Modern era
When was the first evaporator patented?
Maple syrup
Around the time of the American Civil War, syrup makers started using large, flat sheet metal pans as they were more efficient for boiling than heavy, rounded iron kettles, because of a greater surface area for evaporation. Around this time, cane sugar replaced maple sugar as the dominant sweetener in the US; as a result, producers focused marketing efforts on maple syrup. The first evaporator, used to heat and concentrate sap, was patented in 1858. In 1872, an evaporator was developed that featured two pans and a metal arch or firebox, which greatly decreased boiling time. Around 1900, producers bent the tin that formed the bottom of a pan into a series of flues, which increased the heated surface area of the pan and again decreased boiling time. Some producers also added a finishing pan, a separate batch evaporator, as a final stage in the evaporation process. Buckets began to be replaced with plastic bags, which allowed people to see at a distance how much sap had been collected. Syrup producers also began using tractors to haul vats of sap from the trees being tapped (the sugarbush) to the evaporator. Some producers adopted motor-powered tappers and metal tubing systems to convey sap from the tree to a central collection container, but these techniques were not widely used. Heating methods also diversified: modern producers use wood, oil, natural gas, propane, or steam to evaporate sap. Modern filtration methods were perfected to prevent contamination of the syrup. A large number of technological changes took place during the 1970s. Plastic tubing systems that had been experimental since the early part of the century were perfected, and the sap came directly from the tree to the evaporator house. Vacuum pumps were added to the tubing systems, and preheaters were developed to recycle heat lost in the steam. Producers developed reverse-osmosis machines to take a portion of water out of the sap before it was boiled, increasing processing efficiency. Improvements in tubing and vacuum pumps, new filtering techniques, "supercharged" preheaters, and better storage containers have since been developed. Research continues on pest control and improved woodlot management. In 2009, researchers at the University of Vermont unveiled a new type of tap that prevents backflow of sap into the tree, reducing bacterial contamination and preventing the tree from attempting to heal the bore hole. Experiments show that it may be possible to use saplings in a plantation instead of mature trees dramatically boosting productivity per acre.