Comparison of Structural Changes in Bovine Long and Semitendinosus Muscles During Cooking

Abstract

Structural characteristics of aged (10 days) bovine longissimus and semitendinosus muscles as affected by thermal treatment were evaluated with scanning electron microscopy (SEM) and transmission electron microscopy PEM). Steaks were oven roasted at 177°C to internal temperatures of either 63, 68, or 73°C. At 63°C both muscle samples exhibited coagulation and denaturation of the perimysium and sarcolemma and progressively increased to near complete coagulation and denaturation at 73°C. Well-defined myofibrillar surface features were present in semitendinosus samples at 63°C and increased sarcomere denaturation and shrinkage were observed at the higher temperatures. Whereas, the overall topographical features of longissimus myofibrils were not well-defined and exhibited a granular appearance even at 63°C. TEM of samples heated to 63°C revealed less distinct myofibrils in longissimus than in semitendinosus samples. Disintegration of filaments in the I-band and shrinkage of filaments in the A-band occurred at 63°C. Increased disintegration of actin filaments in the I-band at the junction of the Z-disc and shrinkage and disruption of the A-band material occurred as temperatures were increased. Z-disc material remained intact with some evidence of disruption at the higher temperatures. Although progressive disruption of muscle fiber ultrastructure occurred as steaks were heated to higher internal temperatures, these changes did not result in increased muscle tenderness. Instead the samples became progressively less tender as internal temperatures were increased likely due to the shrinkage and hardening of filamentous material in the A-bands. Increased disintegration of filaments in the I-band as temperature was increased apparently did not contribute to an improvement in tenderness.

Preparation and storage stability of retort processed Chettinad chicken

“…The release of moisture in the gravy during heat denaturation of proteins might have contributed for sampling error during storage studies. Leander et al (1980) also observed that when meat is cooked, water, soluble proteins, and fats are expelled from the tissue. This was again supported by Martens et al (1982).…”

Marbling, Fat Trim and Doneness Effects on Sensory Attributes, Cooking Loss and Composition of Cooked Beef Steaks

“…Well done steaks were rated less tender than medium or rare steaks (PcO.05) as previously noted by Leander et al (1980). Well done steaks and medium steaks were rated less juicy (slightly juicy) than rare steaks (moderately juicy) as expected.…”

Composição centesimal, perdas de peso e maciez de lombo (longissimus dorsi) suíno submetido a diferentes tratamentos de congelamento e descongelamento

“…Além disso, a desnaturação é responsável por mudanças na estrutura e carga das proteínas, também causando redução da CRA (Fennema, 1993). Leander et al (1980) relatam que, com o aumento da temperatura, ocorre encurtamento dos sarcômeros das fibras musculares, forçando a saída dos fluidos e ocasionando as chamadas "perdas pela cocção".…”