Fermented meat products Flashcards
What is fermented meat product
meats that are deliberately inoculated during processing to ensure sufficient control of microbial activity
IS there a starter culture for meat or not?
Most manufacturers use starter cultures of LAB, although “traditional” methods may rely on naturally occurring microflora
However, meat fermentations can be started three ways:
- Natural Fermentation, which relies on indigenous microflora
- Back inoculation, which involves inoculating new meat with a portion of a previous batch, and
- Starter culture, which involves inoculating meat with frozen or freeze dried culture
Why starter culture are started to be used
- The use of starter cultures in meat products is relatively new, and the rationale for their use is that they improve the safety, flavor, and repeatability of meat fermented products
- Prior to the use of starter cultures outbreaks associate with Staphylococci were common
Is there a lot of LAB naturally in meat?
•LAB are a minor component of the microflora in fresh meat, but when meat is stored in anaerobic conditions (under vacuum) the resulting microenvironment facilitates their growth
what are the requirements for starter culture for meat?
•The starter cultures used in meat must be homofermentative to produce enough acid to rapidly lower the pH of the meat, able to grow in 6% salt, and have the capacity to enhance the flavor of the meat without producing slimes
What was the first available meat starter and why
- The first commercially available meat starter was Pediococcus acidilactici
- It was present in fermented meats (although did not dominate the culture)
- It survives lyophilization
- It rapidly produces lactic acid
- It has a higher optimal growth temperature than Lactobacillus sp.
- It is salt tolerant up to at least 6.5%
•There is also a ____ starter culture that can be used alone or in combination with P. acidilactici for dry and semidry sausage
Lb. plantarum
How rapidly and for how much the meat starter culture can decrease pH
from 5.6 to 4.8 in 8 hours
Why there is a color development in fermented meats?
- Certain bacteria such as staphylococci and kocuria can be commonly added to starter cultures to reduce nitrate/nitrite to nitric oxide via nitrate and nitrite reductase to develop meat into the characteristic pink colour after heating
- Some Lactobacillus can also reduce nitrite/nitrate for this reaction
- Red color development in meat can also be attributed to the consumption of oxygen
- •Increased oxygen consumption (by growing facultative aerobes) reduces oxygen tension on the meat surface
- •Bacteria can then form a physical barrier that limits oxygen from diffusing to the meat underneath
- •Metmyoglobin forms (brown)
- •As the microbes continue to consume oxygen, metmyoglobin gets reduced to myoglobin derivatives (bright red)
What is bacteriocins and why they are added
- Bacteriocins are antimicrobial peptides that either kill or inhibit the growth of certain other Gram-positive bacteria
- Since fermented meats are processed without heat treatment, the addition of bacteriocin producing strains was suggested to ameliorate safety concerns
What kind of preservatives bacteriocins are?
•Because of their minimal risk to human health bacteriocins are considered natural food preservatives
What produces bacteriocins
•Several species of Lactobacillus produce bacteriocins
Advantages of using cultures with bacteriocins
- Antimicrobial activity against pathogens and spoilage bacteria
- Increased shelf life
- Reduced rate of meat tissue degradation
•-____ represent the largest category of fermented meat products
Dry and semidry sausages
Where dry and semidry sausages originated from
Mediterranean region
Tastes and sensory characteristics coming from __ in dry and semidry sausages
- Addition of salt
- Fermentation by indigenous LAB
- Indigenous yeasts
- Rapid drying conditions of the Mediterranean
What is the general outline process for feremtned sausages
- Fermented sausages are generally heavily seasoned and stuffed into anaerobic sausage casings which favor the growth of LAB
- Typically these products are not smoked, and are preserved by the accumulation of lactic acid, organic acid, and alcohols
What is summer sausage and difference
- In contrast to the Mediterranean, Northern European Sausages were prepared during the winter and stored until summer, thus the name Summer Sausage
- These sausages have more water than the varieties from the Mediterranean, are more lightly spiced, and are heavily smoked at colder temperatures
- They are comparable to todays semidry sausages
What characteristics of dry and semidry sausages are regulated by safety agencies and what is the exception
•Compositional characteristics of dry and semidry sausages (such as moisture-to-protein ratios (MPR), pH limits, and ingredients) are tightly regulated by safety agencies (Health Canada, Federal Drug Administration)
Unless commercially sterilized
non-refrigerated semidry, shelf-stable sausages must be (pH, packaging, brine, additives)
- •Fermented to a pH of 4.5 or lower
- •Must be intact (or vacuum packed if sliced)
- •Have an internal brine concentration no less than 5%
- •Are cured with nitrite•Be smoked with wood
Semidry sausage manufacture must involve the following basic steps (7 steps)
I.Reduce the particle size of high-quality raw meat
II.Incorporate salt and nitrate or nitrite, glucose, spices, seasonings, and specific starter culture
III.Uniformly blend all ingredients
IV.Vacuum stuff the meat into a semipermeable casing to minimize the presence of oxygen
V.Incubate at or near the starter cultures optimum growth temperature until a specific pH end point is achieved (or until carbohydrates are utilized)
VI.Heat (not always required) to inactivate starter culture and ensure pathogen destruction
VII.Dry (aging) to the required MPR
When microbial contamination of meat occurs? What type of bacteria? How spoilage can occur?
- Bacterial contamination of meat will always happen during the slaughter process (most bacteria come from the hide, skin, or intestinal contents)
- These include predominantly Gram-negative bacteria
- Meats used for fermented sausages should be immediately chilled to <4.5C, have a small number of CFUs, and be free from defects
- If spoilage occurs it will usually be the result of Gram-negative, proteolytic bacteria that produce a putrid “rotten-egg” smell
What bacteria are initially present on meat?
•Small numbers of salt-tolerant LAB are initially present in the meat, and become the dominant population under anaerobic conditions
How concentration of LAB changes during meat fermentation?
•Initially LAB are 3-4 log CFU/g, but they increase during fermentation to 7-8 log CFU/g
•___ and ____ also can occur in fermented meats and tend to decline as pH increases
Staphylococcaceae and Micrococcaceae
What is the function of LAB and staphylococci?
- Some LAB are proteolytic and lipolytic and contribute to flavor as a consequence of the break down products
- Staphylococci can reduce nitrate to nitrite and generate nitric oxide, which reacts to myoglobin to produce the characteristic cured colour of fermented meats
What LAb is not desired in meat and why
- •Lactobacillus viridescens causes greening due to the production of hydrogen peroxide•
- Lactobacillus brevis and Leuconostoc mesenteroides can produce CO2, resulting in gas pockets
- •Brochothrix can cause unpleasant souring
Organisms of the greatest concerns in sausages?
- Staphylococcus aureus,
- E. coli,
- Salmonella,
- Listeria monocytogenes,
- Campylobacter,
- and the nematode Trichinella spiralis.
Why microbiological safety is a thing or sausages
- Pathogenic bacteria can pose a serious health threat if not controlled on raw materials and in finished fermented meats
- During fermentation of meat products there is not sufficient heat treatment to kill pathogenic bacteria
- Non-heated products rely on reductions in aw, combined with salt and pH to control pathogens
Fish sauce- a dish from where and how used
•Fish sauces tend to be associated with Asian culture, and are generally consumed as a condiment with rice and vary in colour from clear brown to yellow-brown
How fish sauce is acquired (time and process): commercial vs traditional
- Sauces have a salty taste and are predominantly derived from decanting or pressing fish or shrimp that have been fermented from 9-months or a year
- Commercial fish sauce production begins by layering fish, shrimp, or shellfish with salt in concrete vats at approximately 3:1 (fish to salt), sealing the vats, and allowing a supernatant to develop, then carefully removing this liquid•
When liquid is recovered from the fish it is further aged
Fish sauce: scheme with days
The first liquid to remove when fermenting for fish sauce: content, how it can be enhanced, flavor, how flavor is influenced
- The first liquid to be removed from the fermenting fish contains peptides, amino acids, ammonia, and volatile fatty acids and is considered the highest quality product
- Extracts may be enhanced by adding caramel, caramelized sugar, molasses, roasted corn, or roasted barley to enhance the colour
- The characteristic aroma and flavor of fish sauces are very complex and are derived from a combination of enzymatic activity, oxidation during fermentation, and the production of volatile fatty acids
- The flavor also has a strong salt component, but is influenced by pH, fish composition, and fermentation temperature.
What is fish paste?
•Fish pastes are consumed raw or cooked as a condiment with rice and vegetables and may be a source of dietary protein for low-income families
How fish paste is produced? z9mention flavor, is bacteria plays a huge role)
- Paste production consists of mixing cleaned, eviscerated whole or ground fish, shrimp, plankton, or squid with a fish to salt ratio of 3:1 (fish to salt) and then placing them in vats to ferment
- Proteolytic enzymes from the visceral tissue, and to some extent from bacteria, break down the fish tissue until it has a pasty consistency.
- Pickle, which is the liquid exudate from the fermentation, forms as a result of the osmotic differential of the brine solution and fish tissue are decanted and consumed as fish sauce
- When the pickle stops forming the fish paste is ready for consumption•
The fish paste has a salty, cheese like aroma
•Bacteria do not appear to play a major role in fish proteolysis, but do contribute to flavor, aroma, and spoilage
What is Feseekh?
•Feseekh is a traditional Egyptian dish prepared by leaving an intact (un-eviscerated) mullet fish to dry in the sun. After the fish is dried it is fermented in a vat of brine for 45 days
Why Feseekh can be dangerous?
- This dish is associated with a high mortality rate in Egypt due to botulism
- It caused an outbreak of botulism in Ontario as well
- Un-eviscerated fermented fish products are known to be a high-risk item for botulism since there is concentration of C. botulinum spores in the viscera and the external salting has difficulty reaching these areas
