June 2, 2025, 9:03 am | Read time: 4 minutes
If broccoli stays in boiling water too long, it becomes so soft that it can be mashed against the roof of your mouth. This is neither particularly appetizing nor does the overcooked vegetable retain many vitamins. FITBOOK nutrition expert Sophie Brünke shares how to prepare your vegetables to keep them crisp and vitamin-rich.
When cooking, up to 60 percent of vitamins can be lost, especially if the cooking water is poured off and not reused, such as for a broth base.1 By “cooking,” I mean that the vegetables are cooked in 100-degree water—even though the term is generally used for various kitchen tasks. If you want to do something good for yourself by eating vegetables, you should switch to other cooking methods to preserve vitamins.
Overview
Steaming – with a Steamer Insert or in a Pressure Cooker
When steaming, water is also brought to a boil, but it does not come into contact with the food. Instead, the vegetables are gently cooked in steam. To do this, place the food in a metal or bamboo steamer insert that can be placed in a pot. These come in various sizes for conventional pots. Alternatively, a simple kitchen sieve will do. There are also special devices like electric steamers or microwave containers for steaming. If you want to save a lot of time, use a pressure cooker. Due to the additional pressure, most vegetables only need one to two minutes to become al dente.
Back to the classic steaming method: Once the water in the pot boils, the steam rises through small openings in the insert and gently cooks the vegetables—under a closed lid to prevent the steam from escaping. Be careful when opening: The steam can be very hot.
A clear advantage of this method is that water-soluble nutrients like vitamin C and B vitamins do not leach into the cooking water and are largely retained. Flavors and spices also remain in the food instead of being “washed out,” resulting in a more intense taste.
Preserve Vitamins by Stewing Vegetables in Their Own Juice
When stewing, food is cooked in its own juice or with only a little additional liquid. The food is placed in a shallow pot or pan with a tightly fitting lid to prevent steam and aromas from escaping.
First, everything is briefly heated and then cooked at medium heat in a closed pot. Stirring is not necessary—instead, occasionally shake the pot gently. The resulting cooking liquid is ideal as a base for a sauce. As a rule of thumb, the more water-rich the vegetable (e.g., zucchini, tomatoes), the less liquid needs to be added. For frozen vegetables, the inherent moisture is usually sufficient.
Both stewing and steaming result in a manageable vitamin loss of about ten to twelve percent.
Roman Pot and Sous-vide
In addition to stewing in a pan, you can also use a Roman pot in the oven. The process remains the same, but it opens up new possibilities, as you can also stew other foods like fish or meat in the oven.
A modified form of stewing is sous-vide, where vegetables, fish, or meat are packed in a plastic bag and cooked at low temperatures. Here, flavors and spices fully penetrate the food, making the taste particularly intense.
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Blanching Is Particularly Quick
Blanching means briefly cooking food in boiling water and then shocking it in ice water. This immediately stops the cooking process. The vegetables remain crisp and retain their color—yet they are more digestible. The method is also suitable as a preparation for freezing, as the heat kills germs and decomposing enzymes. Blanching is especially useful for spinach, broccoli, carrots, or cabbage.
Here’s how it works: Wash the vegetables, cut them into pieces, and briefly cook them in boiling salted water–depending on the type, a few seconds (e.g., Swiss chard) to seven minutes (e.g., broccoli). Then, immediately place them in ice water.