Question

describe some reasons why raw minced and aerobically stored meat spoils faster than 1) cut, raw pieces of meat stored anaerobically. In which of the three products do lactic acid bacteria not play a role as spoilers

Answer 1

The muscle tissue is very sterile in healthy animal before slaughter but when slaughter occurs, due to the exposure of muscle to the contaminants like intestinal contents, mis handling, improper cleaning (unclean water) of carcass after evisceration (removal of internal organs) could conatminate the carcass

the total bacterial counts ranges from 10² -10⁵ cfu/gram in fresh meat. off-odours are seen when the count more than 10⁷ cfu/g, slime formation and color change etc are observed if the microbial load more than 10⁸ cfu/g

predominant microflora of fresh meat : Gram-negative bacteria : Pseudomonas, Acinetobacter, Psychrobacter and Moraxella Gram-positive bacteria: Bacillus, clostridia, staphylococcus

raw minced meat and aerobically stored meat spoils faster than cut, raw pieces of meat stored anaerobically reasons:

1) minced meat Vs cut raw pieces

mincing meat poses more chances of increased microbial load reasons

• greater surface area of minced meat gives better access to food for the growth of microbes.
• processing could contribute additional contamination (equipment, blades, handling etc)
• some times mincing of meat with lymph nodes (where microbes lodge while circulation) could contribute more contamination

2) aerobic Vs anaerobic packaging:

changes under aerobic packaging :

• aerobic packing allow the growth of aerobic bacteria usually psuedomonas (predominant spoilage bacteria in aerobically stored raw meat and poultry)
• unsaturated fatty acids present in the meat could get oxidized by lipolytic bacter can produce off-flavours
• aerobic conditions also encourages growth of molds

these listed changes are well controlled in anaerobic packaging that is why minced raw meat and aerobically packed meats spoils faster than anerobically packed meats

Lactic acid bacteria:

LAB bacteria are able to grow well at anerobic conditions also could grow in the presence of very less oxygen.

that is why LAB is predominant in anaerobically packed meat because the LAB become dominant when the aerobic spoilage bacteria gets inhibited

answer: in minced raw meat and aerobically packed meat LAB do not play a role as spoilers. Anaerobically packed meat pieces could be spoiled by LAB and become sour if not stored properly