Cooking up a storm with the right techniques

We all know cooking in fat is unhealthier than using water, but how often do we consider what nutrients are retained and lost in food when it's cooked? Obviously, taste has a large role, but we should really be striving to find a balance between flavour and nutrition.

To understand the benefits and disadvantages of how we cook, we really need to know why we cook. There are several reasons, though; to make food tastier, easier to chew and easier to digest. Cooking can also bring out the best in some foods, making them more nutritious.

This applies to tomatoes; when lightly cooked, their levels of lycopene increase, and this antioxidant can help prevent certain cancers, heart disease, and macular degeneration of the eye.

However, according to Peter Lucas, Professor of Anthropology at George Washington University, we don't need to cook foods for as long as we do. "You only need to cook something for a fraction of the time that you actually do in order for it to be digested properly.

"The cooking times that people adopt when they normally say 'this is cooked' seem to reflect strong mechanical changes in the food. In other words, these are things that affect your perception of food texture and allow you to eat it much easier, and in much shorter eating times than you would do if [the food was] raw."

Love me tender

Cooking can make food tender but also make it tough, indigestible and even cause carcinogens, so it's important not to overcook foods.

Meat needs to be tenderised, and balance plays a vital part. Think of a perfectly cooked steak: tender, moist and deliciously tasty. However, you can also have an overcooked, leathery steak that tastes of nothing. So how can cooking affect texture and taste so drastically?

Meat is made up of muscle fibre and connective tissue, which is quite tough and not very edible when raw. When heated, the fibres break down, making it more tender and easier to digest.

The cooking method and temperature determine how tender and edible the meat is. It's best to marinate or baste meat before roasting or grilling, otherwise the heat causes moisture to evaporate (along with the fat), resulting in a shrunken, toughened piece of meat. And it's not just water and fat that get lost, but often flavour, too.

Stewing meat is a way of retaining its nutrients -- the low temperature means vitamins are less likely to be lost.

However, generally, rapid cooking techniques are better for retaining nutrients than slower methods. These include pressure-cooking, microwaving, steaming, stir-frying, broiling, grilling and sauteing.

Most of us boil vegetables and think we are getting vitamins and minerals.

Off the boil

However, boiling can destroy a lot of nutrients, especially in vegetables that contain water-soluble vitamins (vitamin C and B complex), such as peppers, tomatoes and leafy green vegetables.

There are several ways to minimise loss of nutrients, including cooking in a small amount of boiling water covered with a lid, and only putting the vegetables in the saucepan once the water has come to the boil, so they are in contact with the water for the shortest possible time. It's good to use the leftover water to make a gravy or soup -- so you don't miss out on nutrients.

Steaming retains more nutrients, but the longer cooking method can mean losing more than you might expect. It is better to steam vegetables for a short time.

Preparation is important, too -- never wash cut vegetables, cut them as big and as close to the cooking time as possible, try to retain peel where possible (washing carrots and potatoes instead), as the bulk of vitamins are often near the skin, and use sharp, stainless steel peelers.