Thanks Christina! Some people think that thier being healthy by not using cornstarch but think about what cooking the sauce down to a paste does to the nutritional value. The more you cook it the less nutritional value. My great grandmother was from Northern Italy. She used cornstarch to thicken sauces and and pie fillings as well as coat things to pan fry in olive oil. Corn starch is ony bad if someone has an alergy to corn products. Which is very rare.

I'm with you, Donny, as far cookbooks and stuff goes. My commentary and technique is based on a Sicilian Grampa. We never added thickeners. But of course, cooking is chemistry, and the enjoyment comes from experimentation.

I've got the last of my tomatoes on the stove right now (frost coming on Friday). I'll try a small batch with your cornstarch method and see how it turns out!

Oh yah! Throw you cook books out and stop cooking by recipe's and learn to cook by thoery.

Well I made the assumption that the question was about canned tomato paste. And the other part of the question was about acidity. Canned tomato paste is thickend with corn starch and cooking it down doesn't do alot for acidity. Any good chef knows you balance any thing that is acidic. I mentioned the ways of doing it. So there you go.

Apologies to Donny, but I'm with Serene. The key to paste is to prep it like a sauce, then cook the moisture out of it; low and slow.

Eeek! No, I wouldn't thicken tomato sauce with cornstarch and call it tomato paste. It's very easy to make from tomatoes and a little olive oil and salt. See http://www.saveur.com/article/Recipes/Homemade-Tomato-Paste for example, but I've never bought a tomato paste with cornstarch in it, and wouldn't use it in my homemade paste, which turns out really well.

Well, tomato paste is basically tomato sauce thickened with corn starch. If you want low acidity in tomato paset or sauce, balance the sauce or paste with a few pinches of sugar or honey. Add either ( I prefer honey) until the acidic bite goes away but doesn't sweeten the sauce. Wine of good quality (good quality wine usually is low acid) can also balance the sauce and add complexity as well. A cheap wine can make this worse if it has an acidic or hot with alcohol bite.


If starting from scratch means starting with your garden tomato's look for a recipe for making tomato sauce. Which usaully states Cutting an X on the tip of the tomato add to a boiling pot of water for 5 min remove, shock in cold water, peel, de-seed and cook down until masurated, finish with a blender or emersion blender.

Or Oven Roast tomato's until fully cooked and run them through a food mill and reduce pulp over low heat until thick.

Once you have made tomato sauce add a corn starch slurry until sauce thickens to a past like consistancy ( you must have tomato sauce boiling or near boiling to activate the thickening process of corn starch. Stir constantly. The amount of corn starch will depend on the amount of tomato sauce.

Corn Starch Slurry: A mixture of corn starch and water. At home I add three heeping spoonfuls of corn starch to a Coffee mug and add water and stir until mixed. Then I'll add a little at a time watching and checking the sauce consistancy. Stir slurry every time before you add more ( ti doesn't stay mixed) until I have desired consistancy.