Microbiology discussion questions

Chemistry Discussion Question and classmates response:

DQ2 must be 2paragraphs and classmates response must be 1 paragraph. Must be you own work.

DQ1

Click on the following link:

http://portal.errc.ars.usda.gov/Overview.aspx

Move further down in the document to see table 1 and table 2.

a.Based on the information in the table1, explain why beef or pork are more likely to be contaminated with a bacterial pathogen like E. coli than is a fruit juice like grapefruit juice or orange juice.

b.Based on the information in tables 1 and 2, devise a method to ensure that your chicken breast (poultry, male, pectoralis major) was not contaminated with Salmonella.Would it be harder or easier to devise a method to ensure your spinach was not contaminated?Why?

c.Search the internet for recent Salmonella outbreaks.What 2-3 foods are most commonly associated with such outbreaks?Based on the information in Table 1 and Table 2, can you recommend ways in which these foods could be processed, preserved, or prepared to minimize chance of infection?

Classmate’s responses:

1. First, we must remember that few bacteria grow at an acidic pH below about pH 4. In table 1, we see the minimum pH that E. coli will grow is 4.4, the optimum pH that E. coli grows is 6.7, and the maximum pH that E. coli will grow is 9.0.

The pH range of beef is 5.25-5.9 and the pH range of pork is 5.6-5.88. Grapefruit juice’s pH is 4.2 and orange juices pH is 3.63. Because the pH of beef and pork are within the ranges in which E. coli grows best, those meats are more likely to be contaminated with a bacterial pathogen like E. coli. Grapefruit and orange juice’s pH levels are below the range in which E. coli will grow.

In table 1, we see the minimum pH that Salmonella will grow is 3.8, the optimum pH Salmonella grows is 7.0-7.5, and the maximum pH that Salmonella will grow is 9.5. The pH of a chicken breast is 5.8, which is within Salmonella’s preferred range of growth. The chicken breast should be refrigerated or frozen until ready to be cooked (kept under 5.1 degrees Celsius) to slow any growth of Salmonella and cooked thoroughly (above 46.2 degrees Celsius) to ensure that the chicken is not contaminated with Salmonella.

Fresh spinach for salads would be more difficult because we wouldn’t need to boil the spinach to eat it in a salad; however, if boiling fresh spinach (getting temperature above 46.2 degrees Celsius) Salmonella contamination would be easier to control.  Refrigerating the spinach would slow the growth of Salmonella but it would not kill the pathogens.

Live poultry, Raw Cashew Cheese and Tyson chicken have been listed as 2014 Salmonella outbreaks. Eggs are also a common food associated with Salmonella outbreaks. After coming into contact with any animal, humans should wash hands immediately. We should also wash our hands immediately after handling raw meat, especially poultry. Raw meat and eggs should be refrigerated (or frozen) to slow the growth of Salmonella. Eggs and chicken should also be cooked thoroughly (above 46.2 degrees Celsius) to ensure that the chicken is not contaminated with Salmonella.