The effect of ageing treatment on the microbiology and storage characteristics of beef in modified atmosphere packs containing 25% CO2 plus 75% O2

Food by-products as potential antioxidant and antimicrobial additives in chill stored raw lamb patties

The aim of this work was to study the in vitro antioxidant potential of aqueous extracts obtained from tomato (TOM), red grape (GRA), olive (OLI) and pomegranate (POM) by-products as well as to evaluate the effect of their addition into lamb meat patties (1000mg/kg) in order to improve shelf life. A negative (CON) and a positive control (sodium ascorbate, ASC) were also included in the experiment. Results for radical scavenging activity, metal chelating activity and reducing power indicated that GRA and OLI extracts could inhibit oxidation more efficiently than POM and TOM extracts (P<0.01). Consistently, GRA and OLI treatments showed the highest redness (a*) (P<0.01) and antioxidant activity, both for lipids and proteins, throughout storage (P<0.001). Furthermore, in general, microbial counts were reduced by the addition of by-products extracts. These results suggest that the extracts obtained from grape and olive pomaces could be effectively used to replace sodium ascorbate in lamb meat products.

Changes of microbial spoilage, lipid-protein oxidation and physicochemical properties during post mortem refrigerated storage of goat meat

Examined was the effect of post mortem refrigerated storage on microbial spoilage, lipid-protein oxidation and physicochemical traits of goat meat. Seven Boer bucks were slaughtered, eviscerated and aged for 24 h. The Longissimus lumborum (LL) and Semitendinosus (ST) muscles were excised and subjected to 13 days post mortem refrigerated storage. The pH, lipid and protein oxidation, tenderness, color and drip loss were determined in LL while microbiological analysis was performed on ST. Bacterial counts generally increased with increasing aging time and the limit for fresh meat was reached at day 14 post mortem. Significant differences were observed in malondialdehyde (MDA) content at day 7 of storage. The thiol concentration significantly reduced as aging time increased. The band intensities of myosin heavy chain (MHC) and troponin-T significantly decreased as storage progressed, while actin remained relatively stable. After 14 days of aging, tenderness showed significant improvement while muscle pH and drip loss reduced with increase in storage time. Samples aged for 14 days had higher lightness (P < 0.05) and lower (P < 0.05) yellowness and redness. Post mortem refrigerated storage influenced oxidative and microbial stability and physico-chemical properties of goat meat.

Extending the storage life of raw chilled meats

Preservative packagings for raw meats must both delay the deterioration of the appearance of the product and retard the onset of bacterial spoilage. Preserving the product appearance is largely a matter of slowing or preventing the formation of brown metmyoglobin at muscle surfaces. Browning is slowed in atmospheres which are rich in oxygen, and persistent browning is entirely prevented when meat is packaged under oxygen-depleted atmospheres. Bacterial spoilage is delayed by packaging under aerobic atmospheres rich in carbon dioxide, or by packaging under anaerobic conditions. However, the control of bacterial spoilage also requires that product temperatures be maintained close to the optimum for chilled storage, and attention to the hygienic condition of the product before it is packaged. Packaging techniques for conforming an extended storage life on most raw meats are available, and long term economic trends seem to require a general improvement of the storage life of raw meats. However, current commercial systems for distributing meat are largely geared to the handling of highly perishable product, and the potential economic advantages from trading in more stable product will not be fully realizable while such systems persist. Consequently, commercial progress towards greater storage stability for chilled meats is likely to be uneven and uncertain.

Bacterial populations associated with bulk packaged beef supplemented with dietary vitamin E

Five Simmentaler type calves were fed diets supplemented with 500 mg vitamin E per day and five fed control diets, Rump steaks from each carcass were PVC-overwrapped and bulk packaged in 100% CO2 or 20% CO2:80% O2. Bulk packs were stored up to 42 days at 4 degrees C and PVC-overwrapped samples subsequently displayed up to 7 days at 4 degrees C. After display the Aerobic Plate Count (APC) of steaks was determined and four colonies were randomly selected from the highest dilution APC plates showing growth. A total of 627 colonies were obtained. Gram-reaction, catalase, oxidase, morphology and motility of the isolates were determined. The gram-negative and gram-positive isolates were then identified using a dichotomous identification key. Enterobacteriaceae, Pseudomonas spp. and Acinetobacter spp. predominated on rump steaks from both feeding treatments and in packaging treatments. After 42 days bulk storage Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria and Acinetobacter spp. predominated in 20% CO2:80% O2 and 100% CO2 bulk packaging. Enterobacteriaceae, Pseudomonas spp. and Acinetobacter spp. predominated on rump steaks, from both feeding and packaging treatments, during the aerobic display period of 7 days.

Influence of aging treatment on the bacterial quality of South African springbok (Antidorcas marsupialis marsupialis) wholesale cuts

The left sides of 20 springbok carcasses were aged with the skin on (treatment 1), while the right sides were aged without the skin (treatment 2). Another 20 carcasses were skinned, halved and cut into wholesale cuts. The loin and leg cuts from the right sides were deboned before vacuum packaging (treatment 3), while the loin and leg cuts from the left sides were vacuum packed with the bone in (treatment 4). All the carcass sides (36 h post mortem) and vacuum packed cuts (36 h post mortem) were aged for either 2, 5, 12 and 19 days respectively (ca. 0 degrees C). The examined groups of bacteria indicate that, for an ageing period of 12 days or less, vacuum packaging does not have an advantage over the hung in air method. However, when considering an extended ageing period ( > 12 days) vacuum packaging ensures that spoilage bacteria are inhibited and that the Enterobacteriaceae group of bacteria do not increase (ca. 0 degrees C), while the results clearly show that this is not the case with the hung in air ageing treatments (1 and 2).