摘要:

A photoelectric colour comparator, similar to that designed by Bolton and Williams (1), has been constructed and used to compare the colours of meat samples at different pH. Light falls at an angle of 45° on the surface of the sample, and the amount scattered at right angles from the surface in the red, green, and blue regions of the spectrum, defined by standard colour filters in the path of the scattered light, is measured photoelectrically as a percentage of the amount similarly scattered in the same spectral regions from a standard white surface under the same light intensity. The precision of the measurements on meats was ± 0.25% scatter with any one of the three filters.When samples of pork, beef, and mutton were used, after adjustment of the pH by injections of lactic acid or ammonia, the relation between pH and colour was found to be similar for the three meats, with maximum scatter of red, green, and blue at pH about 5.0–5.5. When uninjected samples of pork were used, scatter in the three spectral regions decreased over the pH range 5.4–6.6, paralleling the changes observed with injected samples within the same pH limits. The visual appearance of the meats is greyish at pH levels acid to the region of maximum scatter and pink in the region of maximum scatter, shading to dark red at higher pH levels. Darkening is paralleled by a decrease in the scatter, while changes in the quality of the colour are accompanied by changes in the ratio of red/green and red/blue.

ISSN:1923-4287    

DOI:10.1139/cjr39d-001

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

A recording apparatus for estimating tenderness of meat is described. Samples of approximately equal cross section are cut between blunt jaws brought together by a constantly increasing force. The movement of the jaws is recorded on a drum revolving at constant rate, producing a curve on which the co-ordinates of any point can be interpreted in terms of the thickness of sample cut by a given force. By measuring the areas beneath the curves, and applying a correction for variations in initial thickness of the samples, comparative values for the work required to cut the samples can be obtained. The standard deviation of the mean of duplicate determinations on a single sample is ± 3%.The relation between pH and tenderness was investigated by using samples of pork from three animals and adjusting the pH by injections of lactic acid or ammonia solutions. Toughness was at a maximum at pH about 5.0–6.0; at higher or lower pH levels the meat became progressively more tender. Studies with beef gave similar results, but there was some indication that maximum toughness occurs at a somewhat lower pH. Between different animals the pH at which maximum toughness occurred was more variable in beef than in pork.

ISSN:1923-4287    

DOI:10.1139/cjr39d-002

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

Sheep became unthrifty when fed non-leguminous hays and ground oats over a period of seven months. Numerous feed and mineral supplements were fed in an endeavour to prevent the development of the unthrifty symptoms as well as to determine the nutrient or nutrients lacking in the deficient ration. Pasture, calcium and phosphorus, cod liver oil, tankage, linseed meal, bran, and alfalfa meal, when fed as supplements, delayed the appearance of unthriftiness. The feeding of iron and copper proved detrimental. Wheat germ meal did not improve conditions. Alfalfa ash proved to be the best of all the supplements studied in the maintenance of normal thrift. The beneficial effect of alfalfa ash indicated that the deficiency of the non-leguminous ration that caused unthriftiness was one or more of the minerals that were present in the alfalfa hay.When cobalt was fed as a supplement to a few ewes that had developed the characteristic symptoms of unthriftiness, there followed a rapid increase in weight and improvement in thrift. Chemical analyses of various hays, alfalfa ash, and soil snowed that the non-leguminous hays contained only small quantities of cobalt, similar to the amounts contained in New Zealand grass that caused similar symptoms to develop. Alfalfa hay grown on similar soil contained relatively large amounts of cobalt, whereas alfalfa hay grown in the Lethbridge district contained only small amounts of cobalt. The writers suggest that a cobalt problem may exist in Western Canada.

ISSN:1923-4287    

DOI:10.1139/cjr39d-003

出版商:NRC Research Press    

年代:1939

数据来源: NRC