Water In Cooking Processes

1.0 Introduction:

Water can be observed as being a major component of many foods as well as one of the more important groups of nutrients worldwide. This is primarily due to the influences water has on texture, appearance and the taste of food.

Nutritionally, water helps to maintain body temperature and plays a role in transportation of nutrients and wastes providing the solution for hundreds of chemical reactions. Water also plays a role in sanitation in food practices as well as food preservation and therefore it is essential for the food industry (Kemmer N, F.,1988). In dried foods, water has a predominant role in the physical and chemical properties as well as the mechanisms that control their deterioration. As a result of this, water is necessary for life due to its high volatility at normal conditions of food processing and storage and therefore it is ubiquitous in the atmosphere (Ward, 2002)

This report will analyse and scope the role of water in food processing operations and the processes linked to water. The report will then exemplify some food practices and demonstrate the function of water in industries.

2.0 Chemical structure of water:

One of the most abundant chemicals worldwide is water. Its chemical formula (H20) is composed of two atoms of Hydrogen and one atom of Oxygen bonded together covalently, which is shown below (Kemmer N, F,1988).

Water has a slightly negative and positive end making it able to interact with itself and form highly organised intermolecular networks. It is able to do so due to the forces between the negative and positive ends of each water molecule, resulting in a force that allows the molecules to form a hydrogen bond. Hydrogen bonding is a type of weak electrostatic attraction between both positive and negative ends. Therefore because every water molecule can form a Hydrogen bond, it is easy to develop an elaborate network of molecules (Brown, LeMay & Bursten, 2006).

Water is evaluated to being a very unusual substance with many physical properties; not only is it colorless, but it's also tasteless, odorless, feels wet and dissolves almost everything (Miller, G.T., 2005). It also exists in three main forms such as liquid, solid and gas, and is cycled throughout the water cycle in life. Water can absorb a large amount of heat and it sticks together in droplet like form. The hydrogen bonds water attains also gives water a great surface tension (Wahlqvist, M.L. 2002).

Many substances, such as household sugar, dissolve in water. That is, their molecules separate from each other, each becoming surrounded by water molecules. When a substance dissolves in a liquid, the mixture is termed a solution. The dissolved substance (in this case sugar) is the solute, and the liquid that does the dissolving (in this case water) is the solvent. Water is an excellent solvent for many substances because of its polar bonds.

3.0 Water uses in food and beverage processing:

In many food-processing plants, water is used on a large scale for many purposes. These can include the conditioning of raw materials such as soaking, cleaning, blanching and chilling. It can also include cooling, sanitization, steam generation for sterilization, power and process heating and also direct in-process use (Potter, N.N.,1995)

The general purpose of water is to sanitize raw materials, processing equipment, plant facility and ancillary equipment in the industry chosen. Processed water should only be used for cooking or added directly to the product to make sure it is potable and of sufficient quality. This includes being free of dissolved minerals that make water excessively hard or affect taste. For example, most of the products used in beverage production consist of processed water, so treatment is needed to achieve taste quality (Kemmer N, F.,1988).

Processed water uses include the washing of raw materials and the processing of equipment; conveying products from one processing area to another; dissolving or extracting and the addition to the finished product. Cooling water may be used to operate refrigeration equipment and to condense steam from evaporators; it can also be used to cool processing equipment such as compressors or cookers and engine jackets. Steam may be generated for cooking as well as for heating evaporators, or for space heating. In some industries enough steam is required to justify installation of a turbine to extract power from steam before it is sent to cogeneration. If the steam can come into direct contact with food, there are strict limits on chemicals used for both steam and boiler water treatment, and on their maximum concentration (Ward, J.D., 2002).

Steam may also be generated for cooking, for heating evaporators, or for space heating. In some industries enough steam is required to justify installation of a turbine to extract power from the steam before it is sent to process (cogeneration). If the steam can come into direct contact with food, there are strict limits on chemicals used for both steam and boiler water treatment, and on their maximum concentration.

4.0 Food industries and the functions of water:

4.1 Sugar Industry

Kemmer (1988) shows that the sugar industry uses the largest scale of processed water with a variety of processing operations, therefore offering a good example of water use in food processing. These processes start with sugar beet harvests being washed and then transported to the factory, when this is done they are sliced and preheated in a cosseted scolder in water heated to 70 degrees. The sugar beet is then separated and raw juice is then produced and purified by the separation of sugar and non-sugar substances. This is done by lime and carbon dioxide in which is added in order to precipitate out the non-sugar substances. Once the juice is evaporated in several stages its sugar content elevates to about 67 % and it is then boiled until light golden transparent crystals are formed, this process is called crystallization. The syrup is then separated from the crystals by being spun off and rinsed off with water and steam. Repetition of these processes produces refined sugar, i.e. very pure crystal sugar of the highest quality.

4.2 Fruit and Vegetable Industry

Major water use is associated with the fruit and vegetable industry which include the washing steps for raw and processed produce, peeling and pitting practices, blanching, fluming the