Does your pressure cooker scorch and burn at the thought of pressure cooking a tomato-based recipe? Are you tired of chipping away last night’s dinner from the base of your pressure cooker? Think you can’t pressure cook a recipe that is boiled, soaked, or stewed in tomatoes?!?! I’m sharing my pro tips for getting delicious scorch-free tomato-based sauces and recipes in your pressure cooker.
First, let’s get a big pressure cooking myth out of the way…
It’s not the sugar
I’ve seen this myth perpetuated in cookbooks, websites and discussion boards: Pressure cooking tomato sauce scorches because of the sugars in the tomato.
It’s not true.
Here’s why: sugar, once heated, is a liquid, and a liquid is not very thick, it will not sit at the bottom of the pressure cooker, it will boil. I’ve brought a pressure cooker to pressure with 50% sugar or honey on more than one occasion – see my lemon marmalade and old-fashioned strawberry jam recipes. These recipes don’t scorch. Plus, the label on my jar of tomato puree (passata) says that it only contains 4.5% sugar which is a lot less than what is in those jam and marmalade recipes.
So let’s be clear, that it is not the sugar in the tomato sauce that melds your recipe to the base of the cooker into a jagged layer of carbon.
It’s the thickness
What is actually burning tomato-based recipes is the viscosity, or thickness, of the tomato liquid. Here’s a good explanation about what is technically happening.
Tomato sauce, which is considerably thicker than water, puts up more of a fight. Like ketchup, tomato sauce is a highly viscous substance, which is to say that it resists movement because there’s considerable amount of friction between its molecules. It’s also technically known as a plastic liquid. This means that a substantial amount of effort or force is required to make it flow, but once it starts moving, it does so quite easily. So when the liquid in tomato sauce reaches its boiling point, steam pressure builds up beneath the surface of the sauce. For a while, the sauce remains unmoved, but finally the pressure comes to a head and the sauce gives way, erupting to release the steam.
-(“Why Does Tomato Sauce Splatter Everywhere When It Cooks?”)
While the sauce remains “unmoved” it is actually sitting on the base of the pressure cooker, scorching. Each tomato product has its own viscosity. The thicker the tomato product the more liquid needs to be added to prevent the recipe from scorching. Here are the guidelines I came up with and follow when writing a tomato-based pressure cooker recipe.
Pressure Cooker Tomato Product Quick-referenceThe items are listed in order of viscosity (thickness) along with my notes on how to use them. The more viscous an item, the more likely that it will rest in the base of the pressure cooker and scorch. Please note that "a cup" is equivalent to 250ml, 1/2 cup 125ml, and so on.
|commercial pasta |
sauce or salsa
|very viscous||These products often contain thickeners and gels that will stop prevent the sauce from boiling. Add to the recipe after pressure cooking or follow a recipe that does not use these products. Otherwise, follow instructions for puree, below.|
|tomato paste |
|very viscous||Dilute with ten to twelve times the amount of water to pressure cook by itself. That's about a cup of additional liquid per tablespoon used.|
|viscous||Dilute with the same amount of liquid to pressure cook - that's one cup of additional liquid per cup of puree.|
(fresh or canned)
|somewhat viscous||Dilute with two-thirds the amount of liquid to pressure cook - that's 2/3 cup of additional liquid per cup of crushed tomatoes.|
|chopped tomatoes |
(fresh or canned)
|not very viscous||Dilute with half the amount of liquid yo pressure cook - that's 1/2 cup of additional liquid per cup of chopped tomatoes and their juice.|
|not very viscous||Mash fresh tomatoes to release enough liquid for the pressure cooker to reach pressure.|
Now, remember, the liquid added to tomato products can be water, stock, or wine or – it can be contributed by the other ingredients added to the sauce. For example, carrots and onions are about 88% water, a bell peppers 92% and ground meat is about 73%- so a pound (500g) of ground beef can contribute almost 1 1/2 cups (350ml) of liquid to a tomato-based sauce which can easily mitigate some of the scorch. You don’t need to figure all of this out – I already make all of these calculations for you in the recipes on this website and my cookbook.
7 tips to perfecting tomato-based recipes
In addition to using the right balance of cooking liquid for each tomato products, here are a few more things to keep in mind:
DO Un-thick the Tomato Product – Follow our guidelines, in the Pressure Cooker Tomato Product Quick-reference table above, to figure out how much additional liquid your tomato product needs for the recipe.
DO Scrape it – Don’t build the groundwork for things to stick onto anything else that is already sticking. Scrape the base of the pressure cooker well to lift-up onions, pasta, rice, etc. A good time to do this is usually during a de-glaze step (where you add wine or stock) or just before closing. My weapon of choice for this task is a flat-head bamboo spatula.
DON’T Puree – Don’t blend or puree’ ingredients before pressure cooking – or at least wait until after pressure cooking. Keeping most of the ingredients in large pieces keeps the sauce from getting thick before you’re finished pressure cooking.
DO Bring’em To A Boil – For iffy tomato-based recipes, bring all of the ingredients to a rolling boil before slapping on the pressure cooker lid. This ensures that everything in the cooker moving quickly enough to generate steam and, eventually, build pressure.
DO Layer Like Sass – Lorna Sass, the Queen of Pressure Cooking, introduced a novel way to keep thick tomato sauces from scorching in her cookbooks. She layers recipe ingredients in the pressure cooker by the thickness (stock first, veggies after, tomato sauce last) and then directs the cook not to stir the pot before closing the lid to pressure cook (here’s an example).
DON’T Go Processed – Never use prepared “pasta” or “salsa” sauces as they usually contain starches, gums, flours and other thickeners which will prevent the cooker from reaching pressure. If that’s all you’ve got, mix it in after pressure cooking and simmer the flavor into the food.
DO Bain Marie It – One of our readers, shared in the forums that when there is no other option they use the pressure cooker bain marie (aka pan in pot) method to keep their sauce from sticking.
What are your tips for avoiding scorches from tomato-based recipes? Post them in the comments!
Tomato-based Pressure Cooker Recipes
Here are our no-fail tomato-based pressure cooker recipes that put all of this information and tips into action:
Let us know in the comments if there a particular tomato-based recipe that’s proved elusive or what you do to keep your tomato-based recipe from scorching.
- “Does The Viscosity Of A Liquid Affect Its Boiling Point?“. Reference.com. N.p., 2016. Web. 11 Aug. 2016.
- “Why Does Tomato Sauce Splatter Everywhere When It Cooks?“. Slate Magazine. N.p., 2016. Web. 11 Aug. 2016.