The Right Way to Cook Vegetables

CONSERVATION OF NUTRIENTS

Though we buy fresh and seasonal vegetables, are we sure whether after cooking we are able to retain the maximum nutrients?

Did you know that how you cook them makes a huge difference in how well you retain those nutrients? 

Some cooking methods preserve nutrients and even help them enter your bloodstream, while others can destroy them. So once you bring home those vegetables from the market, look to the strategies here to get the most nutritional bang.

STEAM, DON’T BOIL: TO GET THE MAXIMUM NUTRITIONAL BENEFITS, YOU NEED TO COOK VEGETABLES CORRECTLY!!!

“Eat more local vegetables” is long-standing advice for a healthy diet – and for good reason. A diet high in vegetables has been tied to a lower risk of high blood pressure, heart attack, stroke, cataracts, macular degeneration, cognitive decline, and digestive-tract cancers. Thanks to their protective mix of vitamins, minerals, fiber, and phytochemicals, vegetables are thought to help dampen inflammation, fend off harmful free radicals, and boost immunity.

To reap their maximum nutritional benefits, we need to cook them right.

While all cooking methods alter the nutrient composition of vegetables (and fruits), some destroy particular nutrients while others retain the nutrient content. 

VULNERABLE VITAMINS

Vitamin C and many of the B vitamins are the most unstable nutrients when it comes to cooking. Because they're water-soluble, they leach out of vegetables into the cooking water. If you boil your vegetables using too much water, you'll end up with less thiamine, folate, vitamin B6, vitamin B12, and a lot less vitamin C.

According to a review by researchers, as much as 55 percent of vitamin C in vegetables is lost during home cooking (compared with raw). Vitamin C is also easily degraded by heat.

Polyphenols – phytochemicals plentiful in greens/ keerai and colored veggies– are also susceptible to degradation during cooking.

Fat-soluble nutrients such as vitamins A, E, and K are more stable and fare better during cooking. So do carotenoids (e.g., beta-carotene, alpha-carotene, lycopene, lutein), antioxidants found in carrots, gourds, sweet potato, and, in the case of lycopene, tomatoes.

WHY STEAMING?

Water is the enemy when it comes to nutrient losses during cooking. That's why steaming is one of the best methods to preserve easily damaged nutrients, such as vitamin C and many B vitamins. Since vegetables don't come in contact with cooking water during steaming, more vitamins are retained.

Dry cooking methods such as grilling, roasting, and stir-frying also retain a greater amount of nutrients than boiling but not more than steaming. If you prefer to boil your vegetables, save the nutrient-rich cooking water to add to curries and while making Rotis.

Saving nutrients during the process of cooking is called conservation.

Cooking affects how vegetables retain nutrients, but how you prepare them matters, too.  

Guidelines to minimize nutrient losses during the preparation of veggies-

1. Choose fresh foods that are not over-ripe, bruised, cut, or scraped.
2. Wash vegetables before cutting. Soaking or washing time should be reduced to minimize nutrient loss. 
3. Cut vegetables into big pieces so that exposure of vitamins to water is less while cooking and washing.
4. Use a vegetable peeler to remove the skin as it helps remove only a very thin layer of skin.
5. Mostly try to cook with the peel on as many key nutrients are found in or just under the vegetable peel, so leave the peel on whenever possible.
6. Use minimum water for cooking. Bring the water to boil and add preferably steam the vegetables. (I use my Idli cooker as a steamer- Soft veggies take 3 mins on high and hard veggies take 4-5 mins on high)
7. Cook vegetables by steaming and indirect pressure cooking i.e. there should be no direct contact of veggies to the vessel bottom. just to avoid the direct heat (for very little time though) to conserve nutrients.  
8. Steaming helps a lot since there is no direct contact with heat thereby heat-sensitive micronutrients are retained. 
9. Cover the vessel with a lid while cooking as it hastens cooking.
10. Vegetable salads should be prepared just before serving to conserve nutrients.
11. Use acids such as lime juice or natural vinegar to salads as it prevents loss of Vitamin C since Vitamin C is stable in acid.
12. Cook for the minimum time necessary to make the food palatable and safe.
    
13. Do not use baking soda to help keep the green color of vegetables, as this increases the loss of vitamin C.
14. Cook greens in an Open pan to retain the lush green color and don't overcook it. 
15. Do not use copper utensils. (Copper helps to destroy vitamin C.)

ARE RAW VEGETABLES HEALTHIER THAN COOKED?

Many people think raw vegetables are more nutritious than cooked, but that's not the case. Cooking vegetables breaks down the plants' cell walls, releasing more of the nutrients bound to those cell walls (Like Sonication where intense sound waves are used to release the intracellular components, whereas here we use heat). Cooked vegetables supply more antioxidants, including beta-carotene, lutein, and lycopene, than they do when raw.

Cooked vegetables also deliver more minerals. Few green leafy veggies are also high in calcium, but a compound called oxalic acid binds with calcium. Heating releases bound calcium, making more of the mineral available for the body to absorb. Cooking vegetables also increases the amount of magnesium and iron that are available to the body.

Even so, in some cases, vegetables may be better for us raw than cooked. Cruciferous vegetables – cabbage, cauliflower, broccoli, bok choy, Brussels sprouts – contain an enzyme called myrosinase, which, when you chop or chew these vegetables, converts glucosinolates (phytochemicals) to anti-cancer compounds called isothiocyanates.

The problem: Myrosinase is easily destroyed by heat. Cooking cruciferous vegetables reduces the conversion of glucosinolates to their active isothiocyanates, which may reduce their cancer-fighting potential.

According to research published in 2009, steaming led to the lowest loss of glucosinolates in cruciferous veggies like Cauli and Broccoli, while stir-frying and boiling (both higher-heat and direst heat contact cooking methods) caused the greatest loss.

ARE FROZEN VEGETABLES LESS NUTRITIOUS?

Cooking isn't the only way vegetables can lose nutrients. Before fresh vegetables reach your steamer basket, some of their nutritional value can be degraded during the time they're transported to a distribution center, displayed in the grocery store, and stored in your crisper. When possible, buy produce from farmers' markets to reduce the time from harvest to table.

Only when vegetables are out of season, consider frozen like Peas, Corn. 

These frozen veggies closely match the nutrient content of their freshly picked counterparts because they're flash-frozen at peak ripeness, a time when they're most nutrient-packed. (Because they are  usually picked before they are ripe, giving them less time to develop their full nutritional potential.)

The bottom line: No one cooking method will preserve 100 percent of the nutrients and protective phytochemicals in vegetables. So don’t limit yourself to one cooking method or eating only salad. Eat your vegetables roasted, grilled, steamed, boiled in soup, and raw, though Steaming is considered the most healthy one. Enjoy them fresh (locally grown when possible) and try growing them too. Explore the produces around since the more variety you have, the more likely you are to eat them. 

And that's the whole point.

References:

1. TNAU Agritech Portal

2. ICAR- IARI Indian Agricultural Research Institute

3. Fruits and Horticultural Technology- GOI