THE EFFECTS OF ORIENTATION AND STORAGE TIME ON THE PREDICTION OF BEEFRIB COMPOSITION USING ELECTROMAGNETIC SCANNING

To investigate the effects of orientation of beef ribs in an electroma gnetic field and storage time on the prediction of rib composition, 64 ribs (IMPS 103) were scanned (2.5 MHz) in three different orientation s: posterior end first (POS), dorsal end first (DOR), and fat side fir st, blade end down (BLD). Scans were obtained after 1 and 5 d of stor age. Scan peak, rib weight, 3/4 fat depth, length, and temperature wer e used to predict percentage and weight of dissectable and fat-free le an. The mean peak for the BLD scans was four to six times higher than the POS or DOR scans. Ribs scanned in the BLD orientation on d 5 had t he highest coefficient of determination (CD; 94.0) and the lowest resi dual standard deviation (RSD; .22 kg) for prediction of lean weight. T he POS and DOR scans were similar at d 5 (CD = 91.4 and 90.3, respecti vely) with RSD of .30 and .31 kg, respectively. Prediction of lean per centage resulted in lower CD than predicting lean weight. For percenta ge of lean, BLD scans at d 5 once again resulted in the best CD (81.6) and lowest RSD (1.5%). Prediction of percentage lean using POS or DOR orientation resulted in CD of 71.2 and 67.1 and RSD of 2.0 and 2.1%, respectively. The CD were similar for POS and DOR scans at d 1 and d 5 . Predicting fat-free lean weight resulted in equal or lower CD than d issected lean and higher CD for lean percentage. It seems that orienta tion during scanning, when consistent, is not a major concern. As the time between scanning and dissection increases, dehydration weight los s may need to be measured.