Food Laboratory Testing

Biology Laboratory Report Practical 4 Food tests

Introduction The main components of food are proteins, fats, carbohydrates, and, of course, water. Proteins, lipids and carbohydrates are carriers about energy necessary for vital activity. They are a plastic material for the formation of structures of the body, as well as used for the synthesis of hormones and substances that transmit signals in the nervous system. Our food also includes food (plant) fibers, has recently seemed unnecessary ballast, but of great importance to the organism. Main components of food are vitamins and minerals. They are not sources of energy, but are necessary for the functioning of various body systems, including many hundreds of enzymes catalyzing the metabolism. Calcium and phosphorus, in addition, are the basis of the skeleton. Different food groups vary in content of nutrients. For example, animal products - a good source of protein. Cereal and pulse products, along with vegetable protein contain a lot of starches. Many fruits and fruit, and honey - the sources of simple sugars (glucose and fructose), oil seeds and received from the vegetable oils - a source of vegetable fat. Our food has flavor and aromatic substances, volatile (substances that kill bacteria), it can also be present and dangerous to human chemicals. Today, we have to learn basic laboratory techniques, such as handling the reagents, using Gilson pipettes etc, study and try to identify chemical tests for food compounds. Materials and methods Reagents Monosaccharaides (glucose, fructose, maltose), sucrose (disaccharide) Starch (polysaccharide), egg albumin (protein) DCPIP, Vitamin C Olive oil + Sudan III Ethanol (highly flammable) Iodine solution (irritant) Benedicts reagents KOH + CuSO4 HCl (irritant) Honey solution Apple juice solution Milk solution Precautions Gloves Safety goggle Lab coat Gilson + tips 20 test tubes

Procedure Control solutions Reagents were mixed with solutions and given positive results. For example: starch reacted with iodine and given solution with deep blue- black color, saccharides (mono-, di-) reacted with Benedict’s reagent and heated in the water bath, then was taken liquids with green/orange/red-brown/brick-red color, etc. (results illustrated in the Table 1) Table 1 Iodine DCPIP KOH Benedict’s reagent Oil + water+ Sudan III I.

Starch

Deep blueblack color -

-

Monosaccharide Disaccharide Protein

-

+CuSO4 -> purple color -

Orange color Orange color -

-

Lipid

-

-

-

Form bilayer (dark red and light red color) -

Vitamin C

-

Losing the color

-

-

II. Test solutions There are three tubes with test solutions numbered 1, 2 and 3. They had already tested to the compound by methods and reagents which had used in the control solutions. Results of this test shown in the Table 2.

Table 2 Iodine DCPIP KOH Benedict’s reagent + Results and discussion Unknown test tubes 1 2 3 Starch Saccharides + + + Protein + Lipid + Vitamin C + + + Oil + water+ Sudan III + -

1 2 3

-

-

I think test tube 1 contains an apple juice because according to my results it contained carbohydrates and lipids. And as we may already know juices have those substances too. In my opinion, in the second tube was honey solution, because it contains only saccharides. Finally, at the third tube was milk solution, because it also had saccharides and proteins. The organic substance of the cell: carbohydrates, fats, proteins, nucleic acids, ATP. Macromolecules are large and complex molecular structure of organic compounds consisting of simpler molecules. Carbohydrates - organic compounds consisting of carbon, hydrogen and oxygen. Simple carbohydrates are glucose, fructose and maltose. Glucose is presenting in the fruits, vegetables, human blood, fructose - in the fruit and honey. Complex carbohydrates - a macromolecule composed of the remnants of the molecules of simple carbohydrates. Examples of complex carbohydrates: cellulose (fiber), starch, glycogen - animal starch, which is formed in the liver. The formation of molecules of cellulose, starch and glycogen from the remnants of glucose molecules. Lipid is organic matter with hydrophobic surface (insoluble in water).

Conclusion In this lab work we had experience in identification of carbohydrates, lipids, proteins and vitamin C. They had observed by different reagents which could help us to identify them. We had experience on using laboratory techniques too.

Reference list Gerald Karp (2010). Cell Biology. The 6th edition. Singapore. John Wiley. A.Bray, H. Johnson, L. Raff, R. Walter (2010). Essential Cell Biology. The 3rd edition. USA. Garland Science, Taylor & Francis Group. Arpaci, O. (2000). Biology 2. Istanbul, Turkey: Zambak Publications.