Morse B. Solomon

Effects of diet and live weight at slaughter on kid meat quality

Forty male twin kids of the Majorera breed were used in a 2×2 design, in which the diet, suckled on dam (SD) or milk replacer (MR) and live weight at slaughter (6 or 10kg) were the main variables. Muscle pH and colour (CIE, L*a*b*) were determined in the longissimus (LD), semimembranosus (SM) and triceps brachii (TB) muscles, immediately after slaughter and chilling (24h). Water-holding capacity, shear force, chemical composition (moisture, fat, protein and collagen content and solubility) were determined. Muscle fibre populations were also studied. SD kid meat was slightly more tender and juicy, and the Chroma value was lower than in MR animals. The meat from the kids that were slaughtered at 10kg was significantly darker in all muscles tested and slightly less tender 6kg LWS kid meat had more moisture and less protein than that of 10kg LWS kids. Muscle fibre area was statistically higher in the 10-kg LWS kids. It was concluded that the meat quality of the heavier kids was not significantly different from that of the lighter kids and that slaughter at the greater weight would result in more meat being marketed.

Hydrodynamic shockwave tenderization effects using a cylinder processor on early deboned broiler breasts

In separate experiments, chicken broiler breasts were deboned (45 min postmortem, 52 min, respectively) and either exposed to high pressure hydrodynamic shockwaves (HSW) 25 min after deboning (77 min postmortem) or after 24 h of storage (4°C) respectively, and compared to companion control breasts. HSW were produced in a cylindrical HSW processor with 40-g explosive. Warner-Bratzler shear (WBS) values of the HSW breasts treated at 77 min postmortem were not different than the controls. HSW treatment decreased (P<0.05) the WBS values of the stored and cooked breasts by 42.0% as compared to non-treated controls. Cooking losses were not affected by HSW. In general, raw and cooked color characteristics (CIE L*a*b*) were not affected by the HSW. HSW treatment at 25 min after deboning (77 min postmortem) may require a higher pressure front or delayed treatment after postmortem aging to improve tenderness.

Tenderization of chicken and turkey breasts with electrically produced hydrodynamic shockwaves

Eighty early deboned (45 min, post mortem) postrigor chicken breasts were exposed (24 h post mortem) to two levels (number of pulse firing networks, PFN; 45% energy) of electrically produced hydrodynamic shockwaves (HSW). In addition, 21 turkey breasts (72 h post mortem) were HSW treated (two PFN, 72% energy). Samples were water cooked in bags (78°C internal). Two PFNs were required to decrease (P<0.05) chicken Warner-Bratzler shear (WBS) force by 22% from the control (4.67 kg). WBS force of the HSW treated turkey breast decreased (P<0.05) by 12% from the control (3.20 kg). Cooking loss was higher (P<0.05) in the turkey breast portions but not in the chicken breasts. The electrically produced shockwave process has the potential to provide chicken processors with the ability to early debone and produce tender breasts and to provide turkey processors with tenderness-enhanced fillets.

Effects of growth-promoting implants on morphology of Longissimus and Semitendinosus muscles in finishing steers.

Growth-promoting implants lead to increased muscle accretion in ruminants. To elucidate the effects at a cellular level, muscle fiber distribution and cross-sectional area (CSA) of longissimus (LM) and semitendinosus (ST) muscles were compared in implanted and control steers. Sixty-four Charolais steers were assigned to one of four treatments (16 steers/treatment): (1) no implant, (2) Synovex-S® (estradiol benzoate+progesterone), (3) Ralgro® (zeranol) or (4) Revalor-S® (trenbolone acetate+estradiol-17β). The experiment was carried out using four slaughter groups (SGRP). Sixteen steers each were slaughtered after 48, 104, 160 and 175 days (four steers/treatment) on trial. Steers on an implant treatment were first implanted at 15 months of age (day 0) and re-implanted at 56 and 112 days. Muscle fibers in the LM and ST (for both live biopsy and post-mortem samples) were characterized as either slow-twitch oxidative (SO), fast-twitch oxidative-glycolytic (FOG) and fast-twitch glycolytic (FG) fibers. Fiber distribution was minimally affected by SGRP in these physiologically mature steers. Implantation with Synovex did not alter fiber distribution in either muscle compared with control steers. Both Synovex-implanted and control steers showed a decrease of FG and an increase of FOG fibers in the LM from day 0 to SGRP 2 followed by an increase of FG and a decrease of FOG fibers. Ralgro- and Revalor-implanted steers had an almost constant fiber distribution in the LM throughout the experiment resulting in higher precentages of FG fibers in SGRP 2 (P<0.05) than SYN or CON steers. Biopsy samples of the LM muscle which were excised 51 days (SGRP 1-3) or 65 days (SGRP 4) before slaughter proved to be suitable for the determination of fiber distribution in live animals. Fiber area increased in post-mortem samples of both muscles from SGRP 1-3 in all treatment groups followed by a plateau. Implantation with Revalor led to an additional increase in fiber area from SGRP 3 and 4 (P<0.05). Synovex did not affect fiber area compared with control steers whereas Ralgro and Revalor implants led to larger fibers in SGRP 3 and 4, respectively. It can be concluded that some growth-promoting implants result in noticeable differences in muscle hypertrophic responses which coincide with their different effectiveness to enhance lean mass accretion.

Sorting for beef tenderness using high performance liquid chromatography and capillary electrophoresis: A research note ☆

This study utilized two sampling methods to examine changes in sarcoplasmic proteins during aging of beef and their relation to tenderness. Water-soluble proteins either obtained by manually expressing exudates from the meat (drip) or by an extraction procedure using homogenization and centrifugation (ext) were analyzed for longissimus lumborum muscle using HPLC and capillary electrophoresis (CE) on days 2, 7, 10 and 14 postmortem. A peak that consistently increased with aging was identified using HPLC. Among nine peaks detected in the CE analysis, peak 9 (100kDa) that increased and peak 4 (30kDa) that decreased with aging were correlated (P<0.05) to tenderness as determined by Warner-Bratzler shear force (WBSF). For pooled data of all aging periods, drip sample explained the most variability (49%) in shear force compared to ext sample (25%) using HPLC analyses. At 2 days postmortem, a multiple linear regression model explained 83% of the variation in WBSF using CE-ext or HPLC-drip samples. Sixty percent of the variability in shear force was explained by CE-ext samples for day 7 data. The variability in shear force as explained by either drip or ext sample was less than 51 percent for 10 and 14 days postmortem data. The drip samples were comparable to ext samples in predicting WBSF values for both tough (>46N WBSF on day 2) and tender (<46N WBSF on day 2) strip loins using CE and HPLC procedure. Results suggest that a simple drip sampling may have a potential for use with either HPLC or CE analyses on day 2 postmortem for sorting carcasses into tenderness groups.

Effect of different types and locations of the electrode source of an extra low voltage electrical stimulation system on beef quality.

An extra low voltage (45V) electrical stimulation (ES) system was used to determine the effects of using different types and locations of the positive electrode and negative ground of the ES system on beef carcass quality. Thirty-three Angus heifers (22 months of age) were assigned at slaughter to one of six ES treatments (trt): (1) rectal probe with a ground inserted in the incision made below the brisket during exsanguination, (2) rectal probe with ground inserted in the neck above the atlas joint, (3) rectal probe with a ground attached to the lower mandible, (4) muzzle clamp with a ground inserted in the shackled leg, (5) nasal clamp with a ground inserted in the shackled leg and (6) non-stimulated controls. Stimulation was generated using a full wave rectified pulsating direct current of 16 Hz for a duration of 90s within 3 min of exsanguination. Carcasses were chilled at 2°C and evaluated at 24h post mortem. Regardless of type or where the electrodes were placed within the carcass, all ES trt produced a more rapid drop in pH than the control group. Differences in the effectiveness of the various ES trt on improving meat tenderness were observed. For four selected muscles of the carcass (longissimus, semimembranosus, biceps femoris and triceps brachii) the most consistent and uniform improvement in tenderness was found using ES trt 1 or trt 3. The only drawback associated with trt 1 was the ineffectiveness in eliminating the formation of heat-ring. The other ES trt were successful in alleviating this problem. This study indicates that type and locations of electrode source in an extra voltage ES system are important factors to consider in developing an efficacious low voltage ES system. This work also suggests successful implementation of extra low voltage carcass ES for commercial use if specific types of rectal probe electrode systems are used.

Measurement of Muscle Exudate Protein Composition as an Indicator of Beef Tenderness

UNLABELLED The objective of this study was to determine the relationship between the protein composition of muscle exudates and meat tenderness in beef. Frozen, intact beef strip loins (n = 24) were each divided into 3 equal portions (anterior, middle, and posterior). Steaks were removed from each portion, individually vacuum packaged, thawed at 4 °C, and aged for 0, 7, or 14 d. After the designated aging period, exudate was collected from the packaging and 1 steak from each strip loin portion was utilized for shear force measurements. Muscle exudates were analyzed for protein content (biuret assay) and composition (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Shear force decreased (P < 0.0001) with aging from 0 to 14 d. The protein concentrations of the muscle exudates were not influenced by the aging period and were not related to the amount of exudate expressed. Electrophoretic analyses of the muscle exudates indicated that with aging the relative abundance of 4 proteins decreased (P < 0.01) and 10 proteins increased (P < 0.05) within the protein profiles of the exudates. The relative abundance of the 167, 97, and 47 kDa proteins in exudates at day 0 were significantly correlated (|r| = 0.57 to 0.77) to shear force at day 14. These data demonstrate that exudate protein composition changes with postmortem aging and beef tenderness. PRACTICAL APPLICATION This research showed that the protein profiles of exudates that accumulate on the surface and in the packaging of beef change with meat aging and tenderness. These data suggest that muscle exudates may be a good source of protein markers that are useful in the development of rapid, noninvasive methodologies for predicting beef tenderness.

Response of bovine muscles to direct high voltage electrical stimuli

Left sides of beef carcasses were stimulated (ES) using multiple-contact electrodes for both the positive and negative electrodes. These electrodes were attached to the carcass side in the neck and shoulder (arm) region (positive electrodes) and the hindquarter (round) region (negative electrodes). Stimulation was generated using 600 V, 60 Hz, 2·8 A alternating current for a duration of 2 min (impulses: 2 s on and 2 s off). Right sides served as controls. Carcass sides were chilled at 2°C. Stimulated sides showed a more rapid pH fall during the first 5 h post-stimulation in the longissimus dorsi, semimembranosus, semitendinosus, biceps femoris and triceps brachii (long head) muscles. Lower shear values for muscles in direct contact with the ES electrodes were observed compared to controls, except in the case of the semitendinosus muscle, where no difference was found. Data from the present study suggest that muscles, which quite often do not respond to ES and do not exhibit an improvement in tenderness, perhaps because they may not be located in the current pathway, can show improvements in tenderness if the current is distributed in the direction of these muscles. However, a muscles response to the electrical stimuli, with the accompanying rapid decline in pH, does not necessarily ensure a significant improvement in tenderness.

Use of gelatin gels as a reference material for performance evaluation of meat shear force measurements.

UNLABELLED Establishing standards for meat tenderness based on Warner-Bratzler shear force (WBSF) is complicated by the lack of methods for certifying WBSF testing among texture systems or laboratories. The objective of this study was to determine the suitability of using gelatin gels as reference materials for performance testing of texture measurement systems. Three replications of 5 gels (15%, 20%, 25%, 30%, and 35% gelatin) were prepared, vacuum packaged, and stored at 4 °C until use. Three randomly selected strips from each gel were subjected to WBSF testing on 4 instruments (A, B, C, or D) on days 1 and 8. Additional strips from each gel were subjected to WBSF testing on instruments A and C on day 29. Regression line estimates for each set of gels were analyzed. Gel WBSF values ranged from 10 to 177 N. The WBSF by gel concentration response was highly linear (P<0.0001) for all replications, instruments, and days of analysis. R2-values across all sets of gels ranged from 0.9562 to 0.9998. On days 1 and 8, instruments A and D exhibited higher slope (P<0.0001) and lower intercept (P<0.0001) estimates than instruments B and C. Regression line parameters (slope, intercept, and R2-values) were not influenced (P>0.05) by length of gel storage (1, 8, and 29 d). Data from this study suggest that gelatin gels can be used for evaluating WBSF values from various instruments and for validating the performance of meat shear force testing. PRACTICAL APPLICATION   Validating the performance of meat shear force testing is vital to establishing meat tenderness standards. The gelatin gel standards developed in this study exhibited a highly linear, repeatable relationship with shear force and were found to be stable for at least a month. These gel standards would provide a tool for the meat industry to harmonize shear force measurements across laboratories and various texture measuring instruments.

Transgenic Farm Animals

Conventional science to improve muscle and meat parameters has involved breeding strategies, such as selection of dominant traits or selection of preferred traits by cross breeding, and the use of endogenous and exogenous hormones. Improvements in the quality of food products that enter the market have largely been the result of postharvest intervention strategies. Biotechnology is a more extreme scientific method that offers the potential to improve the quality, yield, and safety of food products by direct genetic manipulation. In the December 13, 2007 issue of the Southeast Farm Press, an article by Roy Roberson pointed out that biotechnology is driving most segments of U.S. farm growth. He indicated that nationwide, the agriculture industry is booming and much of that growth is the result of biotechnology advancements. For example, the United States produces over half the worldwide acreage of bio-engineered crops (GMO), and this growth is expected to continue worldwide. With respect to livestock, biotechnology is a more novel approach to the original methods of genetic selection and crossbreeding, or administration and manipulation of various hormones (i.e., growth). Biotechnology in animals is primarily achieved by cloning, transgenesis, or transgenesis followed by cloning. Animal cloning is a method used to produce genetically identical copies of a selected animal (i.e., one which possesses high breeding value), while transgenesis is the process of altering an animal’s genome by introducing (via gene transfer) a new or foreign gene (i.e., DNA) not found in the recipient species, or deleting or modifying an endogenous gene with the ultimate goal of producing an animal expressing a beneficial function or a superior attribute (e.g., adding a gene that promotes increased muscle growth). The gene or genes that are transferred or modified is called the transgene (TG). A combination of the two methods, i.e., transgenic cloning, is the process of producing a clone whose