Claus Borggaard

Development of technology for the early post mortem prediction of water holding capacity and drip loss in fresh pork.

Two different technologies were tested on the slaughterline for their ability to predict drip loss at 24 h, namely near infrared reflectance (NIR) and impedance measurements using a tetra polar measuring geometry at a frequency of 1000 Hz. The results demonstrate that NIR measurements (900-1800 nm) acquired during a 6 min period starting only 30 min post exsanguination through a fibre optic probe in combination with multivariate data analysis can be used for predicting drip loss 24 h after slaughter. A correlation higher than 0.8 was observed for a trial on 99 carcasses measured at a commercial slaughterhouse. The tetrapolar impedance measurements did not perform as well as NIR yielding a correlation of 0.5 with 24 h drip loss.

Optical measurements of pH in meat

The pH changes occurring in a carcass during the first 24 h after slaughter are important for the quality of the final meat or meat products. Protein denaturation will occur if pH falls to too low a level or if a relatively low pH sets in at a time after slaughter where the carcass temperature is still high. This will result in meat with poor water holding capacity and in extreme cases in meat that is PSE. pH is measured electrochemically using either glass or solid state (IS-FET) electrodes. However, electrochemically based methods are slow to use and do not offer good precision on unhomogenized meat. In this work it has been investigated whether pH can be measured spectroscopically in reflectance using the visual and near infrared spectral regions. On a limited number of pig meat samples (46 longissimus dorsi and 46 semimembranosus muscles) correlations of 0.85 have been achieved using the fast spectroscopic techniques opposed to glass electrode measurements done in duplicate. The prediction errors for the spectroscopic techniques are found to be comparable to the precision of the reference method.

Determination of RN(-) phenotype in pigs at slaughter-line using visual and near-infrared spectroscopy.

The specific characteristics of meat from the Hampshire breed of pig, including high glycogen content and low ultimate pH and technological yield, have been associated with the dominant RN gene. In Sweden, purebred Hampshire or Hampshire x Yorkshire is often used as terminal sire in the three-way crosses used for pig meat production. For the industry producing cured and cooked hams there is a need to detect the RN(-) carriers of the pigs early post mortem in order to select non-carriers for ham production. In the present study, the possibility of separating RN(-) carriers from non-carriers using a combination of visual and near-infrared (NIR) spectroscopic measurements in reflectance mode through a fibre-optic probe has been studied on commercial pigs in a slaughterhouse. The NIR measurements were performed 30 min post-mortem. Sixty-three animals were considered to be carriers and 33 animals non-carriers based on their glycolytic potential in M. semimembranosus (above 200 μmol/g for RN(-)rn(+) and below 180 μmol/g for rn(+)rn(+)). By using NIR together with classification with neural networks, RN(-) carriers could be separated from non-carriers. None of the carriers and only four non-carriers of the RN gene were misclassified as carriers of the RN gene. The ultimate pH could be predicted using linear partial least squares regression with a correlation coefficient of 0.57 and an accuracy of 0.074 root mean square error of prediction.