FdSc: Animal Health and Welfare
Practical 1 - Determination of the ash content of foods
Foodstuffs are divided into five categories; crude protein – the total level of nitrogen in a feed, ether extract – the total fat content of a feed, nitrogen free extract – the soluble carbohydrate in a feed, crude fibre - cellulose, fibre with nitrogen attached & alkali insoluble lignin and total ash content – an indication of the mineral content of feeds.
The aim of this report is to try and find out the total ash content of Wainwrights Adult Complete Dog Food With Duck And Rice through a food ...view middle of the document...
2. Place the dish in a baking oven to dry out the sample over 24 hours.
3. Re-weigh the sample in the silica dish, this is now the weight of the sample.
4. Set up the Bunsen burner apparatus. Place the silica dish containing the sample on top of the apparatus and begin to heat the sample slowly. Do not set fire to the sample, this will result in a loss of material to the atmosphere in the form of particles. The sample should turn black.
5. Once the sample reaches around 100°C continue to heat until it turns white.
6. Allow the sample to cool to room temperature in a desiccator.
7. Weigh the finished sample.
To calculate the percentage of ash in the food sample, use the following equation:
% ash = (Weight of ash / Weight of dog food) x 100
To achieve the percentage of ash in the food sample, the equation was put into place.
In the experiment carried out, the weight of the ash was 0.547g and the weight of the dog food was 5.014g so:
(0.547 / 5.014) = 0.10909 x 100 = 10.909%
Weight of dog food sample | Weight of crucible | Weight of ash |
5.014g | 19.998 | 0.547g |
Wainwrights dog food packaging states that it contains 7% crude ash and the results found in this experiment found 10.909% crude ash, this could be due to a number of reasons such as: parts of the experiment being done incorrectly, the packaging stating the wrong percentage, the equipment used being incorrect, the sample not being burnt for long enough, the sample setting on fire and losing material to the atmosphere in the form of particles.
In this experiment, some parts of the method were done incorrectly, including: the sample was not measured to be 100°C and didn’t turn fully white, leaving room to believe there was still organic matter left in the crucible. More reasons for unexpected results could be that the sample set on fire multiple times burning off matter to the atmosphere, including parts of the...