Determining the Effectiveness of a Food Preservative (THIS IS A CASE Essay

Determining the Effectiveness of a Food Preservative (THIS IS A CASE STUDY) - Essay Example Direct microscopic counts cannot distinguish between dead and living bacteria. Dead bacteria result from the fact that the â€Å"natural environments [for bacteria] do not always resemble standard laboratory culture media† (Roszak & Colwell, 1987). Hence, death of some bacteria is expected. Standard plate counts may not be able to differentiate among the different types of bacteria but is reliable when it comes to giving information about disease-causing bacteria such as Pseudomonas aeruginosa (â€Å"Swimming Pool,† 2010). Identifying the growth and metabolism of organisms such as P. aeruginosa in cottage cheese can give insights on how effective a preservative is or, more specifically, how long it will last in protecting the cheese from bacteria. Moreover, standard plate counts seem to be the method of choice when it comes to experiments with cottage cheese, as long as the laboratory environment and all other variables are properly regulated (Fedio et al., 1994). Another thing is that, P. aeruginosa forms three colony types – a small and rough one, one with a fried-egg appearance, and one with a mucoid appearance (Todar, 2011). Due to such differences in colonies, the number of bacteria will therefore obviously be relatively hard to determine through a d irect microscopic count and hence will require a standard plate count. Besides, a standard plate count is appropriate for counting colony-forming bacteria (Todar, 2009). Turbidity measurements, just like direct microscopic counts, may fail to give an accurate bacterial count because it â€Å"cannot detect cell densities less than 107 cells per ml† (Todar, 2009). This means that colonies must have approximately at least 10,000,000 cells before it can be detected through turbidity measurements. Considering that colonies of P. aeruginosa are varied in many aspects like appearance, it is possible to obtain samples where colonies would have cells less than the minimum limit that can be detected