Making ginger biscuits but it has treacle don't have it.
Can I use golden syrup instant.
Thank you. Sue...

I appreeciate the cooking answers that include a bit chemical science like spiffypaws. Sort of answers why a substitution in a recipe didn't work.

The ph of these 2 ingredients is different; you may need to adjust the leavening in your recipe.

Molasses is a by-product of sugar production and is bitter, but that is not a bad thing. It has its place for so many wonderful recipes. Golden syrup in more like Karo syrup. You would lose the wonderful flavour notes molasses gives to ginger muffins and cookies if you use Golden Syrup. I would not substitute one for the other.

Do you have Treacle available? It's very similar to molassas but a bit sweeter/milder, I hear. It would be a good substitute. Don't use Black Treacle, it's stronger and more bitter, similar to black strap molassas which it isn't used in gingerbread..

They are similar, but definitely different products. You will really want to use the molasses for the gingerbread, as it adds flavor notes you are not going to get from the golden syrup. Golden syrup is sweeter, and sort of butterscotchy in flavor. Molasses is richer and a bit bitter and metallic in flavor (not in a bad way.) Gingerbread's classic flavor comes from the combination of the spices and the molasses. If you do make the muffins with golden syrup, you may want to call them spice muffins instead of gingerbread.