BOTTLING TOMATOES & THE ACIDITY CUSP
Monday August 16th 2010, 1:05 pm

black cherry tomatoes in a miniature colander

Month eight Tigress’s can jam canning challenge and for August the ingredient chosen by the inspired and inspiring Julia is tomatoes. My relationship with this ubiquitous fruit has been a checkered one. I hated tomatoes as a kid but learnt to tolerate them later on. I do like them as a sauce for pizza, applied with a lightness of touch though. I can now eat cherry tomatoes raw and, like biting into any fruit, appreciate their sweetness so I suppose you could say I’ve made progress.
But it is as objects of beauty that tomatoes especially come into their own. The resurgence of interest in growing heritage varieties has brought all these wonderfully coloured tomatoes to the fore; striped, heart and pear shaped, shaded like a shop display of lipsticks, from gold to chocolate. They are all so fantastically photogenic and worth growing for looks alone.
As an ingredient for canning, they are on the acidity cusp. Tomatoes require special attention for bottling safely using the water processing method or else should be pressure canned. They are only just on the acid side of neutral and acidity can vary for different varieties, so it is necessary to add a little more acidity in the form of lemon juice or citric acid to make sure they stay safely putt. It is important that time spent preserving has a very definite pay off later so it makes sense for me to bottle really useful tomato passata-type sauces for cooking up further down the line into pizza toppings, pasta sauces or as additions to winter casseroles.

pink heartshaped tomatoes

Each year I begin the growing season with high hopes for an extensive range of weird and wonderful tomato varieties. I don’t have a greenhouse so can only grow toms out in the open. We’ve had two consecutive years of blight bringing these plans to a soggy and disappointingly diseased halt, but this year the weather has been kinder. Tinned tomatoes are as cheap as chips, so I don’t think it is really cost effective to bottle tomatoes unless you have your own homegrown supply or you are able to mop up someone elses glut. The plants I have growing in the garden are still some way from the ‘glut’ stage. Thankfully my neighbour Jane has a greenhouse as well as green fingers. She sells her excess garden produce from her garden wall. Last week I picked up four generous punnets of yellow and red tomatoes from the wall and dropped my payment into the honesty box provided.

homegrown cherry tomato varieties

So first a basic tomato sauce. These cherry tomato varieties are as sweet as anything though perhaps not the most ideal kinds for bottling. For sauces, larger fleshy varieties like Roma and San Marzano are good. Skinning so many tiny fruits was definitely out of the question for starters. Tomatoes can be very watery, which means that they will require considerable cooking to reduce, thicken and intensify the flavour, unless some of the liquid is removed first.
In order to give a fresher flavoured result with less cooking time I began by slitting each fruit and removing the seeds by running my thumb quickly through their middles, collecting the seeds in a sieve placed over a bowl. Any collected juice would come in handy later. After a brief cooking time of 10 minutes the de-seeded tomatoes were then processed using a passata mill, running it through several times to separate the skins from the pulp. The passata mill is a bit of kit I acquired some years ago when dreaming of a bounteous tomato crop that never materialised. The mill has sat unused in its box ever since so this was its first opportunity to prove its worth. I must say that I wasn’t too impressed. Passata-ing the tomatoes was a messy and annoying business (compounded by trying to take photographs at the same time). Tomato juice splattered all over the place and possibly it was my fault, but juice was squirting out the handle side as well! Next time I will most likely use my regular food mill over a bowl, which though still requiring patience would be less messy and more controllable. Depending on the scale of the project, to remove skins and any stray seeds you could simply push the tomatoes through a sieve if you prefer. Still too watery for my liking, I strained the flesh again briefly in a sieve collecting more juice to add to what had been collected earlier. 2.5Kg (5 1/2lbs) of tomatoes resulted in 775g (1 3/4lbs) puree and 750ml (1.3 pts) of juice.

processing tomatoes with a passata mill

HOW TO BOTTLE TOMATO PUREE

Prepare the water bath, jars and seals ready for bottling (canning). For more info about how to hot water process, refer to the guide here.
Put the pureed tomatoes in a pan and simmer for a short time to reach a consistency that suits you so excess juice has evaporated. If the puree is already thick enough simply bring to boiling point. I added 1 tsp sea salt (a non essential, so add salt to own taste or leave out all together) plus an aditional acidic booster. As a general guide you need to add one of the following to every 500ml (1 pt) tomato puree: 1Tbsp lemon juice or 1/4 tsp citric acid. I used balsamic vinegar instead, adding 2 Tbsp balsamic vinegar per 500ml (1pt) puree.
Place a basil leaf inside each jar against the glass and fill jars with tomato, leaving headspace required for your type of jar. Remove bubbles from sides of jars using a small spatula, wipe rims clean and seal. Process 500ml (1 pt) jars for 35 mins and 1ltr (quart) jars for 45 mins. Remove jars from water bath and leave till cold before testing the seals. Any jars with loose seals will require reprocessing or you can keep them in the fridge for using up within a few days. Remember to label all your jars before storing them.
My tomatoes made 2 x 350g (12oz) jars of sauce plus a bit more that I had with pasta for my dinner that evening.

bottled tomato sauce

WHAT TO DO WITH THE JUICE

It seemed a shame to waste the lovely sweet juice collected whilst extracting the tomato puree, so I decided to turn it into tomato jelly. You could flavour tomato jelly with fresh ginger and ground coriander or finely chopped chilli. After much deliberation I eventually chose vanilla and white pepper for a jelly with a sweet / savoury crossover. This jelly is delicious on sourdough toast with cream cheese and I used it to fill tiny savoury pastry cases, topped with sour cream or crumbled goats cheese for a really exquisite little mouthful.
As tomato juice is lacking in pectin, a boost in the form of the addition of lemon or apple juice is helpful. Having bottled some whitecurrant juice several weeks earlier to use at times like this, I added some of that for its setting quality. Preserving sugar containing added pectin could also be employed here. Adjust proportions to suit what you have available.

TOMATO, VANILLA AND WHITE PEPPER JELLY

750ml (1.3 pts) tomato juice (a byproduct of making the puree above)
550g (1 1/4lb) sugar
Juice of 1 lemon or 150ml (2/3 cup) whitecurrant juice
1 vanilla pod, split and seeds scraped from inside
1/2 tsp ground white pepper

Prepare the water bath, jars and seals ready for canning. For more info about how to hot water process, refer to the guide here.

Pour the juice through a jelly bag, collecting the juice in a measuring jug. To every 600ml (1 pt) juice add 450g (1 lb sugar). Place all the ingredients in a preserving pan. Stir constantly over low heat until the sugar has dissolved then turn the heat up to bring to a rolling boil. Boil to setting point, (it took me about 10 minutes) when a blob of syrup on a cold plate will formed a skin when you push your finger over the top of it. If using a jam thermometer it will register 220F 105C. Remove the vanilla pod and fill hot jars, leaving the required headroom for their type. De-bubble the sides using a small spatula or chopstick, wipe jar rims clean, before sealing and placing in the hot water bath. Process for 10 minutes, remove from the bath, then leave till cold before testing the seals. Label and store.

tomato jelly tarts served as a canape topped with sour cream

The ratio of sugar to juice is the classic one used when making jellies. This jelly is very nice indeed but I will be tempted to cut down on the amount of sugar when I make this next. It is often safe to keep jams and jellies without hot water processing (canning) them. If you do can them you are making doubly certain that they will be preserved safely for a year or even longer.




[...] laundry etc laundryetc.co.uk/2010/08/16/bottling-tomatoes-the-acidity-cusp/ – view page – cached Month eight Tigress’s can jam canning challenge and for August the ingredient chosen by the inspired and inspiring Julia is tomatoes. My relationship with this ubiquitous fruit has been a chequered one. I hated tomatoes as a kid but learnt to like them – ish later on. I do like them as a sauce for pizza, applied with a lightness of touch though. I can now eat cherry tomatoes raw and, like… Read moreMonth eight Tigress’s can jam canning challenge and for August the ingredient chosen by the inspired and inspiring Julia is tomatoes. My relationship with this ubiquitous fruit has been a chequered one. I hated tomatoes as a kid but learnt to like them – ish later on. I do like them as a sauce for pizza, applied with a lightness of touch though. I can now eat cherry tomatoes raw and, like biting into any fruit, appreciate their sweetness so I suppose you could say I’ve made progress. View page Tweets about this link [...]

Pingback by Twitter Trackbacks for laundry etc [laundryetc.co.uk] on Topsy.com 08.16.10 @ 1:31 pm

Beautiful! This jelly idea is fabulous. When I have ended up with excess juice I have simply canned it and used it as I would a stock in soups or rice or risotto.

I have a victorio strainer, a similar tool to your passata, which I love for making applesauce and now will try for tomatoes. I’m sorry yours didn’t work well for you.

Comment by Anduin 08.16.10 @ 11:45 pm

Oh, my lord. That jelly is astounding. I must have it! Guess that means I’ll have to make it. I’m not sniffing, though, at the puree. I just have a thing for jelly.

Comment by Julia 08.17.10 @ 3:04 am

I’ve never sieved out the tomato juices when making sauce – interesting. I’ve always just let it cook down “as is” with the rest of the pulp. But then, I don’t sieve the sauce at all, just puree it all together a bit and leave some chunky bits.
Your jelly though makes me want to have a bit of juice just to try the recipe!

Comment by Mangochild 08.17.10 @ 10:50 am

I think I will steal your balsamic idea, if you please. Much nicer than lemon juice in the context.

Comment by Sarah B. Hood 08.19.10 @ 11:15 pm

What a find…love this blog… and your pegs header… hope to be back indeed!

Comment by sophie munns 08.25.10 @ 3:01 am

I’m the founder/moderator for Punk Domestics (www.punkdomestics.com), a community site for those of use obsessed with, er, interested in DIY food. It’s sort of like Tastespotting, but specific to the niche. I’d love for you to submit this to the site. Good stuff!

Comment by Sean 08.25.10 @ 3:59 pm

Hello
Well, this is the best stumble I’ve had for a while. I am about on embark on my real first attempt at tomato canning and I am investigating. Anyway this post is a terrific (and beautiful) resource and noted. I am now off to read more of your blog. My dad is a Lancashire lad and I have (had) an Aunt Nora and still have an Uncle Tom.

Comment by Rachel 08.28.10 @ 1:40 pm

Oh my now I want a passata, despite the fact that you don’t seem a fan. I love that you used balsamic in the puree for added acidity. I follow along with the canjam. Here’s my August entry: http://www.canningwithkids.com/blog/2010/08/nicely-spicy-peach-salsa.html

Comment by Paige 08.30.10 @ 8:07 pm