Sulfuric acid or sulfur essence is a very strong mineral acid with the chemical formula H2SO4 and a density of 1.83 g/cm3. Sulfuric acid for the first time withDistillation of green alum with copper(II) sulfate was produced by Jabir Ibn Hayyan. The acid has a polar structure and dissolves in water in any proportion. This acid has a hydrogen pion due to its OH bond, and for this reason, it has a high boiling point.

The melting point of sulfuric acid is 10°C and its boiling point is 337°C. Sulfuric acid has many mobile applications in industries and has a high production tonnage.

One of the important applications of sulfuric acid is to use it in the dairy industry to detect and measure milk fat percentage.

Properties of sulfuric acid

• Colorless
• Odorless
• High viscosity
• Viscose material
• Very high solubility in water

Getting to know the Gerber test

The Gerber test is used to measure the percentage of fat in milk. This test is very widespread and is performed in most countries of the world, especially Iran. The reason for the popularity of this test is the high speed, low price and high accuracy of this test. This test was first performed in 1892 by Dr. Nicolas Gerber, a Swiss chemist and one of the great founders of the Swiss dairy industry. This test is able to obtain the fat percentage of all types of milk, including cow’s milk, buffalo milk, etc.

The basis of the Gerber test

The purpose of this test is to measure the fat in milk. The fat in milk is surrounded by a protein membrane, so we use sulfuric acid to break this membrane. Also, with the help of centrifugal force, we collect the fat coming out of the protein membrane and then measure it. Amylic alcohol is also used to prevent the formation of carbon particles and speed up this test.

Equipment needed in the Gerber test

Fat meter: It is a device for final measurement of milk fat. The fat meter has a graduated column, a cylindrical tank and an ampoule at the end. According to the standard, the fat meter has 6 different types, which types have percentages from 0 to 4 to 10 in the graduated part. Of course, some fat meters of cow’s milk are graded up to 14%. The accuracy of the graduated cylinder of the fat meter is around ±0.05%. The end of the ampoule of the lipid meter has a matte part that is used to number the samples so that they are not confused with other samples. Also, the size of the opening of the fat gauge depends on its special cap or cork.

Centrifuge: In the following, we will discuss the issue that centrifugal force is used in this test, and this part of the test is performed by a centrifuge. The centrifuge used in the Gerber test should have an average speed of 1,000 to 1,200 rpm, and the test sample should be placed in the machine at an angle of 45 degrees. Centrifuges that are used for Gerber testing in factories should allow the placement of 30 to 40 samples. You can refer to the section below for more information, including prices, types of centrifuges, etc.

Laboratory measuring devices:  In this test, we need the exact size and volume of the sample, so we must use special laboratory measuring devices. To measure the volume of milk from regular 11 ml pipettes or 11 ml syringes, to measure sulfuric acid from a 10 ml bubble pipette or a 10 ml beaker, and also to measure amylic alcohol from a 1 ml bubble pipette or beaker. 1 ml is used.

Water bath: The water bath of the laboratory must be resistant to sulfuric acid, so that if an error occurs and the fat meter falls on time and breaks, the sulfuric acid inside the sample will not damage the water bath. It should also be able to maintain the temperature in the range of 65 to 70 degrees Celsius

Required materials:

Tested milk – sulfuric acid – amylic alcohol (C5H11OH)

Test method:

First, we must bring all the equipment and samples to a temperature of 20 degrees Celsius. This temperature causes the fat to spread homogeneously in the milk. Then we stir it to spread the fats in the milk. It should be noted that in the next step, there is no foam on the surface of the milk, so continue stirring for some time and then stop.

Place the dipsticks in their place (with the ampoule facing down) and then pour 10 ml of sulfuric acid into the dipstick using a 10ml bubble pipette so that the opening of the dipstick is not stained with this acid. Then, using another pipette, add 11 ml of milk slowly and diagonally from the opening of the fat meter. In the next step, add 1 ml of amylic alcohol to the fat meter with the help of its special pipette.

Then close the lid (or cork or special protectors that block the door completely). Then start shaking gently. Be aware that you must use gloves with a handkerchief so that the heat of the sample does not hurt your hand because the interactions that take place in the sample reach a temperature of 80 degrees Celsius.

Then put it in the centrifuge with the closed lid facing down. Then the centrifuge starts working and turn it off after 5 minutes. In this section, you can read the amount of separated fat from the graduated scale.