Food Microbiology - Lab Report Example

Download file to see previous pages Results indicate the overall standard in terms of hygiene of food processing and the food chain. The microbial levels permitted for food to be determined safe are regulated by law. The study is carried out in three stages performed as three experiments. In the first experiment, aerobic plate count is done for E.coli count and coliform count on given food item (Roberts, D, 2003, Gilbert et al, 2000). It is evident that coliforms and E.coli are present in human faeces. Their presence in food items can indicate post processing contamination. The aerobic count is used to determine the overall level of microbial contamination of food items and provides an indication for poor processing or post processing techniques especially where the count exceed the legal permitted levels. In the second experiment pre-cooked food is observed for faecal contamination. In the third experiment the quality of milk samples (pasteurized and raw) are checked for the presence of fecal contamination.
The Petri dish with colonies between 15 and 300 were selected to be significant in number whereas Petri plates with TMTC (too many to count) were not considered to be significant. Calculation is performed with the formula mentioned. Plates with dilution factor of 10-8 showed no growth and hence it is reported as < 20 CFU/g of food sample. The amount of sample plated is the volume of dilution pipette on the plate. Average value was chosen to get the exact value. For the dilution factor 10-4 CFU/g is 3 which is not normally expected.
Discussion:
The serial dilutions, or successive dilution of a specimen e.g. 1:10 dilution equals 1 ml of sample plus 9 ml of diluents, a 1:100 dilution equals 1 ml of a 1:10 dilution plus 9 ml of diluents. This is the process to enhance the probability of finding the most probable microorganism even at higher dilution. If the microorganism is present in the highest dilution then this is depicted when inoculated on the medium solidified on Petri ...Download file to see next pagesRead More