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63 Cards in this Set
- Front
- Back
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Water Activity (Aw) |
The moisture that is available in food
Aw= vapor pressure of the food/vapor pressure of the water If it's...... Greater than 0.90 = bacteria, yeast Less than 0.90 = molds |
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Microbial Needs |
1) Moisture 2) Temperature 3) Nutrients |
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Van Leeuwenhoek |
1693- first proposed that microbes cause disease
-AND he was the first person to see microbes and magnify them by putting lenses together the right way
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Pasteur |
1822-1895 -carried out experiments of spontaneous generation |
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Microorganisms... |
-cause disease -are destroyed by heat |
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Joseph Lister |
British Surgeon, (1827-1912) -surgical mortality -civil war -carbolic acid (phenol) -Listeria -Listerine |
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Microorganisms in Food |
Bacteria + Fungi |
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Fungi |
Molds & Yeasts |
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Molds |
-multicellular, hyphae (branches under the surface, spores on top) -colors -fuzzy/cotton-like -many tiny spores > air > new growth -withstand extremes of: ~ Aw, pH, Temp. more than bacteria -pH: 2-8 -Aw: 0.90 and below
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Yeast |
-single cell -larger than bacteria -divide by budding (creates daughter cell) -creamy white vs. molds -Aw: 0.90-0.94 (lower than bacteria, higher than molds) -pH: lower than bacteria
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Yeast (uses) |
used for baking and for wine
-foods contaminated with yeast have a fruity odor and an alcoholic smell or taste |
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Bacteria |
-reproduce by binary fission
-bacilli=rods -cocci=spherical
-some are motile, (flagella allow them to move) -have spores (heat resistant) -some aerobic, some anaerobic (meaning they can grow w/o oxygen) |
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1) Lag Phase |
a period of adjustment in a microbial growth pattern, first part of graph |
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2) Log Phase |
the period of growth of a population of cells in a culture medium during which numbers increase exponentially and which is represented by a part of the growth curve that is a straight line segment if the logarithm of numbers is plotted against time
2^n ; n= number of divisions
Ex: 100 cells are dividing 10 times: 100 cells * 2^(10) = 102,400 |
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2) (cont.) Generation Time |
??? ex: 20 minutes, 10 divisions = 200 minutes |
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3) Stationary Phase |
(middle part of graph of microbial growth pattern) cell number is stationary at this point in time |
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4) Death Phase |
last part of microbial growth pattern graph, -lack of nutrients -metabolic wastes |
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Temperature |
-huge factor affecting growth -microorganisms each have own temperature optimum -change of few degrees --> different microorganisms
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Thermophile |
HOT -rare -found in bottom of ocean, Yellowstone
110 degrees
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Mesophile |
MEDIUM 60-110 degrees |
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Psychrophile |
COLD -below 45 degrees (32-45, be careful, because these can live with refrigeration to an extent!) -under 40 degrees is few pathogens retard spoilage
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Oxygen |
-factor that affects growth -some organisms need it some don't NEEDS IT : aerobic DOESN'T: anaerobic EITHER OR: facultative
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aerobic |
need oxygen to live genus name: Pseudomonas -spoils hamburgers
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anaerobic |
don't need oxygen to live genus name: Clostridium -first living things on earth -not common -affects oil and seal packaged items |
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Water Activity (Aw) |
-another factor affecting microbial growth available moisture and what microbes can use -H2O required for growth: -removal=preservation = lower Aw -salt & sugar added for preservation |
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pH |
another factor affecting growth -7.0 is best for bacteria |
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Nutrients (H2O) |
Nitrogen- amino acids, proteins carbon- energy - carbs, proteins, lipids minerals needed vitamins in growth medium/food or synthesized |
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Chemicals |
-one way to preserve foods (review pages 91-94 in book)
not typing this out lol ^ |
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Nitrite vs Nitrate |
Sodium Nitrite: NaNO2 Sodium NitrAte: NaNO3
both dissociate into positive and negative (soluble) -certain vegetables contain nitrates -naturally-occuring bacteria in meat convert nitrATE to nitrITE |
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Acetic Acid Fermentation |
(Vinegar fermentation) -low cost (wine vinegar, cider vinegar, and distilled white vinegar) |
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Fermentation |
Review pages 95.5-105 in the book, not really able to type it out all into flashcards. |
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Thermal Processing |
the combination of temperature and time required to eliminate disease-producing microorganisms
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Pasteurization |
milk heated at high temp to prevent microorganisms from growing (161 degrees F for 15 sec) |
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Sterilization |
-250 degrees F for low acid foods |
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Ultra High Temperature (UHT) |
-250-300 degrees for a few seconds -used on creamers |
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Canning |
procedure to keep food stable not common until 20th century
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Nicolas Appert |
invented glass jars as a form of storing food long term, sealed w/ cork and wax, then put into boiling water |
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Factors Affecting Heat Resistance |
-H2O (Dry cells are more resistant)
-FAT (as fat content decreases, less heat is required, ex: whole milk must be heated at 156 degrees to kill of E coli, BUT cream @ 161, and skim milk at only 149 degrees)
-SUGAR (increase heat resistance partly due to decrease in Aw)
-pH |
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BACTERIAL spores |
not for reproduction help protect against heat also drying, cold, and chemicals |
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D value |
the time needed to kill 90% spores (How heat resistant?) on pg 107 see graph that shows the Destruction of Spores over Time)
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Role of Acid (pH) |
adjusts pH of mixture of spaghetti, tomato sauce, and cheese to: 7.0, 5.0, 4.6, 4.0 |
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Conventional vs Aseptic Processing and Packaging |
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FDA |
Food and Drug Administration -ensures safety of all foods EXCEPT: NOT meat, poulty & eggs |
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USDA |
Food Safety & Inspection Service ensures safety of meat, poultry, and eggs |
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CDC |
Center for Disease Control -deal w/ public health -investigate food-borne diseases |
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Animal and Plant Health Services |
(USDA) see this when travelling (airports) protects animals & plants from diseases or pests, so they prevent these diseases from entering the country
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EPA
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Environmental Protection Agency -establishes levels of pesticide residues |
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1784 |
year that the first Food Safety Law was passed -it was passed in MA -"an act against selling unwholesome provisions) |
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Requirements for Confirmed Case of Food-born illness |
affected person must: -seek medical care -have access to medical care -have specimen taken & analyzed properly -have results reported to appropriate public health agency |
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Cases of Food-borne illness |
-9.4 million/year Deaths: 1350/yr hospitalizations: 55,000/yr costs: $1.5-17 billion cause: 66% unkonw |
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Costs of Food Born Illness |
$1.5-17 billion
-direct medical -lost wages -industry recall and destruction -lost business -legal fees (food poisoning lawyers is a big business) -legal statements |
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Food INFECTION |
means LIVE BACTERIA are responsible for illness |
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Salmonella |
example of a food infection (Salmonella xxx= food born illness, around 2,000 species) (salmonella typhi is caused by typhoid fever) #1 cause of confirmed food-born illness in U.S. -in the intestinal tract of animals -found in improperly cooked meat/poultry, eggs |
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Salmonella (cont.) |
symptoms: fever, nausea, vomitting, diarrhea, abdominal pain incubation period: 12-24 hrs duration: 2-3 days -get in through epithelial cells lining small intestine -some reptiles naturally carry it |
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E Coli |
we all have it in our intestines a little naturally cases: 73,000-75,000 / year -can get it from eating uncooked ground beef and handling animals on farms like cattle and animal wastes like manure
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Food INTOXICATION |
means that a toxin formed in food is responsible for illness
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Staphylococcus auerus |
example of food intoxication -can grow at low Aw & is salt tolerant -toxin is formed in food -toxin is heat-stable symptoms: nausea, vomitting, diarrhea incubation period: 1-6 hours -gets in through nose and infections on hands -involved in protein rich foods (ex: ham)
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Clostridium botulinum |
-anaerobe, spore former -reason for high nitrite level in cured meat -few outbreaks symptoms: dryness of mouth and throat, difficulty speaking & swallowing, double vision, symmetrical descending weakness and paralysis -nerve impulses prevented -treated with an anti-toxin foods involved; home canned vegtables
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Viruses |
from the latin word "poison" -might not even be living -no nucleus or cell wall, simply genetic material coated by protein -must rely on a living host to survive and reproduce -also classified as parasites |
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Parasites |
small microscopic creatures that need a host to feed off of and live inside or on |
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Hepatitis A |
a liver disease symptoms: inflamed liver, jaundice, fever, weakness -incubation period: 10-50 days foods involved: raw shellfish or unheated salads via the handler |
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Viral gastroenteritis |
incubation period: 1-2 days symptoms: diarrhea Foods involved: raw shellfsh |
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Trichinosis |
a parasite, a round worm symptoms: gastroenteritis & muscle pain, periorbital edema foods involved: undercooked pork
-larvae in food mature into adults in the small intestine, females discharge new larvae in the lining of the small intestine which are carried by the blood to muscle tissue
prevention: cook or freeze things |
