ABSTRACT
Near-infrared spectroscopy is a rapid screening technique that may be used to determine meat quality traits. While several calibrations on meat quality parameters have been published, the accuracy and robustness of a calibration has rarely been validated with independent samples. In this study, in 207 loin muscles from three independent batches of pigs of different breeds drip loss, colour values, pH and intramuscular fat were determined. Calibrations were made from each combination of two batches and validated with the third batch. Validations of pH, intramuscular fat, drip loss, and L(∗), a(∗), and b(∗) colour values had on average 1.27 times the accuracy of the calibration. Breed did not influence the accuracy of the calibration. Intramuscular fat can be determined with good accuracy. Muscle pH and colour values are reasonably well predicted. Drip loss can not be determined quantitatively with sufficient accuracy, but classification of quality groups is possible.
ABSTRACT
An immunological biosensor for calpastatin was developed on a surface plasmon resonance based system (Biacore Q). The performance of the biosensor assay was evaluated using ovine and bovine muscle and heart extracts with known calpastatin activity. In addition, the relationship between immunologically detectable calpastatin at 1 day postmortem and shear force at 14 days postmortem was investigated for bovine longissimus dorsi. Calpastatin biosensor results for several experiments were linearly related to calpastatin activity measurements with correlation coefficients ranging from 0.51 to 0.99. The intra- and inter-assay CVs were <6% (n=12). During postmortem storage, the amount of immunologically detectable calpastatin decreased faster than the inhibitory activity in the enzymatic assay. Probably, the epitope recognized by the antibody is degraded faster than the inhibitory sites of calpastatin during postmortem storage. Calpastatin content at 1 day postmortem was correlated to shear force at 14 days postmortem (r=0.75). It is anticipated that developments in the near future will allow for at-line calpastatin determinations in beef plants. At present, the calpastatin biosensor assay appears suitable for research purposes where large numbers of samples need to be processed for breed evaluation or selection programs because this assay requires less labor than other methods.
ABSTRACT
Two experiments were done to determine whether short-term supplementation (5 days pre-slaughter) with magnesium acetate, or a combination of magnesium acetate, tryptophan, vitamin E and vitamin C would improve pork quality. In the first experiment the pigs (Pietrain×Yorkshire, n=96) were fed a standard feed or a magnesium supplemented feed for 5 days prior to slaughter. As a possible stress factor half of the animals were slaughtered upon arrival at the slaughterplant whereas the remaining animals were allowed two hours of rest in lairage before slaughter. Magnesium supplementation did not result in an increase in plasma magnesium concentration at slaughter. Omission of lairage resulted in higher plasma glucose concentrations, but plasma lactate concentrations were not affected. Drip loss and ultimate pH were not affected by diet or omission of lairage. Omission of lairage resulted in poorer color characteristics. This effect was prevented by supplementation with magnesium. In the second experiment the pigs (Pietrain×Yorkshire, n=92) were fed a standard feed or this standard feed supplemented with magnesium acetate, tryptophan, vitamin E and vitamin C for 5 days prior to slaughter. Supplementation with vitamin E did not increase muscle vitamin E concentration. Inclusion of supplements in the diet failed to improve water-holding capacity or color characteristics. These results indicate that short-term supplementation with magnesium acetate, tryptophan, vitamin E and vitamin C is of little value in improving pork quality when pigs are not stressed beyond levels associated with routine slaughter procedures.
