How to Stop Tomato Soup From Curdling

Tomatoes and milk do not combine together well when heated, but cream of tomato soups require the combination for thickening. When the acid from tomatoes mixes with the neutral milk, the proteins in the milk gather together in curds. This action mirrors the way cottage cheese makers add acid to milk to separate it during heating. However, you can prevent this from happening to your tomato soup or fix the problem if it occurs with a few simple steps.

Things You'll Need

• Canned condensed tomato soup
• 1 tbsp. flour
• 1 tsp. baking soda
• Saucepan
• Whisk
• 1 can full of milk or whipping cream
• Stick blender

Instructions

1. Pour the contents of the condensed soup into the saucepan. Whisk in 1 tbsp. of flour to bind with the proteins in the milk once added. Turn the heat to medium to bring the soup base to a boil. Save the can for measuring out the milk or cream.

2. Turn the heat down to low so the tomato soup base barely simmers. Avoid using a higher heat because the milk will curdle if boiled after its addition.

3. Add 1 tsp. baking soda to the soup concentrate in the saucepan. Wait for foaming to subside. Baking soda cancels out some of the acid in the tomatoes, lessening the chance for curdling.

4. Fill the soup can with whole milk or heavy whipping cream. Use the product you have available with the highest amount of fat. Fats coat the proteins in the dairy, preventing curdling. Avoid using low fat or skim milk. Whisk the dairy into the saucepan with the tomato base.

5. Heat the mixture slowly until the soup heats through, whisking the entire time to prevent curds from forming.

6. Should the soup still curdle after the milk is added, continue to heat, but trade the whisk for an electric stick blender. Blend the soup in the saucepan until it becomes smooth. Serve immediately.

References

• Cookwise; Shirley O. Corriher; 1997
• Liquids - Science
• Whisk away curds