Effects of Carbon Dioxide, Oxygen, and Their Gas Mixture on the Changes of Microflora and Quality of Ground Pork in Modified Atmosphere Packaging

Abstract

The effects of CO2, O2 and their mixture used for modified atmosphere packaging on the keeping quality and microflora of ground pork stored at 5°C for 15 days were compared with those of air packaging. The increase of viable counts in ground pork packaged with mixed gases was suppressed in proportion to the increase of CO2 ratio in the gas mixture. At the beginning of storage, the microflora in ground pork mainly comprised Micrococcus, yeast and Acinetobacter. On the 15th day, dominant flora were Pseudomonas for 100% O2 and 10% CO2: 90% O2 packages, Brocho-thrix for 20% CO2: 80% O2, 30% CO2: 70% O2 and 40% CO2: 60% O2, and Lactobacillus for 50% CO2: 50% O2, 60% CO2: 40% O2, 70% CO2: 30% O2, 80% CO2: 20% O2, 90% CO2: 10% O2, and 100% CO2 packages. The VBN values of the air, 100% O2 and 10% CO2: 90% O2 packages on the 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% O2 and 10% CO2:90% O2 packages by the 15th day. Redness (color value) of meat was better maintained by the gases with higher O2 ratios. It was evident from these results that CO2:O2 mixed gases with CO2 concentration between 50% and 60% would be most effective to extend the shelf life of ground pork in modified atmosphere packaging. © 1995, Japanese Society for Food Hygiene and Safety. All rights reserved.