Beef retail steaks from establishments in twelve US cities and beef foodservice steaks from establishments in five US cities were evaluated using Warner-Bratzler shear and consumer sensory panels. Postmortem aging times for retail establishments ranged from 1 to 358 d with a mean of 20.5 d, and those from foodservice establishments aging times ranged from 9 to 67 d with an average of 15.9 d. For retail, top blade had the lowest (P < 0.05) WBS values, while cuts from the round top round and bottom round had the highest (P < 0.05) WBS values. Top loin and ribeye steaks had the lowest (P < 0.05) WBS values compared to top sirloin foodservice steaks. Retail top blade steaks received the highest (P < 0.05) ratings by consumers for overall like, tenderness level, like tenderness, juiciness level, and like juiciness; and foodservice top loin steaks received the highest (P < 0.05) for tenderness level, like tenderness, flavor level, juiciness level, and like juiciness. USDA quality grade did have an effect on foodservice ribeye and top sirloin steaks for sensory panels. Prime foodservice ribeye steaks were rated highest (P < 0.05) for overall like, like tenderness, tenderness level, like juiciness, and juiciness level, whereas ungraded ribeye steaks were rated lowest (P < 0.05) for like tenderness and tenderness level. Ungraded foodservice top sirloin steaks were rated highest (P < 0.05) for overall like, like tenderness, like flavor, and like juiciness. Additional improvements to reduce the range of tenderness levels are necessary to increase consumer acceptability.

This thesis is based on physical properties of fish meat and fish products. Texture of fish meat is considered as one of the most perceived character. Major influence on the textural properties of fish meat has chemical composition of fish meat and fish meat structure. Fish products are changed during production by influence of low temperature during frozen storage and influence of high temperature during cooking. Changes in the textural properties of fish muscle caused during the autolytic process after slaughtering. The aim of the thesis was compared different methods for measurement textural properties of fish and fish products. Surimi sticks and pre-fried fish sticks were tested. Common carp (Cyprinus carpio), Rainbow trout (Oncorhynchus mykiss) and Tench (Tinca tinca) were chosen for testing by penetration test (penetration of the probe into the sample) and Warner-Bratzler shear test (sample cutting by Warner-Bratzler shear).

A textura tem posição de destaque na qualidade da carne, podendo ser considerada como a característica sensorial de maior influência na aceitação por parte dos consumidores. Nesse contexto, as técnicas de determinação da textura da carne são de extrema importância. Assim, o objetivo desta dissertação foi o estudo comparativo de três técnicas de determinação da força de cisalhamento de carnes, utilizando-se dois equipamentos diferentes: o Warner-Bratzler Shear com sua lâmina padrão e um Texturômetro modelo TAXT2i (SMS) com duas lâminas de espessuras diferentes (3,05 e 1,01 mm), com a intenção de se obter correlações entre as diferentes técnicas utilizadas. Foram determinadas as forças de cisalhamento em seis cortes cárneos (5 bovinos e 1 suíno) com a finalidade de se obter as correlações numa ampla faixa de força de cisalhamento. Outras análises (Composição química, Perdas de água por cozimento e Microestrutura) foram realizadas para complementar as informações dos efeitos das três técnicas utilizadas sobre as respectivas respostas. Os dados obtidos nos testes de cisalhamento foram submetidos a uma análise descritiva visando determinar as variações entre os resultados de cada corte. A composição química, a microestrutura e as perdas de água foram utilizadas para explicar possíveis causas das variações. Foram feitas análises de regressão, obtendo-se modelos de correlação entre os dados obtidos com o Warner-Bratzler Shear e o texturômetro com as duas lâminas estudadas. Os resultados obtidos com Texturômetro utilizando-se lâmina de 3 mm superestimaram os resultados, indicando menor maciez do que as outras técnicas. Não se observou relação entre a composição química e a perda de água por cozimento com a textura das carnes. Entretanto, os resultados das análises com microscopia eletrônica de varredura permitiram explicar a variabilidade dos resultados da força de cisalhamento. / Texture has a prominent position on the quality of meat, and it can be considered the most influential sensory characteristic on consumers\' acceptance. In this sense, the techniques for texture determination of meat are very important. Thus, the aim of this dissertation was a comparative study of three techniques of determination of shear force of meat, using two different equipments: Warner-Bratzler Shear, with its standard blade; and the Texturometer TAXT2i, with two blades with different thicknesses (3.05 and 1.01 mm), for obtaining correlations between these different techniques. The shear forces were determined in six meat cuts (5 bovines and 1 swine) allowing correlations over a wide range of shear force. Other analyzes (chemical composition, water losses during cooking and microstructure) were performed to supplement the information of the effects of three techniques on shear force results. The data obtained in the shear tests were subjected to a descriptive statistical analysis in order to determine variations between the results for each cut. The chemical composition, microstructure and water losses were used to explain the possible causes of variations. Regression analyzes were performed and linear models of correlation between the data obtained with Warner-Bratzler Shear and the two blades texturometer were established. The results obtained with the 3 mm blade texturometer overestimated the results, suggesting lower softness than the other techniques. There was no relationship between the chemical composition and water loss during cooking with the meat texture. However, the results of analysis with scanning electron microscopy allowed explain the variability of the results of shear force.

A textura tem posição de destaque na qualidade da carne, podendo ser considerada como a característica sensorial de maior influência na aceitação por parte dos consumidores. Nesse contexto, as técnicas de determinação da textura da carne são de extrema importância. Assim, o objetivo desta dissertação foi o estudo comparativo de três técnicas de determinação da força de cisalhamento de carnes, utilizando-se dois equipamentos diferentes: o Warner-Bratzler Shear com sua lâmina padrão e um Texturômetro modelo TAXT2i (SMS) com duas lâminas de espessuras diferentes (3,05 e 1,01 mm), com a intenção de se obter correlações entre as diferentes técnicas utilizadas. Foram determinadas as forças de cisalhamento em seis cortes cárneos (5 bovinos e 1 suíno) com a finalidade de se obter as correlações numa ampla faixa de força de cisalhamento. Outras análises (Composição química, Perdas de água por cozimento e Microestrutura) foram realizadas para complementar as informações dos efeitos das três técnicas utilizadas sobre as respectivas respostas. Os dados obtidos nos testes de cisalhamento foram submetidos a uma análise descritiva visando determinar as variações entre os resultados de cada corte. A composição química, a microestrutura e as perdas de água foram utilizadas para explicar possíveis causas das variações. Foram feitas análises de regressão, obtendo-se modelos de correlação entre os dados obtidos com o Warner-Bratzler Shear e o texturômetro com as duas lâminas estudadas. Os resultados obtidos com Texturômetro utilizando-se lâmina de 3 mm superestimaram os resultados, indicando menor maciez do que as outras técnicas. Não se observou relação entre a composição química e a perda de água por cozimento com a textura das carnes. Entretanto, os resultados das análises com microscopia eletrônica de varredura permitiram explicar a variabilidade dos resultados da força de cisalhamento. / Texture has a prominent position on the quality of meat, and it can be considered the most influential sensory characteristic on consumers\' acceptance. In this sense, the techniques for texture determination of meat are very important. Thus, the aim of this dissertation was a comparative study of three techniques of determination of shear force of meat, using two different equipments: Warner-Bratzler Shear, with its standard blade; and the Texturometer TAXT2i, with two blades with different thicknesses (3.05 and 1.01 mm), for obtaining correlations between these different techniques. The shear forces were determined in six meat cuts (5 bovines and 1 swine) allowing correlations over a wide range of shear force. Other analyzes (chemical composition, water losses during cooking and microstructure) were performed to supplement the information of the effects of three techniques on shear force results. The data obtained in the shear tests were subjected to a descriptive statistical analysis in order to determine variations between the results for each cut. The chemical composition, microstructure and water losses were used to explain the possible causes of variations. Regression analyzes were performed and linear models of correlation between the data obtained with Warner-Bratzler Shear and the two blades texturometer were established. The results obtained with the 3 mm blade texturometer overestimated the results, suggesting lower softness than the other techniques. There was no relationship between the chemical composition and water loss during cooking with the meat texture. However, the results of analysis with scanning electron microscopy allowed explain the variability of the results of shear force.

This study was conducted to determine threshold levels for Warner-Bratzler shear (WBS) force of the beef value cuts. USDA Choice and USDA Select M. biceps femoris, M. gluteus medius, M. infraspinatus, M. longissimus lumborum, M. rectus femoris, M. triceps brachii, and M. vastus lateralis steaks were evaluated for palatability characteristics and tenderness acceptability by a consumer panel (n = 205). Steaks also were evaluated by WBS analysis. The relationship between consumer tenderness-like ratings and WBS was investigated through regression analysis. Threshold WBS levels could not be determined due to the low correlation between consumer tenderness ratings and WBS. Within a muscle, percent tenderness acceptability was determined for each of the tenderness-like ratings. After analyzing the consumer ratings, tenderness acceptability, and WBS values, it was apparent that there may not be a single WBS threshold value suitable for all muscles. Research indicates that there may be muscle-specific WBS threshold levels; these values were not established from this research.

This study was conducted to determine threshold levels for Warner-Bratzler shear (WBS) force of the beef value cuts. USDA Choice and USDA Select M. biceps femoris, M. gluteus medius, M. infraspinatus, M. longissimus lumborum, M. rectus femoris, M. triceps brachii, and M. vastus lateralis steaks were evaluated for palatability characteristics and tenderness acceptability by a consumer panel (n = 205). Steaks also were evaluated by WBS analysis. The relationship between consumer tenderness-like ratings and WBS was investigated through regression analysis. Threshold WBS levels could not be determined due to the low correlation between consumer tenderness ratings and WBS. Within a muscle, percent tenderness acceptability was determined for each of the tenderness-like ratings. After analyzing the consumer ratings, tenderness acceptability, and WBS values, it was apparent that there may not be a single WBS threshold value suitable for all muscles. Research indicates that there may be muscle-specific WBS threshold levels; these values were not established from this research.

This diploma thesis is focused on textural properties of beef meat during aging. Round and sirloin from three heifers of Czech Fleckvieh breed were used for the experiment. Samples were analyzed by Warner-Bratzler test, compression test and penetration test in 4th, 6th, 7th and 8th week of aging. Results of Warner-Bratzler test ranged from 54,72 – 59,96 N and there was not found statistically significant difference. Results from compression test TPA1 were in range 187,75 – 277,05 N and TPA2 results were in range 153,74 – 225,55 N and there was found statistically highly significant difference in most cases. Penetration test results of beef round were in range 5,58 – 6,18 N and there was not found statistically significant difference. Penetration test results of beef sirloin were in range 6,39 – 9,49 N and the difference was not statistically significant in most cases.

O presente trabalho teve como objetivo estimar a variabilidade genética existente entre touros e linhagens da raça Nelore, essas representadas pelos grandes genearcas, no que se refere à qualidade de carcaça e de carne. Os animais utilizados para coleta de dados de carcaça e carne pertenciam ao projeto de melhoramento genético e de avaliação para emissão de CEIP - Certificado Especial de Identificação e Produção, da Agro-Pecuária CFM-Ltda, e tinham idade entre 21 e 28 meses. Foram analisadas as características peso de carcaça quente (PCQ), área de olho de lombo (AOL), espessura de gordura subcutânea (EGS) e marmoreio (MAR). A qualidade de carne foi avaliada para os períodos de 7, 14 e 21 dias de maturação, quanto às perdas por exsudação (PE), perdas por cozimento (PC) e maciez (MAC). A avaliação da variabilidade genética entre linhagens foi efetuada com base em valores das diferenças esperadas na progênie (DEP) para as características PCQ, AOL, EGS, MAR e MAC aos 7, 14 e 21 dias de maturação. Foi encontrada variabilidade entre os touros e as linhagens estudadas sugerindo que um progresso genético pode ser conseguido pela seleção de animais para características de carcaça e carne dentro da raça Nelore. / The present study had as objective to estimate the genetic variability between steers and breed lines of Nellore, these represented by the greatest breeders, referred to carcass and beef quality. The animals used to collect the samples of carcass and beef belonged to the project of genetic improvement and evaluation to emission of CEIP-Special Certificate of Identification and Production of CFM Farm-Ltda. The animals had age between 21 and 28 months. Were analyzed the characteristics of hot carcass weight (PCQ), rib eye area (AOL), backfat thickness (EGS), marbling (MAR).The beef quality was evaluated for the periods of 7, 14 and 21 days of ageing, as reference the drip loss (PE), cooking loss (PC) and tenderness (MAC). The evaluation of the genetic variability between the breed lines was done based in the values of the expected progeny differences (DEP) of the characteristics of PCQ, AOL, EGS, MAR and MAC at days 7, 14 and 21 of ageing. There was found a variability between steers and the breed lines studied, suggesting that a genetic process may be possible by selecting the animals to carcass and beef characteristics in the Nellore breed.

O objetivo do presente trabalho foi determinar a força de cisalhamento Warner-Bratzler do músculo Longissimus lumborum de animais zebuínos machos inteiros (Bos indicus) durante o período de maturação, nas faixas de pH final (pHf 48 horas post mortem) normal (pH entre 5,5 e 5,8) e anormal (pH entre 5,81 e 6,19) e temperaturas internas de cozimento. Concomitante com a avaliação de força de cisalhamento, foram avaliadas também a degradação da desmina e troponina T, o comprimento do sarcômero, o teor de colágeno total e solúvel, as temperaturas máximas de desnaturação das proteínas e a morfologia geral de agregação das fibras do músculo no cozimento. A degradação da desmina e troponina T foi maior no pHf normal, aparecendo produtos de degradação a partir do dia 7 nessa faixa de pHf. Não houve diferenças nos valores de comprimento do sarcômero, descartando-se assim, a contribuição desse parâmetro sobre a temperatura máxima de desnaturação (Tmáx) das proteínas, determinada utilizando calorímetro exploratório diferencial (DSC). Similarmente, não foram encontradas diferenças para os teores de colágeno total e solúvel, e os valores de colágeno total foram baixos, sugerindo que sua contribuição na segunda transição térmica e nos valores de força de cisalhamento foi mínima. As Tmáx1 e Tmáx2, correspondentes à desnaturação da meromiosina leve e pesada, respectivamente, foram menores no pHf normal, mas o efeito foi maior para a Tmáx2. A Tmáx3 da actina e titina aumentou até 14 dias post mortem na faixa de pHf normal, e posteriormente diminuiu significativamente após 21 dias, sugerindo possível degradação dessas proteínas nesse período de dias. Não foram encontradas diferenças nos valores de Tmáx no pHf anormal, em todos os dias post mortem, o que sugere a contribuição de um possível mecanismo de proteção que estabiliza as miofibrilas no aquecimento. Houve maior agregação das fibras do músculo no pHf normal nas temperaturas internas de cozimento de 65 e 80°C, provavelmente devido à maior desnaturação térmica das miofibrilas. Os valores de força de cisalhamento foram maiores com o aumento da temperatura interna de cozimento, devido ao aumento da desnaturação térmica das miofibrilas do músculo. Independente da temperatura interna de cozimento, os valores de força de cisalhamento foram altos em quase todos os dias post mortem para ambas as faixas de pHf, o que sugere a necessidade de utilizar métodos físicos ou químicos para aumentar a maciez do músculo Longissimus lumborum de animais zebuínos. / The aim of this work was to determine the Warner-Bratzler shear force of Longissimus lumborum muscle of Zebu bulls during ageing, at the normal (pH between 5.5 e 5.8) and abnormal (pH between 5.81 e 6.19) ultimate pH (pHu) groups (pH 48 hours post mortem) and internal temperatures of cooking. Concomitant with the Warner-Bratzler shear force evaluation, the degradation of desmin and troponin T, sarcomere length, total and soluble collagen content, maximum temperature of proteins denaturation, and aggregation of muscle fibers during cooking were also evaluated. The degradation of desmin and troponin T was higher in the normal pHu, appearing degradation products at day 7. There were no differences in the sarcomere length values, discarding the contribution of this parameter on the maximum temperature of proteins denaturation (Tmax) determined by differential scanning calorimeter (DSC). Similarly, no differences were found for total and soluble collagen contents, and the total collagen values were low, suggesting that its contribution in the second thermal transition and in the shear force values was minimal. The Tmax1 and Tmax2, corresponding to the denaturation of light and heavy meromyosin, respectively, were lower in the normal pHu group, but the effect was higher for Tmax2. The Tmax3 of actin and titin increased up to 14 days post mortem in the normal pHu group, which subsequently significantly decreased after 21 days, suggesting the possible degradation of these proteins in that period of time. No differences were found in the Tmax values for the abnormal pHu group at all days post mortem, suggesting the contribution of a possible protective mechanism that stabilizes the myofibrils during heating. There was higher aggregation of muscle fibers in the normal pHu, at internal temperatures of cooking of 65 and 80°C, probably due to a higher thermal denaturation of myofibrils. The shear force values were higher with the increase of the internal temperature of cooking due to the increased denaturation of the muscle myofibrils. Regardless of internal temperature of cooking, the shear force values were higher in almost all days post mortem for both pHu groups, which suggest the need of physical or chemical methods to increase the tenderness of Longissimus lumborum muscle of Zebu bulls.

O presente trabalho teve como objetivo estimar a variabilidade genética existente entre touros e linhagens da raça Nelore, essas representadas pelos grandes genearcas, no que se refere à qualidade de carcaça e de carne. Os animais utilizados para coleta de dados de carcaça e carne pertenciam ao projeto de melhoramento genético e de avaliação para emissão de CEIP - Certificado Especial de Identificação e Produção, da Agro-Pecuária CFM-Ltda, e tinham idade entre 21 e 28 meses. Foram analisadas as características peso de carcaça quente (PCQ), área de olho de lombo (AOL), espessura de gordura subcutânea (EGS) e marmoreio (MAR). A qualidade de carne foi avaliada para os períodos de 7, 14 e 21 dias de maturação, quanto às perdas por exsudação (PE), perdas por cozimento (PC) e maciez (MAC). A avaliação da variabilidade genética entre linhagens foi efetuada com base em valores das diferenças esperadas na progênie (DEP) para as características PCQ, AOL, EGS, MAR e MAC aos 7, 14 e 21 dias de maturação. Foi encontrada variabilidade entre os touros e as linhagens estudadas sugerindo que um progresso genético pode ser conseguido pela seleção de animais para características de carcaça e carne dentro da raça Nelore. / The present study had as objective to estimate the genetic variability between steers and breed lines of Nellore, these represented by the greatest breeders, referred to carcass and beef quality. The animals used to collect the samples of carcass and beef belonged to the project of genetic improvement and evaluation to emission of CEIP-Special Certificate of Identification and Production of CFM Farm-Ltda. The animals had age between 21 and 28 months. Were analyzed the characteristics of hot carcass weight (PCQ), rib eye area (AOL), backfat thickness (EGS), marbling (MAR).The beef quality was evaluated for the periods of 7, 14 and 21 days of ageing, as reference the drip loss (PE), cooking loss (PC) and tenderness (MAC). The evaluation of the genetic variability between the breed lines was done based in the values of the expected progeny differences (DEP) of the characteristics of PCQ, AOL, EGS, MAR and MAC at days 7, 14 and 21 of ageing. There was found a variability between steers and the breed lines studied, suggesting that a genetic process may be possible by selecting the animals to carcass and beef characteristics in the Nellore breed.