depending of the boiling point of the water at the moment. It can be calibrate more than once a day depending of this important weather factor. It will also always be regularly compare to the results of another instument we use and called the hydrometer ( density indicator of the sap) . The electronic thermometer will control the pouring of the maple syrup at the coming out from the boiler valves that will automatically open when the maple syrup is enough cook at 66Brix degrees. It will help avoiding over cooking of maple syrup by controling standards of the quality.
The filtering press
It is used to filter the maple syrup at the exit of the boiler before storing it in stainless steel barrels to preserve it and store it in the best conditions. The filtering will occur by passing the maple syrup into several series of special papers all stack together and fixed to a metal structure. This process will simply be used to take out, from the maple syrup, all sediments and will bring the maple syrup is transparency and brilliance by avoiding the deposit of sediments on the bottom of the bottles once the product is bottled.
IMPORTANT NOTICE: This filtering has no impact on the color and grades of the maple syrup.