Fermented meat products Flashcards
purpose of starter cultures
safety, repeatability, flavour (prior to the use of starter cultures, stapholococci infections were common)
what are the 3 ways meat fermentations can be started?
starter culture (inoculate meat with frozen or freeze dried culture), back inoculation, natural fermentation
is LAB a major component of natural meat microflora
no, but when placed in anaerobic conditions, LAB proliferate
properties of meat starter cultures
- able to grow in 6% salt
- homofermentative to rapidly lower the pH
- enhance the flavour of meat without producing slimes
pH drop from meat starter cultures
5.6-4.8 in 8 hours
what is the first commercially available starter bacterium and its properties
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%
how are fermented meat products given color?
- reduction of nitrate/nitirite to nitric acid via nitrate reductase (staph, lacto, kocuria)
- oxygenation (metmyoglobin reduction)
bacteriosin
antimicrobial peptide that inhibits the growth of some gram positive bacteria
- considered a natural food preservative
- produced by several strains of Lactobacillus
benefits of using bacteria that produce bacteriosin
increased shelf-life
reduced meat degradation
antimicrobial activity against pathogens and food spoilage organisms
dry and semidry sausages get their flavour from…
- addition of salt
- fermentation by natural LAB
- indigenous yeasts
- rapid drying conditions of the Mediterranean
properties of summer sausage
These sausages have more water than the varieties from the Mediterranean, are more lightly spiced, and are heavily smoked at colder temperatures
end-point characteristics of non-refrigerated semidry, shelf-stable sausages must be
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
what are the predominant spoilage organisms?
gram-negative bacteria
there is always spoilage during the slaughter process
to overcome this the meats should be immediately chilled to less than 4.5C
which LAB are not desired in fermented meat products?
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
which spoilage organisms are of the greatest concern in meat products?
Staphylococcus aureus, E. coli, Salmonella, Listeria monocytogenes, Campylobacter, and the nematode Trichinella spiralis.
