Quality changes in beef complexus, serratus ventralis, vastus lateralis, vastus medialis, and longissimus dorsi muscles enhanced prior to aging.

Beef complexus (chuck), serratus ventralis (chuck), vastus lateralis (round), vastus medialis (round), and longissimus dorsi (loin) muscles were enhanced (0.3% salt, 0.4% phosphate), vacuum packaged, and aged for 7 or 14 d. Enhancement increased positive sensory attributes (tenderness, juiciness, beef flavor, saltiness) and decreased negative attributes (off-flavors) of all muscles but had greater effects on some than on others. It increased the oily mouthfeel (10%) and saltiness (40%) and decreased the L* value and chroma of the complexus (chuck). It increased tenderness, juiciness, and beef flavor and decreased off-flavors, visual red and brown colors, shear value, and cook loss of the serratus ventralis (chuck), vastus lateralis (round), vastus medialis (round), and longissimus dorsi (loin). Aging slightly decreased rancid and liver off-flavor scores, visual brown color, and shear value and increased the hue angle and L* and b* values.

Effect of enhancement and ageing on flavor and volatile compounds in various beef muscles.

To identify and quantify selected flavor-active volatile compounds and relate them to sensory characteristics, the gluteus medius (round), rectus femoris (round), vastus lateralis (round), vatsus medialis (round), teres major (chuck), infraspinatus (chuck), complexus (chuck), serratus ventralis (chuck), psoas major (loin) and longissimus dorsi (loin) were removed from heifer carcasses, enhanced, vacuum packaged, aged for 7 or 14days, steaks were cut, vacuum packaged and frozen (48h). Flavor-active volatiles affected by enhancement and ageing in the various muscles included nonanal, 2,3-octanedione, pentanal, 3-hydroxy-2-butanone, 2-pentyl furan, 1-octen-3-ol, butanoic acid, pentanal and hexanoic acid, compounds often associated with lipid oxidation. Enhancement decreased hexanal and hexanoic acid. Ageing decreased butanoic acid. Pentanal content varied among muscles depending on enhancement and ageing. Livery off-flavor was positively correlated with pentanal, hexanal, 3-hydroxy-2-butanone and hexanoic acid. Rancid off-flavor was correlated with pentanal and with 2-pentyl furan but not with hexanal.

Quality changes in beef gluteus medius, infraspinatus, psoas major, rectus femoris, and teres major enhanced prior to aging.

The objective of this study was to evaluate the effects of enhancement and aging on quality characteristics of the gluteus medius (round), rectus femoris (round), teres major (chuck), infraspinatus (chuck), and psoas major (loin). Muscles were enhanced, vacuum packaged, and aged for 7 or 14 d. Aging affected enhanced compared with nonenhanced beef differently. After 7 d of aging, enhanced beef experienced more cook loss and was less red (higher hue angle, lower a* values, and chroma) than did nonenhanced beef; after 14 d of aging, these differences were lost. Enhancement increased tenderness and brown color of the gluteus medius (round); however, it decreased visual green and red colors. Enhanced gluteus medius experienced 3.1% lower purge losses, lower L* values, and chroma than their nonenhanced counterparts. Enhancement increased infraspinatus (chuck) tenderness and visual brown color, and decreased visual red and green colors, purge loss, L* value, a* value, and chroma. The enhanced infraspinatus was substantially more tender than the other muscles evaluated, other than the gluteus medius; however, it was also substantially more visually brown. Enhancement decreased purge loss of the psoas major. Enhancement increased L* and a* values, hue angles, and chroma than other enhanced muscles. After enhancement the tenderness of the rectus femoris increased by 10%, decreased purge losses from 4.5% to 1.7%, and decreased green color by 18%. It reduced L* and a* values and chroma. Aging increased tenderness. Overall, muscles from the chuck (infraspinatus and teres major) appeared to benefit the most from enhancement.

Antioxidant and modified atmosphere packaging prevention of discoloration in pork bones during retail display.

The objective of this study was to evaluate the ability of antioxidants to prevent discoloration in pork rib bones. Pork rib bones were removed from carcasses, frozen (-20°C, 24h), split lengthwise, exposed to antioxidant solutions (ascorbic acid, citric acid, propyl gallate or ascorbic/EDTA mix), packaged (modified atmosphere [80% O(2) and 20% CO(2)] or air), then displayed in a retail case at 4°C for 8days. Dark pigment formation was visually evaluated during the display period. Instrumental color was determined at the end of the 8-day display period. Visual bone discoloration increased over time for all treatments. After 2days of display, samples treated with propyl gallate were visually redder, less discolored and less green/black than samples treated with other antioxidants. After 8days of display, propyl gallate-treated samples had higher a* and b* values, as well as chroma (intensity). However, this difference was no longer large enough to be visually detected.

Effect of carbon monoxide and high oxygen modified atmosphere packaging and phosphate enhanced, case-ready pork chops.

The objective of this study was to evaluate the effects of CO-MAP compared to traditional high oxygen MAP (HiOx-MAP) packaging and enhanced with different phosphate on enhanced pork quality. Pork loins were enhanced to 10.5% over initial weight to contain 0.3% salt and 0.4% phosphate (either sodium tripolyphosphate [STP] or a blend of STP and sodium hexametaphosphate) on a finished weight basis. Chops were cut, packaged in atmospheres containing 0.4% CO/30.0% CO(2)/69.6% N(2) (CO-MAP) or 80% O(2)/20% CO(2) (HiOx-MAP), aged in the dark, then placed in a lighted retail display case for 48h. Chops packaged in CO-MAP were redder (higher Minolta a(∗) values) and darker (lower Minolta b(∗) values) than chops packaged in HiOx-MAP. Based on sensory scores, the CO-MAP chops were pinker than the HiOx chops after cooking. CO-MAP chops also experienced less purge loss than chops in HiOx-MAP. Results indicate that CO-MAP had no effect on flavor or consumer acceptability and only minimal effects on other characteristics.

The intracellular segment of the sodium channel beta 1 subunit is required for its efficient association with the channel alpha subunit.

Sodium channels consist of a pore-forming alpha subunit and auxiliary beta 1 and beta 2 subunits. The subunit beta 1 alters the kinetics and voltage-dependence of sodium channels expressed in Xenopus oocytes or mammalian cells. Functional modulation in oocytes depends on specific regions in the N-terminal extracellular domain of beta 1, but does not require the intracellular C-terminal domain. Functional modulation is qualitatively different in mammalian cells, and thus could involve different molecular mechanisms. As a first step toward testing this hypothesis, we examined modulation of brain Na(V)1.2a sodium channel alpha subunits expressed in Chinese hamster lung cells by a mutant beta1 construct with 34 amino acids deleted from the C-terminus. This deletion mutation did not modulate sodium channel function in this cell system. Co-immunoprecipitation data suggest that this loss of functional modulation was caused by inefficient association of the mutant beta 1 with alpha, despite high levels of expression of the mutant protein. In Xenopus oocytes, injection of approximately 10,000 times more mutant beta 1 RNA was required to achieve the level of functional modulation observed with injection of full-length beta 1. Together, these findings suggest that the C-terminal cytoplasmic domain of beta 1 is an important determinant of beta1 binding to the sodium channel alpha subunit in both mammalian cells and Xenopus oocytes.