THE SCIENCE OF COOKING: IN RELATIONSHIP WITH NUTRIENTS RETENTION IN SELECTED FOOD (E.g Vegetables)

 

WHY COOKING ?

Cooking can simply refers to the heat treatment of food, that is been carried out to improve its palatability, digestibility and safety. Drastically speaking, for cooking to take place in food preparation processing, heat must be added to the food materials. To cook food, is the art of impacting or introducing heat into the food. It then means that such process as washing, freezing, slicing etc. of food items is never the art or science of cooking process but rather cookery. 

Homo erectus had begun cooking food as early as 500,000 years ago. In which the degree of hotness, which is more expressed as temperature is been applied to food. 

THE SCIENCE OF COOKING

The science of cooking is the method been used in most areas of food preparation and processing, however simple and all these methods depend on utilization of heat energy. Generally, all cooking methods depend on the following Mode of Heat Transfer:

Conduction

In conduction, heat transfer takes place due to a temperature difference in a body or between bodies in thermal contact, without mixing of mass. Food is heated directly in a metal pan, in a liquid, or surrounded by air. 

Dropping an egg into a pan of boiling water is a good example. The heat from the water is transferred to the egg. As the outside of the egg becomes warm, the heat moves into the center of the egg, continuing inward until the entire egg is heated to the desired temperature with the food. Conduction is the principle involved in the solid electric ranges used as hot plates.

Convection 

This is the process whereby the heat transfer due to motion of a fluid (liquid or gas)

For example, as a pan of soup heats up on the stove, heat moves from the bottom of the pan. This movement of  hot and cool liquids or gases combines. Stirring the pan redistributes the heat from the bottom of the pan throughout the other ingredients. Convection is the reason frozen foods thaw more quickly when placed under cold running water. Convection can also occur mechanically by means of a fan that circulates the air in an oven.

Radiation 

This is the heat transfer by electromagnetic wave. This involves the emission of heat from high temperature source in the form of waves. Such waves pass through air in straight line to reach the surface of the food without any intermediate medium being involved.  e.g. microwaving.

THE SCIENCE METHOD OF COOKING

There are many methods of cooking and each method has its own advantages over others. The only substance that aid cooking is heat. 

Cooking by Steaming: steaming method of cooking is the preparation of food by steaming under varying degree of pressure.

Cooking by Boiling: boiling is the method of cooking in a liquid at the boiling point of the liquid. in which it posses the temperature of about 100°c

 Cooking by frying: is the method of preparing food in which oil is been used. 

Cooking by baking: this is another method of cooking food. Baking is the cooking of food by dry heat in oven in which the action of dry oven heat is modified by steam.

Cooking Time: The time required to cook food is a function of temperature, specific heat capacity and thermal conductivity of the food and the thickness of the food.

NUTRIENT RETENTION IN SELECTED FOOD E.g (Vegetables).

For food to be nutritious it must be prepared in a form that would enable the nutrient to be available in a substantial amount.

Nutrient content is often altered during cooking, based on the type of processing it undergoes.

The factors that affect the nutrient Retention in vegetables are: Water, Heat, Time. During processing, Some vitamins are more stable (less affected by processing) than others. Water-soluble vitamins (B-group and C) are more unstable than fat-soluble vitamins (A,D,E,K) during food processing.

The most unstable vitamins include: folate, thiamine, vitamin C.

More stable vitamins include: niacin (vitamin B3), vitamin K, vitamin D, biotin (vitamin B7), pantothenic acid (vitamin B5).

The water-soluble vitamins are the most vulnerable to processing and cooking.

COOKING METHODS THAT PRESERVE A GREATER NUTRIENTS IN VEGETABLES

Choosing the correct cooking method helps in nutrient retention of selected food.

 The cooking method that generally preserve a greater nutrients, in Vegetables are:

Microwaving and Steaming methods

Microwave methods: microwaves are good not just for reheating food, but also cooking it. They offer a number of advantages when it comes to cooking vegetables.

The main advantage of microwaves is obviously the time factor. 

The magnetic field makes it possible to quickly boil the water within the vegetables and thereby cook them in just a few minutes. 

The major advantages of using Microwave,:

The short cooking time helps preserve heat-sensitive vitamins (like vitamins C and B9). The internal temperature also goes no higher than boiling which helps preserve the flavor of the vegetable.

Since there is little to no water in the container during cooking, few nutrients (like water-soluble vitamins and minerals) are lost during cooking.

Steaming Method: This is the method used during preparation of foods, by steam (moist heat) arising from boiling water under varying degrees of pressure.  Foods cooked by this method are: Beans pudding (moin-moin), others  vegetables.

The main advantage is that; Steaming of foods helps in retention of nutrients. It is a conservative method of cooking that prevents loss of nutrient.

Choosing the correct cooking method will determine the quality of the food as regards to nutrient retention.

Mode of heat transfer in cooking methods, such as grilling, roasting, steaming, microwaving generally preserve a greater amount of vitamins and other nutrients, present in foods.

Article By:

Ojo Olalekan Solomon

Food, Nutrients & Health

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