Читать книгу Analytical Food Microbiology - Ahmed E. Yousef - Страница 72

1 An analytical facility received a laboratory sample containing ground meat. The product weighed 1000 g and the requested microbiological analysis included determining the product’s aerobic mesophilic count. The vendor did not provide information about the microbiological quality or safety of product but according to laboratory’s records, a similar product from the same vendor was analyzed in the previous month and its aerobic mesophilic count was 5.4×104 CFU/g.Develop a sample preparation plan that includes withdrawing analytical sample(s). Hint: Review information provided in Chapter 2.Prepare a dilution scheme that shows the dilutions to be prepared and dilutions to be plated. Consider that the spread‐plating method is to be used.How different would the dilution scheme be if pour‐plating was used instead of spread‐plating?How different would the dilution scheme be if no information or record about this sample was available?

2 Develop a mathematical formula (or formulae) that the analyst can use to design dilution‐plating scheme if the approximate concentration of the targeted population (CFU/g) is known.