10) Fermented Meat

Question 1

what is the definition of a fermented meat product

Answer 1

meats deliberately inoculated during processing to ensure sufficient control of microbial activity

Question 2

what is the importance of starter cultures in fermented meat?

Answer 2

improves safety, flavour and repeatability of meat fermented products

reduces risk of Staphylococci outbreaks

Question 3

what are 3 ways of starting meat fermentations?

Answer 3

1. natural fermentation: relies on indigenous microflora
2. back inoculation: involves inoculating new meat with a portion of a previous batch
3. starter culture: involves inoculating meat with frozen or freeze-dried culture

Question 4

what type of fermentation occurs in meat products due to starter cultures?

Answer 4

LAB homofermentative

Question 5

why must meat starter cultures be homofermentative?

Answer 5

1. acid production lowers pH of meat
2. able to grow in 6% salt
3. capacity to enhance flavor in meat without producing slimes

Question 6

what is the most imp MO in meat starters?

describe it

Answer 6

periococcus acidilactici

• survives lyophilisation (can be freeze dried)
• rapidly produces lactic acid
• higher optimal growth temp than lactobacillus sp
• salt tolerant (to 6.5%)

Question 7

why is staphylococci and kocuria added to starter cultures?

Answer 7

to reduce nitrate/nitrite to nitric oxide via nitrate and nitrite reductase

creates pink color after heating

Question 8

what is the red color in meat due to?

describe this process

Answer 8

O2 consumption

1. increased O2 consumption = decreased O2 tension of meat surface
2. bacteria can form a physical barrier that limits O2 from diffusing to meat underneath
3. metmyoglobin forms (brown)
4. metmyoglobin to myoglobin derivatives (bright red)

Question 9

what are bacteriocins? describe the production and use of then in meat fermentation

Answer 9

• they are antimicrobial peptides that kill or inhibit growth of some Gram-pos bacteria
• produced by some lactobacillus species
• considered natural food preservatives due to minimal health risk
• decreases safety concerns for fermented meats not having ay heat treatments

Question 10

what are 3 advantages of cultures with bacteriocins?

Answer 10

1. antimicrobial activity against pathogens and spoilage bacteria
2. increased shelf life
3. reduced rate of meat tissue degradation

Question 11

describe dry and semi-dry sausages

Answer 11

• originates from Mediterranean region
• sensory and taste characteristics are due to: addition of salt, fermentation by indigenous LAB, indigenous yeasts, rapid drying conditions of the Mediterranean
• being stuffed into anaerobic sausage casings and high salt content = favors LAB growth
• preservation: from lactic acid, organic acid and alcohols
• not smoked

Question 12

describe summer sausages

Answer 12

• originated from North Europe, where sausages were prepared during winter and stored until the summer
• higher water content, more lightly spiced, heavily smoked than Mediterranean
• heavily smoked

Question 13

what are regulations for non-refrigerated semi dry shelf stable sausages?

Answer 13

pH 4.5; intact or vacuum packed, internal brine conc no less than 5%, cured with nitrite, be smoked with wood

Question 14

describe the processing of sausages

Answer 14

1. reduce particle size of meat
2. incorporate salt and nitrate/nitrite, glucose, spices, seasonings, specific starter culture
3. blend ingredients
4. vacuum stuff meat into semi-permeable casing to minimize O2
5. incubate at or near starter cultures optimal growth until specific pH end point is achieved or until CHOs are all used
6. heat (not always required) to inactivate starter culture and ensure pathogen destruction
7. dry aging to required MPR (moisture-to-protein ratio)

Question 15

what is the role of staphylococci in meat ferm?

Answer 15

reduces nitrate to nitrite, which generates nitric oxide, which reacts to myoglobin to produce characteristic cured color

Question 16

what does meat fermentations rely on for microbiological safety?

Answer 16

low Aw + salt + low pH

since there is not enough heat to kill pathogens

Question 17

describe production of commercial fish sauce

Answer 17

• add salt
• seal vat
• allow supernatant to develop
• remove liquid (containing peptides, AAs, ammonia, volatile FAs)
• liquid is further aged
• flavours are added

Question 18

what charcteristic aroma and flavours of fish sauces are due to what?

Answer 18

enzymatic activity, oxidation during fermentation, production of volatile FAs, strong salt component, pH, fish composition, fermentation temp

Question 19

in fish sauce production, what happens when salt is added to fish

(0-25 days)

Answer 19

salt penetrates fish tissues by osmosis; proteases increase soluble protein content of the liquor but eventually stops due to increasing AAs; high bacterial populations (mostly facultative anaerobes)

Question 20

what happens during 80-120 days of fish sauce production

Answer 20

protein rich liquid develops through autolysis

Question 21

what happens during 140-200 days of fish sauce production?

Answer 21

fish tissue is converted to a N containing liquid; lower bacterial populations

Question 22

describe production of fish pastes

Answer 22

 1. mix cleaned and eviscerated fish, shrimp, plankton, etc… to salt ratio 3:1 (fish to salt)
 2. place in vats to ferment
 3. proteolytic enzymes from fish tissue or bacteria break down fish tissue to a paste
 4. pickle liquid from the fermentation is formed due to osmotic differential of brine solution
 5. fish is decanted
 6. When pickle stops forming, fish paste is ready for consumption

Question 23

what is Fessekh?

what safety risks are there?

Answer 23

• egyptian dish
• intact mullet fish is dried in the sun and fermented in a vat of brine for 45 days
• associated with high mortality rate in Egypt due to botulism, since there is concentration of C. botulinum spores in the viscera. External salting has difficulty reaching this.