Quebec maple syrup producers using gold nanoparticles to test quality

Tapping a maple syrup tree at Elsie's Creek Farm in Coldwater, Ont., on Thursday, March 4, 2022 (Steve Mansbridge/CTV News)

The maple syrup we pour on our pancakes is the product of high-precision work, and its quality is scrupulously inspected before it's sold.

But sometimes, unwanted flavours can creep into the syrup and lessen its grade, much to the chagrin of maple syrup producers.

Fortunately, researchers at the Université de Montréal (UdeM), in collaboration with the Producteurs et Producrices acéricoles du Québec (PPAQ) and producers in the field, have developed an easy way to test the sap using gold particles and nanotechnology.

Gold particles as thin as one-hundredth the width of a hair turn red in the liquid where they rest. But when maple sap is added, the liquid turns blue.

"It's like a pH test, or a chlorine test for the pool," explains UdeM chemistry professor Jean-Francois Masson, who co-created the COLORI test.

The more drops you can add before the colour changes, the more likely the syrup will be of good quality.

This year, 250 seasonal kits were distributed as part of a pilot project, and researchers expect to invest more widely in 2024.

The technology allows producers to test for quality before "putting a lot of energy and time" into making their syrup, said PPAQ spokesperson Joël Vaudeville.

They can also sample and compare sap from different trees on the often-large properties.

Vaudeville says the test is "very simple to use" on-site, and an analysis grid is provided so producers can interpret the results themselves.

"It allows them to make business decisions."

According to the Canadian Food Inspection Agency, flavour defects "can be a trace of caramel, which is more common in amber or dark syrup, or a trace of sap of bud, which is more common in late-season syrups," among other things.

Defective syrups are usually used exclusively in processing plants and kept off store shelves.

There are four main classes of syrup. Golden, with a delicate taste, comes with the beginning of the maple season. As time progresses, the colour becomes darker and the taste more pronounced.

"With climate change, spring weather has become very variable," said Masson, adding that for the past ten years, producers have increasingly found "atypical flavour profiles," especially at the end of the season.

Research to further the test was published in the journal ACS Food Science & Technology.

This report by The Canadian Press was first published in French on Marh 26, 2023.