Prediction of fat percentage within marbling score on beef longissimus muscle using 3 different fat determination methods.

Consumers are concerned with fat consumption from meat products, and the ability to determine fat has changed with recent technological advances. The objective of this study was to predict fat percentage within marbling scores and compare 3 fat analysis procedures. Steaks (n = 119) were selected by USDA grading system using an E + V Vision Grading camera at a commercial beef plant during 1 d. Two samples per carcass were cut from the 13th rib, both sides, and transported to the University of Missouri meat laboratory. The sample from the right side of the carcass was allotted to Warner-Bratzler shear force, and the sample from the left side, which was graded by the camera, was allotted to fat extraction. Warner-Bratzler shear force samples were cut into 2.54-cm steaks and aged for 14 d. Steaks allotted to fat extraction were trimmed of all external fat and twice ground using 8- and 4-mm grinding plates. The finely ground beef was then split into its allotted fat-extraction methods. The 3 methods used in fat extraction were 2:1 chloroform/methanol (Folch), ether-extractable fat (ether), and microwave drying and nuclear magnetic resonance (CEM). Warner-Bratzler shear force values were not different between marbling scores (P > 0.05). Regardless of fat extraction method, fat percentage increased as marbling score increased (P < 0.05). All regression equations for fat percentage, regardless of extraction method, were linear. Prediction equation for fat percentage using CEM was -3.46 + 0.016 (marbling score), R(2) of 0.824 (P < 0.0001). Prediction equation for fat percentage using ether was -3.08 + 0.017 (marbling score), R(2) of 0.859 (P < 0.0001). Prediction equation for fat percentage using Folch was -3.42 + 0.019 (marbling score), R(2) of 0.816 (P < 0.0001). When the CEM, Folch, and ether methods were compared, CEM and Folch regression lines had different slopes (P < 0.05). The slope of the regression line for ether was not different (P > 0.05) from CEM or Folch. Overall, ether is the most accurate method based on the R(2) value, but CEM is environmentally safe and the fastest method for determining total crude fat percentage.

Synthesis and template properties of an ethyl phosphotriester modified decadeoxyribonucleotide.

The phosphate groups of nucleic acids are often the targets of mutagenic and carcinogenic alkylating agents. In order to study the effects of alkyl phosphotriester modification on the physical and biochemical properties of DNA, two diastereomeric ethyl phosphotriester modified decadeoxyribonucleotides, d-CpCpApApGp(Et)ApTpTpGpG isomer I and isomer II, were prepared. A phosphotriester synthetic procedure was used to specifically place ethyl triester groups with either an R or S configuration in the central dimer region of the decamer. Terminal deoxynucleotidyl transferase was used to add oligodeoxyadenylate tails to the 3' end of the decamers. The resulting oligomers were tested as templates for Escherichia coli DNA polymerase I with d-(pT)8pCpC as a primer. The rates and extents of polymerization directed by the modified templates were 25% (isomer I) and 50% (isomer II) less than those of an unmodified control template. Thus the presence of an ethyl triester group inhibits polymerization, the effectiveness of which is determined by the orientation of the ethyl group relative to the rest of the template backbone. These results suggest ethyl phosphotriester lesions could inhibit replication rates of cellular DNA.