At the end of last summer I used the last of my tomatoes to make concentrated tomato purée and tomato sauce (ketchup).
As I couldn't find an appropriate canning recipe I froze the puréed concentrate in portion sized batches.
And the ketchup was made, and water bath preserved.
All the lids sealed properly. However, I am left with the last few jars which look like this:
My question is this - is the tomato sauce still safe to use? The lids are definitely still vacuum sealed. And, yes, I did fill to within 1/2 inch of the top of the jar - it appears to have settled lower than that though in the intervening months.
Would the "air space" at the top of the jar cause that darkening to occur?