🍁 Climate change: an unexpected effect on maple syrup quality

A maple sap season brought forward by warming could alter certain flavours that occur late in the harvest

According to Marie Filteau, a professor in the Faculty of Agricultural and Food Sciences, "maple syrup produced at the end of the season can have flavour defects, like the famous buddy taste." Her study suggests that with climate change, the conditions leading to these defects would become rarer during the sap flow period, which would be reflected in the quality of maple syrup.


This prediction corresponds to a very specific period of the maple sap season, a time when the composition of the sap changes and directly influences the quality of the syrup. "The sap becomes enriched with certain nutrients and microbes multiply faster. Since maple water is flowing abundantly, producers cannot always boil it quickly enough," reports the microbiologist. These combined elements can lead to unpleasant tastes and significant losses.

Professor Filteau observed when this sap turning point would occur based on three greenhouse gas emission trajectories. The first scenario forecasts low emissions until carbon neutrality is reached in 2075. The second maintains emissions close to current levels until 2050, before a gradual decline. The third envisions a sharp increase in emissions, tripling by 2075.

In all three cases, the quality of the syrup was influenced by a shift in the sap's turning point. "The warmer the climate gets, the earlier we will harvest, and the less the sap transition period will coincide with the harvest period," she summarizes. Her field observations in recent years support this prediction, as she notices fewer quality defects with the changing climate.

Flow days and technology

However, some studies on the consequences of warming in maple syrup production forecast a decrease in the number of flow days. The researcher points out that this decline could be partly mitigated by a reduction in losses related to quality. The technology used for harvesting could also play a role in adaptation to warming.

In her study, Professor Filteau considered harvesting by gravity, with buckets for example, and vacuum collection, which uses plastic tubing and a pump. The latter has an advantage: since harvesting can occur at colder temperatures, production can start earlier than with gravity.


"It's a small difference that can have a big impact in the end," indicates Marie Filteau. Indeed, her model predicts that maple syrup producers using a pump could achieve "100% good sap," producing syrup without defects, between 2040 and 2060, while gravity systems would achieve this performance between 2060 and 2080.

Professor Marie Filteau continues her research in this direction by evaluating the effect of climate change on the microorganisms of the sugar maple. "I have hope that the tree's microbiota, which evolves rapidly, will help it adapt," she envisions.

The study was published in the journal Heliyon.