EFFECTS OF CARBON-DIOXIDE, OXYGEN, AND TH EIR GAS-MIXTURE ON THE CHANGES OF MICROFLORA AND QUALITY OF GROUND PORK IN MODIFIED ATMOSPHERE PACKAGING

The effects of CO2, O-2 and their mixture used for modified atmosphere packaging on the keeping quality and microflora of ground pork stored at 5 degrees C for 15 days were compared with those of air packaging. The increase of viable counts in ground pork packaged with mixed gase s was suppressed in proportion to the increase of CO2 ratio in the gas mixture. At the beginning of storage, the microflora in ground pork m ainly comprised Micrococcus, yeast and Acinetobacter. On the 15th day, dominant flora were Pseudomonas for 100% O-2 and 10% CO2:90% O-2 pack ages, Brochothrix for 20% CO2 :80% O-2, 30% CO2: 70% O-2 and 40% CO2: 60% O-2, and Lactobacillus for 50% CO2:50% O-2, 60% CO2:40% O-2, 70% C O2:30% O-2, 80% CO2:20% O-2, 90% CO2: 10% O-2, and 100% CO2 packages. The VBN values of the air, 100% O-2 and 10% CO2:90% O-2 packages on th e 15th day of storage were 34.7, 31.2 and 27.4 mg/100 g, respectively, while the Values of the other gas mixture packages were less than 16 mg/100 g. The pH values were less than 6.0 except for the air, 100% O- 2 and 10% CO2:90% O-2 packages by the 15th day. Redness (color value) of meat was better maintained by the gases with higher O-2 ratios. It was evident from these results that CO2:O-2 mixed gases with CO2 conce ntration between 50% and 60% would be most effective to extend the she lf life of ground pork in modified atmosphere packaging.