12 - microbial spoilage

Question 1

what are the two sources of contamination

Answer 1

1. natural

2. external

Question 2

____ is generally considered to be the best bacteria at attaching onto the surface of meat

Answer 2

Pseudomonas

Question 3

What is the best way to preserve processed meat ?

Answer 3

to have a very clean facility to prevent the attarchment of the bacteria to meat surface and animal carcasses must be washed with clean water after slaughtering

Question 4

___ are a major issue in food processing environments

Answer 4

Biofilms

Question 5

But in general aerobic Gram-negative bacteria mostly _____ will dominate the microflora under cold aerobic conditions, and ___ will dominate vacuum-packaged products

Answer 5

Enterobacteriaceae

LAB

Question 6

pseudomonas will promote the growth of ____

Explain why

Answer 6

listeria

because it will hydrolyse proteins and provides amino acids for listeria that is auxotroph

Question 7

What is spoilage?

Answer 7

consumer rejection of food based on undesirable sensory characteristics

Question 8

T or F : there is no scientific definition of spoilage

Answer 8

true

Question 9

T or F : Glucose is more rapidly metabolized by aerobic bacteria (Pseudomonas) than by facultative anaerobes

Answer 9

true

Question 10

What is the is the most important source of energy of spoilage bacteria ?

Answer 10

1- glucose
2- lactate
3- amino acids

Question 11

T or F : When there is proteolysis than it means the bacteria load is heavy

Answer 11

true because it is the last source of energy, after glucose and lactate

Question 12

T or F : there are some microbiological spoilage indicator that we can rely on for accessing microbial safety without any doubt

Answer 12

false, there are at the moment no extremly reliable microbial spoilage indicators

Question 13

What are the points an ideal spoilage indicator should have?

Answer 13

1- be absent or present in very low mount in fresh tissues
2- be produced by spoilage microflora
3- increase with the storage time
4- correlate well with sensory analysis

Question 14

___ is probably the best way to evaluate freshness of spoiled meat

Answer 14

Sensory evaluation

Question 15

what are the common microbes found on fresh meat ?

Answer 15

gram negative rods like pseudomonas, enterobacteriacea and acinetobacter. stapj, etc.

Question 16

T or F : LAB and pseudomonas are found commonly and in high population levels on fresh meat

Answer 16

false, LAB is only found in lower populatino counts on fresh meats

Question 17

__ are the dominating spoilage microorganisms in red meat at cold temperatures

Answer 17

Pseudomonas spp.

Question 18

Pseudomonas are gram __ and LAB are gram ___

Answer 18

pseudomonas : gram -

LAB : gram +

Question 19

why is stress and exercise not good for the meat production

Answer 19

because of the decreased levels of glucose in the tissues leading to rapid proteolysis

Question 20

what are the spoilage microorganisms of processed meats?

Answer 20

1- aerobic : micrococci

2- anaerobic : lactobacilli

Question 21

Slime is usually confined to the surface and is associated with the growth of :

Answer 21

-yeasts
-lactobacillus
-enterococcus
B. thermosphacta

Question 22

Dry-cured meats mostly spoil because of ___ and ___ that tolerate extremely low water content

Answer 22

yeasts or molds

Question 23

Bacterial populations associated with the carcass of chickens at the end of processing have predominantly Gram-___ bacteria

Answer 23

negative, like enterobacteriacea and pseudomonas

Question 24

What is the dominant bacteria in the chicken processing as soon as there is refrigeration storage

Answer 24

pseudomonas

Question 25

what is the step of the chicken processing that results in the most contamination?

Answer 25

evisceration

Question 26

Europe tested a “dry” procedure that excludes scalding and picking. In this procedure the birds are essentially waxed. This lowered the counts of aerobic ____ but increased _____ counts

Answer 26

Gram-negatives

S. aureus

Question 27

what are the steps involved in processing poultry?

Answer 27

1- stunning/killing/bleeding
2- scalding
3- picking
4- evisceration

Question 28

in the case of poultry, what is the first source of energy for spoilage bacteria

Answer 28

glucose and then amino acids

Question 29

in the case of poultry processing, the at refrigeration, the first spoilage microorganisms are

Answer 29

1- pseudomonas

2- yeasts

Question 30

Biogenic diamines including: __, ___ and ___ can be produced postmortem by fish or shellfish tissue

Answer 30

histamine, cadaverine, and putrescine

Question 31

How are produced the biogenic amines?

Answer 31

by the decarboxylation of free amino acids due ot the release of the decarboxylase from micoorganisms.

Question 32

T or F : cooking properly fish can lower the amounts of histamine

Answer 32

false

Question 33

what is another concern in the smoking of not fresh fish

Answer 33

An additional concern is that if nitrite is used in cold-smoked fish products that are not fresh enough, putrescine and cadaverine will react with that nitrite to produce carcinogens.

Question 34

Consuming biogenic amines can cause ____

Answer 34

scombroid food poisonings

Question 35

What is the difference between food poisoning and food infection?

Answer 35

in the case of infection the bacteria grows inside you while in the case of food poisoning, you eating the toxin

Question 36

_____ are routinely present in the water where shrimp are raised

Answer 36

pathogenic vibrios

Question 37

Fecal contamination of growing ponds is not uncommon and coliforms and ____ are common in shrimp rearing environments

Answer 37

Salmonella

Question 38

in shrimps : organisms responsible for refrigerated shrimp spoilage are mainly __ and __

Answer 38

Pseudomonas and Aeromonas