There is no point in eating home-cooked food if it doesn’t fulfil your daily nutrient quota or if your cooking methods are spectacularly leeching away most of the nutrients in it. Excessive heat does destroy the nutritional value of meat and vegetables, but not all of them do so. Our grandmothers knew what they were doing, which is why they had elaborate methods for cooking certain dishes with local ingredients in a certain way.
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You might be surprised to know that studies indicate that frozen fruits and vegetables have higher levels of Vitamin C. This is because transportation and storage processes kill off some nutrients, and by getting frozen from farm to factory, nutrient leeching stops at the source. Besides this, there are other cooking techniques that promise healthier, nutrient-rich fare on your table. By cracking the code on preparation, you can easily optimise every meal's health benefits. Here are the best ways to preserve nutrients while cooking:
1. Steaming
Research shows that steaming vegetables helps retain good levels of water-soluble vitamins and minerals. When vegetables are steamed, they are cooked in the steam rather than being submerged in water, so fewer nutrients tend to leach out. According to one study, carrots and broccoli retained higher nutritional values when boiled compared to when steamed, fried, or served raw. This is because steaming prevents nutrients from dissolving and being lost in cooking water, as occurs with boiling. However, steaming still results in some loss of heat-sensitive vitamins. For example, approximately 66 percent of vitamin C is lost when spinach is steamed, according to another study. On average, steaming causes vitamin C levels to decrease by 15–55 percent compared to raw amounts. Therefore, steaming helps maximise retention of water-soluble nutrients but still results in reductions.
2. Boiling
Boiling vegetables in a small amount of water allows some water-soluble vitamins and minerals to dissolve into the cooking liquid rather than being entirely degraded. Research indicates boiling retains nutrients better than frying or no cooking. However, boiling also leaches vitamins and minerals into the water. One study found that boiling broccoli caused it to lose 22-34 percent of vitamin C. While boiling helps extract some nutrients from food, it also results in significant losses of heat-sensitive vitamins when cooking water is discarded.
3. Stir-frying
Stir-frying in a small amount of oil over high heat quickly seals in flavours and locks in nutrients before they can degrade. It has a short cooking time that protects vitamins from heat exposure. One benefit is that stir-frying does not involve submerging in water, where water-soluble nutrients may dissolve and be lost. However, the high temperatures still break down some vitamins. On average, stir-frying retains slightly more nutrients than boiling but less than methods using even lower heat, like microwaving.
4. Baking
Baking at moderate temperatures of 150–200 °C helps retain nutrients compared to frying at higher temperatures. It also does not require additional fat. Baking exposes food to dry heat rather than water, reducing the leaching of water-soluble nutrients. However, baking still causes the degradation of vitamins and minerals due to heat exposure over the cooking period. On average, baking results in nutrient losses of 20–40 percent, depending on the food.
5. Microwaving
Microwaving uses lower moisture-based heat and a short cooking time, retaining up to 90 percent of vitamins like vitamin C, according to a few studies. One study showed microwaving broccoli retained 90 percent of vitamin C versus steaming or boiling it, which retained only 66–78 percent. Microwaving results in minimal nutrient losses of only 5–10 percent on average. It is among the best methods for maximising the vitamin and mineral content of foods.
6. Roasting
Roasting at high dry heat caramelises sugars for flavour but has a short cooking time, retaining nutrients better than longer methods. However, it provides no benefit over low-heat methods like microwaving in terms of nutrition retention and still results in 10-30 percent losses of vitamins and minerals.
7. Dry-Heat Cooking
Dry heat cooking methods like baking, roasting, and sautéing expose food to hot air instead of moisture. This helps retain many water-soluble nutrients by preventing them from dissolving during the cooking process. However, longer dry-heat cooking times can still break down vitamins and minerals through prolonged heat exposure. Quick sautéing or roasting at high temperatures helps maximise nutrition retention with dry heat styles.
8. Grilling
Grilling over an open flame seals in flavours via the Maillard reaction. However, the high cooking temperatures also cause greater nutrient degradation than methods using shorter, lower temperatures. Grilled foods should be cooked quickly over a hot fire to medium-rare quality to help retain the most vitamins, minerals, and phytonutrients. Marinating ingredients before grilling is a must to help prevent flare-ups that burn and destroy nutrients.
It is a given, but still needs to be said, that all cooking causes some reduction in a food's original nutritional value. Microwaving and steaming retain the most vitamins and minerals on average, while boiling, baking, and stir-frying retain moderate amounts. Frying results in the greatest losses, unless it is coated in batter and fried. The best way to get the most out of food is to consume a variety of cooked and raw fruits and vegetables to maximise overall nutrition.