Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Nov. 25, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Animal Science, [Department of] Agricultural, Food and Nutritional Science, University of Alberta." Includes bibliographical references.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 26, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Monty Kerley. Vita. Includes bibliographical references.

Thesis (Ph.D.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Mar. 22, 2010). Includes bibliographical references.

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This study investigated the influence of microwave and broiling cooking methods on quality parameters of portion size cuts of beef semitendinosus muscle subjected to pre-rigor pressure treatment. The pre-rigor pressurized beef was compared to conventionally processed portion size cuts. Juiciness, tenderness, and flavor were evaluated by objective and subjective tests. Objective tests included water-holding capacity, total moisture, Warner-Bratzler shear, pH, and color of the raw and cooked beef portions. Total lipids and nitrogen content were measured to determined paired sample muscle uniformity. Cooking losses, temperature/time data and electron micrographs were collected as appropriate. Juiciness, tenderness, ease of fiber separation, and flavor of the microwaved and broiled beef portions were subjectively evaluated by a six member trained panel of judges. Pre-rigor pressure treated cooked beef portions showed significantly (P<0.05) greater total moisture, pH, exterior a+ color values and subjective tenderness and ease of fiber separation scores than the untreated portions. No significant differences in interior L, a+ and b+ color values were found between pressure treated and untreated samples. Subjective juiciness and flavor scores were not significantly different between treatments. Total moisture, expressible moisture index, Warner-Bratzler shear, pH, and exterior L and a+ color values were not significantly different between the raw pressure treated and untreated beef portions. Pressure treatment resulted in a significantly higher (P<0.01) exterior b+ color value for the raw treated meat. Total moisture, drip cooking loss, interior a+ (redness) color value, and exterior L (lightness) and b+ (yellowness) color values were significantly higher (P<0.05) in the microwaved beef portions as compared to the broiled portions. Total and evaporation cooking losses were significantly lower (P<0.01) with microwave cooking than broiling in the untreated and pressure treated portions. No significant differences in expressible moisture index, Warner-Bratzler shear, pH, exterior a+ color, and interior L and b+ color values were found between microwave and broiled portions. Panelists evaluation of juiciness, tenderness, ease of fiber separation, and flavor of the beef portions indicated no significant differences between cooking methods. Although total moisture, cooking losses, and color values were significantly different between microwaved and broiled beef portions, in general, microwave and broiling cooking methods gave comparable results for quality parameters in pre-rigor pressure treated cooked beef portions. The significantly higher total moisture and tenderness of pre-rigor pressure treated cooked beef portions indicates the feasibility of this process for use by the meat industry. / Graduation date: 1983

A study was completed to determine the extent of the protein changes occurring in ground beef stored at 2°C for 10 days. Sections of semitendinosus muscle were obtained immediately after the slaughter of three beef animals. Each section was divided into two equal portions, one of which was ground and the other remained intact (control). All samples were handled and stored under aseptic conditions. Grinding markedly accelerated glycolysis as manifested by the rapid pH decline in the ground samples during the initial 24 hours of postmortem storage. After this storage interval, however, there was little difference in pH values between the ground and intact samples. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was employed to monitor changes in myofibrillar and sarcoplasmic proteins extracted from at-death muscles and samples stored for 1, 3, 6, and 10 days at 2°C. The gels were examined visually and scanned densitometrically to detect protein changes. The principal electrophoretic changes in myofibrillar proteins of the ground samples were the gradual disappearance of nebulin and desmin components and the gradual appearance of 110,000-, 95,000-, and 30,000-dalton polypeptides. In addition, there was a progressive increase in the content of a protein around 55,000 daltons and myosin light chain-3. Intact muscles showed similar changes to those of the ground samples except that the latter had a faster initial rate in some of the changes, notably the disappearance of nebulin and the appearance of the 30,000-dalton polypeptide. It seems probable that grinding caused an early release of Ca⁺⁺ from the sarcoplasmic reticulum, which activated the Ca⁺⁺-activated proteinase (CAF). Electrophoretic changes in sarcoplasmic proteins of the ground samples closely resembled those of the intact muscles. The major alterations in both muscle treatments included the gradual appearance of a 100,000-dalton polypeptide and three proteins having molecular weights (M.W.) between 500,000 and 1,000,000 daltons, and the progressive disappearance of 300,000- and 24,000-dalton proteins. The appearance of a 100,000-dalton polypeptide and the three large M.W. proteins presumably originated from myofibrils since they appeared to be related to the changes in myofibrillar proteins. Results of microbial testing indicated very little, if any, sample contamination by psychrotrophic microorganisms. Thus, microbial proteolysis was not a factor in this study. It was concluded that grinding had no pronounced effect on the protein changes of beef muscle other than changes in pH. / Graduation date: 1985

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Digitized by Kansas Correctional Industries

Typescript. / Digitized by Kansas Correctional Industries