Drip loss sampling in porcine m. longissimus dorsi

The effect of the sampling position is investigated when measuring drip loss in porcine longissimus dorsi muscle. Measuring in biological tissue often includes an assumption of homogeneity of the muscle under investigation, an assumption that only applies to a certain extent. However, this assumption is particularly critical when measuring drip loss. In the present experiment two different methods for measuring drip loss were applied. The two methods use a considerably different sample size and thus a difference in sensitivity to the heterogeneity of the object to be measured may be expected. In other words, when measuring drip loss a large sample size may blur information about biological variations in the parameter under investigation. The influence of the sampling position on the drip loss measurement 34 pigs were selected from a random group of 204 pigs. The right and the left longissimus dorsi were excised and used as objects for measuring drip loss with two different methods. Each longissimus dorsi muscle was sliced in 11-15 slices of 2.5 cm thickness. The left longissimus dorsi was sampled in three positions for each slice and the drip loss was measured in each position applying the EZ-DripLoss method. The longissimus dorsi from the right side of the carcasses was measured with the bag method. Our measurements showed a substantial variation in the influence of the sampling position on the result of determination of drip loss. The influence is calculated as the standard deviation (SD) between measurements performed in different positions in transverse and longitudinal direction along the longissimus dorsi muscle. Our work showed that the optimum position of sampling for drip loss determination was 5 cm cranial to the start of the fourth lumbar vertebra, where we found a SD between neighbouring sampling positions of less than 0.74%. We found a high correlation (0.85) between the methods applied even though this value included differences between the right and the left side of the carcass. From one single measurement of drip loss performed on the left longissimus dorsi with the EZ-DripLoss method, we were able to predict the average drip loss of the right longissimus dorsi with a very high correlation (>0.9). We are still searching for an explanation for the 1.2% offset between the two methods employed in this experiment.