http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Lactate dehydrogenase detection immunoassay in roast beef
Recent outbreaks of foodborne illness linked to undercooked meats have raised concerns about the safety of meat products. Currently, USDAFSIS requires minimum cooking of beef roasts to an instantaneous internal temperature of 62.8'C. Development of rapid and accurate techniques to assess if the USDA required heating endpoint temperature had been achieved would enable regulators and quality control personnel to verify the safety of products while ensuring consumer confidence. The objective of this experiment was to determine if a test capable of determining if minimum safe endpoint cooking temperatures had been achieved in beef roasts. Previous research showed lactate dehydrogenase isoenzyme 5 (LDH5) to lose enzymatic activity near 63'C while SDS-PAGE results of beef Semitendinosus muscles (n = 3) cooked to 55, 60, 65, 70, 75, 80, and 85'C showed loss of LDH5 banding between 60 and 65'C. LDH5 polyclonal antibodies were raised in rabbits and immunoblot analysis performed on incrementally heated model roasts. Integrated intensities of immunoblot results revealed a loss of antigenicity between 55 and 65'C (P < .05). The effects of salt and phosphate ingredients in beef roast models were investigated. Model beef Semitendinosus roasts (n = 120) were injected with a 10% brine of either 0% Na5P3010 (P) and 0% NaCl (S), O%P 1%S, O%P 2%S, O%P 3%S, .5%P O%S, .5%P 1%S, .5%P 2%S, or .5%P 3%S. Roasts then were left raw or cooked to 60, 62, 64, or 66'C. Crude protein, pH, extractable protein, SDS-PAGE banding intensities, and immunoblot banding intensities were determined. There were no (P > .05) interactions between cooking and brine ingredient on crude protein content. Cooking and addition of sodium tripolyphosphate increased (P < .05) pH of roasts. Protein concentration in extracts from roasts decreased with heating and addition of S, but increased with addition of P (P < .05). Integrated intensities of SDS-PAGE and immunoblot results indicated that at the lower level of P and as level of S increased, banding declined (P < .05) in cooked treatments over the range of 60 to 66'C. Immunoblot differentiation was possible (P < .05) between roasts cooked to 60 and 62'C in O%P O%S and typical commercial roasts containing .5%P 1 %S and .5%P 2%S.
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