An in-home evaluation of steaks from the M. Serratus ventralis was conducted to determine consumer acceptance. Steaks were also evaluated by Warner-Bratzler shear force (WBS) evaluations. Steaks from the M. Serratus ventralis were either blade tenderized, injected with a salt, phosphate, and papain solution, or served as a control. Consumers (n = 136) were not given a specific method of cookery, but were asked to document cooking method and degree of doneness, overall-like, tenderness desirability, tenderness of cut, juiciness desirability, juiciness of cut, flavor desirability, and flavor intensity. When cooked on the grill, in the oven, or in a skillet, injected steaks received the highest (P < 0.05) ratings for tenderness. Furthermore, consumers rated injected and blade tenderized steaks higher (P<0.05) for overall like when they were cooked on the grill to a higher degree of doneness. Oven cooked steaks that were injected, rated higher (P<0.05) than blade tenderized steaks for juiciness. When cooked on the grill, juiciness ratings were also higher (P<0.05) for injected steaks compared to control steaks. Moreover, injected steaks had significantly lower (P<0.05) WBS values when compared to blade tenderized and control steaks. Overall, ratings for all steaks were adequate, confirming the M. Serratus ventralis as a potential high quality steak for use in the retail market.

An in-home evaluation of beef value cuts from the round was conducted to determine ways to improve palatability attributes for steaks prepared by consumers. The M. vastus lateralis, M. rectus femoris, M. semimembranosus, and M. adductor (n = 266) muscles were either blade tenderized, enhanced with a salt and phosphate solution, or served as a control. Consumers (n = 261) cooked these steaks as they normally would and were asked to document cooking method and degree of doneness, as well as palatability ratings for overall like, tenderness, juiciness, flavor intensity, and flavor desirability for each steak. Enhancing round muscles with a salt and phosphate solution improved most palatability traits compared to those that were blade tenderized or not treated. For M. semimembranosus and M. vastus lateralis, the enhanced steaks received higher (P < 0.05) ratings for all palatability traits. For the most part, cooking method and degree of doneness had little influence on consumer palatability ratings. Where differences occurred, they were muscle specific, which may allow limited recommendations for certain muscles with respect to the most appropriate cooking method and degree of doneness.

Doctor of Philosophy / Department of Animal Sciences and Industry / John A. Unruh / Two experiments were conducted to evaluate the effects of exercise on feedlot cattle well-being, growth performance, and carcass characteristics (Experiments 1 and 2). Additionally, two experiments assessed the volatile compound profiles of beef in response to various postmortem processes (Experiments 3 and 4). Experiment 1 compared heifers (n=30) assigned to either a sedentary treatment or an exercise regimen 3 times/wk (20 min/d for the first 2 wk, 30 min/d for the next 2 wk, and 40 min/d for the final wk). Exercised heifers showed decreased blood insulin, daily gains, final body weights, and lower numerical yield grades in conjunction with decreased a* and b* color values of longissimus muscle lean. Experiment 2 exposed steers (n=419) to 1 of 4 treatments; not exercised (CON), or exercised 3 times/wk by animal handlers for 20-30 min for the first 10 wk (EARLY), the last 7 wk (LATE), or for the entire 116 d finishing period (ALL). EARLY treatment cattle exhibited a decrease in blood insulin while EARLY and ALL treatment cattle produced carcasses with decreased marbling scores in comparison to CON cattle. Experiment 3 assessed the volatile compounds generated by raw and cooked beef gluteus medius steaks (n=30) subjected to blade tenderization and aging times ranging from 5 to 61 d. Raw steaks aged longer than 19 d produced greater concentrations of heptanal, octanal, and nonanal than raw steaks aged 5 d, but cooked steaks showed no change in these compounds in response to aging. Additionally, blade tenderization reduced the concentrations of lipid oxidation and Maillard reaction products in cooked steaks. Experiment 4 investigated cross-sections, external, and internal locations of beef longissimus lumborum steaks (n=54) cooked to 63, 71, or 77 °C and aged for 5, 21, or 37 d. External locations generated aldehydes in greater amounts than internal locations while pyrazines are produced exclusively at external locations. Increases in degree of doneness increased all aldehydes, except nonanal, in steak cross-sections. Aldehydes, except hexanal and octanal, generated from external locations became similar to internal locations as aging times increased. Pyrazines from external locations were reduced by increased aging times.

Beef fajitas have become a popular food item, but the supply of traditional muscles is insufficient to meet the growing demand. There is a need for alternative muscles that have similar eating characteristics to those currently marketed as beef fajitas. Four different treatments - papain (P), blade tenderization (B), papain + blade tenderization (P+B), and control (C) - were applied to sixty USDA Choice M. diaphragma pars costalis, M. transversus abdominis, M. obliquus abdominis internus, M. rhomboideus, M. trapezius, M. latissimus, and M. serratus ventralis. Muscles were cut into sections and frozen at -10ºC for evaluation by a trained sensory panel, consumer panel, and Warner-Bratzler shear force (WBSF) measurements. Trained panelists found that regardless of muscle, the addition of papain improved palatability scores. In general, treatment tended not to affect the palatability scores of the M. diaphragma pars costalis and M. serratus ventralis, which tended to receive higher scores in comparison to the other muscles. In general, the control and blade tenderized M. trapezius received the lowest trained and consumer panel palatability scores and had the highest WBSF values (P < 0.05). Regardless of muscle (except for M. diaphragma pars costalis and M. serratus ventralis), P and P+B treatments reduced WBSF values (P < 0.05). Consumers (n=81) gave the M. transversus abdominis, M. serratus ventralis, and M. latissimus similar (P > 0.05) tenderness ratings when the P treatment was applied. Consumers tended to prefer the flavor and tenderness of beef fajita strips that were treated with P and P+B and indicated a preference to purchase muscles with these treatments. Consumers were willing to purchase M. serratus ventralis treated with P+B and M. latissimus treated with P the majority of the time. Papain improved the eating quality of the muscles studied. The M. latissimus and M. serratus ventralis when treated with papain alone or in combination with blade tenderization, performed well enough to be considered as alternatives for traditional beef fajitas.

La tenerezza è la caratteristica più importante per definire l'accettabilità dei prodotti da parte dei consumatori, mentre le carni ottenute da bovini allevati con sistema estensivo solitamente sono dure. Dopo una dissertazione sulle reazioni biochimiche che avvengono durante il periodo di frollatura e che provoca l’intenerimento della carne, questo studio si è proposto di applicare diverse tecniche per migliorare la tenerezza della carne derivante da animali allevati in estensivo, cercando di modulare le reazioni biochimiche. In questo studio tre differenti tecniche, infusione di calcio (Ca), contrazione da freddo indotta (VFC) e la sospensione per le pelvi (PS), anziché per il tendine di Achille (AT), sono state testate in fase di pre-rigor sulla razza Maremmana e Frisona. L’infusione di Ca ha riportato uno sforzo di taglio più basso rispetto al gruppo di controllo (5,17 vs 10,48 kg) mentre il gruppo VFC ha occupato una posizione intermedia. L’attacco per le pelvi ha dimostrato una differenza significativa sullo sforzo di taglio e sulla lunghezza dei sarcomeri sui muscoli Longissimus thoracis e Biceps femoralis (4,26 vs 5,88 kg e 3,83 vs 4,78 kg e 1,97 e 1,64 µm e 2,10 vs 1,76 µm, rispettivamente per i muscoli per WBS e lunghezza dei sarcomeri in PS e AT). In conclusione, questi metodi possono influire sul processo di intenerimento della carne. / Tenderness is the most important characteristic to define products acceptability by consumers, while meat obtained from bull rearing in extensive system is usually tough. After a wide dissertation on biochemical reactions that occur during the ageing time that cause tenderization of meat, this study propose differences techniques to improve meat tenderness acting on this important pathway. In this study three different methods, Calcium infusion (Ca), Very Fast Chilling (VFC) and pelvic suspension hanging from aitch bone (PS) or the Achilles tendon (AT) are applied in pre-rigor phase on Maremmana and Holstein meat. Ca injection has reported the lowest shear force on cooked meat compared to control group (5.17 vs. 10.48 kg) instead VFC group has intermediate values. Pelvic hanging has shown significant differences on shear force and sarcomere length on Longissimus thoracis (LD) and Biceps femoralis (BF) muscles (4.26 vs. 5.88 kg and 3.83 vs. 4.78 kg and 1.97 and 1.64 µm and 2.10 vs. 1.76 µm respectively for LD and BF per WBS and sarcomere length in PS and AT). In conclusion these methods could influence tenderization processes even if the action of some processes are still unclear.