Decolourization of liquid foods
Food and health are foremost in Man's thoughts and a means of improving his quality of life
Decolourization is almost exclusive to chemical-pharmaceutical industries and to agro-food industries.
Bleaching activated carbon can be used in the following industrial applications:
- decolourization of wine
- decolourization of fruit juices
- decolourization and purification of glucose
- decolourization and purification of oils and fats
- decolourization and purification of chemical-pharmaceutical products
Activated carbon guarantees the possibility of obtaining a final product of pure, constant, and high-performing quality. In the last ten years, the technology regarding activated carbons has made great progress primarily in two directions: improvement in quality and more rational technologies of use with regard to the quality of carbon.
The activity level of activated carbon chosen is very important because depending on the dosage needed, it can weigh heavily on the overall cost, especially when there are costs of handling, filtering, and eliminating sludge.
Before evaluating the adsorbent properties of an activated carbon, we must be sure that it is not a vehicle for impurities capable of interfering with the products to be treated.
The reference regards the organic and mineral impurities often contained in the activated carbons: the first practically nil, considering the temperatures reached in the physical or chemical activation processes; the second, analytically verifiable, are essentially due to the raw material used.
Activated carbons guarantee quality and constancy of the final product
To determine the decolourizing power of activated carbons, among the multitude of testing methods that exist, we would like to point out the following:
Methylene blue index
This establishes how much solution of blue methylene at 0.15% can be decoloured by 100 mg of activated carbon (dry substance) in 5 minutes.
This test has been adopted by manufacturers of activated carbon as the standard method with which the degree of decolourization (decolourizing performance) is measured.
The decolourization of a standardized molasses solution with activated carbons is compared colourimetrically to the decolourization of a standard carbon (measurements of photoelectric extinction). With this method, the decolourization performance of different types of activated carbon can be established. Under conditions reflecting reality, the quantity of each type of activated carbon needed to obtain an equal degree of decolourization can be recorded systematically.
Different quantities of activated carbon - for example 100, 300, 500, 700 mg - are put into glasses and mixed with 100 ml of the solution to be treated. The solution is brought to 80°C or to an actual temperature of operation. For each type of activated carbon tested, 1 litre of the solution to be treated will also be prepared with a sample without activated carbon and will serve as a control sample. It will undergo the same set of tests and be measured optically. On the basis of similar preliminary tests previously held, it would be best to calculate the amount of activated carbon needed to carry out the tests.
The samples are treated bain-marie at the aforementioned temperatures and are agitated at brief intervals. After approximately 30 minutes, adsorption equilibrium will have been established.
Subsequently, the activated carbon is filtered repeatedly until the liquid becomes clear. When necessary, filtering adjuvants are added; for example fossil flour. The clear, filtered liquid is then cooled and brought to room temperature.
There is a colourimetric comparison between the control solution and the samples tested. A series of measurements is obtained.
From the quantitative relationship resulting between two activated carbons, it is possible to reliably compare cost versus efficiency and therefore, evaluate which types of activated carbon are more inexpensive to use.