For me there are few things that correlate with ´good quality´ tinned tomatoes, some of which were discussed above:
- peeled, not chopped [they go mushier & are less acid = flabby when sitting chopped in the tin]
- tin has white coating inside, not just transparent varnish [the tin taste gets into the tomatoes in the latter case]
- San Marzano not cherry tomatoes [nearly all tins have San Marzano variety anyway even when not labelled as such]
- high energy content per 100g [e.g., over 100kJ/100g is good and it means the tin has been made up with a fairly substantial puree; low energy content = tin is made up with water or watery tomato juice & it seems to correlate with tomatoes with bad bits etc, i.e., lower quality]
- relatively low fibre content per 100g [higher fibre content can mean they've chopped up leftover or sieved core bits to include in the puree used to fill up the tin]
I once bought one tin of every kind I could get in UK supermarkets and did a comparison.
As a result of which I found something that doesn't necessarily correlate with quality:
- price [name and shame time? 'brands' with an advertising budget generally had poor price/quality ratio]
I read somewhere that I cannot at this moment find that the 2 reasons San Marzano are used are high solid/liquid ratio & shape - they fit in the tin better, the wikipedia page hints at the 1st
https://en.wikipedia.org/wiki/San_Marzano_tomatobtw I don't see the point of DOP, I think the next valley or province in Italy is just as likely to be able to grow good or even better tomatoes
gpadsa