"We've given up saying we only kill to eat; Kraft dinner and freeze-dried food have put paid to that one" It should be 'kill to only eat'? 'Have put paid to the their leaving of saying they only kill to eat'?
Your question is somewhat confusing but it sounds like you don't understand what the author is saying:
...we only kill to eat;"
This is the correct word order. It means that the only reason the author kills is so that he can have food to eat. It's NOT "kill to only eat".
Kraft is a company that makes ready made food. put paid to is an expression that means putting an end to something.
In essence, what the author is saying is that in the past, people could justify killing [animals & plants] by saying "well, we need to eat, so we have to kill", but that today, with ready-made food like Kraft's and frozen meals, that excuse to kill is no longer valid.
(Although one may wonder where the author thinks Kraft food products come from.)
Hope this clears it up.