Quality changes during refrigerated storage of MA-packaged pre-rigor fillets of farmed Atlantic cod (Gadus morhua L.) using traditional MAP, CO2 emitter, and vacuum.

Quality changes during 3 wk of refrigerated storage (1.3 degrees C) were studied on pre-rigor filleted farmed Atlantic cod packed in modified atmosphere (MAP, 60% CO2 and 40% O2) or vacuum. The packages of MAP contained either a CO2 emitter and low gas volume to product volume (g/p ratio) of 1.3, or a 3.9 g/p ratio and no emitter. The CO2 level remained stable or increased in the packages with CO2 emitter, whereas the CO2 level in the packages with no CO2 emitter decreased to 40% after 4 d of refrigerated storage. High levels of oxygen in the gas mixture prevented formation of trimethyl amine (TMA) during storage of the MA-packed fish, whereas the TMA content increased significantly after 10-d storage in vacuum. MA-packed samples had the highest values of 1-penten-3-ol. Sensory scores of sour, sulfur, and pungent odors were significantly higher for vacuum-packed cod compared to the 2 MA-packaging methods measured 14 d after slaughtering. No differences in sensory scores were observed between the 2 methods of MAP, and shelf life of these samples seemed to be 14 to 21 d. Cod samples packaged in vacuum packages had higher pH values compared to ordinary MAP and packages containing a CO2 emitter. Bacterial growth was inhibited by MAP and resulted at the end of the storage period in dominance of Carnobacterium and some Photobacterium. In MA packages with high O2 levels the Photobacterium was inhibited. It is concluded that CO2 emitters are well suited for reduction of transport volume for MA-packaged farmed cod.

Lipid oxidation in frozen, mechanically deboned turkey meat as affected by packaging parameters and storage conditions.

Mechanically deboned turkey meat (MDTM) was stored in different packaging materials (film produced with natural antioxidant (alpha-tocopherol) or synthetic antioxidant) at -20 degrees C for 12 mo in a vacuum, modified atmosphere, or air. One-half of the samples were thawed at 4 degrees C for 24 h after 1 mo of storage and then refrozen. Oxidative rancidity was evaluated during storage by measuring the development of 2-thiobarbituric acid reactive substances (TBARS), and hexanal, a volatile oxidation product. Vacuum- and modified atmosphere-packaged samples had lower TBARS values and hexanal content than air-packaged samples with corresponding treatments. Hexanal content and TBARS values increased with storage time, and the highest levels were obtained after 6 mo of storage. The largest increase was obtained with presence of oxygen. Mechanically deboned turkey meat stored in packages where a natural antioxidant (alpha-tocopherol) was used in production of one of the PE layers, had, in almost every instance, the lowest TBARS values and hexanal content when stored in vacuum or modified atmosphere. However, this difference was not statistically significant. Neither TBARS values nor hexanal content showed dependency of the temperature profile (frozen or frozen/thawed/refrozen) during storage.

The effect of resuscitation and the incubation-temperature on recovery of uninjured, heat injured and freeze injured enterococci.

Five strains of enterococci were inoculated on the Slanetz and Bartley enterococcus agar (EA), and incubated at 37 degrees C and 44 degrees C following: no injury, heat-injury and freeze-injury. The experiments were repeated introducing a 2 h resuscitation step in Tryptic Soy Agar (TSA) at 37 degrees C and subsequent overlay with EA (TSA/EA) followed by incubation at both 37 degrees C and 44 degrees C. The TSA/EA method gave a significantly better recovery (1% confidence level) than the EA method at both 37 degrees C and 44 degrees C. The effect of incubation-temperature was only significant for two strains of Enterococcus durans, as one strain showed no growth at 44 degrees C and the other strain was recovered significantly (5% confidence level) better at 37 degrees C that at 44 degrees C when employing the EA method. Interpretation of the results using TSA/EA method was easier than that of the EA. Different lactic streptococci and lactobacilli commonly employed in the dairy industry did not develop false positive colonies in TSA/EA incubated at 37 degrees C.