OK, so now that we cleared up that the sap needs to be processed we can move on... Because the processing calls for heating the watery sap until it thickens, all possible bacteria is killed and I have never had any problems with anything like that. If you put the processed, hot syrup in...
I hope you realize that it does not come out of the tree as "maple syrup." After it is processed I usually store it in jars in my refrigerator, however, I am told that if it is processed and canned it does not need refrigeration.