(Molly) L4 - Food Safety | Quizlet

potential hazards in cold smoked fish

1. listeria monocytogenes

2. clostridium botulinum type E

3. biogenic amines

4. parasites

flow diagram of cold smoked fish

1. receiving raw materials (refrigerated/fresh caught or frozen)

2. storage of raw matierial

3. seperate fish, fillets etc into batches of uniform size

4. brining of fish

5. removing fish from brine: drain and/or rinse with fresh water: place fish on hooks or racks

6. cold smoking

7. cooling (2 step process)

8. packaging

9. storage and distribution

describe the cold smoking process

fish arranged to allow for uniform smoke absorption, heat exposure and DH

smoke generated, liquid or combination

temperatures

a. not exceed 32 deg C for >20 hours

b. not exceed 10 deg C for >24 hours

c. not exceed 49 deg C for >6 hours for cold-smoked sablefish

describe the 2 step process of cooling

cool to 10 deg C within 3 hours and to 3.0-3.3 deg C within 12 hours

what packaging can be used for cold smoked fish

air packed

- must contain 2.5% WPS

vacuum or MA packed

1. must contain 3.5% NaCl or

2. combination of 3.0% WPS and at least 100ppm but no more than 200ppm sodium nitrite

during storage and distribution of cold smoked fish the temp must be kept at

3-3.3 deg C at all times

describe clostridium botulinum

gram +, anaerobic, spore-forming bacteria that produce botulinum neurotoxin

toxins: A,B,C,D,E,F and G depending on their antigenic properties

botulism can be caused by 4 different scenarios

1. foodborne botulism - ingestion of toxin preformed in foods

2. infant botulism - spores are ingested, germinate and lead to toxin formation in the intestine

3. wound botulism

4. adult botulism - caused by intestinal germination + growth

source of psychotrophic C botulinum

occurs naturally in the aquatic environment, so its presence in low numbers on fresh fish must be anticipated

spores may also be isolated infrequently from cold-smoked fish, although numbers if present are low

clostridium botulinum type E can be isolated from (3)

water

aquatic sediments

aquatic organisms

in general, number of c botulinum spores in fish are...

low: 1-2 spores (to a few hundred) per kg

some studies have found higher levels such as 2000-3000 spores/kg

why must the risk of toxin formation of c botulinum in cold smoked fish be taken seriously

because the processing of cold smoked fish does not involve a heating step that eliminates the spores (or any other vegetative cells)

fish in an excellent substrate for..

c botulinum type E

The toxins produced by all of the different C. botulinum types are......

The toxins produced by all of the different C. botulinum types are heat labile.

The heat resistance of C. botulinum type E toxin depends on.........

The heat resistance of C. botulinum type E toxin depends on the pH:

describe how pH affects c botulinum

• the toxin is destroyed by moderate heating at neutral pH and

• is more resistant at lower pH values (pH 4.0- 5.0).

heat treatments used for food preparation are sufficient to destroy the toxin

true or false

true

it would not be considered acceptable to rely on cooking to inactivate any C. botulinum toxin that may be present in food.

true or false

true

type E toxin is not resistant to NaCl

true / fasle

false

• Type E toxin is resistant to NaCl; it is stable for weeks in 26% NaCl

does frozen storage affect spores of c botulinum

no

how is freezing beneficial in the prevention of c botulinum

freezing is an efficient way to completely prevent:

• germination and

• growth of C. botulinum

the cold smoking process uses temperatures at which C. botulinum grows well,

how can this process prevent growth of c botulinum

cold smoking is a highly aerated process;

• no growth of the organism occurs during this processing step

pH of cold-smoked salmon varies between

6 and 6.3

in general pH of fish varies ....

between 6 and 7

Eh

redox potential

what causes a high redox potential in fish,

what effect can this have

high redox potential (Eh) in some fish -> caused by the presence of trimethylamine oxide

can render the bacterium more susceptible to NaCl than under conditions of low Eh.

what are considered critical parameters to control c botulinum growth and toxin production when stored under vacuum

salt and refrigeration

how to perform challenge test for c botulinum

by combining NaCL control with chill storage - can prevent toxin formation for certain periods of time

eg at 5 deg C for at least 2-3 weeks at 2-2.5% NaCL

WPS

water phase salt

toxin formation is controlled with a combination of

moderate level of NaCL 3.5% WPS and

storage at chill temperature <4.4 deg for at least 4 weeks

clostridium botulinum is a ..... organism and is ...............

• Clostridium botulinum is an anaerobic organism and is sensitive to oxygen.

Due to the intolerance to O2, most attention has been paid to .......

Due to the intolerance to O2, most attention has been paid to vacuum- and CO2 -packaged products.

ROP

reduced oxygen packaging

what allows for short time periods of elevated temperatures up to 10 deg

combination of 3.5% NaCL (as wps) and a chill storage of 4.4 deg c

will prevent toxin formation in

- ROP cold-smoked fish

- for several weeks beyond its sensory shelf life

when can pocked of anaerobic condition be created

• even when not packed under vacuum or modified atmosphere,

• where slices of fish overlap or

• where aerobic spoilage bacteria consume the oxygen present

the effect of nitrite is influenced by...

pH

NaCl and

temp

• Nitrite level of ....... is necessary for the control of C botulinum growth and toxin formation

• Nitrite level of 100 to 200 ppm is necessary for the control of C botulinum growth and toxin formation

lactate is ..........to psychrotrophic C. botulinum

lactate is inhibitory to psychrotrophic C. botulinum

the lag phase of spores was prolonged from .......... when 2% lactate was added

8 hours to 28 hours

the effect of lactate was more pronounced with thr concurrent addition of ......

NaCL

adding 2% NaCl to the 2% lactate increased the lag phase to 58 days

why may sorbate be used in cold-smoked fish

vegetative cell growth is inhibited by sorbate, particularly at low pH

sorbic acid most effective at pH <6.0-6.5

sorbic acid most effective at pH ....

sorbic acid most effective at pH <6.0-6.5

the aerobic microflora of some products may ....

serve to enhance the risk of toxin formation

the growth of some other microorganisms may inhibit growth and toxin production by c botulinum

can you give an examples

bacillus isolates were inhibiting toxin production

TO CONTROL C. BOTULINUM GROWTH AND TOXIN PRODUCTION IN ROP PRODUCTS THE FOLLOWING CONSIDERATIONS ARE INDICATED:

1. a minimum 3.5% WPS concentration in the thickest part of the fillet for

vacuum or modified or atmosphere packaged

OR (USA)

a combination of at least 3% WPS and a nitrite level of 100 to 200 ppm

2. Packages containing refrigerated, cold-smoked fish should be

labeled:

"Keep Refrigerated at 40 º F 4.4 °C or below".

3. Packages containing frozen, cold moked fish should be labeled:

"This product must remain frozen until thawed at refrigeration

temperatures and shall not be refrozen,

4. Products should not be packaged in ROP by the retailer