The influence of inherent muscle quality upon the storage life of chilled pork stored in CO 2 at −1.5 °C

Abstract

A total of 120 pork loin sections (1 kg) representative of five inherent muscle quality groups [24 each; extremely PSE (pale, soft and exudative), PSE, normal, DFD (dark, firm and dry), and extremely DFD]were used to evaluate the effects of inherent muscle quality on the keeping quality of chilled pork stored for up to 15 weeks in CO 2 at −1.5 °C. B. thermosphacta, pseudomonads, and enterics did not grow on any muscle quality group during storage in 2.5 1 of carbon dioxide per kg of product. Lactic acid bacteria became the dominant flora on all muscle quality groups during storage and reached maximum numbers during the first six weeks of storage. Purge losses increased during the first three weeks of storage from all muscle quality groups but were generally the highest from pork with normal muscle quality throughout storage. The pH of pork with PSE characteristics tended to normalize with extended storage, and the color of pork with extremely aberrant quality appeared to normalize by approximately one level of muscle quality after 15 weeks of storage. Pork with DFD characteristics required the longest duration of storage to display surface discoloration. The retail appearance of pork from all muscle quality groups was well within the acceptable range after 15 weeks of storage, but the retail appearance of pork with normal and DFD characteristics deteriorated progressively during storage. Off-odors became detectable in all muscle quality groups after 12 weeks of storage but were more pronounced from pork with DFD characteristics. However, the intensity of these off-odors did not become more than slight even in DFD samples. Although the odor acceptability began to decline after 12 weeks of storage, all samples remained quite acceptable in odor after 15 weeks of storage. Muscle quality exerted little influence on cooking times and losses throughout storage. Pork with normal quality characteristics was generally less tender prior to storage. Although muscle quality exerted little influence on other palatability attributes, both flavor desirability and overall palatability deteriorated during storage in all samples and reached the point of unacceptability after six weeks of storage, when lactic acid bacteria attained maximum numbers.