Changes in the Microbiology of Vacuum‐packaged Beef

Abstract

The development of the microbial flora on meat stored in vacuum‐bags at 0–2° for up to 9 weeks was studied. Although the proportion of lactic acid bacteria increased relative to the aerobic spoilage organisms, the numbers of the latter continued to increase throughout storage. The initial contamination of the meat before vacuum‐packaging was important; meat with a very low initial number had lower numbers of bacteria throughout storage for up to 9 weeks and steaks cut from such meat which had been stored always had 1–2 days’ additional aerobic shelf life at 4°. Spoilage of these steaks was due either to slime formation and off‐odour associated with high counts of presumptive Pseudomonas spp., or by discoloration and souring (lactic acid bacteria). Extract release volume and pH measurements performed on the vacuum‐packaged primal joints were only of value in determining the onset of aerobic spoilage when large numbers of Gram negative organisms were present, whereas the titrimetric method of spoilage evaluation of the vacuum‐packaged meat showed a correlation with spoilage due to lactic organisms.

Microbiological Hazards Assessment of Psychrotrophic Microflora in Bovine Carcasses Slaughtered in North West Romania

“…In this respect, the dominant microflora is in fact the Gram negative one (73.98%), among which the psychrotrophic bacteria is represented in large numbers (71.39%), following these microorganisms' properties of rapidly growing at refrigerating temperatures, compared to the mesophilic microflora. Similar studies made by Sutherland et al (1975), Hanna et al (1977), Ayres et al (1980) and Cousin (2000), have revealed that the initial microflora in the bovine carcasses is dominated by the Gram positive represented by staphylococci, micrococci, streptococci, Bacillus and Lactobacillus germs, in variable amounts, ranging between 55-75%, while the Gram negative microflora is represented by the genera: Pseudomonas, Acinetobacter, Moraxella, Aeromonas, accounting for approximately 25-45%. At refrigerating tempretures, there is a change in the microbial configuration which takes place, so that, the psychrotrophical germs, represented by the microorganisms from the genera Pseudomonas (54%), Moraxella (9%), Acinetobacter (10%), Aeromonas (9%), Psychrobacter along with a lower quantity of psihrotrophic germs from the Enterobacteriaceae family (Serratia, Enterobacter), become the dominant population (Cousin, 2000).…”

“…1). The highest values of the microbial load was noticed during the second and third trimester, when it was revealed an exceeding in the recommended maximum limit (5.0 log CFU/cm 2 ) at 32 samples (44.44%) (Sutherland et al, 1975;Hanna et al, 1977;Ayres et al, 1980;Cousin, 2000). The psychrotrofic germ load in the case of the samples collected in unit B, ranged between 5.46±0.14 log CFU/cm 2 in the first trimester and 6.04±0.51 log CFU/cm 2 in the third trimester with minimum values of 5.30±0.20 log CFU/cm 2 in the month of January and a maximum of 7.16±0.05 log CFU/cm 2 in May, noticing that at 17 samples the value was higher than the limit recommended, which means 72%, from the total samples' number ( Fig.…”

Quality Changes of Pork in Relation to Packaging Conditions During Chilled Storage in Households

“…The offodour detected from the WP samples was described as putrid, stuffy, stale and slightly sweet-sour. According to Sutherland et al (1975), a high count of Pseudomonas spp. (> 6 Log CFU/cm 2 ) is accountable to the formation of sweet-rotten odour on aerobic storage of meat.…”

Microbiological, physical and chemical studies on fresh red meats packaged under different modified gas atmospheres

“…Vacuum packaging of meat selects for the growth of lactic acid-producing bacteria (Sutherland et al, 1975). Pierson et al (1970) found that 90-95% of the total bacterial count in vacuum-packaged beef stored for 15 days at 3.3°C were lactobacilli.…”