Finally I am trying out my Maple Syrup Beer, its been sitting in the fridge in a glass keg for 2 months. First fermentation with brewing sugar and second fermentation with maple syrup. The beer tastes great and infused carbonized. I am wondering since I used 500 ml Maple syrup would the beer go bad sooner then brewing sugar?
From experience with using maple syrup in secondary fermentation, the shelf life of the beer was unchanged from its normal life span. The same simple sugars will be consumed and the sugars that do not ferment out will remain in solution making for a sweeter beer in the end than if you had used just dextrose to secondary ferment with. This will also be slightly different depending on the grade of the maple syrup you used, the attached link will give some more insight on how to use other sources of sugar for secondary fermentation.I did find however that the aromatics from using maple in secondary were much greater that with used just as a flavor addition in a keg; and far greater than when maple syrup was used in just primary fermentation. Cheers https://byo.com/article/sweetness-brewing-sugars-how-to-use-them/
Maple syrup consists of sucrose. While fermenting, it is split up by the yeast into glucose (dextrose) and fructose, which are fermented: turned into alcohol and carbon dioxide.
Brewing sugar is glucose (dextrose), which is also completely fermented.
So, while these things look different, they are actually reduced to the same simple components which are fermented in the same way.
Which means that your beer will keep as well made with maple sugar as with brewing sugar.