The osmosis units
The osmosis unit utilises the phenomenon of reverse osmosis, by which water can be
separated 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.
 |
 |
| Osmosis unit |
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 evaporator
| 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 and 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. |
Evaporator in production |
The
Brix value corresponds to the percentage of sucrose by weight. For example, 66o Brix 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.
|
