Changing syrup color?

[Mille705]

So we have always pulled finish syrup off our evaporator, used gravity filter cones and bottle into quarts and pints. I am going to a filter press this year and storing some in 10-15 gallon kegs. So if I pull syrup off the evaporator and allow it to cool until I get enough gallons to press. Reheat to press, seal in a 15 gallon drum. 3 months later reheat the drum to bottle smaller bottles will all these heat cycles darken the syrup?

[maple flats]

each heat cycle darkens the syrup. If you only heat it to 185, each time you darken it less than if you heated it to 195-200+ each time. I like to use a Hanna Checker which gives you the % of light transmission thru the sample vial (Cuvette). I label the result on each keg. that helps you as you reheat, because you know where in the 25% width of that grade. Also, as I blend, which I do to get darker syrup, I stop mixing as I get to about the middle of which ever grade I'm mixing for. The grades are 100-75% golden, 74-50 amber, 49-25 dark and under 25% very dark. Thus I shoot for 85-90 for golden (if I can), about 65-70 for amber, 35-40 for dark. I rarely get any Very Dark. Then as I need to reheat I have some wiggle room.
Before I had a Hanna Checker, I used the temporary test kits. Even then I made note of just where the sample fell in that grade, light, middle or dark end. I just made up a code for my own info.
As you are getting close to having enough to fill a barrel it also helps if you heat what you have saved, add it to what you draw off, then filter and fill the barrel. Some of the syrup thus gets 1 less heating. Then, when you bottle, heat to 185, (I filter again), then bottle. Try to not get it hotter than 185, but still above 180. If using a water jacketed bottler it's easy, if heating it on propane (or the kitchen stove not as easy, but you just need to keep a close eye on it.