We travel with grand babies all of the time. Taking baby items through security is not a huge deal (anymore). Just have the baby with you! Our trip in October, I had applesauce cups and juice boxes in my zip lock bag, but the TSA agent sent me to a different line than the kids. One TSA person asked about it (normally they don't ask). I had it out sitting, so was not hiding it. I said it was for the baby and she asked where the baby was, so we had to yell 4 lanes over, "hold up the baby". Her response to me, "next time stay with the baby". I said "I tried, but you guys sent us to this line and split us up." Taking a normal amout of baby bottles and food is allowed. Alot of TSA folks are very kid friendly and family friendly. Every now and then you encounter one who is sour and those are the ones people post about.
Also, if you need to heat the bottle up, ask for a cup of hot water as soon as you get on the plane and the FA will help you out. Too late after take off to warm that bottle.