Understanding Buddy Off-flavour in Maple Syrup
Todd Leuty, Agroforestry Specialist
When Buddy is Not a Friend!
Acquiring the ability to identify common off-flavours in maple syrup is important for producers. Detecting buddy off-flavour in fresh sap can be difficult, although much easier to taste in finished syrup. Buddy syrup can be described as an unpleasant chocolatey aroma and flavour having a lingering bad aftertaste. Buddy flavour in maple syrup is a food quality issue, not a food safety issue.
When it occurs, buddy off-flavour prevents maple syrup from fetching the best prices as retail and farm gate products, and downgrades it to a processing grade if the problem is only mild. Maple syrup that has excessive buddy flavour would be discarded at a significant financial loss to the producer.
Buddy off-flavour is an annual, natural occurrence for all syrup producers to try to avoid. It is caused by Mother Nature where its appearance represents the internal mechanism that drives each tree to resume growth following winter dormancy.
Harvesting buddy sap when it occurs earlier than expected can cause great frustration for syrup producers. The resulting buddy syrup has to be kept separate from the good quality syrup in clearly labelled bulk containers, which only delays the decision on what to do with it until after the production season. Once buddy sap appears, subsequent sap flows will also be buddy.
Metabolism is another naturally occurring off-flavour in sap that often appears in the first sap flow, but can also appear sporadically during the sap harvest season, due to extended mid-winter thaws. Unlike buddy sap, off-flavour caused by metabolism can stop and good quality sap can resume. Buddy sap and metabolism in sap can be differentiated by flavour, typically in the finished syrup.
Maple researchers have dedicated several decades to studying the cause of buddy off-flavour in syrup. Bench-top electronic devices that use light refraction techniques on syrup samples can detect the presence of buddy flavour compounds and several other contributors of bad flavour.
Samples of suspect syrup can be sent to Centre ACER, the federal maple research facility in Saint-Hyacinthe Quebec, where for a fee, technicians will test your syrup for buddy off-flavour and its intensity.
Studies involving sap chemistry and investigations into physiological changes that occur in sugar maple trees between winter dormancy and bud break have identified the presence of sulphur-based compounds. The sulphur compounds develop naturally in sap as the buds begin to grow. It is believed that these sulphur compounds cause buddy off-flavour in maple syrup. Similar to eggs, onions and cabbage vegetables, sulphur compounds are known to cause odours and flavours that would be unwelcome in maple syrup. The sulphur compounds are produced through chemical reactions as the trees begin to use nitrogen-based nutrients. Nitrogen, stored sucrose and other nutrients are utilized to initiate bud development, flowering and early shoot growth as ambient temperatures begin to warm the sugar bush.
Currently, maple researchers are testing a number of techniques that might remove the sulphur compounds and buddy flavour from finished syrup, while maintaining the purity of the syrup. For syrup producers, it would be very beneficial for maple researchers to develop a quick and inexpensive test for use in the sugar house, to detect buddy sap prior to wasting fuel and labour.
Boiling down buddy sap will produce buddy maple syrup, which is expensive to make, however will have a low to zero dollar value. Buddy flavour in fresh sap and syrup negatively impacts food quality and reduces profits for maple syrup producers. On the positive side, the causal agent of buddy flavour is actually an indication that new growth has begun in the sugar bush, a response that tells us the trees are alive, which is good when it happens in spring.
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