To begin place the longissimus thoracis, or LT muscle, on the working platform. Measure the rib eye area in the 12th and 13th rib interface using a small grid with a dot in the middle. Sum all squares within the rib eye, tracing perimeter, and those along the contour, passing through the middle dot.
To measure the back fat thickness, place the caliper at a right angle to the line of the subcutaneous fat from the interface point between the 12th and 13th ribs. Calibrate the pH meter probe with pH-4 and 7 buffers at room temperature. Measure the meat pH at three locations of the longissimus thoracis, or LT muscle.
Manually record the data readings, export the data sheet, and calculate the average of the three readings. Homogenize the LT muscle in a methanol chloroform solution for two minutes. Centrifuge the muscle suspension at 700 G for 10 minutes at 20 degrees Celsius to segregate the hydrophilic, solid, and hydrophobic phases.
Aspirate the alcoholic layer. Filter the homogenate through filter paper on a funnel with a slight suction. Apply pressure with the bottom of a beaker when the residue becomes dry.
Transfer the filtrate to a 500 milliliter graduated cylinder and let it stand for a few minutes. Record the volume of the chloroform layer. Place the sample in an oven at 110 degrees Celsius until complete solvent evaporation.
Then, cool the sample in a desiccator overnight. The next day, reweigh the beaker, and determine the intramuscular fat content by calculating the difference between the initial and final weights of the beaker. To calibrate the colorimeter, place the white calibration plate near the middle of the plate.
Confirm the calibration once the lamp flashes three times. After 30 minutes of blooming at four degrees Celsius, obtain color readings from three different locations on the LT muscle. Compute the average from three measurements.
To determine the purge loss of the beef loin section, measure the variance between the initial weight before freezing, the weight after freezing and thawing, and the final weight. To gauge the water-holding capacity, first, weigh the meat sample before subjecting it to a pressure of 10 kilograms for five minutes. Then, weigh the meat sample again and assess the water holding capacity by calculating the weight differences.
Position LT muscles on a grid attached to a glass refractory, place the digital thermometer in the sample, and cook the muscles in an industrial electric oven until reaching a final temperature of 71 degrees Celsius. After cooling, weigh the sample, and refrigerate at four degrees Celsius for 24 hours. Use the given formula to calculate the cooking losses.
To determine drip loss, weigh the refractory before cooking the sample. Place the samples on a grid over a glass refractory to allow drainage of meat juices and fat during cooking. After cooking, again, weigh the refractory.
Weigh only the sample before and after cooking to determine evaporation loss. After recording raw and cooked weights, calculate the percentage of drip loss as the weight of drip after cooking, divided by the weight of the thawed meat sample. Calculate the evaporation loss percentage using the given formula.
For the determination of Warner-Bratzler shear force, section eight cores using a texture analyzer equipped with a Warner-Bratzler blade and V-shaped cutting edge. After excluding the low and high extremes, report the results as the average of six values per sample. Homogenize three grams of LT muscles for 30 seconds in a potassium buffer at two degrees Celsius.
Then, centrifuge the sample at 1000 G for 15 minutes at four degrees Celsius, and resuspend the pellet in 10 volumes of isolating medium using a stir rod. Again, centrifuge and resuspend the pellet in 2.5 volumes of isolating medium. Pass the suspension through a polyethylene strainer to separate the connective tissue and debris.
Use an additional 2.5 volumes of isolating medium to allow the myofibrils to pass through the strainer. Next, dilute an aliquot of myofibril suspension with an isolating medium. Determine the protein concentration of the suspension of myofibrils using the biuret method.
Immediately, measure the absorbance at 540 nanometers. Multiply the absorbance value by 200 to obtain the myofibrillar fragmentation index for each value. Significant differences in hot carcass weight, rib eye area, and back fat thickness were observed with crossbred animals showing higher values, indicating a heterosis effect.
Meat quality traits comparisons showed no significant differences in meat pH, purge loss, extractable volume percentage, and cooking loss between Nellore and F1 Angus Nellore bulls. However, crossbred bulls had higher intramuscular fat, yellowness, water holding capacity, and myofibrillar fragmentation index. The meat of Nellore bulls showed reduced tenderness with higher Warner-Bratzular shear force and drip loss, indicating it is tougher than the meat of F1 Angus Nellore bulls.
