Typescripe (photocopy). / Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1986 H66 / Master of Science

A preliminary trial to determine the effect of repeated freezing and thawing on beef striploins, showed that the effect of thawing on frozen non-aged beef significantly improved tenderness, flavour and acceptability, indicating that thawing had a similar effect to aging. In the subsequent study, 207 beef striploins were collected from the Southern Crossbreeding Project (SXB: 70 heifers grainfed for 80 days, 70 steers grainfed for 180 days), Davies Gene Mapping Project (DGM: 30 steers grainfed for 180 days) and also 37 Hanwoo striploins imported into Australia from Korea. SXB animals consisted of Hereford cross calves sired by Belgian Blue, Limousin, South Devon, Hereford, Angus, Wagyu and Jersey bulls. DGM animals consisted of purebred Limousins and Jerseys and Limousin by Jersey crosses. Sensory analysis of beef striploins involved semi-trained taste panel assessments, using nine-point category scales for initial and sustained juiciness, beef flavour, beef fat flavour, oily flavour, buttery flavour, chicken-skin flavour, corn flavour, grassy flavour and overall acceptability. Flavour acceptability was positively enhanced by increased levels of intramuscular fat (IMF%). Significant differences in breed were apparent for juiciness, beef flavour, buttery flavour and flavour acceptability, after adjusting data to a constant level of intramuscular fat, suggesting that some variation in flavour may be genetic. The Korean Hanwoo displayed a numerically higher intensity of chicken score and lower intensity of beef flavour. Australian cattle breeds differed in fatty acid composition between each other and also to that of the Korean Hanwoo. The latter had 57% mono-unsaturated fatty acids, which was significantly higher (P<0.001) than the Australian breeds (47%). Since IMF% was confounded with breed, breed differences were not significant when adjusted for IMF%. Jersey animals most closely resembled the Hanwoo in fatty acid profile, whilst animals containing Limousin differed markedly from the Hanwoo. A chemical sensor was able to establish significant differences between Korean Hanwoo and Australian animals and predominantly mirrored differences in fatty acid composition and to some extent flavour. Development of prediction equations from individual fatty acids was disappointing (R2< 15%). However, when fatty acid data, IMF% and chemical sensor data were combined to form prediction equations, moderate R2 values were obtained of (24% to 43%). / Thesis (M.Ag.Sc.)--School of Agriculture & Wine, 2001.

Peroxisome proliferator-activated receptor (PPARy) is a transcription factor that regulates adipogenic genes and preadipocyte factor-1 (pref-1) is a transmembrane protein that regulates preadipocyte differnetiation. The role of PPARy was investigated using reverse transcription polymerase chain reaction (RT-PCR) by measuring PPARy mRNA levels in bovine adipose depots and longissimus dorsi muscle. No significant differences in PPARy mRNA levels were observed between 10 Charolais and 10 Holstein cattle for either tissue. Differences were observed between depots within these breeds. Correlations were performed among PPARy, carcass characteristics, and adipogenic genes. Pref-1 antibodies were used to immunolocate preadipocytes in bovine muscle tissue to the perimycium, near fat cells and blood vessels. The preadipocytes may exist in muscle tissue for short periods of time or may arise from a source external to the muscle. A computer image analysis program was developed for the quanitifaction and characterization of intramuscular fat in whole muscle tissues. / xvi, 154 leaves : ill. (some col.) ; 28 cm.

Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2006. / Consumers demand beef products of consistent and satisfactory tenderness, acceptable meat colour, the necessary nutritional value, as well as being microbiologically safe. However, inconsistency in meat quality, and particularly tenderness, is a problem that has continuously plagued the meat industry Firstly, an investigation was undertaken to determine the muscle variation, particularly in the tenderness of South African beef muscles. Beef muscles were removed from the right-side of beef carcasses and the physical, chemical and sensory characteristics determined 72 h post-mortem. As the beef muscles differed significantly (P≤0.05) in these attributes, the need for increased attention to enhanced processing and meat ageing is accentuated. Therefore, two further investigations were executed, including an enhancement study and a shelf-life study. The enhancement study determined the time effect of a blend of sodium and potassium salts, various phosphates and lactates on the physical quality, chemical composition and sensory quality of South African beef muscles. The corresponding muscles were removed from the left-side of the same beef carcasses and infused 3 d postmortem. The changes in beef quality over 19 d and the initial proximate and mineral composition were determined. The infused beef increased in tenderness, while maintaining an acceptable red colour. The infused muscles had higher moisture and ash contents, and lower lipid and protein contents. The mineral content of the treated muscles increased due to the minerals contained in the infusion blend. For the sensory analysis, beef muscles were stored under vacuum for 24 h (4°C) until the physical data had been collected. Thereafter, the muscles were stored at −18°C until the descriptive sensory analysis could be performed. The infusion of beef muscles successfully enhanced the sensory attributes, resulting in significantly (P≤0.05) more juicy and tender beef. When used in a consumer preference test, the infused samples illustrated a significantly (P≤0.05) higher degree of liking. In the shelf-life study the effect of the blend on the physical attributes, proximate composition and microbial growth of South African beef muscle was determined. One muscle from the left-side of beef carcasses was infused 4 d post-mortem. The purge loss, colour changes and the microbial growth on the muscle steaks over 10 d (overwrap storage) was determined. The infused muscle showed greater colour loss (lower a*, b* and chroma values) during the 10-d period. Physical analysis (purge loss) indicated a significant difference (P≤0.05), with the treated sample losing 2.78% more purge. The infusion extended the microbiological shelf-life of beef by 1 d. Improvement of beef quality and its consistency is essential for the survival of the beef industry. The infusion of beef muscles has the potential to improve the current status of low meat consumption and inconsistent tenderness of fresh beef in South Africa. Despite decreased colour stability in the infused steaks, negatively affecting the purchasing decision of the consumer, the blend could still be applied successfully in the South African meat industry to extend the shelf-life of fresh beef and improve meat quality attributes, providing the consumer with a more acceptable beef product.

The main objective of the study was to determine the effect of farm to abattoir environmental conditions and their subsequent effects on behavioural and physiological responses, as well as the quality of meat from Nguni (NG) and non-descript (ND) beef steers reared extensively on natural pastures. The forty 16 – 19 months old steers (20 ND and 20 NG) used in the current study were grouped together, medically treated, allowed three weeks acclimatizing period and were used in this trial over a four-month period. The weather and periodical variations influence on time budgets and body weights of these steers were determined. Furthermore, the effects of on-farm successive handling on behavioural scores and physiological responses of the same steers were determined. Later in the trial, some pre-slaughter effects on response-behaviour, bleed-out times and selected blood physiological responses were determined. Finally, the effect of genotype, muscle type, lairage duration, slaughter order and stress responsiveness on pH24, temperature, colour (L*, a*, b*, C, HA), thawing (TL) and cooking (CL) losses and Warner Bratzler Shear Force (WBSF) of the meat harvested from the same steers were determined. The daily time budgets of steers in natural pastures changed with temperature, humidity, observation week and time of the day. The grazing behaviour was observed throughout the observation days (> 37 percent); though it was reduced (26.9±2.64 percent) on days with higher temperatures and low humidity. Higher proportions of drinking (1.5±1.04 percent) and standing (20.8±4.63 percent) behaviours prolonged in such weather conditions, which were mostly during midday. The avoidance-related behaviour of the steers during handling varies, with the steers showing more avoidance and aggression in other weeks than some. These variations could however be traced back to the events of that particular day/time of handling. Only Weighing Box (WBS) and stepping (SS) scores differed (P<0.05) with genotype; with more calm NG steers (> 40 percent) and not kicking than the ND steers that were more vocal (20–60 percent) and kicking (> 5 percent). In addition, the weekly behavioural responses were reflected (P<0.05) in the measured cortisol, glucose and lactate. However, regardless of the prominent negative behaviour seen over time, the levels of the measured blood constituents continued to drop. Furthermore, steers of different genotypes displayed similar (P>0.05) response to the identical pre-slaughter conditions they were exposed to. However, steers that were Transport Group 1 (TG1) showed more avoidance (63.2 percent) pre-slaughter than those in TG2 (23.9 percent). Furthermore, all the steers that were in slaughter Group 2 (SG2) showed less avoidance behaviour than those in other groups. Vocalization was observed only for ND steers (5 percent), in TG1 and SG2. Some connections between the observed pre-slaughter activities and some behavioural and physiological changes of these steers were established; with TG1 and SG1 steers showing higher cortisol (140±14.50 and 175.9±17.24 nmol/L, respectively) and lactate (12.4±0.83 and 13.5±1.12 mmolL) levels than the other groups. Lastly, the muscle type, genotype, lairage duration, slaughter order and stress responsiveness have an effect on some meat quality characteristics of the two genotypes; with the L. dorsi muscle having highest WBSF (38.0±1.35N) than the Superficial pectoral muscle (Brisket muscle) (30.7±1.35N). Additionally, steers lairaged for a shorter time produced a L. dorsi with higher WBSF (41.6±2.34N) and a Brisket with lower TL (2.7±0.24 percent). It can therefore be concluded that the conditions and activities at the farm, during transportation, lairaging and slaughter at the abattoir have an influence on some behavioural and physiological changes and the quality of beef harvested from the Nguni and non-descript steers that were extensively-reared in natural pastures. However, the relationship patterns between these different conditions are not clear.

Made available in DSpace on 2015-03-26T14:02:15Z (GMT). No. of bitstreams: 1 texto completo.pdf: 341737 bytes, checksum: 2320e1a02c656f3fe7ee7ad365d16d3b (MD5) Previous issue date: 2012-12-06 / This study has assessed the impact of commercial slaughterhouse livestock antemortem rest time on their glucose, lactate and cortisol concentrations, and on parameters of beef quality, such as shear strength, drip losses, and color. A total of 60 nelore calves were assessed in seven treatments. The effects of 0, 4, 8, 12, 16, 20, and 24 hours of rest time were examined for cattle submitted to fasting and hydric diet in the lairage of theslaughterhouse. Cattle submitted to pre-slaughter fasting had lower levels of glucose and lactate in their blood (P < 0.05). Regarding the blood parameters examined, rest time has only affected glucose concentration. Beef quality, with regard to drip losses, color, and shear strength, was not affected by rest time (P > 0.05). Thus, beef was characterized as tender meat. However, beef color characteristics (L, a, b e c) have been affected (P > 0.05); differences were found only for hue (h*) and color saturation (c*), when comparing the mean of treatments that included rest time in relation to time 0 to the mean of times of resting. However, such differences do not justify changes in beef color itself, since the main parameters of color like the redness a *, yellow b*, and luminosity L* did not differ among treatments. / Avaliou-se o efeito do tempo de descanso ante-mortem de bovinos em frigorífico comercial sobre níveis de glicose, lactato e cortisol sanguíneos e parâmetros de qualidade da carne, como força de cisalhamento, pH, perdas por exsudação e cor objetiva. Foram utilizados 60 tourinhos, Nelore, distribuídos em sete tratamentos. Avaliaram-se os efeitos do tempo de descanso de 0, 4, 8, 12, 16, 20 ou 24 horas dos bovinos sob jejum e dieta hídrica, nos currais do matadouro frigorífico. Os animais submetidos ao jejum pré-abate apresentaram menores níveis de glicose e lactato no sangue em relação ao tratamento sem descanso (P < 0,05). Dos parâmetros sanguíneos avaliados, o tempo de descanso pré-abate influenciou apenas a concentração de glicose. A qualidade da carne dos bovinos, quanto à perda por exsudatos e força de cisalhamento, não foi influenciada pelos tempos de descanso (P > 0,05), sendo possível caracterizá-la a carne como macia. Para as características de coloração da carne, a cor (L, a, b e c) teve influência (P < 0,05); houve diferença apenas para os índices de tonalidade (h*) e saturação (c*) da cor da carne, comparando-se a média dos tratamentos com descanso em relação ao tempo 0 com a dos tempos de descanso. Contudo, essa diferença não justifica diferenças para coloração da carne em si, visto que os principais parâmetros da cor, como o índice de vermelho a*, amarelo b* e a luminosidade L*, apresentaram diferenças (P < 0,05) entre os tratamentos.

Made available in DSpace on 2014-06-11T19:32:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-07-05Bitstream added on 2014-06-13T20:04:48Z : No. of bitstreams: 1 morales_dc_dr_botfmvz.pdf: 1150740 bytes, checksum: 82142a24852f131d92e839bf0cd1454f (MD5) / O objetivo do presente estudo foi identificar as isoformas da Cadeia Pesada de Miosina (Myosin Heavy Chain - MyHC) por eletroforese (SDS-PAGE), nos músculos Semitendinosus por biopsia durante o crescimento e ao abate e no músculo Longissimus dorsi ao abate. Foram utilizados 20 bovinos inteiros da raça Nelore submetidos ao modelo biológico superprecoce em um delineamento inteiramente casualizado. Foi realizada a caracterização morfológica das fibras musculares quanto ao tipo (SO, FOG e FG) e diâmetro nos mesmos músculos. Em relação ao músculo Semitendinosus somente foram identificadas duas bandas da cadeia pesada de miosina, a MyHC do tipo I e a MyHC do tipo II sem diferenciação da isoforma do tipo II e no músculo Longissimus dorsi foram identificadas as isoformas dos tipos I, II a e II x. Quanto a caracterização dos tipos de fibras no músculo Semitendinosus as mesmas estavam distribuídas em mosaico com predomínio de fibras glicolíticas FOG e FG e houve um aumento significativo (P<0,05) da área dos três tipos de fibras da biopsia para o abate. No músculo Longissimus dorsi constatou-se predominância de fibras do tipo FG em relação as fibras do tipo FOG e SO (P<0,05). Também em relação ao diâmetro das mesmas, as fibras SO apresentaram menor diâmetro (P<0,05) em relação aos demais tipos. Comparando-se os dois músculos no abate, observa-se que o músculo Longissimus dorsi apresenta maior área (P<0,05) tanto em relação as fibras SO como quanto as fibras FG. Com relação ao diâmetro observa-se maiores valores (P<0,05) também para as fibras do músculo Longissimus dorsi, principalmente em relação as fibras FG. / The objective of this study was identify the myosin heavy chain isoforms in Semitendinosus (biopsy and slaughter) and Longissimus dorsi (slaughter) by electrophoresis (SDS PAGE) and the muscles fiber types (SO, FOG and FG) in Brazilian yearly cattle system - Superprecoce. Were used twenty young bulls Bos indicus (Nellore) in completely randomized design. In relation of Semitendinosus muscle were identified only two MyHC isoforms (type I and II) without any diferentiation of type II, and in the Longissimus dorsi muscle were identified the MyHC isoforms I, II a and II x. About the characterization of fiber types, in the Semitendinosus, the same were distributed in Mosaic with predominance of the FG and FOG fibers and siginificant increase (P<0,05) of the fibers of biopsy to slaughter. In Longissimus dorsi muscle were observed predominance of FG fibers in relation to FOG and SO fibers (P<0,05) and in relation to diameter, the SO fibers showed smallest values. Comparing the two muscles, the Longissimus dorsi, showed high area in relation the SO and FG fibers and high diameter especially in the FG fibers.

A pre rigor cut was made through the 12th thoracic vertebrae of one side of a beef carcass, while the other side, processed conventionally, served as the control. The effect of this cut upon yield grade, sensory attributes and tenderness of Longissimus steaks was determined. The treatment caused no differences (P>0.05) in yield grade or in CIE L* a* b* values and oxymyoglobin, reduced myoglobin and metmyoglobin values measured on samples at the treatment site. Sensory panel ratings of visual attributes of color and overall appearance were less desirable (P<0.05) for the treated sides, while for visible texture ratings, there was no significant difference. Purge, cooking loss, percentage moisture, fat and protein, and total collagen were not affected by the treatment (P>0.05). Sarcomere length, and sensory panel ratings of myofibrillar tenderness, connective tissue, and overall tenderness were significantly more desirable for the treated sides. There was no significant difference in fragmentation index or peak force values between treatments, although these values tended to be lower for the treated sides than for the control sides. / Master of Science

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: A total of 32 cattle were divided into four groups of eight each (A1-8, A9-16, A17-24, B1-B8) to be slaughtered on different days over a period of 45 days. All the cattle in Groups A were of Bonsmara type and those in Group B were of Charolais type. Three treatments, Tenderstretch (TS), Tendercut (TC) and Hock suspension (HS) were randomly allocated to each of the 48 sides from group A. Only two treatments (TC and HS) were implemented on the carcass sides in Group B alternating between the right and left sides. Two muscles from each side namely Gluteus medius and Longissimus dorsi were evaluated for purge, cooking loss, shear force and sarcomere length after 2, 4, 6, 10 and 14 days of aging. Paired t-Tests were performed for each pair of treatments and each day separately, on all variables accessed (Snedecor, 1980). The differences in purge and cooking loss between treatments were all found to be inconclusive for each day of aging. Although purge had significant differences between the treatments TC and TS for the GM and LD muscle after 14 days of aging (P = 0.0341 and P = 0.0348 respectively) these were found to be open to doubt as the treatment that delivers the most purge differs between muscles and that the two treatments delivered no differences compared to its HS values. Aging had a significant effect on purge as it doubles after 14 days of aging. Cooking loss values only differed significantly on day 2 for the LD muscle between treatments TC and HS. The differences in shear force were all smaller than 0.3205 kg/ 1.27cm and not consistent over all carcasses. A mean positive improvement in tenderness was calculated from high difference in mean values from some carcasses although some carcasses showed a decrease in tenderness when using TS and TC, which suggests that the treatments are of no relevance towards the industry. Although the differences in shear force become smaller as aging commences, it is not constant, a phenomenon most probably due to the variance between animals. Aging again had the most significant effect (P<.0001) on shear force. Correlations between sarcomere lengths and shear force were low for all the treatments on the GM muscle (HS = -0.453; TC = -0.401 and TS = -0.2) but in the LD muscle the TS method showed a higher correlation (TS = -0.665) than the other treatments (HS = 0.059 and TC = 0.059). / AFRIKAANSE OPSOMMING: `n Totaal van 32 beeste was opgedeel in vier groepe van agt elk (A1-8, A9-16, A17-24, B1-B8) wat geslag is op verskillende dae oor n periode van 45 dae. Beeste van die A groep was almal Bonsmara tipe en die van die B groep charolais tipe. Drie behandelings naamlik Tenderstretch (TS), Tendercut (TC) en Hak suspensie (HS) was ewekansig tot die 48 sye van die karkasse van groep A toegedeel. Groep B se 16 sye is net met TC en HS ewekansig tot die linker en regter sy toegedeel. Twee spiere naamlik Gluteus medius en Longissimus dorsi was geevalueer vir drup verlies, kook verlies, sarkomeer lengte en taaihied na 2, 4, 6, 10 en 14 dae se veroudering. Gepaarde t – toetse is gedoen vir elke paar behandelings vir elke dag van veroudering op al die veranderlikes genoem. Die verskil in drup verlies en kook verlies tussen behandelings was as nie betekeinisvol bestempel. Behalwe vir die feit dat drup verlies betekenisvolle verskille getoon het tussen die behandelings TC en TS vir die GM (P = 0.0341) en die LD (P = 0.0348) spiere na 14 dae se veroudering was dit bevind as nie betekenisvol juis oor dat die twee behandelings teenoor hul HS waardes geen verskille getoon het nie. Veroudering van die vleis het wel die grootste betekenisvolle verskil in drupverlies gemaak waar dit amper verdubbel soos die vleis verouder vir 14 dae. Kookverlies het net op dag twee n betekenisvolle verskil getoon in die LD spier vir die HS – TC kombinasie. Die verskil in taaiheid was almal kleiner as 0.3205 kg/ 1.27cm en nie kostant vir alle karkasse nie. n’ Positiewe gemiddelde verbetering in sagtheid is verkry deur die kalkulasie van hoë positiewe waardes en lae negatiewe waardes vir sommmige karkasse wat n laer sagtheid getoon het wanneer TS en TC gebruik is. Hierdie onkonsekwente verbeterings in sagtheid maak dat hierdie behandelings van min praktiese nut vir die bedryf is. Alhoewel hierdie verskille tussen behandelings kleiner raak tydens veroudering, is dit nie konstant nie, wat as gevolg van die variasies tussen diere kan wees. Veroudering het weereens die mees betekenisvolle effek op die vleis getoon (P< 0.001). Die korrelasie tussen sarkomeer lengte en WBSF taaiheid was laag vir alle behandelings in die GM spier (HS = -0.453; TC = -0.401 en TS = -0.2) behalwe vir die LD spier waar die TS behandeling n hoer korrelasie van TS = -0.665 as die ander twee behandelings (HS = 0.059 en TC = 0.059) opgelewer het.