Monday, March 17, 2014

Homemade Tomato Soup That Doesn't Curdle

I have made a lot of cream of tomato soup to get to this recipe:

4 cups hot tomato soup base
poured into
1 cup hot white sauce

These are some versions that I tried:

- hot, thickened tomatoes poured into cold milk (curdled)
- hot thickened tomatoes poured into hot milk (curdled)
- cold milk added to hot, thickened tomatoes (no note written down, but I bet it curdled)

Then, my friend Jan told me that the acid (tomato) and base (milk) must be similar amounts, and the acid must be added to the base.

However, I was not fond of the pale pink tomato soup that resulted from so much milk added.  Rebecca started messing around in her lab (kitchen) and reporting results.  I started independent testing to verify her results in my lab (kitchen), with the results verified by a consumer panel (family).

Look, if tomato soup curdles, it's still tasty.  It's just that the milk turns into sticky little curds and the soup looks freckled, not creamy.  I've never actually thrown out a test batches, just grumbled my way through it.

Last summer, following Rebecca's method, I made and canned tomato soup base.  It's tomatoes cooked with onions, celery, and salt, and then pureed. (Right, Rebecca?  I can't find anything I wrote down anywhere, so I'm going on my paltry memory)

To make tomato soup, I simply heat a quart jar of this tomato soup base while I'm making a white sauce in a saucepan. 1-2 Tbsp. butter, melted (maybe a little mushroom or onion in here if you like), with 1-2 Tbsp. flour whisked in and then cooked together until bubbly.  1 cup warm milk whisked in and whisk whisk whisk over medium-low heat until it steams and thickens.

I usually prefer straightforward cream of tomato soup, but you can add some basil or other herbs, a little cooked rice, or, as mentioned above, something like mushrooms, onions, garlic, or celery in the white sauce.

Serve with crackers, grilled cheese sandwiches, or cheese quesadillas.

Just to muddy the research, how do you make homemade cream of tomato soup?


Dianna said...

I have a homemade tomato-rice soup recipe that calls for the soup to be cooled somewhat before adding the milk. It works sometimes. Last time it curdled so badly my husband thought it had cheese in it!

I have found, though, that canned evaporated milk generally does not curdle.

sillygirl said...

My mother made tomato soup with milk - I make it the same way and I don't remember that hers curdled but it sure does for me now. We eat it anyway but I have wondered why it did that - have canned tomatoes gotten more acidic? She always used homecanned - so did I for many years. I also make a version when I have fresh basil leaves - cut shreds and also add some blue cheese.

AP said...

I make the More With Less recipe, but use a can of tomatoes rather than tomato juice. I also love the "doodles" in the soup!

jenny_o said...

I never make it because I can't eat tomatoes, but I did some googling and the concensus is that there are three main reasons why milk curdles: if it is heated too quickly or if it's boiled at all, if it is low-fat (because it's the milk protein that curdles and fat helps prevent that), and if there is too much salt added to it. (To avoid the first one, add a small amount of the hot liquid to the milk to bring up the temperature gradually before adding the milk to the base.) I think you would have preferred personal experience but I haz none :)

Zoƫ said...

I like this post.

I'm wondering if the freshness of milk doesn't have something to do with it. I haven't conducted a formal experiment but it seems to me that really fresh milk (as in, just a day or two out of the cow) doesn't curdle as quickly as older milk. Not sure how you can solve that problem if you are buying milk...

I made tomato soup concentrate for the first last year. It sounds like yours except that I add the flour and butter to it before canning and then I simple add an equal part milk and heat it up. It hasn't seemed to curdle as badly as when I used to make it from scratch every time. Who knows why!

Unknown said...

Good ideas!!!

Margo said...

Jenny_o, this is very helpful research, actually! Thank you! I am usually afraid to open the floodgates of Google and much prefer asking the experienced people around me. Or (in your case) the clever researchers.

Zoe, what is your method for putting the butter and flour in the canned puree? I might try it your way this summer.

momma-lana said...

My Mom fed us so much tomato soup when I was growing up that I really cannot stand the stuff. I think she must have really fed it to us when we were sick because that is what I associate it with. I wonder what foods my grown children connect with being sick--probably applesauce which is why they will not eat it now.

Angela said...

I have heard of a recipe with no cream at all- essentially you make a butter flour roux then add the tomatoes and it seems creamy- but doesn't actually have any cream in it. I wonder now though if a tomato soup base with a few potatoes boiled in it then pureed would give a nice cream-less creamy tomato soup. might have to try that...

jenny_o said...

Haha - Margo, let us just hope the research is correct :)

Sew Blessed Maw [Judy] said...

I make a tomato/potato soup, [the same soup recipe that my mom and mother in law made]..It uses milk in it. It does not curdle. I cook the soup and right before adding the milk, I add a small amount of baking soda [about 1/2 teaspoon ]. My mom always says that the soda keeps the milk from curdling??? I don't know if this will work for your soup? But it would be worth a try.
NOte-- You will need to lessen the amount of salt that you put in your soup, as the soda makes it more salty.
Hope this helps.

Rosalyn said...

I learned from some of my quilting friends that you just add a tiny bit of baking soda to your tomato juice as you are heating it and milk can be added anytime and it does NOT curdle. I now use this method and we are really enjoying hot tomato soup from our own canned tomatoes.

Sarah Barry said...

I'm such a fan of creamy tomato soup (without curdles)! Can't wait to experiment.

Rebecca said...

Yep. That's my base. I add approx. 2 tsp. sugar per quart jar, too. One year I added lovage because I had a forest of the stuff but I don't really recommend that. Parsley would be good.