Production methods have been streamlined since colonial days, yet remain basically unchanged. Sap must first be collected and boiled down to obtain pure syrup without chemical agents or preservatives. Maple syrup is made by boiling between 20 and 50 litres (5.3 and 13 US gal) of sap (depending on its concentration) over an open fire until 1 litre (0.26 US gal) of syrup is obtained, usually at a temperature 4.1 °C (7.4 °F) over the boiling point of water. Syrup can be boiled entirely over one heat source or can be drawn off into smaller batches and boiled at a more controlled temperature.
Boiling the syrup is a tightly controlled process, which ensures appropriate sugar content. Syrup boiled too long will eventually crystallize, whereas under-boiled syrup will be watery, and will quickly spoil. The finished syrup has a density of 66° on the Brix scale (a hydrometric scale used to measure sugar solutions). The syrup is then filtered to remove sugar sand, crystals made up largely of sugar and calcium malate. These crystals are not toxic, but create a “gritty” texture in the syrup if not filtered out. The filtered syrup is graded and packaged while still hot, usually at a temperature of 82 °C (180 °F) or greater. The containers are turned over after being sealed to sterilize the cap with the hot syrup. Packages can be made of metal, glass, or coated plastic, depending on volume and target market. The syrup can also be heated longer and further processed to create a variety of other maple products, including maple sugar, maple butter or cream, and maple candy or taffy.
