Objective Tenderness Research Articles

Effects of Quality Grade and Aging Time on Yields, Objective Tenderness, Protein Degradation, and Microbial Growth of Dry and Wet Aged Short Loins

Effects of Quality Grade and Aging Time on Yields, Objective Tenderness, Protein Degradation, and Microbial Growth of Dry and Wet Aged Short Loins

Comparison of Nutrient Composition, Quality, and Sensory Differences among Dorper, Domestic Commercial Crossbred and Australian Commercial Crossbred Lamb Meat

ObjectivesThe Dorper sheep breed is gaining popularity in the U.S. because of the general perception that Dorper breed produces lamb meat with greater tenderness, milder flavor, and greater consumer preference in comparison to the wool sheep breeds. However, limited research has been conducted to characterize the genetic effects on lamb meat quality and comparative information on the Dorper sheep breed. Thus, the objective of this study was to compare the nutritional, quality, and sensory attributes among Dorper sheep breed, domestic commercial crossbred (DCC) and Australian crossbred lamb meat.Materials and MethodsA total of 60 untrimmed lamb saddles (NAMP #231) from 3 treatments (Dorper, n = 20; DCC, n = 20; and Australian, n = 20) were purchased from commercial packing plants and warehouses. Lamb saddles from all treatments were aged in cooler (2°C) according to their production dates to achieve an aging time between 29 and 32 d. All aged saddles were frozen (–20°C) until sample preparation. On the sample preparation day, each saddle was cut on a bandsaw to 2.54 cm chops, deboned and trimmed to 0.30 cm subcutaneous fat. The chops were used to measure pH, objective color (L*, a*, and b*), objective tenderness [Warner-Bratzler Shear Force (WBSF)], cook loss (differences in weight between raw and cooked samples) and nutrient analysis (moisture, protein, fat, ash, carbohydrate, and calories). A consumer panel of 120 untrained participants was used to evaluate tenderness, flavor, juiciness, and overall acceptance using a 9-point hedonic scale (1 = Dislike extremely and 9 = Like extremely). A trained panel with 6 trained panelists was used to evaluate flavor intensity, tenderness, and off-flavor intensity using an unstructured line scale anchored at both ends (0 = absence or low intensity of specified attribute, 100 = extreme intensity of specified flavor attribute).ResultsThe DCC lamb meat had lower (P 0.05) in flavor acceptability compared to DCC and Dorper lamb meat. Untrained panelists preferred (P 0.05) were found for L*, a*, b*, cook loss, moisture, fat, ash, calories, juiciness and flavor intensity among the treatments.ConclusionThese results indicated that there are apparent meat quality differences among the 3 lamb meat sources. Overall, consumers preferred DCC lamb meat compared to Dorper and Australian lamb meat. However, factors such as specific genetic makeups, age, and diets were not accounted in this research. Additional research with a more controlled environment is needed to shed light on the true palatability traits of Dorper lamb meat.

Comparison of Nutrient Composition, Quality, and Sensory Differences among Dorper, Domestic Commercial Crossbred and Australian Commercial Crossbred Lamb Meat

ObjectivesThe Dorper sheep breed is gaining popularity in the U.S. because of the general perception that Dorper breed produces lamb meat with greater tenderness, milder flavor, and greater consumer preference in comparison to the wool sheep breeds. However, limited research has been conducted to characterize the genetic effects on lamb meat quality and comparative information on the Dorper sheep breed. Thus, the objective of this study was to compare the nutritional, quality, and sensory attributes among Dorper sheep breed, domestic commercial crossbred (DCC) and Australian crossbred lamb meat.Materials and MethodsA total of 60 untrimmed lamb saddles (NAMP #231) from 3 treatments (Dorper, n = 20; DCC, n = 20; and Australian, n = 20) were purchased from commercial packing plants and warehouses. Lamb saddles from all treatments were aged in cooler (2°C) according to their production dates to achieve an aging time between 29 and 32 d. All aged saddles were frozen (–20°C) until sample preparation. On the sample preparation day, each saddle was cut on a bandsaw to 2.54 cm chops, deboned and trimmed to 0.30 cm subcutaneous fat. The chops were used to measure pH, objective color (L*, a*, and b*), objective tenderness [Warner-Bratzler Shear Force (WBSF)], cook loss (differences in weight between raw and cooked samples) and nutrient analysis (moisture, protein, fat, ash, carbohydrate, and calories). A consumer panel of 120 untrained participants was used to evaluate tenderness, flavor, juiciness, and overall acceptance using a 9-point hedonic scale (1 = Dislike extremely and 9 = Like extremely). A trained panel with 6 trained panelists was used to evaluate flavor intensity, tenderness, and off-flavor intensity using an unstructured line scale anchored at both ends (0 = absence or low intensity of specified attribute, 100 = extreme intensity of specified flavor attribute).ResultsThe DCC lamb meat had lower (P 0.05) in flavor acceptability compared to DCC and Dorper lamb meat. Untrained panelists preferred (P 0.05) were found for L*, a*, b*, cook loss, moisture, fat, ash, calories, juiciness and flavor intensity among the treatments.ConclusionThese results indicated that there are apparent meat quality differences among the 3 lamb meat sources. Overall, consumers preferred DCC lamb meat compared to Dorper and Australian lamb meat. However, factors such as specific genetic makeups, age, and diets were not accounted in this research. Additional research with a more controlled environment is needed to shed light on the true palatability traits of Dorper lamb meat.

Is Blade Tenderization Still Needed for Inherently Tender Top Sirloin Steaks?

ObjectivesAlthough blade tenderization has historically been used to enhance tenderness, it may create a food safety concern. Therefore, the objective of this study was to determine if consumer satisfaction improves by blade tenderizing today’s inherently tender beef.Materials and MethodsPaired USDA Choice top sirloin butts (n = 20 total pieces) were collected from 10 carcasses representative of the typical carcass in today’s fed beef market. Carcasses from dairy-type cattle, Bos indicus-influenced cattle, and from cattle over 30 mo of age were not used. No selection preference was given to carcass sex class, weight, or presence or absence of black hide, but excessively heavy or light carcasses that would not yield a representative sample of what today’s consumers call an “average steak” were not selected. Subprimals were subjected to a 28-day refrigerated wet aging period before treatments were administered, with “d 0” defined as the day of carcass fabrication. Top sirloins from the left side of the carcass were blade tenderized once before portioning into steaks, whereas top sirloins from the right side of the carcass received no treatment and served as the control. Paired top sirloin butts were subjected to Warner-Bratzler Shear (WBS) force testing as a measure of objective tenderness. Consumer sensory evaluation was used to determine if consumer liking of tenderness, flavor, juiciness, and overall liking differed for steaks from blade tenderized (BT) subprimals versus those from non-blade tenderized (NBT) subprimals. Steaks were cut into fourths after cooking, with each sample (one-fourth of a steak) presented on a plate along with a metal steak knife and a plastic fork. This serving style allowed panelists to cut into the product, which sometimes influences consumer acceptability. Data were analyzed with paired t-tests using the matched pairs function of JMP (Version 12, SAS Inst. Inc., Cary, NC), at an alpha of 5%.ResultsConsumers assigned BT steaks higher (P < 0.05; Table 1) ratings for tenderness liking rating, flavor liking rating, and overall liking rating compared to NBT steaks. No differences (P > 0.05) were seen for juiciness liking ratings or WBS force values.ConclusionAlthough today’s beef is inherently tender, these data show that blade tenderization improved consumer sensory panel ratings for tenderness, flavor, and overall likeability for beef top sirloin steaks. Therefore, discontinuing the use of blade tenderization could result in less favorable consumer eating experiences.

Adding Value on M. Infraspinatus Caudal Tip

ObjectivesAdding value to beef products is an alternative to improve industry profitability. Recently, the m. subscapularis was presented to consumers as a novel beef cut that provides great eating experience due to its tenderness. The caudal tip of the m. infraspinatus is often left on the rib after separation of the chuck and it is usually used as 80/20 trim. The objective of this experiment was to evaluate tenderness and cooking yields of the m. infraspinatus caudal tip and verify the opportunity of exploring this cut as an added-value product.Materials and MethodsBoth m. subscapularis and caudal tip of m. infraspinatus were obtained from a commercial abattoir. Muscles were fabricated from A-maturity carcasses, USDA Choice-graded. A total of 15 m. subscapularis and 30 caudal tips of the m. infraspinatus were transferred under refrigeration to the University of Nevada, Reno Meat Quality Lab, where they were aged until complete 15 d post mortem at 5°C. Due to its size, two caudal tips were randomly combined into a single sample. A total of 15 experimental units per treatment (muscle) were analyzed for Warner-Bratzler Shear Force and cooking yields. Samples were cooked on a tabletop grill and after temperature reached 35°C, samples were flipped and cooked until temperature reached 70°C at the geometric center. After cooking, samples were cooled for 24h (cooled to approximately 5°C) and at least 6 cores (1.27 cm in diameter) were obtained from each sample. Cores were sheared with a Warner-Bratzler blade where the crosshead speed was 500 mm/min with a 100kg load cell. Data was analyzed by using PROC GLIMMIX of SAS (SAS Inst. Inc., Cary, NC) as a CRD.ResultsAlthough numerical differences were observed for cooking yields, results did not differ statistically (P = 0.78). For m. subscapularis and caudal tip of m. infraspinatus, cooking loss was 21.37 and 20.99% of total weight, respectively. Similar WBSF values were observed for both muscles (P = 0.11). Values for objective tenderness for m. subscapularis and the caudal tip of m. infraspinatus were 2.35 and 2.63 Kgf, respectively.ConclusionThe m. infraspinatus caudal tip showed similar cooking yields and objective tenderness when compared to m. subscapularis. Results of this work suggest that it is possible to add value to m. infraspinatus caudal tip and improve industry profitability.

Terneza, grasa intramuscular y de cobertura en carne de novillos faenados en Corrientes (Argentina)

La terneza de la carne es el atributo más apreciado por los consumidores, encontrándose condicionada por muchos factores. El objetivo de este trabajo fue generar información sobre terneza objetiva post maduración de la carne bovina y determinar valores de grasa intramuscular y de cobertura en animales de diferentes biotipos y edades faenados en Corrientes. El trabajo se realizó en un frigorífico tipo A y en la Facultad de Ciencias Veterinarias de la UNNE. Se evaluó el músculo longisimus dorsi de novillos tipo Brangus y Braford, de 4, 6 y 8 dientes. Se registró el peso individual de res caliente, así como la conformación y terminación. Las muestras divididas en dos fueron maduradas durante 7 y 14 días envasadas al vacío. La terneza se evaluó por la cizalla de Warner-Bratzler, la grasa total por el método de Soxhlet y la grasa de cobertura con un escalímetro. Se utilizó el análisis de la covarianza a tres vías incluyendo el peso de la res como covariable. El periodo de maduración afectó la terneza. Se registraron diferencias estadísticas entre tratamientos a los 14 días, no así a los 7 días. Durante este periodo, la diferencia de peso lograda se atribuyó al número de dientes y la covariable. El espesor de grasa dorsal se vio afectado por el número de dientes al igual que en la grasa intramuscular, donde además afectó la covariable. La maduración al vacío mejoró la terneza de la carne, siendo este efecto manifiesto en individuos más jóvenes, incrementándose la grasa de cobertura con la edad, no así la grasa intramuscular. La carne producto de animales faenados en la Provincia de Corrientes debe ser considerada de buena calidad, ya que según características de terneza y porcentajes de grasa intramuscular y de cobertura encontradas, responde a las más altas exigencias del mercado.

Effect of growth-promoting technologies on Longissimus lumborum muscle fiber morphometrics, collagen solubility, and cooked meat tenderness.

The objective of the study was to examine the effect of growth-promoting technologies (GP) on Longissimus lumborum steak tenderness, muscle fiber cross-sectional area (CSA), and collagen solubility. Crossbred feedlot heifers ( = 33; initial BW 464 ± 6 kg) were blocked by BW and assigned to 1 of 3 treatments: no GP (CON; = 11); implant, no zilpaterol hydrochloride (IMP; = 11); implant and zilpaterol hydrochloride (COMBO; = 11). Heifers assigned to receive an implant were administered Component TE-200 on d 0 of the study, and the COMBO group received 8.3 mg/kg DM of zilpaterol hydrochloride for the final 21 d of feeding with a 3 d withdrawal period. Following harvest, strip loins were collected and fabricated into 4 roasts and aged for 3, 14, 21, or 35 d postmortem. Fiber type was determined by immunohistochemistry. After aging, objective tenderness and collagen solubility were measured. There was a treatment × day of aging (DOA) interaction for Warner-Bratzler shear force (WBSF; < 0.01). At d 3 of aging, IMP and COMBO steaks had greater WBSF than CON steaks ( < 0.01). By d 14 of aging, the WBSF of IMP steaks was not different ( = 0.21) than CON steaks, but COMBO steaks had greater shear values than steaks of other treatments ( < 0.02). The COMBO steaks only remained tougher ( = 0.04) than the CON steaks following 35 DOA. Compared to CON muscles, IMP and COMBO type I and IIX muscle fibers were larger ( < 0.03). Treatment, DOA, or the two-way interactions did not impact measures of total and insoluble collagen ( > 0.31). Soluble collagen amount tended to be affected ( 0.06) by a treatment × DOA interaction which was due to COMBO muscle having more soluble collagen than the other 2 treatments on d 21 of aging ( < 0.02). Correlation analysis indicated that type I, IIA, and IIX fiber CSA are positively correlated with WBSF at d 3 and 14 of aging ( < 0.01), but only type IIX fibers are correlated at d 21 and 35 of aging ( < 0.03). At these time periods, total and insoluble collagen became positively correlated with WBSF ( < 0.01). This would indicate that relationship between muscle fiber CSA and WBSF decreases during postmortem aging, while the association between WBSF and collagen characteristics strengthens. The use of GP negatively impacted meat tenderness primarily through increased muscle fiber CSA and not through altering collagen solubility.

Comportamento mecânico e estrutural de diferentes cortes cárneos em teste de determinação da força de cisalhamento

Resumo Neste trabalho, foram avaliados os comportamentos mecânico e estrutural de diferentes cortes cárneos em testes de determinação da força de cisalhamento, com o objetivo de identificar possíveis diferenças que podem interferir negativamente na mensuração da maciez objetiva. Seis cortes cárneos: Contrafilé (Longissimus dorsi), Maminha (Tensor fasciae latae), Lagarto (Semitendinosus), Filé-mignon (Psoas major) e Picanha (Biceps femoris) bovinos, e Lombo suíno (Longissimus dorsi) foram analisados de acordo com o método Warner-Bratzler, usando um texturômetro equipado com lâmina de 1 mm de espessura. As superfícies cisalhadas foram analisadas por microscopia eletrônica de varredura e as curvas mecânicas geradas durante os testes foram estudadas. Diferentes comportamentos foram observados nas curvas mecânicas e na microestrutura dos cortes cárneos em estudo. Alguns cortes apresentaram picos máximos bem definidos, enquanto outros apresentaram curvas mais abertas com maior distribuição da força durante os testes. Os cortes também apresentaram diferenças quanto à altura dos picos, que variou entre diferentes cortes e até em um mesmo corte. Nas microestruturas, foram observados diferentes comportamentos como: fibras deformadas por tracionamento, fibras aglomeradas devido a forte compressão e irregularidades na espessura e formato de fibras. Assim, concluiu-se que o teste de determinação da força de cisalhamento utilizado envolve outros princípios, como compressão e elongação, dependendo do corte cárneo estudado.

Functional properties of bicarbonates and lactic acid on chicken breast retail display properties and cooked meat quality

Whole chicken breast was injected with potassium bicarbonate (PB), sodium bicarbonate (SB), and potassium lactate (K-lactate) and salt, alone or in combination at different concentration levels. The objectives were to 1) investigate the effects of different concentration of PB, SB, and PL on instrumental color, water-holding capacity (WHC), objective tenderness, expressible moisture, and moisture content and 2) evaluate whether sodium-containing ingredients can be replaced with potassium as a potential strategy to reduce total sodium content in the finished product. Results showed that chicken breast tissue marinated with SB and PB had greater moisture retention, display characteristics, and cooked product qualities than chicken breast tissue injected with water and the nonmarinated control. The L* values (lightness) did not change over the period of retail display and were not different compared to the control (P > 0.05). The chicken breast enhanced with SB, PB, and K-lactate retained better retail display color than the controls (marinated with water and nonmarinated). Increasing the potassium bicarbonate concentration from 0.5 to 1.5% significantly improved the water-holding capacity (82.17 to 92.61%; P < 0.05) and led to better cook yield (83.84 to 91.96%). Shear force values were lower at the 0.5% level for both SB and PB compared to the control. PB performed better on retail display and cooked meat quality than SB. This study suggests that chicken breast tissue can be marinated with KB as a healthier alternative to phosphate or SB.

Rendimento de carcaça e qualidade da carne de codornas de corte alimentadas com rações de diferentes níveis de proteína e suplementadas com aminoácidos essenciais

Objetivou-se avaliar diferentes níveis de proteína bruta e a suplementação de aminoácidos essenciais sobre o rendimento de carcaça e a qualidade da carne de peito de codornas de corte dos 28 aos 42 dias de idade. O delineamento utilizado foi inteiramente casualizado, com cinco tratamentos (19, 21, 23, 25, 27% PB), cinco repetições e 12 aves (seis fêmeas e seis machos) cada. Aos 42 dias de idade, quatro aves de cada parcela foram abatidas e avaliadas quanto ao rendimento de carcaça quente (RCQ) e resfriada (RCF), de peito (RP), de coxa e sobrecoxa (RCS), potencial hidrogeniônico (pH), capacidade de retenção de água (CRA), perda de peso por cozimento (PPC), cor e luminosidade e maciez objetiva (MO) do músculo. Observou-se efeito dos níveis de PB em todas as variáveis, exceto para CRA e luminosidade da carne de peito. Dessa forma, conclui-se que 19% de PB e a suplementação de aminoácidos essenciais na ração de codornas de corte seja satisfatório para o rendimento de carcaça, de peito e de qualidade da carne.

Influência do sexo e idade de abate sobre rendimento de carcaça e qualidade da carne de codornas de corte

O trabalho foi conduzido com o objetivo de se avaliar o efeito de duas idades de abate sobre o rendimento de carcaça e propriedades finais da carne de codornas de corte (Coturnix coturnix). Foram abatidas 40 codornas (machos e fêmeas) aos 35 e aos 42 dias de idade obtendo-se o peso corporal, peso de carcaça quente e resfriada, peso de peito, peso de perna, rendimento de carcaça quente e fria, rendimento de peito, rendimento de pernas, pH inicial e final (24 horas "post mortem", capacidade de retenção de água (CRA), cor (L*, a*, b*), perda de peso por cocção (PPC) e maciez objetiva (força de cisalhamento). Não houve diferença no rendimento de carcaça e cortes entre as idades de abate, entretanto as aves abatidas aos 42 dias de idade apresentaram-se com maior peso corporal. Para os parâmetros da qualidade da carne, observou-se que o pH inicial foi menor para as aves abatidas aos 42 dias de idade. Fêmeas abatidas aos 35 dias de idade apresentaram carne com menor teor de vermelho. Machos apresentaram a carne com pH mais baixo. Dessa forma o abate dos animais aos 42 dias de idade proporcionou melhor desempenho e melhores características de carcaça aos machos.

Effects of vitamin E on color stability and palatability of strip loin steaks from cattle fed distillers grains

The objective of this study was to determine the effect of preslaughter antioxidant supplementation to cattle fed wet distillers grains on carcass yield and quality grade, and on the color stability and consumer acceptability of steaks. Two hundred five crossbred steers were fed 35% wet distillers grains with the supplementation of 4 different levels of α-tocopheryl acetate: 0, 125, 250, and 500 IU•animal(-1)•d(-1) for 97 d. Chuck rolls (n = 69) and strip loins (n = 185) were collected and processed at 4 and 7 d postslaughter, respectively. Chucks were ground and separated into 0.23-kg samples. Strip loins were faced and cut into 2.54-cm steaks and packaged in a polyvinyl chloride overwrapped (PVC) package, a vacuum package, or modified atmosphere packages (MAP) for further color, α-tocopherol, objective tenderness, palatability, and proximate analysis. Color was measured objectively using a HunterLab Miniscan XE spectrophotometer (HunterLab Associates Inc., Reston, VA) and subjectively by a trained color panel, and a consumer panel was used to indicate which treatments affected retail acceptability and purchase decisions. Warner-Bratzler shear force measurements were used for objective tenderness, and a trained panel assessed subjective palatability characteristics. Instrumental color measurements revealed little difference for ground beef in both PVC and MAP packages, but diets with 500 and 250 IU•animal(-1)•d(-1) of vitamin E had a longer (P < 0.05) retention of redness and yellowness in steaks as compared with steaks from animals receiving less vitamin E. Subjective color evaluation for strip steaks indicated that greater vitamin E was more likely (P < 0.05) to maintain color stability, overall acceptability, and consumer purchase preference while decreasing percentage of discoloration. No significant differences (P > 0.10) were observed for objective tenderness and sensory attributes of strip steaks, and no differences (P > 0.10) were observed in protein, fat, and moisture percentages of ground beef. Lipid oxidation analysis indicated that steaks packaged in PVC for 7 d and MAP for 1, 3, and 7 d, and ground beef packaged in MAP and PVC for 0 and 7 d of retail display required greater inclusion of vitamin E (500 and 250 IU•animal(-1)•d(-1)) to remain below the 2.28 mg of malonaldehyde/kg threshold. Ultimately, 500 IU•animal(-1)•d(-1) of vitamin E should be supplemented to cattle fed wet distillers grain-based diets when products are packaged in MAP to maximize retail shelf life.

PRE‐RIGOR MANIPULATION OF BEEF FORESHANK ALTERS SARCOMERE LENGTH OF INDIVIDUAL CHUCK MUSCLES

ABSTRACT Sixteen beef carcasses were harvested to determine the effect of pre‐rigor foreshank positioning on the ultimate sarcomere length and objective tenderness values of seven chuck muscles. After final inspection, the left side foreshank was positioned caudal to the point of the shoulder and secured until the completion of rigor. The right side foreshank served as the control and was allowed to hang in the normal position, cranial to the point of the shoulder. Biceps brachii, infraspinatus, pectoralis profundus, serratus ventralis, supraspinatus, teres major and triceps brachii muscles were excised from each carcass half for sarcomere length and Warner–Bratzler shear force determinations. Results indicate that sarcomere length was altered (P &lt; 0.05) for all muscles. When the foreshank was placed in the caudal position pre‐rigor, both the serratus ventralis and triceps brachii muscles had higher (P &lt; 0.05) shear values than when the foreshank was allowed to remain in its natural position.PRACTICAL APPLICATIONSAs the beef industry continues to search for methods to add value to the chuck, these data may offer insight into a practical method to increase sarcomere length and enhance palatability and marketability of underutilized muscles.

Effects of lactate/phosphate injection enhancement on oxidation stability and protein degradation in early postmortem beef cuts packaged in high oxygen modified atmosphere

The influence of lactate/phosphate enhancement on meat color and lipid oxidation stability, tenderness, protein degradation, and protein aggregation of early postmortem beef muscles packaged in a high oxygen modified atmosphere packaging (HiOx-MAP; 80% O2, 20% CO2) were studied. At 24 hr postmortem, three bovine muscles (longissimus, semimembranosus, and adductor; n=10, respectively) were enhanced (10% injection rate) with either lactate (2.5%)/phosphate (0.3%) solution or water, packaged in HiOx-MAP, stored 9 days at 1°C, and then displayed for 7 days at 1°C. The lactate/phosphate injection significantly improved color stability (higher a* values) of all three bovine muscles throughout display period. Accumulation of lipid oxidation determined by 2-thiobarbituric acid-reactive substances values was also decreased (P<0.05) in the lactate/phosphate injection compared to the water treatment during storage and display periods. The objective tenderness values of longissimus and semimembranosus were also improved (P<0.05) by the lactate/phosphate enhancement treatment compared to the water treatment based on star probe measurement. There were no significant differences found in desmin and troponin-T degradation, or oxidative cross-linking of myosin between treatments. The results suggest that lactate/phosphate enhancement has beneficial effects on color and lipid oxidation stability, and tenderness development of beef cuts under HiOx-MAP conditions.

Results from six generations of selection for intramuscular fat in Duroc swine using real-time ultrasound. II. Genetic parameters and trends1

Design of breeding programs requires knowledge of variance components that exist for traits included in specific breeding goals and the genetic relationships that exist among traits of economic importance. A study was conducted to evaluate direct and correlated genetic responses to selection for intramuscular fat (IMF) and to estimate genetic parameters for economically important traits in Duroc swine. Forty gilts were purchased from US breeders and randomly mated for 2 generations to boars available in regional boar studs to develop a base population of 56 litters. Littermate pairs of gilts from this population were randomly assigned to a select line (SL) or control line (CL) and mated to the same boar to establish genetic ties between lines. In the SL, the top 10 boars and 75 gilts were selected based on IMF EBV obtained from a bivariate animal model that included IMF evaluated on the carcass and IMF predicted via ultrasound. One boar from each sire family and 50 to 60 gilts representing all sire families were randomly selected to maintain the CL. Carcass and ultrasound IMF were both moderately heritable (0.31 and 0.38, respectively). Moderate to high genetic relationships were estimated among carcass backfat and meat quality measures of IMF, Instron tenderness, and objective loin muscle color. Based on estimates obtained in this study, more desirable genetic merit for pH is associated with greater genetic value for loin color, tenderness, and sensory characteristics. Intramuscular fat measures obtained on the carcass and predicted using ultrasound technology were highly correlated (r(g) = 0.86 from a 12-trait analysis; r(g) = 0.90 from a 5-trait analysis). Estimated genetic relationships among IMF measures and other traits evaluated were generally consistent. Intramuscular fat measures were also genetically associated with Instron tenderness and flavor score in a desirable direction. Direct genetic response in IMF measures observed in the SL corresponded to a significant decrease in EBV for carcass loin muscle area (-0.90 cm(2) per generation) and an increase in carcass backfat EBV (0.98 mm per generation). Selection for IMF has led to more desirable EBV for objective tenderness and has had an adverse effect on additive genetic merit for objective loin color.

Comparison of Air and Immersion Chilling on Meat Quality and Shelf Life of Marinated Broiler Breast Fillets

Marinated broiler breast fillets were evaluated using both air- and immersion-chilling treatments. Ninety fillets from air-chilled broiler carcasses and 90 fillets from immersion-chilled broiler carcasses were obtained from a processor to determine differences in meat quality, sensory, and shelf life. At 24 h postmortem, the fillets were vacuum-tumbled (25 in Hg, 30 min, 14 rpm, 4 degrees C) in 2 replications per treatment with a 20% solution (wt/wt) yielding 0.70% NaCl and 0.45% sodium tripolyphosphate in the final product. One-third of the fillets in each replication were packaged in a tray covered with plastic wrap and stored in retail cases to simulate retail shelf-life conditions. The remaining fillets were stored at 4 degrees C for 24 h until analysis for marinade retention, cook loss, consumer evaluation, and objective tenderness. The immersion-chilled fillets had a significantly lower pH (5.56) and were lighter (L* 54.73) when compared with the air-chilled fillets (5.64, L* 50.13, respectively). The air-chilled fillets had a significantly higher marinade pickup (15.51%) than the immersion-chilled (14.07%) fillets. However, there were no significant differences in cook loss percentage in either treatment (approximately 20.03). Shear value was significantly higher in the immersion-chilled fillets (4.14 N), indicating less tender meat than the air-chilled fillets (3.62 N). In the consumer analyses, the air-chilled fillets were significantly different. Of the respondents that noted differences, 19% indicated differences in texture, and 9.67% indicated taste differences. The air-chilled treatment had significantly lower aerobic plate count in postpackaging d 0, 3, and 9. Also, coliforms were significantly lower in the air-chilled treatment through d 6. Therefore, air chilling carcasses may improve color, marination yield, tenderness, and increase the shelf life of retail-packaged broiler breast fillets.

Efeito do cozimento na qualidade do músculo Semitendinosus

O presente experimento foi realizado para determinar a efetividade do tratamento térmico em água e vapor a 80 °C tendo como objetivo a inativação do Clostridium botulinum tipo E, utilizando-se amostras de Semintendinosus. Foram realizadas ainda a avaliação da maciez objetiva, utilizando-se a análise de força de cisalhamento, e a avaliação sensorial dos atributos de suculência, maciez subjetiva, "flavor" e presença de colágeno. O tratamento a 80 °C foi efetivo na eliminação do microrganismo, contudo não houve diferença significativa no atributo maciez objetiva (força de cisalhamento) avaliado nos dois tratamentos utilizados. A avaliação sensorial apresentou correlação positiva entre os atributos maciez e suculência, enquanto o colágeno apresentou correlação negativa com a maciez. O "flavor" não apresentou correlação com os atributos maciez, suculência e presença de colágeno.

Meat tenderness evaluation using dual energy X-ray absorptiometry (DEXA)

Previous investigations indicated that a correlation exists between the preprocessed dual energy X-ray images of an airport security scanner and subjective tenderness in meat samples [PCT International Patent Application No. PCT/NZ01/00108, 2001. A method for the non-invasive measurement of properties of meat. Filed 11 June 2001]. We performed studies to confirm the patented claims and to pin-point the correlation factors based on unprocessed X-ray images. In two separate trials the peak shear force was determined on cooked samples as a measure of objective tenderness, and DEXA images scanned. The results of Trial 1 suggest that DEXA scans of whole steaks are suitable for tenderness estimation, as a coefficient of determination of R 2 = 0.69 was calculated for a multiple non-linear regression. These results need to be considered in light of high within-steak coefficients of variation (mean = 16% and max = 27%). An additional, though weak correlation ( R 2 = 0.26), was found between a single DEXA parameter correlated to composition and mechanical tenderness. Apparently small sample size and scanning of cooked and frozen meat samples rather than raw steaks were at least partially responsible for the inconclusive results of the second trial, where no correlation could be found exceeding R 2 = 0.12. More research is encouraged using state-of-the-art scanning techniques and optimized experimental design.

Avaliação de características de qualidade da carne de suínos por meio de componentes principais

Dados de 326 animais de uma população F2 de suínos foram utilizados para avaliar a redução da dimensionalidade do espaço multivariado por meio de componentes principais. Foram consideradas as seguintes características: pH aos 45 minutos e 24 horas post-mortem (pH45 e pHu, respectivamente), perda de peso por gotejamento (GOTEJ), perda de peso por cozimento (COZ), perda de peso total (PTOT), gordura intramuscular (GORINT), maciez objetiva (MACIEZ), luminosidade (L), índice de vermelho (a) e índice de amarelo (b). Quatro componentes principais, obtidos a partir da matriz de correlação, apresentaram variância inferior a 0,7 (autovalor inferior a 0,7), o que sugere quatro variáveis para descarte, por apresentarem maiores coeficientes, em valor absoluto, a partir do último componente principal. Adicionalmente, as variáveis descartadas apresentaram correlação linear simples significativa com as demais, ou seja, foram redundantes. Com base nesses resultados, recomenda-se a manutenção das características pH45, pHu, L, a, GORINT e COZ em experimentos futuros.

Quantitative trait loci mapping for meat quality traits in swine chromosome 6

The current study was carried out to perform QTL mapping on swine chromosome 6 (SSC6) associated to meat quality traits. The F2 population was produced by outbreed crossing using two native Brazilian breed Piau boars and 18 commercial sows. A total of 557 F2 animals were genotyped for 13 microsatellite markers. The traits evaluated on the F2 population were: pH measured 45 minutes and 24 hours post mortem (pH 45, pH24, respectively), drip loss (DL), cooking loss (CL), total loss (TL), intramuscular fat content (IMF), objective tenderness (OT), lightness (L), redness (A), yellowness (B), hue angle (h) and chrome (c). Data were analyzed by multiple regression developed for analysis of outbreed line crosses, using the QTL Express Software. Significant QTL were detected for pH45 and DL traits, and suggestive QTL for DL. QTL were not found for other traits. The pH45 and DL traits may be under the influence of one gene or a gene group located at about 76, 88 and 97cM. More markers should be included in the regions where F-value peaks and suggestive QTL for the DL trait were detected to ascertain whether they are real QTL.