Yum, maple syrup. It’s perfect on pancakes or crumpets, and can even do a star turn in sweet-savoury meat dishes ( or , anyone?). Plus, it may have health benefit powers, as studies suggest it might prevent Alzheimer’s and other degenerative diseases, and the effectiveness of antibiotics. But the big question is: where do you store it so that it doesn’t go off? And if it does show signs of mould, is it still safe to eat?
What makes maple syrup
“Maple syrup is a sweetener made from the sap of the Acer tree during spring,” Nenad Naumovski, Assistant Professor in Food Science and Human Nutrition at , tells SBS. “The sap itself is a solution of water and sugar (sucrose) and contains a variety of other compounds including amino acids and phenols.”
According to Tom Ross, Associate Professor in Food Microbiology, Food Safety Centre, School of Land and Food, , it’s the high concentration of sugar in the syrup which makes the difference to its “”, the water in food which is not bound to food molecules. “The ‘water activity’ of syrups is [generally] at a level which inhibits microbial growth, including bacteria, yeasts and moulds.”
But maple syrup can develop moulds. Indeed, this article was prompted by one of the SBS Food team found mould – AFTER pouring syrup on breakfast - in a bottle of maple syrup accidentally left in a cupboard.
As Ross explains: “The water activity scale runs from 0 to 1. A water activity of 0 means completely dry, while a water activity of 1 is pure water, with nothing dissolved in it. Any food with a water activity less than 0.6 will prevent any microbial growth.” The water activity of maple syrup “is generally about 0.87 to 0.88” – which means some moulds can grow on maple syrup.
“Some of the moulds that can grow [on food], such as , produce compounds that, after prolonged exposure, are linked to different forms of cancer,” he says.
What happens when maple syrup is opened
“Maple syrup, kept at room temperature, is known to get contaminated with moulds (usually from the air after the bottle is opened) and it’s possible that some of those moulds produce carcinogens,” says Ross. “The carcinogens can then get distributed in the whole bottle of maple syrup because they are soluble.”
A small dose of these carcinogens probably won't lead to illness, but repeated exposure might. “Maple syrup that has visible mould growth might contain aflatoxins. It’s hard to be certain without actually identifying the mould that is growing, and that takes a lot of time and money. The best advice is to not eat maple syrup that has signs of mould growth.”
Take the maple out of your fridge and whip up these
Source: China Squirrel
You shouldn’t boil maple syrup which has shown signs of mould either, in the hopes of killing any bacteria. “The toxins we are talking about can survive heating at 160°C,” says Ross. “The boiling temperature of maple syrup is only a little over 100°C.”
It’s fine to have unopened bottles on a cupboard shelf. “Maple syrup should be free from mould as long as it is in the original, unopened, container because it is heat treated in the bottle to kill any moulds that might have been there,” he says. But once opened, you should move your maple syrup to the fridge. “Invisible moulds cells are common in the air, and when the bottle is opened, can fall into the bottle and then start to grow. The cold temperature [of a fridge], and the low water activity, will work together to slow or prevent the mould from growing.”
What about other sweeteners?
“Coconut nectar syrup does not require storage in the refrigerator, due to its very high sugar content, which is around 93 per cent,” says Naumovski.
“Honey also has a relatively high carbohydrate content at around 80 per cent, and it does not need to be stored in the fridge in the short term [up to around six months],” he says. Naumovski advises storing honey at room temperature (around 26°C), and in airtight containers as it can absorb moisture from the surrounding atmosphere. “If you’re planning to store it for longer, the best temperature would be below 10 degrees Celsius, which is commonly found in fridge.”
And if golden syrup is your topping of choice? The cupboard is fine. “Golden syrup is quite stable and has a very useful shelf-life of over two years,” says Naumovski. “It commonly does not have the use-buy date. However, once opened, it is advisable to use it within the two years.”
Where’s the best storage place?
According to Lydia Buchtmann, Communication Director at the , only the manufacturer knows the recipe of their food and how long their product will last. “This is why use by and best before dates as well as storage instructions are set by the manufacturer and displayed on the label,” she tells SBS. “ and always use a product by any ‘use by’ date. A product can be consumed after a ‘best before’ date but might have lost some quality.”
Food Safety Week runs November 11- 18 – find more information from the .
