NUFS 363 Final

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NUFS 363 Final
2013-12-13 03:12:54
NUFS 363 Food Microbiology

Condensed main points for final
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  1. How is F calculated?
    F = Dr(a-b)

    • Dr = D at 121oC
    • a = initial population
    • b = final population
  2. Name some processing aids
    • Microwaves
    • UV
    • Gamma Rays
    • X-rays
    • Cold Pasteurization
    • PEF (Pulsed Electric Field technology)
    • HHP (High Hydrostatic Pressure)
  3. What are the 3 forms of radiation processes?
    Radurization: low dose, quality enhancement, like pasteurization, reduction of spoilage organisms

    Radicidation: equivalent to pasteurization, reduction of pathogens

    Radappatization: equivalent to sterilization, high dose, medical equipment
  4. What are the applications of chemical preservatives?
    • - Minimize health risk
    • - Improve nutritional quality
    • - Enhance storage quality
    • - Improve sensory properties
  5. What is pKa?
    Amount of undissociated acid
  6. What prevents ropiness and mold in baked goods?
    Propionibacterium shermanii
  7. What is the active form of nitrates and what is the pKa of it?
    • Nitrous acid
    • pKa 3.4
  8. How do nitrates work?
    • Converted to nitrite
    • Cell proteins react with nitrite to form iron-nitric oxide complexes
    • Destruction of iron-sulfur enzymes
    • Growth inhibited
  9. What is the risk of using nitrates?

    Nitrite + free amino group = potential carcinogen
  10. What is the "natural" version of nitrites?
    Cultured celery extract
  11. Why are sulfites not permitted in meat?
    Destroys vitamin B1
  12. What are the properties of class I bacteriocins?
    • Lantibiotics
    • Small, heat stable peptides
    • Extensive post-translational modifications
    • Unusual AAs (lanthionine)
    • Ribosomally synthesized
  13. What are the properties of class II bacteriocins?
    • Small, heat stable, hydrophobic peptides
    • Limited post-translational modifications
  14. What are the properties of class III bacteriocins?
    Large, hydrophilic proteins
  15. What are the properties of class IV bacteriocins?
    Circular bacteriocins
  16. Bacteriocin synthesis MUST haves?
    • Structural gene(s)
    • Immunity gene
  17. Bacteriocin MAY haves? (not always required)
    • Transport genes
    • Modification genes
    • Regulation genes
  18. What is an example of a Class I bacteriocin and how does it work?
    • Nicin
    • Affects cell membrane = pores
    • Inhibits C. botulinum outgrowth
    • Reduces canning process & heating time
  19. What is an example of a Class II bacteriocin and what does it fight?
    • Miocin
    • Listeria monocytogenes
  20. What is the "natural" version of Miocin?
    Cultured corn syrup
  21. What are some properties of LAB?
    • Ferment carbs to lactic acid
    • Gram (+), non-sporulating, nonmotile
    • Grow anywhere with right pH and carbs
  22. What are the 2 types of fermentation of lactobacilli?
    • Homofermentative (obligate)
    • Heterofermentative (obligate and facultative)
  23. What 2 spp. are involved in yogurt?
    • Lactobacillus delbrueckii subsp. bulgaricus
    • - strong proteolytic activity, provides AAs for Staph

    • Staphylococcus thermophiles
    • - limited proteolytic activity, provides flavour
  24. What are the products of Propionibacterium shermanii?
    Propionic acid, CO2, acetic acid

    Nutty flavour, holes in Swiss cheese
  25. What are the 4 aspects of Starter Culture?
    • Rapid fermentation of lactose
    • Proteinase activity
    • Phage resistance
    • Production of inhibitory compounds
  26. What are the 3 stages of yeast fermentation?
    • Conversion of biomass to fermentable sugars
    • Fermentation
    • Recovery of alcohol & product formation
  27. What are the 3 different kinds of potable ethanol?
    • Unfortified: beers, wines
    • Fortified: ports, sherry
    • Distilled spirits: whiskey, gin, vodka, rum
  28. What is the bacteria in Hops?
    • Humulus lupulus
    • Flavour & preservation
  29. What is malt?
    Germinated barley, activates amylases
  30. What are the 3 things involved in labeling guidelines?
    • Identification of strain (latin name/strain ID)
    • Quantitative declaration (CFU/serving)
    • Ingredient list (common name/bacterial culture)
  31. What are the safety considerations for ProB's?
    • Antibiotic resistance
    • Production of antibiotics
    • Pathogenic potential
    • Metabolic activities (D-lactate production, bile salt deconjugase activity)

  32. What should PreB's be able to do?
    • Resist gastric activity, hydrolysis
    • Ferment by intestinal microflora
    • Stimulate growth/activity of selected intestinal bacteria (ProB's and "good" microflora)
  33. What are the health benefits of ProB's and PreB's?
    • Normalized intestinal microbiota
    • Stimulate immune system
    • Metabolic effects (eg. lactose hydrolysis)
  34. What are 2 types of monitoring of cleaning/sanitation?
    • Microbial counts: next day results, more accurate
    • Bioluminescence: same day results, measures ATP, less accurate
  35. What are general features of Viral foodbourne illness?
    • Few particles needed
    • Shed in stools of infected individuals
    • Need living cells to replicate
    • Stable outside of host/acid-resistant
  36. Symptoms of Norovirus
    • Projectile vomiting, abrupt onset of non-bloody diarrhea, abdominal cramps, headaches, etc. 
    • Resolves within 24-48 hrs (24 hr flu)
  37. Symptoms of Hepatitis A
    • Jaundice, fever, nausea, anorexia, malaise, dark urine, abdominal discomfort.
    • Lasts less than 2 months
  38. Symptoms of Rotavirus
    • Vomiting, non-bloody diarrhea (watery, explosive), fever, dehydration, electrolyte imbalance
    • Affects mostly children
  39. How are viruses controlled in food?
    • Prevent contamination
    • Thermal processes
    • Sanitation (hand sanitizers don't count)
  40. What parasites were talked about?
    • Giardia lamblia
    • Cryptosporidium parvum
    • Cyclospora cayetanensis
    • Toxoplasma gondii
    • Trichinella spiralis
  41. What are the properties of Giardia lamblia?
    • Protozoan
    • Waterborne
    • Livestock & foodborne (poor hygiene)
    • Highly contagious
    • 1 cyst dose
    • Asymptomatic carriers
    • Diarrhea 1-2 wks
  42. What are the properties of Cryptosporidium parvum?
    • Contaminated drinking water
    • Raw/undercooked food contaminated with oocysts
    • Onset 5-21 d
    • Severe diarrhea, cramps, headache, nausea, vomiting (fever, coughing)
    • Long exposure in immunocompromised = death
  43. What are the properties of Cyclospora cayetanensis?
    • Worldwide
    • Transmitted through water, food, person
    • Onset 2-11 d
    • 1 cyst dose?
    • Sever diarrhea
    • Sometimes weight loss, bloating, stomach cramps, nausea, vomiting, etc.
  44. What are the main points about Toxoplasma gondii?
    • Obligate intracellular parasite
    • From cat feces (only known host)
    • Severe illness in fetus'
  45. What are the properties of Trichinella spiralis?
    • Undercooked pork/wild game
    • 1 larvae dose
    • Freeze to control
    • 1-2 d nausea, diarrhea, vomiting, fatigue, fever, discomfort
    • 2-8 wk headaches, fever, chills, cough, eye swelling, muscle pain, constipation, diarrhea, etc.