White bean soup is a creamy, hearty soup made from navy beans or other white beans, vegetables, and broth. It is a popular soup throughout the Mediterranean region as well as in the Americas. The creaminess of the soup comes from puréeing some of the cooked beans to thicken the broth. However, some recipes also call for adding a starch thickener to further thicken the soup and give it a velvety texture. The most common thickeners used in white bean soup recipes are flour, cornstarch, and puréed potatoes. The choice of thickener depends on the flavor and texture the cook is trying to achieve.
Flour as a Thickener
Flour is one of the most commonly used thickeners for soups and stews. All-purpose flour or white flour can be whisked into the hot liquid to create a roux. A roux is a mixture of equal parts fat (usually butter or oil) and flour that is cooked over low heat. The starch in the flour absorbs the liquid and turns it into a smooth, thick mixture.
For white bean soup, 2-3 tablespoons of flour whisked into the hot broth and beans will help create a velvety texture. The roux must be whisked continuously to prevent lumps from forming. It also must cook for a few minutes to eliminate the raw, starchy taste of flour. The amount of flour can be adjusted based on how thick the cook wants the soup.
Too much flour can make the soup overly thick and pasty. Flour adds only a subtle flavor that complements the beans and vegetables. It allows the other ingredients to remain the star components.
Advantages of Flour
– Flour is readily available and inexpensive
– It dissolves easily into soups and sauces
– Adds a velvety texture without changing flavors
– Thickens at a wide range of temperatures
Disadvantages of Flour
– Can make the soup gluey or pasty if too much is used
– Raw flour taste if not cooked properly
– Less thickening power compared to other starches
– Requires making a separate roux
Cornstarch as a Thickener
Cornstarch is another popular thickener used in soups and stews. It is a finely ground starch made from corn kernels. Cornstarch has twice the thickening power of flour, so only 1-2 tablespoons are needed to thicken 4-6 cups of liquid.
The cornstarch should be whisked into a slurry with a bit of cold liquid before adding it to the hot soup. This prevents clumping. The soup should be brought back up to a simmer to activate the cornstarch. Simmer for 1-2 minutes as the soup thickens.
Compared to flour, cornstarch results in a clearer, glossier texture. The flavor is neutral and does not interfere with the bean and vegetable flavors. Too much cornstarch can make the soup overly thick and gloppy.
Advantages of Cornstarch
– Provides a clear, glossy texture
– Very powerful thickening capability
– Neutral in flavor
– Dissolves easily in liquids when mixed with a slurry
Disadvantages of Cornstarch
– Can make soup gummy or gloppy if overused
– Loses its thickening power if overheated or cooked too long
– Not as readily available as flour in some regions
Puréed Potatoes as a Thickener
In addition to flour and cornstarch, cooked and puréed potatoes can be used to thicken and add body to white bean soups. Potatoes add texture and nutrition while creating a rich, hearty broth.
About 2-3 medium sized potatoes can be peeled, cubed and cooked until very soft. The cooked potatoes are then mashed or blended into a smooth purée. This potato purée is then stirred into the hot soup.
Potatoes contain starch that helps thicken the surrounding liquid as it cooks. But potatoes also add fiber, potassium, vitamin C and other nutrients. The flavor of potatoes complements the beans and vegetables commonly used in white bean soup.
Too much potato can make the soup heavy and dense. Finding the right ratio takes some trial and error. But it creates a satisfying soup that is naturally thickened.
Advantages of Potato
– Adds fiber and nutrients
– Provides rich texture and flavor
– Thickens soup naturally as it cooks
– Allows avoiding flour or cornstarch
Disadvantages of Potato
– Can make soup too dense or thick if overused
– Requires extra steps of cooking and puréeing potatoes
– Hard to control exact thickness compared to starches
Factors that Affect Thickening
When using a starch thickener in white bean soup, it helps to be aware of factors that determine how well it will thicken the liquid:
Type of starch – Flour, cornstarch, and potatoes each contain different amounts of starch and absorb liquid differently. Cornstarch is the most powerful thickener.
Amount used – The more starch added, the thicker the soup becomes. Too much can make it unpleasantly thick.
Acidity of liquid – Acids interfere with the absorption of liquid by starch. Bean cooking liquid is not very acidic.
Cooking temperature – Starches thicken optimally at simmering temperatures around 180°F to 205°F.
Cooking time – Starch needs sufficient cooking time to fully thicken liquid. Over-cooking can thin the soup again.
Ingredients in soup – Other ingredients like beans, vegetables, and protein add texture and affect liquid absorption.
Prep method – Properly dispersing starch in a slurry or roux prevents clumping and improves distribution.
Understanding these factors helps cooks control starch thickening and achieve the ideal creamy bean soup texture.
Sample Recipes
To illustrate how different thickeners are used, here are three white bean soup recipes using flour, cornstarch, and potato as the main thickener:
Flour-Thickened White Bean Soup
Ingredients:
– 1 pound dried navy beans
– 1 onion, diced
– 2 carrots, peeled and diced
– 2 stalks celery, diced
– 3 cloves garlic, minced
– 5 cups vegetable or chicken broth
– 2 bay leaves
– 1 teaspoon thyme
– 3 tablespoons olive oil
– 3 tablespoons all-purpose flour
– Salt and pepper to taste
Instructions:
1. Soak beans overnight. Drain and rinse beans.
2. In a pot, cover beans with water and bring to a boil. Reduce heat and simmer 1 hour until beans are tender.
3. Heat oil in pan. Sauté onion, carrots, celery and garlic 5 minutes.
4. Add sautéed vegetables, broth, bay leaves and thyme to cooked beans. Simmer 30 minutes.
5. Make a roux by whisking flour and olive oil together. Whisk roux into soup.
6. Simmer 15 minutes until soup thickens.
7. Purée 1 cup of beans and return to pot for thicker texture.
8. Season with salt and pepper to taste.
Cornstarch-Thickened White Bean Soup
Ingredients:
– 1 bag (16 oz) dried cannellini beans
– 1 quart chicken broth
– 1 onion, chopped
– 3 cloves garlic, minced
– 1 teaspoon oregano
– 2 large tomatoes, diced
– 2 carrots, peeled and diced
– 1 bay leaf
– 2 tablespoons cornstarch
– 1⁄4 cup cold water
– Salt and pepper to taste
Instructions:
1. Rinse beans and soak overnight. Drain soaked beans.
2. In a pot, combine beans, broth, onions, garlic, oregano and bay leaf. Bring to a boil, the reduce heat and simmer for 1 1⁄2 hours.
3. In a small bowl, dissolve cornstarch in cold water.
4. Add carrots and tomatoes to pot and continue simmering 30 minutes until beans are tender.
5. Stir in cornstarch mixture and simmer 5 minutes until soup thickens.
6. Season with salt and pepper.
Potato-Thickened White Bean Soup
Ingredients:
– 1 pound great Northern beans, soaked overnight
– 2 tablespoons olive oil
– 1 onion, diced
– 2 carrots, peeled and diced
– 2 stalks celery, diced
– 2 cloves garlic, minced
– 6 cups vegetable broth
– 2 medium russet potatoes, peeled and cubed
– 1 teaspoon basil
– 1 teaspoon oregano
– Salt and pepper to taste
Instructions:
1. Drain soaked beans and add to a pot with broth. Bring to a boil, then reduce heat and simmer 90 minutes.
2. In a skillet, heat olive oil over medium high heat. Sauté onion, carrots, celery and garlic for 5 minutes.
3. Add sautéed vegetables to beans and cook 30 minutes.
4. In a small pot, cook potatoes until very tender, about 15-20 minutes.
5. Drain potatoes, reserving 1/4 cup liquid. Mash potatoes, adding reserved liquid as needed.
6. Stir mashed potatoes into soup and simmer 15 minutes to thicken.
7. Season with basil, oregano, salt and pepper.
Conclusion
There are several good options for thickening creamy white bean soups. Flour, cornstarch, and puréed potatoes can all add texture and body to the broth. Each has advantages and disadvantages. Flour provides a classic velvety texture but requires making a roux. Cornstarch is very effective with just a bit needed, but can make the soup gloppy. Potatoes add fiber and nutrients while giving a rich, hearty result.
The best thickener depends on the flavor, ingredients, and desired texture of the finished soup. When adding any starch, start with a smaller amount and adjust as needed for the ideal creamy bean soup. Proper cooking and dispersion prevents clumping or rawness. With the right thickener and method, white bean soup can be elevated from watery to luscious and comforting.