Maximise your food's nutrients

June 30 2015

Cook your food the right way to ensure it retains all its goodness — Kathleen Alleaume reports.
We all know to ditch the deep fryer when it comes to cooking a healthy meal, but you may not think about how other cooking methods are impacting the amount of nutrients you’ll receive. Here are some ways in which to ensure your food retains much of its nutritional value.

115045356 Fruits and Vegetables

There are two ways in which fruits and vegetables lose their vitamins and minerals when cooked. The first is when nutrients leach into water when boiled. The second is when they are broken down through heat.

This is not to say you should never heat another fruit or vegetable again. Rather, to retain as many nutrients as possible, the key is a short cooking time and using as little water as possible. This is why steaming (including microwave steaming) is the healthiest, as it allows the vegetables to stew in their own juices, offering the best retention of water-soluble vitamins (vitamin C and B-complex).

Since boiling uses high temperatures and requires large volumes of water, boiling can wash away water-soluble vitamins by up to 70 percent — this also includes potatoes as they contain vitamin C.

However, if you absolutely have to boil your vegetables, always cover your pot to hold in the heat and help reduce cooking time, and consume their leached-out nutrients by keeping the water and using it to make fresh soup or stock. Likewise for poaching fruit. Try to reuse the water you used for poaching, and keep the fibre-rich skins on the fruit to retain nutrients.

For more delicate vegetables like leafy and Asian greens, stir-frying is your best bet, provided you use a small amount of good quality oil to help the vegetables retain their heat-fragile vitamins and antioxidants. Cook until the vegetables just begin to wilt and the stems remain firm with a bit of crunch.

Puréeing vegetables such as carrots, pumpkins and beets helps to retain beta carotene (vitamin A) — a fat soluble vitamin which can be absorbed more easily when combined with oil.

Unfortunately, baking, grilling, frying and barbecuing tend to brown and damage food by forming carcinogenic compounds, known as acrylamide. If you still prefer your vegetables cooked this way, avoid over-charring and reduce cooking time wherever possible.

Bottom Line: Resist the temptation to cook your fruit and veg too long. Perfectly cooked fruit and veg are brightly coloured and tender-crisp, rather than mushy.

Nuts

Both raw and roasted nuts (whether dry or oil roasted) have similar nutrient contents, although there are some small differences. During the roasting process, most nutrients, particularly minerals, become slightly more concentrated due to the loss of moisture.

But it’s not only about cooking when it comes to maintaining nutrient integrity of nuts: how you store the nuts counts, too. To keep nuts in the best condition, store them in an airtight container in the fridge or freezer. Nuts can be refrigerated for up to 4 months and frozen for up to 6. To maintain a fresh and nutty flavour, it’s best to bring nuts back to room temperature before eating.

Top Tip: Nuts have a lot of nutrients, including protein and good fats, but do contain a lot of kilojoules, so stick to just a handful of nuts a day and avoid additives like salt and sugar.

Oils

Besides flavour and nutritional content, the smoking point is an important factor to consider when choosing oils. This is the point (temperature) at which the oil begins to break down and smoke, affecting the chemical composition, nutritional value and flavour, and releasing harmful free radicals.

An oil with a high smoking point (peanut, sesame, and canola) are best used for sautéing, stir-frying and baking, whereas oils with a very low smoking point (extra virgin olive oil and flax seed) should only be used for very low-heat cooking or used unheated as a dressing.

Top Tip: Always heat the pan first, then add the oil. The longer the oil spends in contact with the hot surface, the higher a chance it has of going over its smoking point which can damage the oil.

Pulses and Legumes

101329266 Most legumes need to be soaked to make them easier to digest and absorb the nutrients. But split peas and lentils don’t need to be soaked — just boil them for about 20 minutes or add them directly to your casserole as it cooks.

Top Tip: If you don’t have time to soak legumes overnight, try the ‘quick soak’ method: Bring a large pot of water to the boil, add legumes, return to boil. Turn off, cover and stand for one hour.

Meat

When foods like meat, poultry and fish are heated over high temperatures and blackened or charred, the high heat of grilling (like that of your backyard barbecue) reacts with the proteins found in the meat creating certain cancer-causing compounds known as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs).

These compounds also form when fat drips and burns on the grill, creating smoke, which may get deposited on whatever you’re grilling. This doesn’t mean you ditch the summertime sizzle. Fortunately, for the barbeque enthusiast, experts have provided some risk-free cooking tips.

  •  Keep flames at bay by not placing meat directly over coals
  • Keep meat portions small to cut down on grilling time. Instead of grilling a whole steak, make kebabs since they cook more quickly
  • Avoiding prolonged cooking times (especially at high temperatures). The shorter the cooking time at high heat, the healthier
  • Marinating meat first prevents foods from charring and also keeps meat tender and adds flavour to your meal.

Cooked vs Raw

You can see why raw foodists cut out cooking altogether, claiming that uncooked food maintains all of its nutritional value and supports optimal health. While eating raw food is necessary for good health and is an important feature of a healthy diet, there are certain vegetables that do require cooking simply because it’s easier for the body to digest and absorb some of their nutrients. Why? Heat facilitates the release of antioxidants by breaking down cell walls, providing optimal nutrient absorption.

For example, lycopene, a potent antioxidant, is better absorbed from cooked tomatoes than from raw tomatoes. Other vegetables, like potatoes, need to be cooked well to get the maximum benefit from specific phytonutrients and improve the digestibility of the starches. Raw broccoli, cabbage and cauliflower contain goitrogenic compounds which can potentially cause problems for those with poor thyroid function if eaten in excess. Pregnant women are also advised not to eat raw vegetables to reduce the risk of food poisoning.