Week 5: Healthy food preparation



The kitchen is similar to a chemical laboratory as there are physical agents that act on food. Food preparation does not mean cooking only. It also implies steps like soaking, steeping, sedimentation or emulsion. Cooking food has both benefits and disadvantage especially since certain foods may be harmful if eaten raw. It is important to note that the overall goal of healthy cooking and food preparation is to get maximum nutrients contained in food.  Let us consider the following as it pertains to food preparation. 

Healthy food supply: 

Foods of plant origin form the basis of a healthy diet and they include cereals, fruits, vegetables, garden greens, nuts and seeds, whole grain products and organic vegetables. Raw foods such as salads and fresh fruit can serve desserts making use of olive oil, garlic and lemon for dressing.  Foods like egg, milk, full cream dairy products, meat and their derivatives should be limited in consumption.

Kitchen Utensils and Cook wares:

A simple rule would be to choose materials that interact less with the food. Choose high-quality stainless-steel wares. Avoid cook wares made of aluminum, enameled earthenware and utensils made of copper and iron as they are quite unstable. When using a Teflon coated cookware, do not go above 300 degree centigrade of heat. Also avoid scratches in them.  

Hygiene, Cooking Oil and Dressing:

Wash your hands well before handling food and ensure absolute cleanliness with utensils and kitchen surfaces. Avoid washing the interior of your pots with iron sponge or scouring pad. For your cooking oil, vegetable oils are much healthier than animal fats and little salt (Sea salt or iodized salt) can be used as dressings. 

Chopping and slicing

Here is a helpful tip – Chop or slice foods close to the time of use. Here’s why – The more a food is chopped, the wider the surface area and the surface interacts with the atmosphere. Oxygen in the atmosphere reacts with it and then there is oxidation. Enzymes are also released from the tearing of the plant cells as a result of the chop then germs found in the environment reacts with the surface of the food chopped. This leads to oxidation, loss of nutrients, enzymes and contamination by microbials.  Good example will be to chop your onions when you are ready to use them. 

Balance between raw and cooked foods

Cook only foods that need cooking. Then compensate for eating cooked foods by eating raw ones daily. Avoid reheating foods or keeping them hot for a prolonged period. Nutrients can be destroyed that way. 

Advantages of cooking

Cooking aids digestion and destroys pathogens. E.g., It disarms some toxic substances found in cassava or eggplant. It makes certain foods more attractive and tastier. Avoid exposing food to heat for too long to the extent they burn or turn brown so as to prevent carcinogenic substances

Disadvantages of Cooking

It can lead to loss of nutrients. See the following examples- Vitamins, especially vitamins B, C, and the folates can be destroyed by heat. Minerals especially water-soluble minerals are lost with boiling water when thrown away.  Proteins are denatured from heat. Some Amino Acids like lysine get lost with toasting and carbohydrates may carbonize with excessive heat and lose value. For fats, with excessive heat, a part oxidizes and changes to toxic substance. Other disadvantages are the loss of enzymes especially in fruits and vegetables, formation of carcinogenic substances when exposed to high temperature, contamination by the cooking material. 

Effect of cooking on different food groups

Legumes must be cooked when dry. Eggs are better cooked than eaten raw due to the bacteria – Salmonella. Meats & Fish should be cooked properly. Fruits should be eaten raw. Vegetables can be blanched.  Cooking aids digestion through softening of dietary fibre but also destroys vitamins. Avoid overcooking them. Potatoes, Cassava and eggplant should be cooked properly to avoid toxins. Mushrooms should be cooked so that you can avoid cancer causing agents. Cooking nuts and seeds destroys Vitamin B1. Moreover, they are harder to digest. 

Methods of cooking

These include oven baking, roasting, frying, grilling, barbecuing, air frying, blanching, boiling, steaming, simmering, sauteing and use of microwaves. 

Cooking without liquid

These include oven baking, grilling and even barbecuing. Moreover, the flavors of the food are enhanced. Disadvantages are it requires high temperature and destroys vitamins and active substances. Barbecuing meat and fish can also release cancer causing substances.

Cooking in liquid

These include blanching, boiling, simmering. Advantages are the food does not soak in oil and the fat content of the food does not decompose Disadvantage is it leads to loss of water-soluble vitamins and minerals into the water. Therefore, limit the amount of water used. 

Cooking with fat 

Sauteing: involves the complete or partial cooking of foods. 

Light frying: Here, foods acquire a golden tone. 

Stir-frying: often done at a high temperature but for a short time. 

Deep frying: usually a golden crust develops. 

Slow cooking: A little water is added to the fat medium

Stewed: Equal mixture of both oil and water. Advantages are stronger flavor and slow cooking with little water and oil is safer than fast cooking. 

Other methods of cooking

Cooking in a high-pressure cooker. Cooking in a double boiler. Steaming- Done in a basket placed on a pot. Baking in aluminum foil – food is wrapped in foil that has been lightly greased. Cooking without waterA special pot is usually needed. Microwaves involves high temperature but no contact with the heat source. 

To improve cooking and preserve nutrients, reduce fat, sugar and salt content and also Increase fibre content of foods. 

Examples of methods of reducing fat

Measure oil in cooking with a teaspoon, rather than pouring. Add just one teaspoon per serving. Avoid frying foods. Boil with a little water. Roast meat/chicken/fish or vegetables in the oven instead of deep frying. For shallow frying, use just a small amount of oil or oil spray. Add a little water or stock when needed to keep the pan moist if needed. Trim all visible fat off meat and skin off chicken before cooking. Use low fat versions of milk. Avoid hard margarine and minimize use of butter. Add lots of vegetables and or legumes to recipes

Reducing sugar and salt

Avoid sugar if you need to lose weight. Avoid pastries, rather eat whole foods like sweet potatoes. Cut down the sugar and fat in recipes for pastries as pastries are usually high in fat and sugar. Try to replace sugar with a little honey (the energy value is similar). Generally, avoid processed foods and use little salt to cook. Avoid adding salt on the table after cooking. Taste your food before adding salt out of habit. 

To Increase fibre content of foods

Prepare smoothies and take as breakfast. Add vegetables to dishes. E.g., yam porridge with vegetables. Grind vegetable and mix with African mound foods. Sieve pap (fermented grains) with large-holes sieve to retain some of its fibre. Grind beans with the skin to make beans pudding. Prepare African mound foods with vegetable soup. 

To cook with legumes: Add split peas to rice. Cook rice and beans. Make beans pudding without peeling the beans. Cook beans and corn with little oil


Remember to use safe cooking utensils and cook wares. Prepare food in a hygienic environment. Use low heat to cook. Avoid cooking at high temperatures (especially Barbecuing). Avoid throwing away water used for cooking as you can reuse in soups and sauces. Learn to add vegetables and legumes to recipes