Effect of Different Packaging Treatments on Microbiological and Sensory Evaluation of Precooked Beef Roasts

Thirty boneless top round roasts were used in each of two trials to determine the effects of various packaging treatments on precooked roast beef acceptability. Roasts were dry roasted to an internal temperature of 60°C, cooled for 1 h and packaged by one of three methods: (a) vacuum packaging, (b) packaging in 100% CO₂ atmosphere or (c) packaging in 15% CO₂:30% O₂:55% N₂ atmosphere. Roasts were held at 4°C for up to 21 d. Enumeration of mesophiles and psychrotrophs, sensory evaluations and shrinkage percentages were determined at 0, 7, 14 and 21 d of storage to evaluate acceptability. Counts of mesophiles and psychrotrophs from 100% CO₂-treated roasts were significantly lower (P<0.05) than counts from vacuum-packaged roasts after 14 and 21 d of storage, whereas counts from gas mixture-treated roasts were not (P>0.05) different. After 7 d of storage, microbial numbers were similar, regardless of treatment. Sensory evaluation analyses showed that vacuum-packaged roasts exhibited little deterioration of quality characteristics at 21 d of storage, whereas both gas-treated roasts demonstrated quality deterioration by 14 and 21 d of storage. Vacuum-packaged roasts were preferred by panelists at 14 and 21 d, but CO₂-treated roasts were preferred at 7 d. No treatment effects were evident upon shrinkage until 21 storage days. At 21 d, vacuum-packaged roasts exhibited the lowest moisture loss.