Why shouldn't you re-heat baby food?

When hot food is cooled it pes through a warm temperature at which bacteria can quickly multiply.The quicker it's cooled the safer it is, but if you then re-heat it, it pes through that warm phase again, and any bugs in it will multiply again. For adults, it's fairly safe as long as you get it hot enough the second time to kill the bugs, but it's not worth taking the risk with babies. If the baby won't eat it all the first time, try heating half and keeping the other half chilled. That should be OK as long as you use it up within 24 hours or so.