FOOD CHEM - WATER

• 4 Branches of Chemistry: Organic, Inorganic, physical and Biochemistry
• Food Chemistry is a chemical process and interactions of all biological and non-biological components of food. It covers the basic composition, structure, and properties of food and chemical changes occurring during processing and utilization.
• Substances are elements that make up chemical compounds
• Chemistry informs us about changes in food during processing and storage.
• Chemistry explains the change in the cooking process, including how ingredients interact and how our body uses food.
• Chemical substances play an important role in food production and preservation.
• food additives can prolong the shelf life of foods.
• Flavoring is used to make food tastier. Other chemicals can be used to fight diseases in farm animals or crops.
• Laboratory testing provides analytical data on the quality of a production or production process to support quality control in the HACCP.
• HACCP is Hazard Analysis Critical Control Point
• Food is a substance usually composed of carbohydrates, fats, proteins, water, and other components.
• Major constituents of food: Carbohydrates, Fats and Protein
• Minor constituents of food: vitamins, minerals, enzymes, pigments, flavor, acids.
• Important constituent of food is Water
• Water may occur as an intracellular or extracellular component in vegetables and animal products.➢ It may also occur as a dispersing medium or solvent in many foods and as the dispersed phase in some emulsified products such as butter and margarines.
• The importance of water in food is described as the moisture content. 

   
• Water exists in 3 forms in food: free water, absorbed water and bound water.
• Free water is the most water in the food, that is lightly entrapped and therefore easily pressed in food, it act as dispersing agent and solvent, can be removed by drying and it can easily evaporate.
• Absorbed water is water associates in layer through intermolecular hydrogen bonds around hydrophilic food molecules, the water is held tightly in cell walls or protoplasm and is held tightly to protein.
• Bound water  is the water that remains unfrozen at temp. below 0⁰C usually -20⁰C. Also, it is the amount of water in a food that is unavailable as solvent, the amount of unfreezable water, based on protein content, vary from one food to another.
• 8-10% of the total water in animal is bound or unavailable for ice formation
• 0.4 gm bound water on egg white
• -6% bound water in most fruits and vegetables
• Free water is mostly easily removed from food by evaporation 
• Some methods to remove bound water: Oven drying, Vaccum oven, and Distillation methods
• The method to determine moisture content is to weigh sample, dry it and weight it again
• In Oven drying method the sample is weight, the sample is usually weighed into a flat bottom shallow dish made up of aluminum or similar material which will not react with the food nor pick up water readily.Weighed samples are placed in an oven for specified time and temperature. The oven temperature is usually set at 100⁰C or 105⁰C and the time varies depending on the sample.
• They are dried until they reach constant mass. The difference in weight is the water which has evaporated.
• Vacuum Oven weight samples are placed under reduced pressure (typically 25-100mm Hg) in a vacuum oven for a specified time and temperature and their dried mass is determined.
• the total solid content is a measure of the amount of material remaining after all the water has evaporated.
• Water is solid in state when freezes in 0 degree celcius
• Water in its liquid states covers the majority of earth’s surface
• Water in gaseous state converts into water vapor at 100 degree celcius
• Water consists of 2 hydrogen atoms and one oxygen atom held together by covalent bonds.
• Water is colorless and transparent chemical substance that made up of 71% of the earth’s surface.
• Hydrogen moves closer with each other resulting in V-shape arrangement.
• Water is polar because it has a positive and negative charge that bonds together.
• Water is an excellent solvent because of its ability to dissolve polar, but not nonpolar
• Water has high heat capacity regulates the temperature in the environment, it takes a lot of energy to raise a tempt by a degree and to evaporate.
• Water has high heat of vaporization water converts liquid to steam