30C-9 |
Postmortem pH, muscle, and refrigerated storage effects on ability of vacuum-packaged pork to re-bloom |
L. ZHU1, B. Bidner2, and S. Brewer1. (1) Dept. of Food Science & Human Nutrition, Univ. of Illinois, Urbana-Champaign, 399 Bevier Hall, 905 S. Goodwin, Urbana, IL 61801, (2) Dept. of Animal Science, Univ. of Illinois, Urbana-Champaign, 216 Meat Science Lab., 1503 S. Maryland, Urbana, IL 61801 The blooming process results in the desirable bright-pink color of pork. Re-blooming is important for vacuum-packaged pork to be acceptable to consumers. The objective of this study was to evaluate effects of postmortem pH, muscle location, and refrigerated storage on the ability of vacuum-packaged pork to re-bloom. Longissimus lumborum et thoracis(LT), gluteus medius(GM) and semimembranosus(SM) muscles were excised from carcasses 24 hr postmortem, then separated into pH groups: low (pH 5.2-5.5), medium (pH 5.6-6.0) and high (6.1-6.8). Muscles were sliced, vacuum packed individually, and stored at 4°C. At day 0, 7, 14, 21, and 28, samples were allowed to bloom at 4°C. L*, a*, b*, hue and Chroma were determined over 30 min. Percent change during the 30 min period was used to evaluate blooming ability. All color characteristics, except L* value, changed during the blooming period. a* value increments of LT, GM and SM muscles were 46.93%, 41.35%, and 39.66%, respectively; hue angle decrements of LT, GM and SM were 7.75%, 6.41%, and 5.07%, respectively. LT muscle bloomed the most and SM the least. a*, b* and Chroma incremental changes of fresh samples were smaller than those of stored samples. The lower the sample pH, the more a* and b* values and Chroma increased during blooming, and the earlier in the storage period that change occurred. Hue angle decrements for low pH samples were greater, and occurred earlier, than did those for the medium and high pH samples. Refrigerated storage of vacuum packaged pork for 7 days or longer and lower pH resulted in more rapid blooming. Understanding factors that influence blooming of myoglobin is important in understanding meat color and discoloration during storage, because meat color at retail has a major influence on consumer acceptability.
Session 30C, Muscle Foods: Tenderness, Quality, Processing, Marination, Oxidation, and Shelf-Life
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