Food Chemistry and Microbiology Flashcards
most important cause of food spoilage
microorganisms
may be beneficial or harmful in food
microbes
examples of non-harmful microbes in foods
beneficial bacteria (yogurt/cheese)
spoilage microbes (lactic acid/pseudomonas)
fungi (molds/yeast)
(T/F) Pathogens ARE NOT spoilage microbes
True
second largest cause of food spoilage
chemical food spoilage (enzymes)
causes of chemical food spoilage
exposure to air/light (rancidity/lipid oxidation)
breakdown of fats in food
rancidity
naturally present in foods that often cause breakdowns of carbs, fats, and proteins
enzyme reactions
food that is subject to decay, ruin, or destruction
perishables
all raw meats must be considered contaminated with _____ and _____ _____
pathogens
spoilage microbes
primary concern with intact meats
surface contamination
examples of intact meats
large cuts of beef/pork
steaks/roasts
ground and chopped meat
comminuted meats
primary concern with comminuted meats
any surface contamination is spread throughout the product
examples of comminuted meat
sausage
ground beef
what causes rancidity
oxidation
bacteria metabolize meat proteins for free amino acids
the bacteria produce enzymes that metabolize the proteins causing off-odor and flavor
putrefaction
anaerobic bacteria cause the production of organic acids which lowers the pH, leads to sour flavor
souring and gassing
the types of greening
green cores
green rings
surface greening
bacteria produce hydrogen peroxide within the meat which is a strong oxidizing agent that degrades the meat pigment and turns it green
green cores
similar to green cores except at varying depths in the meat
green rings
this type of greening takes time to occur (about 5 days)
surface greening
bacteria and yeasts contaminate the meat and multiply to excessive numbers
slime
is most common in meats like sausage and cured hams
needs oxygen to grow
mold
causes the typical “fish” odor
trimethylamine
broken down to lactic acid, lowering pH, acting as a preservative limiting bacterial growth
glycogen
categories of fish
fresh, stale, putrid
bright appearance
no odor
clear eyes
red gills
glistening scales
smooth/clear surface
firm flesh
bright blood
fresh fish
dull-dry appearance
slight odor
opaque eyes
reddish grey gills
dull/loose scales
viscous surface
soft flesh
dark brown blood
stale fish
dull-dry appearance
offensive odor
sunken, no color eyes
dark brown gills
dry/loose scales
dry surface
flabby flesh
dirty brown blood
putrid fish
problems during egg formation
ruptures in the oviduct/ovary
disease of the oviduct/ovary
allow gases to pass in/out of the egg
porous shells
egg will exhibit a thin egg white when broken out on a plate
occurs in older eggs
yolk will drift off center
stuck yolk
bacteria found in chicken fecal material and in the reproductive tract
can easily infect eggs during formation
salmonella
most common spoilage concerns that occur in dairy products
milk souring
roping
sweet curdling/slight coagulation
caused by bacteria that produce enzymes within dairy products
malty, rancid, yeasty, bitter, fruity, putrid flavors, purple/reddish colors
most common spoilage microorganisms associated with cheeses
molds
yeasts
anaerobic spore-formers
can reduce microbial growth in cheese
low pH
salting
low temperature of ripening
low oxidation
main concern of FF&V
surface contamination
two main categories of FF&V
ground grown
vine/tree grown
highest risk category of FF&V
ground grown b/c most contaminated
vegetable spoilage is most often caused by
bacteria
fruit spoilage is most often caused by
mold
FF&V come in two main forms
intact
cut/processed
not a TCS (time and temperature control for safety) food
spoilage organisms can cause quality deterioration but not pathogenic concerns
temperature danger zone (TDZ) is not important
intact FF&V
food may or may not allow pathogenic growth
must maintain temperatures of 41 degrees fahrenheit or below
cut/processed FF&V
food that is partially or somewhat subject to decay, ruin, or destruction
semi-perishables
examples of semi-perishables
cans, bags, boxes, jars
cereal, bread, canned goods
(T/F) TDZ is important for semi-perishable food
False
defined as a food that has the ability to support the rapid and progressive growth of infectious and toxin-producing microorganisms
Time and Temperature Control for Safety (TCS)
examples of TCS
red meat
poultry
shellfish
eggs
dairy products
examples of non-TCS
hard boiled eggs
most cheeses
intact FF&V
six factors that affect growth of pathogens
Food
Acid
Temperature
Time
Oxygen
Moisture
most bacteria prefer foods that are high in ____ and ____
protein
carbohydrates
foods with a pH of ____ or higher allow pathogens to grow
4.6
Temperature Danger Zone
41-135 degrees Fahrenheit
bacteria may double every __ to __ minutes
10 to 30
___ hrs in the TDZ can allow bacteria to grow to high enough numbers to cause illness
4
aerobic
require oxygen
anaerobic
do not require oxygen
both aerobic and anaerobic
facultative
require oxygen to survive but they require environments containing lower levels of oxygen
microaerophilic
water activity (Aw) of ____ or higher can allow pathogens to grow
0.85
bound water
unavailable for bacteria to grow
free water
available for microbial growth
government approved substances added to food during production or processing
food additives
contains poisonous ingredients, unapproved additives, or is made of decomposed or unsanitary ingredients
adulterated food
other ways to prevent and control food pathogens
Food handler health
Food handler hygiene
Cleaning/sanitation of food contact surfaces
Complete and thorough cooking
Chlorine rinse of FF&V
Approved Sources
