Update August 2017
Three years later, I’m going to consider this an archive page. My views have changed and I’m constantly learning.
I myself wouldn’t do pasta sauce this way anymore. I am leaving it up as I know many people are curious about the idea of using a pressure cooker for pasta sauce.
The results just took too much futzing and too much time, and, they are going to vary a lot for people depending on whether your pressure cooker vents moisture out as steam or not and how much — there are different types including electronic now.
My current thinking is that roasting is the best way to reduce a lot of tomatoes for a sauce:
- you can do it en masse with several sheets at once;
- it’s very energy efficient (remember, ovens are not on all the time, they only cycle on as needed to maintain temperature);
- it involves the least active time from the cook;
- you can peel after roasting — the skin slips right off.
I have written about that here: Roasting tomatoes
The exception would be if you are making a home-canning recipe, and it calls for the tomatoes to be reduced to a sauce in another way such as boiling in a pot. While many tested, safe home canning recipes can be notorious for not giving reasons behind why they want something done in a certain way, in general it’s that way for a good reason, and you do want to follow the directions of the people who developed that recipe.
If you do want to make a pasta sauce for home canning, bear in mind that safety aspects must be paid attention to once you seal food in a jar and stick it on an unrefrigerated shelf. Do not use someone’s Italian nonna’s recipe you find on the web. Botulism spores must be controlled for, and those old recipes do not take that into account.
Here is a growing list of safe, tested pasta sauce recipes for home canning — some of which call for boiled down tomatoes, some of which call for tomatoes reduced through roasting, so you can take your pick. Many recipes will call for added acidity in the form of lemon juice or citric acid. Don’t skip that step, it’s there to ensure a safe pH.
So again, I’m leaving this up just for those who are curious if anyone ever documented attempts to use a pressure cooker to reduce a tomato sauce.
If you’ve tried and had success, let me know, saying what model of pressure cooker you used. I’d be particularly interested in hearing from people who used an Instant Pot or similar type of electronic pressure cooker.
Note: Above all, DO NOT attempt to use your electronic pressure cooker to home can jars of pasta sauce. The National Center for Home Food Preservation warns explicitly against that. They are not canners, regardless of what manufacturers may have originally said. Instant Pot, for instance, has publicly withdrawn their support for using their appliances for canners. See: Should I can in my electric multi-cooker appliance?
Remember, freezing is always a great option! If you freeze in jars, leave good headspace, and use only straight-sided jars (jars with shoulders may explode on you in the freezer as your sauce expands during freezing.)
I’d recommend you read this pressure cooker pasta sauce article by Laura Pazzaglia over at Hip Pressure Cooking.
My piece was originally written in 2014, two years before Laura wrote hers. I wish I’d had her advice back in 2014!
This turns fresh tomato purée into a very thick tomato sauce with no tomato paste needed, nor any stirring needed once the cooking has begun.
Wash the tomatoes, quarter them (no need to peel or seed, but do so if that is your preference), process through food processor. You will end up with a thick purée / juice.
(Note: Cooking times WILL vary based on the variety of tomato being used. If you are using tomatoes really meant to be more juicy, fresh-eating type tomatoes as opposed to sauce tomatoes which are naturally less watery, then you may need to double cooking times below.)
Bring this purée to a rolling boil in the pressure cooker, with no oil, tomato paste, etc, added, stirring with a wooden spoon until you can’t break the boil anymore, then put the lid on, seal it, bring to pressure, and set on low pressure. Here are the cooking times under pressure:
4 cups (32 oz / .95 litres) of purée: 30 minutes
8 cups (64 oz / 1.9 litres) of purée: 40 minutes
16 cups (128 oz / 3.8 litres) of purée: 60 minutes
24 cups (192 oz / 5.7 litres) of purée: 85 minutes
At the end, let pressure release naturally.
If it is still runnier than you wanted, bring back up to pressure and cook some more — all things being equal, say, 15 to 20 minute intervals.
Yield: exactly one half the volume you started with.
The nitty gritty follows, for those interested
I’m going to give you my experiment step by step so that you will understand how the cooking time affects the thickness of tomato sauce in a pressure cooker. I’m also going to provide photos so that you can see how the sauce shapes up after different periods of time.
My pressure cooker is a Nutricook™. I used the veg setting on it; that is a low pressure setting of around 40 kPa (5.8 Psi).
I used to not be one for skinning and seeding tomatoes. I pooh poohed the idea, as many people do nowadays. But now that I’ve learnt proper techniques, it’s really not a bother, and it does result in a more palatable product.
I’ve also come to desire having those tomato skins for dehydrating. Once they are dried, they can be whizzed into a powder, that can then be used as a garnish on dishes, or as the base for a great meat rub, etc.
If you are making a pasta sauce recipe for home canning, and your directions tell you to peel, then you must peel. The people who developed that recipe will be counting on that reduced microbial load going into the canner. See here for tips on peeling tomatoes.
I began by puréeing the tomatoes in a blender, but it’s a pain: they get stuck and you have to remove the jug, jiggle it so they will fall down more and hit the blade, etc. When I switched to a food processor for the tomatoes, the work went much faster and it did just as good a job.
Getting started with the pressure cooker tomato sauce
Above, you see my initial starting setup. When I switched from the blender to a food processor, the processing of the tomatoes into a tomato purée went much faster.
I did my initial test with 8 cups (2 US quarts / 64 oz / 1.9 litres) of tomato purée.
I should have done this looking at the metric side; the comparisons later on would have been so much easier. Anyway, I didn’t, so the rest of the world and future generations will hate me. But then again, with measuring jugs this big, it’s not as though we’re talking graduated cylinder precision anyway, eh?
There above is what the puréed sauce looked like, fresh out of the food processor, and ready to start cooking with.
I poured the sauce in the pressure cooker pot with nothing else: no oil, no herbs, no bay leaf, no salt and pepper, no tomato paste, nada. This is a basic sauce test.
With the lid off, I brought the raw tomato sauce to a good rolling boil, stirring frequently with a non-reactive, wooden spoon (habit from times past when dealing with tomatoes) as the boiling started. I was very leery of this initial coming to temperature stage: I did not want the sugars in the tomato to scorch at the bottom of the pot under the heat high necessary at first in pressure cooking (another good reason to keep tomato paste out at this stage, by the way.) When the boiling got so vigorous that it was frothing and I couldn’t stir it down anymore, I put the lid on and sealed it.
I set the time for the first cooking for 15 minutes, on the veg setting on the Nutricook (lowest pressure.) I figured that wouldn’t be enough, but I wanted to be able to assess the progress in stages.
After 15 minutes of cooking time
After 15 minutes, the starting volume of 8 cups / 64 oz / 1.9 litres has reduced to: 6 3/4 cups / 54 oz / 1.6 litres.
That’s a reduction of 15 % from the initial raw purée (1.9 litres to 1.6 litres = 300 ml).
There it is above. It’s something that I’d term “fully cooked tomato juice.” It’s ready to be bottled or frozen as processed tomato juice, to be used in a soup, or as a juice, or simmered down further in an open pot into a thick sauce with the addition of tomato paste, flavourings, onion, peppers, mushrooms, etc.
But our goal is to see if we can avoid the whole simmering cauldron scenario to make it a thick sauce. The added bonus is that reduced volume requires less space in the already over-crowded deep freezer. So onward.
After 30 minutes of cooking time
After a total of 30 minutes, the volume has reduced to: 5 1/2 cups / 44 oz / 1.3 litres.
That’s a reduction of 30 % from the initial raw purée (1.9 litres to 1.3 litres = 600 ml).
There it is above. It is thick enough to pass for most homemade pasta sauce uses, quite nice.
It’s like a nice fresh-made sauce, what an Italian might call a “sugo”, with no need for tomato paste in it for that semi-thick texture typical of a quick, homemade “sugo” (sauce.)
However, I’d like to see if a small amount more of cooking will thicken it even further. If it takes hours more of pressure cooking to thicken it significantly more, forget it. But if a few minutes more can make a difference, I’d like to know.
So I’m going to give it another 10 minutes.
After 40 minutes of cooking time
After a total of 40 minutes, the volume has reduced to: 4 cups / 32 oz / 950 ml.
That’s a reduction of 50 % from the initial raw purée (1.9 litres to .95 litres = 950 ml).
There it is above. It is thick enough for swirls in it to hold.
It’s quite thick and heavy; you’d almost think there were tomato paste in it.
In fact, it’s so thick that…..
You literally can stand a spoon up in it!
If you’re looking for something as thick as a sauce that came out of a commercial jar, 40 minutes is the timing you are after for this volume of raw tomato purée. You won’t be disappointed, and there is no need for tomato paste.
40 minutes in a Nutricook pressure cooker, anyway. Times may vary a bit either way in your pressure cooker.
Also, please note: I would speculate that the time required might have been longer if fresh veg that give off water had been added. Veg such as bell pepper, onion, zucchini, mushroom, eggplant, etc, because as they cooked and broke down, they would have released more water into the pot that needed to be cooked away.
Pump up the volume
I had 12 dozen tomatoes to process. When puréed, that yielded I think it was about 6 or 7 of those large measuring jugs. Anyway, if I processed one jug at a time through the pressure cooker, I was gonna be there all night. Literally.
Plus, in a real-life tomato sauce making situation, you have bazillions of tomatoes to process at once. When it rains tomatoes, it pours. It cascades. You don’t cook 2 or 3 cups of the stuff at a time.
So, I tripled the volume being cooked at one time. I wanted to go more than double, but I wanted to stay well under the safe fill line on the pressure cooker; as well, I didn’t want to scorch the bottom while I waited for a totally huge amount of liquid to come to temperature (always the worry in a pressure cooker.) So, I triple it was. A leap for sure, but not a totally crazy one.
No photos, as the evening was getting very late, and the magic was leaving the room on this topic, but here are the results.
I started with 24 cups / 192 oz / 5.7 litres of fresh tomato purée. Again, good rolling boil, stirring frequently, before the lid went on. Veg setting / low pressure.
After 15 minutes: 21 cups / 168 oz / 5 litres. Tomato juice.
After 40 minutes: 17 1/2 cups / 140 oz / 4.1 litres. Maybe just a tad thinner than what you’d describe as a “quick homemade sauce”. Usable, but most people would want thicker.
After 60 minutes: 15 cups / 112 oz / 3.3 litres. A thickish homemade style sauce, but the spoon won’t stand up yet.
After 85 minutes: 13 cups / 104 oz / 3 litres. A very thick sauce that the spoon will stand up in. We’re done here.
Caution: If you are using a Nutricook, and you are doing a long session like this with a lot of liquid being expelled as steam, I would remove your Nutricook timer every 25 minutes or so to wipe away any water condensing under the timer. Just a quick wipe with a paper towel will do it and put it back in; don’t press the buttons to mess up the time. Better safe than sorry, as condensation can kill a Nutricook timer faster than you can say Jack Robinson.
Note: the cooking time might actually be quicker because I did start and stop the pressure cooker three times to record the ongoing results.
I haven’t tried using canned tomatoes yet, but in the dead of winter when fresh tomatoes cost a bomb I definitely would.
Here’s what I would try. I would pass canned tomatoes, juice and all, through a food processor until I had 8 cups (64 oz / 1.9 litres) of tomato purée.
I would bring that to a rolling boil in the pressure cooker, with no oil, tomato paste, etc, added, stirring with a wooden spoon until you can’t break the boil anymore, then put the lid on, seal it, bring to pressure, and set on low pressure for 30 minutes. Let pressure release naturally.
I’m suggesting 30 minutes rather than 40 (as per the fresh tomatoes) as canned tomatoes have already had a bit of a head start by being cooked in the can during the canning process. Check after 30 minutes, and see. If needed, recover, bring back up to pressure and cook a bit more.
Tip: it’s pretty easy these days to get no-salt added canned tomatoes at no additional expensive so why not get those and take one more small step to regain control of sodium levels in your kitchen?
The tomato sauce, as is, is pretty boring (aside from the fantastic tomato taste), BUT the beauty is, it is flexible; you could use it just as you would a canned plain tomato sauce, which is to say as an ingredient in something, or, you can take it and run with it now. Add some herbs, some oil, some roasted veg, some sautéed minced onion, garlic, carrot and celery and simmer a bit; some cooked ground beef maybe.
For extra velvety richness, you can add some tomato paste (you may wish to try to find unadulterated tomato paste, which hasn’t had a boatload of sugar added.)
P.S. See Laura Pazzaglia’s advice on how to cook perfect al dente pasta in a pressure cooker, every time. It works. I do it all the time now.
In fact, if you’re interested at all in pressure cooking, Laura’s book “Hip Pressure Cooking: Fast, Fresh, and Flavorful” (2014) is ground-breaking and I can’t recommend it highly enough. An eminently usable book that teaches you both recipes and principles.
* Nutricook™ is a registered trademark of SEB, France.