The effects of prolonged storage under vacuum or CO 2 on the flavor and texture profiles of chilled pork

Abstract

The microbial contamination on pork loin samples was reduced by aseptical separation of the outer surfaces. They were then packaged under vacuum or carbon dioxide (CO 2) in quantities in excess of those required to saturate the tissues. All samples were then stored at −1·5°C. Floras of lactobacilli and enterobacteria or lactobacilli alone spoiled vacuum-packaged samples by 18 weeks. Metmyoglobin precipitated from the exudate and adsorbed onto meat surfaces, discoloring samples by 18 weeks. Inappropriate metallic and bitter notes became more intense during storage, deteriorating the flavor of samples. However flavor deterioration was not of sufficient magnitude to result in rejection of samples prior to onset of microbial spoilage. The texture of muscle tissue remained unaltered. Floras of lactobacilli also developed on samples packed under CO 2. However, these samples remained unspoiled until samples were exhausted at 24 weeks. However, after 18 weeks the appearance of some samples was compromised by bright pink patches apparently arising from the accumulation of myoglobin from the exudate. Flavor deterioration was similar to that observed for vacuum-packaged samples, but metallic and bitter notes did not reach sufficient intensity to cause rejection. As with vacuum-packaged samples overall texture perception remained unaltered, but the samples became progressively drier. Therefore, pork appears to undergo relatively slow autolytic deterioration during storage under both vacuum and CO 2. Oxygen ingress into vacuum packs results primarily in deterioration of visual properties after relatively long storage times.