Instrumental colour classification of veal carcasses.

Three experiments, involving over 56 000 veal carcasses, were carried out to develop a method for instrumental colour classification of veal carcasses at 45 min post mortem with the Minolta CR300. The method should produce results similar to those of the 10-point colour-system, which is currently in use in The Netherlands. In the first experiment, the colour of veal carcasses was visually assessed by three observers and instrumentally measured with two Minolta CR300 devices. The average of the results of the three observers and the two Minolta devices were used for discriminant analysis to analyse yield classification rules, which allowed to assignment of the carcasses to classes of the 10-point colour-system. Identical classifications for Minolta and observer were obtained for 63.2% of the carcasses. In the second and third experiment, the classification rules with the Minolta CR300 were used to predict the colour class. For the new samples, identical classification results were obtained for 50-55% of the carcasses. In 41-44% of the carcasses the classification results differed by less than one class. The results show that the Minolta CR300 is under practical conditions able to predict the 10-point colour classes and can be used for on-line colour classification in a slaughterhouse.

Differences in quality characteristics of normal, PSE and DFD pork.

Differences in water-holding capacity, colour and tenderness/toughness were studied in 21 pork loins belonging to three quality categories, i.e. dark firm dry (DFD), normal and pale soft exudative (PSE). The division into the three groups was based upon the ultimate pH-values of the loins (< pH 5·5, pH 5·5-6·0, pH > 6·4). The PSE loins were characterized by a poor waterholding capacity, higher cooking loss and paler colour in contrast to the DFD category. The normal loins took an intermediate position. Neither sarcomere length, determined on fresh muscle tissue, nor Armour tenderometer values showed significant differences between the various quality categories. This was in contrast to the Warner-Bratzler (W-B) shear force values, determined on cooked loins, which had the lowest values in the DFD category. A strong relationship between the W-B values and the cooking losses was found. It was concluded that neither sarcomere length nor Armour tenderometer measurements were able to predict the shear force values of cooked pork loins.