Bottling San Marzano Tomatoes

[Rhona]

They are lower in acid than other types, apparently, and I'm a bit concerned that might affect the preserving quality.

We've grown masses specifically for preserving (they're not great eaters) and I'd rather bottle than freeze/dry if possible.

Am I being a bit paranoid, or do you think the lower acid would cause a problem?

[Alison]

I didn't know they were low in acid, is that just a perception from taste thing or a recognized fact? Also, when you say they are lower in acid, do you know how they compare with other fruits? My understanding of it is that you can bottle fruits pretty easily using water bath methods etc but with veg you need to go high pressure. If you're using a proper canner then I wouldn't worry, if using more traditional methods then I'd weight it up by comparing with other OK fruits.

[Rhona]

Thanks - the lower-acid is a recognized fact, rather than just taste thing. I don't have a pressure canner, but might be persuaded to buy one this year. If I don't it'll be trad methods.

I'll maybe have a google around for more info.

[Nicos]

Right...now then.... We've just used our steriliser for the first time and the only directions on it are temperatures for some products. No times mentioned

Anyway - I've just had a look- and this is what it says....

70C fruit juices
75C to pasturise
80C fruit with stones
90C fruit with pips, jams
100C everything else fruit , veg, meat

so according to that, I would do them at 90-100C

We did our Marmande and acidic cherry toms at the same time at 90C for 20 mins...I suppose time will tell!

[Hilary B]

I wouldn't think 100C was enough for meat!
I had an old cook book that gave instructions for 'bottling' a chicken, it included 2½ hours in the pressure-cooker. (included were instrucions on how to 'portion' and pack the chicken so that there was a minimum of wasted space). Even then it recommended being prepared to discard any bottle if there was an odd smell when opened.
If in doubt with less-acid tomatoes, maybe add a little lemon juice?

[SarzWix]

If you're in doubt Rhona, a teaspoon of either citric acid or lemon juice to each jar, plus a teaspoon of sugar is supposed to tip the acidity level enough. This info from my "Canning & Preserving for Dummies" book.

[Nicos]

I wouldn't think 100C was enough for meat!

...if you suddenly don't hear from me ..then you know what's happened!!

Clear as day though- it does say 100C- but that's in sealed jars so I suppose it'll be self pressurising???

(actually- so far not been brave enough to think about meats)

[roitelet]

Just looked in my Mum's 1940 cookery book and it says:- tomatoes add 1/2 a tspn salt to each bottle of tomatoes and heat gently to 190F over the first hour and then hold at that temperature for 30mins test for a seal by lifting the jars by their lids after 48hrs. If the lids are loose use at once.

Not tried bottling yet but will have to do so as the freezer is full and someone has just given me loads of plums.

[Nicos]

* 190f = 88c

[Hilary B]

Seymour (Self Sufficiency writer) reckoned on canning pork etc, and that would only be at 100 C, but... I wouldn't do it. A pressure cooker takes the temp up further (quite a LOT further, although I can't remember how to work it out) which is why that method is supposed to be safe.