John A. Unruh

Effects of low-voltage electrical stimulation during exsanguination on meat quality and display colour stability.

Five steers from each of four slaughter groups were randomly assigned to a low-voltage electrical stimulation (LVES) treatment during exsanguination (within 5 min after stunning) and five served as controls (C). LVES consisted of 50V of 60 Hz alternating current (1 s on and 1 s off for 2 min). At 28 h, LVES longissimus (LM) was lighter in colour, softer, coarser in texture and tended to have lower marbling estimates than C. LVES LM steaks were lighter red at 0 and 1 days, but more discoloured at 5 days, of display than C steaks. Both the deep (DSM) and superficial (SSM) portions of LVES semimembranosus (SM) steaks were lighter red at 0 and 1 days of display than C steaks. Water-holding capacity for LVES LM and DSM steaks was lower than for C steaks. A trained sensory panel found LVES LM steaks to be less juicy and less tender than C steaks. Also, LVES LM steaks had greater cooking losses than C steaks in two of the four slaughter groups. We conclude that LVES during exsanguination, coupled with relatively slow initial chilling, may be detrimental to muscle quality.

Effects of potassium lactate, sodium chloride, sodium tripolyphosphate, and sodium acetate on colour, colour stability, and oxidative properties of injection-enhanced beef rib steaks.

This study determined the effects of potassium lactate (KL), sodium chloride, sodium tripolyphosphate, and sodium acetate on colour, colour stability, and oxidative properties of injection-enhanced beef rib steaks. Enhancement solutions (8.5% pump) contained combinations of KL (0% or 1.5%), sodium chloride (0.3% or 0.6%), sodium tripolyphosphate (0% or 0.3%), and sodium acetate (0% or 0.1%). Steaks were packaged in a high-oxygen modified atmosphere (80% O(2)/20% CO(2)). Steaks with KL or KL and sodium acetate were darker but more colour stable (P<0.05) than control steaks. Steaks had less glossy surfaces when they contained acetate (P<0.05) and KL (P<0.11). Increasing sodium chloride content resulted in darker, less colour-stable steaks (P<0.05). Removing phosphate had little impact on colour (P>0.05). Both KL and sodium acetate improved visual appearance of injection-enhanced beef rib steaks, whereas the greater salt level were detrimental.

Effects of implanting and feeding zilpaterol hydrochloride on performance, carcass characteristics, and subprimal beef yields of fed cows.

Sixty crossbred cull cows were used to determine the combined effects of a trenbolone acetate-estradiol implant and feeding zilpaterol hydrochloride on performance, carcass characteristics, and subprimal yields of mature cows fed for 70 d. Cows were assigned to 1 of 5 treatments: 1) grazing native grass pasture (G); 2) concentrate-fed (C) a grain sorghum-sorghum silage diet; 3) concentrate-fed and implanted (CI) with Revalor-200 (trenbolone acetate-estradiol); 4) concentrate-fed and fed Zilmax (zilpaterol hydrochloride) beginning on d 38 of the feeding period (CZ); and 5) concentrate-fed, implanted, and fed Zilmax beginning on d 38 (CIZ). The concentrate diet consisted primarily of ground grain sorghum and sorghum silage. During the last 34 d of the feeding trial, concentrate-fed (C, CI, CZ, and CIZ) cows had greater (P < 0.05) gains than G cows. Hot carcass weights and dressing percentages were greater (P < 0.05) for the concentrate-fed cows than for G cows. Longissimus muscle area was largest (P < 0.05) for CIZ cows, whereas subprimal weights from the chuck were heavier (P < 0.05) from CIZ cows than C and G cows, and carcasses from CI and CZ cows had heavier (P < 0.05) chuck subprimal weights than G cows. Rib and round subprimal weights were heavier (P < 0.05) for concentrate-fed cows compared with G cows. In addition, carcasses from CIZ cows had heavier (P < 0.05) total subprimal weights, and total subprimals were a greater percentage of their initial BW than C cows. Rib cut-out and total soft tissue weights from the 9-10-11th rib were less (P < 0.05) for G cows than concentrate-fed cows. Feeding cull cows a concentrate diet increased carcass weight, dressing percentage, and subprimal yields compared with feeding cows a grass-based pasture diet, and the combination of a trenbolone acetate-estradiol implant and feeding zilpaterol hydrochloride can maximize trimmed beef yields from cull cows fed a high-concentrate diet.

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.

Effects of potassium lactate, sodium chloride, and sodium acetate on surface shininess/gloss and sensory properties of injection-enhanced beef strip-loin steaks

The objective was to determine the effects of potassium lactate (0% or 1.5%; KL), sodium chloride (0.3% or 0.6%), and sodium acetate (0% or 0.1%) on injection-enhanced (8.5% pump), beef strip-loin steaks. All treatments contained 0.3% phosphate and 0.058% rosemary. Steaks were packaged in a high-oxygen modified atmosphere (80% O(2)/20% CO(2)) and were evaluated on d 2, 9, and 14 for surface shininess/gloss, shear force, and descriptive sensory attributes. As time in MAP progressed, oxidized, stale, and rancid flavours increased (P<0.05) and surface shininess/gloss decreased (P<0.05). Brown-roasted and beef flavours were most intense (P<0.05) on d 9. Using KL increased (P<0.05) brown-roasted and beef flavours and limited rancid flavour. Sodium acetate decreased (P<0.05) shear force. Adding more salt increased salty and rancid flavours (P<0.05). Sodium acetate and KL both improve sensory attributes of injection-enhanced beef.

Influence of repeated restraint and isolation stress and electrolyte administration on carcass quality and muscle electrolyte content of sheep

Crossbred lambs were assigned, within weight blocks, to one of four treatments applied in a 2 × 2 factorial design (n = 6 per treatment). Treatment main effects included no stress (NS) or three consecutive days of restraint and isolation stress (RIS) and treatment with either water (W) or electrolytes (E). The experimental design resulted in four treatments, namely NS-lambs given W, NS-lambs given E, RIS-lambs given W, and RIS-lambs given E. Stress treatment consisted of moving each lamb from its home stanchion to a separate location and isolation from visual and tactile contact with other lambs for 6 hours daily for 3 days before slaughter. All lambs received a 320 ml oral drench of either W or E on each day after the stress treatment. Stress treatment reduced (P < 0·05) semitendinosus (ST) muscle glycogen by 4·8-fold. At 24 h post mortem, muscle pH for semimembranosus (SM), biceps femoris (BF) and infraspinatus (IF) was higher (P < 0·05) in RIS-lambs that in NS-lambs. Hunter L(∗)a(∗)b(∗) values, measured on muscle cross-section, revealed a lighter (P < 0·05) BF; more (P < 0·05) red BF, ST, and longissimus dorsi (LD); and more (P < 0·05) yellow ST, SM, BF, and LD for NS-than for RIS-lambs. Muscle from RIS-lambs contained less (P < 0·05) potassium than that from NS-lambs. Restraint and isolation stress of lambs resulted in a reduction in muscle glycogen, but only slight increases in ultimate pH and minimal influences on muscle color. Administration of electrolytes had no effect on lamb carcass quality.

Interactive effects between paylean™ (Ractopamine HCl) and dietary lysine on finishing pig growth performance, carcass characteristics and tissue accretion

Summary A total of 432 pigs were used to evaluate the effects of Paylean and dietary lysine on finishing pig growth performance, carcass characteristics and tissue accretion. The 12 dietary treatments included Paylean (0, 4.5, and 9.0 g/ton) and 4 levels of lysine. For pigs fed no Paylean, lysine levels were 0.60, 0.80, 1.00, and 1.20%. For pigs fed 4.5 or 9.0 g/ton of Paylean, lysine levels were 0.80, 1.00, 1.20, and 1.40%. The results indicate that pigs fed Paylean need at least 1.0% dietary lysine to optimize growth, carcass parameters, and tissue accretion.

Carcass and meat quality characteristics of Brahman cross bulls and steers finished on tropical pastures in Costa Rica.

Forty-eight male calves (3/4 Brahman×1/4 Charolais) were used to determine carcass cutability and meat tenderness of Longissimus lumborum (LL), Gluteus medius (GM), Semitendinosus (ST) and Psoas major (PM) steaks from lighter weight carcasses of bulls and steers castrated at 3, 7, or 12 mo of age grown under tropical pasture conditions. Steaks from steers had lower (more tender) LL Warner-Bratzler shear force (WBSF) values than those from bulls. Steaks from steers castrated at 3 mo had lower GM WBSF than those from bulls. For PM steaks, those aged 28 d had lower WBSF than those aged 2d. Steaks aged 28 d had the lowest LL and GM WBSF and steaks aged 2d had the highest LL, GM, and ST WBSF. Castration at younger ages is recommended because it provides improvement in LL and GM tenderness over bulls with no differences in carcass traits or subprimal yields.

Cow biological type affects ground beef colour stability

To determine the effects of cow biological type on colour stability of ground beef, M. semimembranosus from beef-type (BSM) and dairy-type (DSM) cows was obtained 5d postmortem. Three blends (100% BSM, 50% BSM+50% DSM, 100% DSM) were adjusted to 90% and 80% lean points using either young beef trim (YBT) or beef cow trim (BCT), then packaged in high oxygen (High-O(2); 80% O(2)) modified atmosphere (MAP). The BSM+YBT patties had the brightest colour initially, but discoloured rapidly. Although DSM+BCT patties had the darkest colour initially, they discoloured least during display. Metmyoglobin reducing ability of ground DSM was up to fivefold greater than ground BSM, and TBARS values of BSM was twofold greater than DSM by the end of display (4d). Though initially darker than beef cow lean, dairy cow lean has a longer display colour life and may be advantageous to retailers using High-O(2) MAP.

Effects of pre-rigor injection of sodium citrate or acetate, or post-rigor injection of phosphate plus salt on post-mortem glycolysis, pH, and pork quality attributes

Forty pork carcass sides were assigned to one of four treatments: pre-rigor citrate (CIT) or acetate injection (ACE); post-rigor phosphate and salt injection (PHOS); and non-injected control (CON). Loins in 20 sides were injected at 50min post-mortem with 4% solutions of CIT or ACE to approximately 110% of projected loin weights, and 10 loins were injected at 24h post-mortem to 106.6% with a solution of 4.4% PHOS and 2.2% salt. Although CIT increased pH (P<0.05), neither CIT nor ACE altered (P>0.05) glycolytic metabolite concentrations. The pH increase in muscles from the CIT treatment was most likely due to its buffering ability rather than to its glycolytic inhibition. Pre-rigor CIT injection improved tenderness without the detrimental effects on color or flavor found with PHOS, but neither CIT nor ACE altered glycolytic metabolites or improved firmness, wetness, or fresh visual color over CON. Poor flavor attributes of the ACE treatment will hinder its use as an ingredient for pork enhancement solutions.