Effect of Antioxidant Solubility and Concentration on Discoloration of Beef Vertebrae Marrow during Display

ABSTRACT:  Two experiments were conducted to assess the role of aqueous- and lipid-based antioxidants in preventing or limiting beef lumbar vertebrae marrow discoloration. In experiment 1, lumbar vertebrae ( n = 8 replications) were treated with either 0%, 1.5%, or 2.5% (wt/wt) of ascorbic acid or ascorbate-6-palmitate. Vertebrae color (visual and L*a*b*) was evaluated during 5 d of display at 1 °C in high-oxygen modified atmosphere packaging (MAP; 80% oxygen/20% carbon dioxide). Ascorbic acid treatments minimized ( P < 0.05) discoloration compared with ascorbate-6-palmitate. In experiment 2, lumbar vertebrae ( n = 8 replications) were treated with 0, 0.06 M, or 0.10 M ascorbic acid and ascorbate-6-palmitate, packaged in high-oxygen MAP, and displayed for 5 d (1 °C). During display, vertebrae treated with ascorbic acid had a redder color ( P < 0.05) than those treated with ascorbate-6-palmitate, and both treatments were redder ( P < 0.05) than untreated controls. To better understand the mechanism of beef bone marrow discoloration, future work might address the hydrophobic antioxidants' lack of effectiveness and the potential localization of components responsible for bone discoloration within the aqueous phase of erythropoietic marrow.     

Ascorbic acid minimizes lumbar vertebrae discoloration

Ascorbic acid was evaluated as a way of preventing bone discoloration. In experiment 1, beef bone-in t-bone steaks (lumbar vertebrae and longissimus) were treated with 0%, 0.05%, 0.1%, 0.5%, 1.0%, or 1.5% ascorbic acid (n=10). Vertebrae and muscle color (L(*)a(*)b(*)) were evaluated initially and after 24 h in 80% O(2)/20% CO(2). Vertebrae treated with 0%, 0.05%, or 0.1% ascorbic acid significantly discolored while the longissimus maintained a bright-red appearance. Ascorbic acid treatments 0.5%, 1.0%, and 1.5% significantly minimized vertebrae discoloration and neither induced nor prevented longissimus discoloration. In experiment 2, lumbar vertebrae were treated with 0%, 0.05%, 1.5%, or 2.5% ascorbic acid (n=15), packaged in 80% O(2)/20% CO(2), and displayed for five days (1 °C). Visual color was evaluated daily by a trained panel. Ascorbic acid treatment at 1.5% or 2.5% minimized lumbar vertebrae surface discoloration. Through a five-day display at 1 °C, lumbar vertebrae with 2.5% ascorbic acid had the least bone discoloration.     

Exclusion of oxygen from modified atmosphere packages limits beef rib and lumbar vertebrae marrow discoloration during display and storage

Visual and instrumental color (L*a*b* and reflectance from 400 to 700 nm) were used to evaluate packaging atmosphere as a way of minimizing beef marrow discoloration. In experiment 1, rib ends (n=24) packaged in 80% O(2)/20% CO(2) discolored more than ribs packaged in 100% N(2), which resulted in a relatively stable purplish marrow color through a 7-day display at 1 °C. In experiment 2, lumbar vertebrae (n=10) packaged in 80% O(2)/20% CO(2) had a rapid and significant discoloration within 24 h after packaging, likely because of the formation of methemoglobin. Conversely, vertebrae packaged in 80% N(2)/20% CO(2) and 0.4% CO/30% CO(2)/69.6% N(2) remained color stable during 2 and 6 weeks of storage at 4 °C, respectively. Exclusion of oxygen from MAP packages and the addition of low concentrations of CO minimized beef rib and lumbar vertebrae discoloration compared with high-oxygen MAP.     

Comparison of Assays for Metmyoglobin Reducing Ability in Beef Inside and Outside Semimembranosus Muscle

ABSTRACT: The relationships of 6 assays for metmyoglobin (Metmb) reducing ability to color stability and the chemical differences between the inside (ISM) and outside (OSM) beef semimembranosus (SM) muscle after 5 or 14 d storage were investigated. The ISM had less (p < 0.05) color stability than the OSM regardless of time post mortem, and both muscle portions were more color-stable when stored for 5 d rather than 14 d. Among the assays, aerobic reducing ability correlated best with visual color scores (r =−0.58) and Metmb accumulation (r =−0.61) in the SM. The ISM had less reducing ability than the OSM, which can be attributed partially to lower oxygen consumption rate and NAD concentrations (p < 0.05).     

Influence of Chemical Characteristics of Beef Inside and Outside Semimembranosus on Color Traits

The influence of prerigor temperature and pH on muscle chemistry of the inside semimembranosus (ISM) and outside semimembranosus (OSM) in relation to initial color and color uniformity and stability was investigated. Cold‐boned ISM had a slower (p < 0.05) chill rate; faster (p < 0.05) pH decline; higher (p < 0.05) transmission values; and less (p < 0.05) metmyoglobin reducing ability, oxygen consumption, water holding capacity and color stability than the OSM. Cold‐boned steaks were 2‐toned in color and visually unacceptable at d 3 of display. Hot‐boned ISM and OSM chilled at the same rate and had similar pH declines, similar chemical characteristics and uniform stable color for 5 d of display. Chilling beef ISM faster should produce uniform stable color.     

Effects of total iron, myoglobin, hemoglobin, and lipid oxidation of uncooked muscles on livery flavor development and volatiles of cooked beef steaks

Infraspinatus (IN), gluteus medius (GM), and psoas major (PM) steaks were obtained from A- and B-maturity carcasses with either high (6.0) or normal (5.7) pH, and either Slight or Small marbling. Steaks were vacuum aged either 7, 14, 21, or 35 d postmortem, and were broiled and served to a highly trained, flavor-profile sensory panel. Steaks with livery flavor were analyzed by gas chromatography/mass spectrometry for flavor compounds. Steaks aged 7 or 35 d postmortem were analyzed for myoglobin (Mb) and hemoglobin (Hb) concentrations and for total iron (Fe) (35 d steaks only). The IN had greater Fe (P < 0.05) than did the GM or PM. Livery flavor increased (P < 0.05) and beef flavor identification decreased (P < 0.05) in the GM as Fe increased. The PM had the lowest (P < 0.05) Mb/Fe ratios and highest (P < 0.05) Hb/Fe ratios. Several statistically significant, but relatively low correlations between 16-, 17-, and 18-carbon chain fatty acids and livery flavor resulted. Thirteen volatile compounds had higher concentrations in steaks with livery flavor than in those without livery flavor. Livery flavor development is a complex trait that can be affected by concentrations of total Fe, Mb, and fatty acids, but the relationships are relatively low.     

Basic features in immunohistological technique (author's transl)]

Light and electron microscopic demonstration of antigens in tissue is possible by means of labelled antibodies. Direct and indirect immuno-fluorescence techniques and recently also the peroxidase method permit a broader application of this principle. The peroxidase technique has the advantage of requiring less equipment and of providing the possibility to obtain durable specimens. The fluorescence technique permits the association of fluorescence phenomena with certain tissue structures by means of secondary "staining", for instance localization of specific hormone production sites. This allows functional morphological deductions in healthy and pathological conditions. Flawless techniques and controls are required before a specific reaction can be acknowledged since auto-fluorescence phenomena as well as pseudo-specific and cross-reactions are sources of error leading to wrong conclusions. A standardization of methods must therefore be attempted.     

Accelerated chilling and modified atmosphere packaging affect colour and colour stability of injection-enhanced beef round muscles

Beef knuckles were partially hot-boned within 1.5 h postmortem. Biceps femoris (BF), semimembranosus (SM), vastus lateralis (VL), and rectus femoris (RF) muscles were injection enhanced at 6% (experiment 1) or 10% (experiment 2) of non-injected weight and packaged in a high- (HiOx; 80% oxygen and 20% carbon dioxide) or ultra-low oxygen (LoOx; 80% nitrogen and 20% carbon dioxide) modified atmosphere. Hot boning accelerated chilling in all beef round muscles investigated. This resulted in a darker initial beef colour and darker visual colour during display for the BF, RF, and VL, as well as more uniform BF and knuckle steak colour. RF and VL, in experiments 1 and 2, respectively, had the most improved colour and colour stability. Steaks in HiOx MAP had longer colour life in display than steaks that had been in LoOx. Partially removing the beef knuckle early postmortem is a practical process that will improve colour and colour stability of beef round muscles.     

Comparison of ascorbic acid and sodium erythorbate: Effects on the 24h display colour of beef lumbar vertebrae and longissimus lumborum packaged in high-oxygen modified atmospheres

Sodium erythorbate and ascorbic acid were compared as a means to stabilize surface colour of bone-in beef steaks in high-oxygen modified atmosphere (80% oxygen and 20% carbon dioxide). Bone-in strip loins (n = 8) were fabricated into 1.9 -cm thick steaks, of which both the lumbar vertebrae and longissimus lumborum were topically treated with either ascorbic acid or sodium erythorbate (0, 0.05, 0.1, 0.5, 1.0, or 1.5%, wt/wt basis). Colour (L^∗a^∗b^∗) was evaluated before treatment and 24 h after packaging (display at 1 °C). Sodium erythorbate was as effective as ascorbic acid for inhibiting vertebrae discolouration (P > 0.05). Either reducing agent at 0.5, 1.0, or 1.5% improved (P < 0.05) vertebrae redness (compared with 0%, 0.05% and 0.1%). No detrimental effects on muscle colour were observed. When selecting antioxidants intended for bone-in beef steaks displayed in high-oxygen packaging, sodium erythorbate may be a cost effective substitute for ascorbic acid.