CFS Food Microbiology Flashcards
6 cards from real CFS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CFS Food Microbiology flashcards as text
In thermal processing, the D-value (decimal reduction time) is defined as the time required at a given temperature to reduce the microbial population by how much?
Answer: 90% (one log cycle)
The D-value is the time in minutes at a specific temperature needed to reduce the microbial count by 90%, or one log cycle (e.g., from 10,000 to 1,000 CFU/g).
Which pathogen is uniquely dangerous because it can grow and multiply at refrigeration temperatures as low as 0°C (32°F)?
Answer: Listeria monocytogenes
Listeria monocytogenes is a psychrotrophic pathogen capable of growth at refrigeration temperatures (0–4°C), making it a particular concern in ready-to-eat foods stored under refrigeration.
Clostridium botulinum type A produces a dangerous neurotoxin and is a primary concern in which food processing scenario?
Answer: Low-acid canned foods processed under anaerobic conditions
C. botulinum type A thrives in anaerobic, low-acid (pH > 4.6) environments such as improperly processed canned foods, where spores can germinate and produce the lethal botulinum toxin.
What is the primary difference between bacteria and molds relevant to food spoilage?
Answer: Molds are multicellular fungi that grow filamentously; bacteria are unicellular prokaryotes
Molds are eukaryotic, multicellular fungi that grow as filamentous hyphae, while bacteria are unicellular prokaryotes — a fundamental distinction affecting spoilage patterns, control methods, and detection approaches.
The z-value in thermal processing describes which relationship?
Answer: The temperature change required to achieve a 10-fold change in D-value
The z-value is the number of degrees Celsius (or Fahrenheit) required to change the D-value by one log cycle (10-fold), reflecting the temperature sensitivity of a specific microorganism.
Mesophilic bacteria, including most foodborne pathogens, have an optimal growth temperature range of approximately:
Answer: 30–45°C (86–113°F)
Mesophilic bacteria grow optimally between 30–45°C (86–113°F), which includes the range of human body temperature and the food temperature danger zone (5–57°C).