Food Microbiology

• After 2 hours under optimum conditions, a bacterial population starting with 3 organisms and having a generation time of 20 minutes will grow to 192 organisms.

Matching Descriptions to People:

• Louis Pasteur demonstrated that air was not the cause of spoilage.
• Anton Van Leeuwenhoek developed the first microscope.
• Nicholas Appert is the father of canning.
• Robert Koch received the Nobel Prize in 1905 for demonstrating that a particular organism can cause disease and be transmitted from one animal to another.
• Viruses do not replicate in food and living cells.
• Bacteria reproduce through binary fission.

Viral Reproduction Cycle Steps

• Food carries virus to intestinal tract
• Virus attaches to cell
• Virus injects its genetic material into the host cell
• Virus replicates and new particles burst out of the cell.
• All fungi do not produce mycotoxins.
• Aflatoxin is found in all of the above.
• Diarrhea isn't an outcome of chronic exposure to low levels of mycotoxins.
• Patulin isn't a carcinogen produced by molds growing on corn.

Generation Times for Foodborne Pathogens

• Bacillus cereus has a generation time of 0.96 hours.
• Listeria monocytogenes has a generation time of 1.36 hours.
• Escherichia coli has a generation time of 1.16 hours.
• Salmonella spp. has a generation time of 1.17 hours.
• Bacillus cereus would grow fastest under the same conditions assuming that lag phase is not observed.
• The lower limit used as criteria for countable microbial colonies on media plates is 25.
• Fermented products typically don't have a high pH.
• Water activity is determined by measuring the vapor pressure of water above a food and comparing it to pure water.
• Microorganisms are capable of producing all of the above.
• Bacteria grow fastest under optimal conditions.
• All of the above are factors that affect the growth of microorganisms.
• Bacteria usually require the highest pH (lowest acid level) for growth.
• Pathogenic bacteria require an A, greater than 0.85 for growth.
• The water activity of 100 g of a certain brand of mayonnaise that contain 77.6% oil, 1.74% salt and 17.2% moisture; cannot be calculated with given information.
• Plate 4 should be counted to determine the number in the original sample, assuming food has a population of 150,000 microorganisms per mL.
• Thermophiles are microorganisms that prefer the warmest temperatures for growth.
• The hurdle concept applies multiple food preservation methods to ensure food safety by inactivating different microorganisms.
• Time-temperature abuse isn't associated with botulism.
• Staphylococcus aureus produces toxins that don't commonly lead to death, but causes symptoms such as abdominal pain, cramps, vomiting, and a low body temperature.
• Clostridium botulinum is an illness that causes muscle paralysis with higher rates of death.

Bacillus cereus Illness Types

• Diarrheal type often resembles Clostridium perfringens.
• Emetic type often resembles Staphylococcus aureus.
• Diarrheal is an infection in the GI tract that leads to an intoxication.
• Emetic type is when the microorganism grows and produces the toxin in the food, leading to intoxication upon consumption
• Food should be kept hot at 140°F (60°C) after cooking to be safe.
• It is not safe for infants to consume honey.
• Clostridium botulinum is a spore-forming bacterium that will not germinate at a pH of < 4.8.