[Chemistry Class Notes] Food Chemistry Pdf for Exam

Food is one of the basic needs of life, without which one cannot survive for more than a few weeks. Have you ever wondered, what is our food made of and how does it undergo changes?

Food chemistry is the study of chemical composition and the interactions between the components present in food. Food chemists mainly focus on how the plant and animal-based foods are prepared, processed and distributed. Food also undergoes changes because of the elements present in it. Food chemistry helps us to find out what causes these changes and what are the primary components that make up our food.

For example, the wine and beer industries use the process of fermentation of grapes and barley by microorganisms to prepare these alcoholic beverages. In the same manner, the conversion of milk into curd by lactobacillus bacteria is an example of a chemical change that takes place in milk due to the formation of lactic acid from lactose. 

The concepts of food chemistry have been borrowed from chemical bonds and interactions, biopolymer science, colloidal interactions, chemical thermodynamics, etc. 

Components of Food

The main components of food are as follows: 

Carbohydrates are a group of compounds that are found in plants and animals. They have the general or empirical formula as Cm(H2O)n. Since they essentially contain carbon and water, they are referred to as hydrates of carbon or carbohydrates. Carbohydrates are energy giving foods. They are digested, absorbed and assimilated by the body after being changed into simpler substances such as glucose, which is then oxidized to release energy. Simple carbohydrates include sugars and complex carbohydrates include starch and fibre. A monosaccharide is the simplest carbohydrate. Glucose and fructose are monosaccharides. 

Grains such as wheat and rice, fruits such as bananas, bread, etc. are important sources of carbohydrates. 

Proteins are complex macromolecules that play an important role in the functioning of cells. They are primarily composed of nitrogen, hydrogen, oxygen and carbon. They may also contain zinc, phosphorus and copper in small quantities. Proteins are called bodybuilding foods, as they are essential for the growth and repair of the body. Proteins can be obtained from both plants and animals. Some plant sources of proteins include legumes, grains, nuts whereas the animal sources include meat, milk and eggs. 

Lipids are molecules that are non-polar in nature and are relatively insoluble in water. They include fatty acids, phospholipids, glycolipids, terpenoids etc. They may have a linear structure or a ring-like structure. They can be either aliphatic or aromatic. Lipids exhibit some polarity but a major part of their molecule is hydrophobic or nonpolar. The food sources of lipids include grains such as soybean and corn. They are also found in many animal products such as cheese, meat, milk etc.  

Water is an important component of food and it can have a composition ranging anywhere between 50 to 95%. The presence of water in food is one of the main reasons for higher bacterial growth which can lead to quick spoilage of food, if not preserved properly. Reducing the amount of water present in food is one of the most important ways to enhance the shelf life of food products.

Vitamins and minerals are the nutrients that are required by the body in small amounts. They are also called protective foods because they help the body to fight against diseases and infections. Vitamins can be classified as water-soluble or fat-soluble. If sufficient vitamins are not included in the diet, then their shortage can lead to various deficiency diseases, such as anaemia, beriberi, scurvy, etc. Minerals such as potassium, magnesium, and calcium are also required by the body in tiny amounts. Some of them are naturally found in food, but they can also be taken as supplements. 

• Colours, Flavours and Additives

Artificial flavours, colours and additives can be added to food to improve the smell, taste and for the purposes of processing and preserving. 

Enzymes are biological catalysts that help in speeding up a biochemical reaction. They can complete a chemical reaction in a lesser amount of time with lesser expense of energy. Enzymes are used in many food processes, such as brewing, fermentation, baking etc.