Methods for determining relative tenderness of muscle have been accompanied by a large degree of experimental error. Part of this error has been due to the measuring device, animal variation and muscle variation, but a large portion of the experimental error can be attributed to sampling error. It is important to devise a uniform, consistent method for taking cores of meat to be measured by the mechanical shear machine (e.g. Warner-Bratzler).
More and more research is devoted to the study of muscle and its
characteristics, especially in relation to tenderness. Most mechanical methods for measuring tenderness require a uniform section of muscle, and considerable difficulty has been experienced in providing uniform individual cores. This has been particularly true when meat is bored immediately after cooking. The best treatment is to bore cooked meat after it is chilled to 4C. Another practice that aids in providing uniform cores is that of heating meat samples to an internal temperature of 72C. Meat heated to 72C is well cooked, drier, firmer and thus holds its shape better during boring than muscle cooked at a lower temperature (60C).
Until now meat cores to be measured by the Warner-Bratzler shear apparatus were obtained manually and there was a tendency for the cores to be of a concave or hourglass shape, which was considered to affect the shear tests. This was especially true when the hand boring method on meat cooked medium to rare.
Kastner and Henrickson (1969) devised a tool that will assure cores of uniform diameter. This companion tool to the shear machine consists of a Black and Decker type III drill stand, drill and a metal rod adapter machine to fit inside the standard bore. The borer has one metal projection 2 mm in diameter, extending 2.5 mm perpendicular and 2 cm idstant from the terminal end. The male insert was milled with a recess in the thickened end to receive the metal projection. The projection on te bore holds the bore to the modified "chuck" device during operation and allows the bore to be easily detached for core removal and cleaning. The study of these can be summarized in the abstract from the article. Porcine longissimus dorsi muscle was cut into 5.08 cm sections,heated to an internal temprature of 72C and chilled to 4C. Pork muscle cooked to 72C and chilled to 4C before boring, was firmer, drier ad thus better able to hold its shape during coring than muscle cooked to 60C, and bored warm. Two cores were taken from each pork loin chop. One core was bored by hand, the other by machine. Three different core sizes were used (2.54 cm, ' 1.90 cm and 1.27 cm). Each core diameter was measured at the same three locations as te core was sheared. A significant (P<0.005) difference in diameter was observed between the hand and machine cut cores when te 1.90 cm and 1.27 cm bores wee used. at these core diameters, there was less variation between the machine bored cores than those removed by hand. there was no significant differece between the core diameters of the two different boring methods, when te 2.54 cm bore was used. in all cases machine bored cores were larger in diameter and required a greater shear force than cores removed by hand. mean shear force values indiated that one cannot double the 1.27 cm core shear value and receive comparable results for the 2.54 cm core shear forces.
Kastner, C.L. and R.L. Henrickson. 1969. Providing uniform meat cores for
mechanical shear force measurement. Journal of Food Science 34:603
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´ Updated: Wednesday, October 31, 2007.
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