Term
| how is generation time recorded? |
|
Definition
|
|
Term
| what are the three main aspects that affect generation time in food products? |
|
Definition
food composition
storage conditions
combination of microorgansims |
|
|
Term
| explain replacement growth? |
|
Definition
| one MO thrives creating a byproduct that allows another MO to thrive. a sequence of MO growth |
|
|
Term
| what are the general symbiotic relationships between organsisms? |
|
Definition
antagonism/parasitism (+/-)
commensalism (+/o)
amensalism (-/o)
mutualism/synergism (+/+)
competition (-/-) - antagonistic also? |
|
|
Term
| what is an example of a food product that exploits replacement MO growth? |
|
Definition
|
|
Term
| what are the stages of the logistical growht curve? |
|
Definition
|
|
Term
| what 2 factors determine what the target growth curve for MOs in a food product is? |
|
Definition
1. the generation time of the organisms
2. the desired outcome of the food product (fresh, canned, etc.) |
|
|
Term
| what is the equation for calculating generation time? |
|
Definition
|
|
Term
| what do the variables G,t,z,x refer to in the generation time equation? |
|
Definition
G = generation time
t = lenght of study in minutes
z = final CFU
x = initial CFU |
|
|
Term
| what type of water contributes to water activity? what type does not? |
|
Definition
free water - does
bound water - does not |
|
|
Term
|
Definition
| the process by which gas or liquid accumulates on the surface of a solid |
|
|
Term
| what is an adsorption isotherm? |
|
Definition
| a function that relates % moisture to water activity |
|
|
Term
|
Definition
| water vapor pressure of food/water vapor pressure of pure water |
|
|
Term
| what does type I curve represent on the adsorption isotherm? |
|
Definition
| bound water, water adsorbed on surface of particles |
|
|
Term
| what attractive forces are responsible for 'bound' water? |
|
Definition
| Hydrogen bonding, Van der Waals forces |
|
|
Term
| What does the type II curve of the adsorption isotherm represent? |
|
Definition
| monolayer moisture content - monolayer adsorbed and first multilayers added |
|
|
Term
| what does the type III curve of the adsorption isotherm represent? |
|
Definition
|
|
Term
| what type of isotherm curve does dry cocoa represent? |
|
Definition
|
|
Term
| explain hysterisis in relation to the adsorption isotherm. |
|
Definition
| isotherm curve is different depending on whether the substance is undergoing adsorption or desorption. previous state alters relation between moisture content and water activity |
|
|
Term
| what is the affect on water activity caused by increasing either pressure or temperature? |
|
Definition
| the water activity increases (isotherm shifts right) - releases bound water? |
|
|
Term
| a substance at 10% moisture content would have more water activity if undergoing adsorption or desorption? |
|
Definition
|
|
Term
|
Definition
|
|
Term
| at what level of Aw can almost all MO's grow? |
|
Definition
|
|
Term
| at what level of Aw are almost all bacteria inhibited? |
|
Definition
|
|
Term
| at what level of Aw are all yeasts inhibited? |
|
Definition
|
|
Term
| at what level of Aw are xerophilic MOs inhibited? |
|
Definition
|
|
Term
| at what level of Aw are halophilic MOs inhibited? |
|
Definition
| 0.65 (depending on salt content) |
|
|
Term
| what is the difference between mold and yeasts? |
|
Definition
yeast - unicellular fungi
mold - multicellular fungi |
|
|
Term
| what does xerophilic mean? |
|
Definition
|
|
Term
|
Definition
| 'salt-loving' MOs that can live in high salt environments w/relatively low water activity |
|
|
Term
| what bacteria is most tolerant to low water activity? what level of tolerance? |
|
Definition
|
|
Term
| why is Staph.aureus of special concern to food scientists? |
|
Definition
1.most tolerant bacteria to low Aw
2.causes food intoxication (heat tolerant enterotoxin)
3.it is everywhere (endemic and ubiquitous) |
|
|
Term
| what level are high Aw foods? examples |
|
Definition
0.98+
fresh fruits/vegetables/meats, yogurt, many beverages |
|
|
Term
| what types of foods would have Aw at 0.93-0.98? examples |
|
Definition
foods with <10%NaCl and <50% sugar
foods with few added ingredients
velveeta, tomato paste |
|
|
Term
| what types of foods would have Aw at 0.85-0.93? examples |
|
Definition
foods w/>10% NaCl
chedder cheese, lunchmeat |
|
|
Term
| what types of foods would have Aw at 0.60-0.85? examples |
|
Definition
foods w/long shelf life
jelly, cereal, dried fruits, IM foods |
|
|
Term
| what are IM foods? example |
|
Definition
intermediate moisture foods
foods between Aw 0.60-0.85 that have a large amount of added salt/sugar
soft dog treats |
|
|
Term
| what are some foods at <0.60 Aw? |
|
Definition
|
|
Term
| what is the Henderson Hasselbach equation? |
|
Definition
| pH = pKa + log([A-]/[HA]) |
|
|
Term
|
Definition
|
|
Term
| why does pH affect food texture? |
|
Definition
| free H+ react with amino acid side groups affecting protein shape |
|
|
Term
| what happens when a cell is exposed to Hydronium ions? |
|
Definition
| H+ pass freely across the plasma membrane and disable the metabolism of the cell |
|
|
Term
| how do weak acids affect MO's? |
|
Definition
| both Hydronium ions and undissociated acid pass through plasma membrane affecting the enzyme activity of the cell and disrupting the H+ gradient |
|
|
Term
| What strategy does Enterobacter aerogenes have to combat low pH? |
|
Definition
| can perform butanediol fermentation resulting in acetoin which raises pH |
|
|
Term
| what range of pH can molds as a group tolerate? |
|
Definition
|
|
Term
| what range of pH can yeasts as a group tolerate? |
|
Definition
|
|
Term
| what range of pH can bacteria as a group tolerate? |
|
Definition
|
|
Term
| what group of bacteria tolerate a larger range of pH than most? |
|
Definition
|
|
Term
| what range of pH do lactic acid bacteria tolerate? |
|
Definition
|
|
Term
| what range of pH does Staphylococcus tolerate? |
|
Definition
|
|
Term
| at what pH is CBot inhibited? |
|
Definition
| less than or equal to 4.6 |
|
|
Term
| what pH range is 'low-acid food'? |
|
Definition
|
|
Term
| what 6 factors are evaluated when deciding which acid to add to a food product? |
|
Definition
1. which is best for MO's that are the biggest threat
effect on: 2. texture
3. flavor
4. color
5. what is buffering capacity
6.cost |
|
|
Term
| why is changing pH a concern with vegetables? |
|
Definition
low protein
proteins act as buffers |
|
|
Term
| what are the 8 approved acids for food use? |
|
Definition
FLC STAMP
fumaric
lactic
citric
sodiumacid sulfate
tartaric
acetic
malic
phosphuric |
|
|
Term
|
Definition
| at what pH the acid dissociates |
|
|
Term
| should pKa be higher or lower than target pH to be effective in smaller amounts? |
|
Definition
|
|
Term
| if the target pH is less than the pKa of an acid, what will need to happen? |
|
Definition
| will need greater amounts of the acid |
|
|
Term
| what are the 3 biggest food companies in the US? |
|
Definition
1. Tyson foods
2. Kraft
3. Pepsi-Co |
|
|
Term
| what 3 roles can buffers play in a food product? |
|
Definition
1. decrease flavor variations
2. decrease color changes
3. improve stability of artificial sweeteners (aspartame) |
|
|
Term
|
Definition
|
|
Term
| how does pKa relate to buffering capacity? |
|
Definition
| an acid has the most buffering capacity at the pH of its pKa |
|
|
Term
| what do buffers normally consist of? |
|
Definition
| an acid and the salt of that acid |
|
|
Term
| what acid stimulates the production of saliva? |
|
Definition
|
|
Term
| how is oxidation/reduction potential notated? |
|
Definition
+Eh - oxidized
-Eh - reduced |
|
|
Term
| what general type of MO is a reduced environment likely to support? |
|
Definition
|
|
Term
| what specific microbial growth factor is targetted by vacuum sealing? |
|
Definition
Oxidation/reduction potential
Eh |
|
|
Term
| what 5 microbial inhibitors are naturally found in egg whites? |
|
Definition
lysozymes
ovoinhibitor
ovomucoids
avidin
conalbumin
(COOLA) |
|
|
Term
| which of the MO inhibitors in egg whites is most effective againes gm(-)? |
|
Definition
|
|
Term
| which MO inhibitor in egg whites is especially effective against gm(+)? |
|
Definition
| lysozyme and ovoinhibitor |
|
|
Term
| how does lysozyme function as MO inhibitor? |
|
Definition
| binds to cell wall, makes phagocytosis by WBC easier |
|
|
Term
| how does ovoinhibitor inhibit MOs? |
|
Definition
| inhibits proteases slowing protein synthesis by MOs |
|
|
Term
| how does ovoinhibitor inhibit MOs? |
|
Definition
| inhibits proteases slowing protein synthesis by MOs |
|
|
Term
| what MO inhibitor in egg whites provides biggest control agains Bacillus and Clostridium? |
|
Definition
|
|
Term
| how do ovomucoids inhibit MOs? |
|
Definition
| inhibits enzymes that break down proteins (trypsin and chymotrypsin) |
|
|
Term
| what enzymes produced by MOs to digest proteins is inhibited by ovomucoids? |
|
Definition
|
|
Term
| how does avidin function as an MO inhibitor? |
|
Definition
| 'occupies' biotin, binds two molecules of biotin together so it cant be used by MOs |
|
|
Term
|
Definition
|
|
Term
| how does conalbumin inhibit MOs? |
|
Definition
| 'occupies' Fe, makes it unavailable to MOs that need it |
|
|
Term
|
Definition
|
|
Term
| what is the significance of mastitis to milk production? |
|
Definition
cow with mastitis would be given anti-biotics
antibiotics are strictly prohibited in US milk so cow needs to be milked seperately, milk disposed of in some way, and cow monitored after recovery to make sure no trace anti-biotics are left in milk |
|
|
Term
|
Definition
| kit used by farmers to test milk for anti-biotics |
|
|
Term
| what trace foreign chemicals may be found in milk? |
|
Definition
pesticides
sanitizing compounds |
|
|
Term
| what 4 natural anti-MO defenses are present in milk? |
|
Definition
leukocytes
antibodies
lactoferrin
fatty acids |
|
|
Term
|
Definition
| phagocytic white blood cell |
|
|
Term
| how does lactoferrin inhibit MOs? |
|
Definition
| 'occupies' Fe (like conalbumin in egg whites) |
|
|
Term
| what type of fatty acid is most inhibitory to MOs? |
|
Definition
|
|
Term
| what does a bacteriostatic inhibitor do? |
|
Definition
curbs the growth curve
doesn't kill bacteria, slow growth |
|
|
Term
|
Definition
| hydrocarbon chain with carboxyl end |
|
|
Term
| what natural anti MO in soybeans? |
|
Definition
| trypsin (inhibitory type/amount) |
|
|
Term
| what natural anti-MO in cranberries? |
|
Definition
|
|
Term
| what natural anti-MO in nuts, tea, wines? |
|
Definition
|
|
Term
| what natural anti-MO in cinnamon? |
|
Definition
|
|
Term
| what gas is commonly used to treat foods for MOs? |
|
Definition
|
|
Term
| what type of inhibitor is sulfor dioxide? |
|
Definition
bacteriocidal
and bacteriostatic |
|
|
Term
| why is sulfur dioxide used as anti-MO treatment? |
|
Definition
broad range effectiveness
gm(-), yeasts, molds |
|
|
Term
| where is sulfur dioxide commonly used? |
|
Definition
bagged cut vegetables
wine and fruit beverages
dried fruit |
|
|
Term
| why is sulfur dioxide used in wine and banana chips? |
|
Definition
|
|
Term
| why must sulfur dioxide always be included in the label? |
|
Definition
| some people have allergies |
|
|
Term
| what types of food change generally results from the hydrolysis of food molecules? |
|
Definition
|
|
Term
| what might be the cause of mushy food with an off flavor? |
|
Definition
hydrolysis of food molecules (mushiness)
incomplete metabolism of fats/proteins (off-flavor) |
|
|
Term
| what type of food moleculesmay be hydrolyzed by MOs? |
|
Definition
|
|
Term
| what type of food molecules are fermented? |
|
Definition
|
|
Term
| define and give an example of serial metabolism? |
|
Definition
one endproduct feeds the next set of reactions
fruit juice -> wine -> vinegar |
|
|
Term
| what percentage of harvested produce is lost to spoilage? |
|
Definition
|
|
Term
| what % of fruits are water? |
|
Definition
|
|
Term
| what defenses do fruits have to MO spoilage? |
|
Definition
1. low pH
2. physical barrier
3. essential oils (often anti-MO) |
|
|
Term
| what broad type of MO is the biggest concern for fruit spoilage? |
|
Definition
|
|
Term
| what is the main culprit in citrus spoilage? |
|
Definition
|
|
Term
| what mold retardent is sprayed on harvested citrus fruit? |
|
Definition
|
|
Term
| what mold is a problem with strawberry spoilage? |
|
Definition
|
|
Term
| what part of the strawberry does Rhizopus affect? what does it cause to happen? |
|
Definition
affects epithelial tissue
causes tissue to collapse/lose shape |
|
|
Term
| what practices does the strawberry industry use to defend against Rhizopus? |
|
Definition
1. picked by hand
2. boxes not re-used
3. plastic packaging pre-sterilized w/closable lids |
|
|
Term
| what is the main culprit in apple spoilage? |
|
Definition
|
|
Term
| what causes soft brown rot in apples? |
|
Definition
|
|
Term
| what mycotoxin is produced by Penicillium expansum? |
|
Definition
|
|
Term
| how does the apple industry target Penicillium expansum? |
|
Definition
1. apple 'drops' not used
2. pasteurization of cider
3. apples stored in conditions that are not conducive to P.exp growth |
|
|
Term
| what are the four main reasons for spoilage of canned fruit? |
|
Definition
1. insufficient processing
2. thermophilic anaerobes
3. damage to the can
4. heat resistant mold |
|
|
Term
| what thermophilic anaerobe is known for causing fruit canning spoilages? |
|
Definition
|
|
Term
| what conditions cause flat sour fruit spoilage? organism? |
|
Definition
pH atleast 3.8 and storage temperatures atleast 40 C
Bacillus coagulans |
|
|
Term
| what heat resistant mold is often responsible for fruit canning spoilages? |
|
Definition
|
|
Term
| what broad group of MOs is most responsible for vegetable spoilage? |
|
Definition
|
|
Term
| what is the most common type of vegetable spoilage? what species usually responsible? |
|
Definition
bacterial soft rot
Erwinia and Pseudomonas |
|
|
Term
| what are the characteristics of bacterial soft rot? |
|
Definition
1. soft, mushy consistency
2. bad odor
3. water soaked appearance |
|
|
Term
| how do enzyme do Erwinia and Pseudomonas have that causes bacterial soft rot? |
|
Definition
|
|
Term
| breakdown of what food molecule often is responsible for bad odors in food? |
|
Definition
|
|
Term
| explain the likely stages of spoilage leading up to a bad smelling vegetable. |
|
Definition
Erwinia/Pseudomonas ->
bacterial soft rot ->
CHO breakdown by fermenting MOs ->
pH lowered ->
proteins brokedown ->
NH2 released |
|
|
Term
| how can Agrobacterium contribute to spoilage? |
|
Definition
| causes increased production of IAA which quickens senescence |
|
|
Term
| how are raw cucumbers treated for prolonged storage? |
|
Definition
|
|
Term
| what unusual distinction does the federal definition of a pickle contain? |
|
Definition
| must contain no metallic compunds except salt |
|
|
Term
| what % NaCl in pickle barrel? |
|
Definition
|
|
Term
| what succession of organisms perform the pickiling of cucumbers? what dictates this order? |
|
Definition
Pediococcus ->
Lactobacillus plantarus ->
Lactobacillus brevis
dropping pH caused by each MO allows for the next one to take over |
|
|
Term
| what are the main causes of pickle malfermentation? |
|
Definition
|
|
Term
| what are the products of a pickle malfermentation? what desired product is NOT produced? |
|
Definition
H2 and CO2
lactic acid not produced |
|
|
Term
| how would you know that malfermentation has taken place in a batch of pickles? |
|
Definition
|
|
Term
| what are the 2 major proteins in milk? |
|
Definition
|
|
Term
| what is the main carbohydrate in milk? |
|
Definition
|
|
Term
|
Definition
| the emulsification of milk fats and proteins |
|
|
Term
| explain molecularly the changes that occur when milk has been homogenized. |
|
Definition
| the hydrophobic fat globules are surrounded by the hydrophobic end of the milk proteins which have their hydrophillic ends facing the outside of the cluster |
|
|
Term
| what is the target organism in milk pasteurization? |
|
Definition
|
|
Term
| what does Coxiella burnetti cause? |
|
Definition
|
|
Term
| what percent fat is whole milk? |
|
Definition
|
|
Term
| what are the 2 goals of milk pasteurization? |
|
Definition
1. destroy Coxiella burnetti
2. extend shelf life |
|
|
Term
| what is the shelf life of pasteurized compared to non-pasteurized milk? |
|
Definition
|
|
Term
| what is the standard for milk pasteurization? |
|
Definition
|
|
Term
| How is HTST pasteurization performed? |
|
Definition
|
|
Term
| how is UHT pasteurization performed? |
|
Definition
|
|
Term
| what happens at higher pasteurization temperatures? |
|
Definition
| proteins are denatured, texture and flavor change |
|
|
Term
| True or false: UHT kills more bacteria than HTST |
|
Definition
|
|
Term
| what are some terms used to describe off-flavors in milk? |
|
Definition
| fruity, malty, grassy, putrid, unclean |
|
|
Term
| what type of MOs generally responsible for off flavors in milk? |
|
Definition
|
|
Term
| what gm(-) psychrotrophs associated with off flavors in milk? |
|
Definition
| Pseudomonas and Alcaligenes |
|
|
Term
| what are the main spoilage molds of bread? |
|
Definition
| Rhizopus, Aspergillis, Penicillium, Monilia sitophila |
|
|
Term
| what mold is a major concern for bakeries because it is very hard to remove from an environment once it is established? |
|
Definition
|
|
Term
| what type of psychrotrophs may spoil refrigerator dough products? |
|
Definition
|
|
Term
| what metabolic products associated with heterolactic bacteria? |
|
Definition
| lactic acid and gas (CO2 H2) |
|
|
Term
| what are the 2 most common heterolactics? |
|
Definition
| Lactobacillus and Leuconostoc |
|
|
Term
| what bacteria causes ropy bread? |
|
Definition
|
|
Term
| what fungus causes pink bread mold? |
|
Definition
|
|
Term
| why is Bacillus lichenformis not eliminated by baking? |
|
Definition
| spores are heat resistant |
|
|
Term
| what additive is found in virtually all bread and flour products to protect against 'ropy bread'? |
|
Definition
|
|
Term
| what organism does calcium propionate inhibit? |
|
Definition
|
|
