1921.] Wright.—Chemical Technology of Meat Industry. 
83 
It is known that there are present in small amounts fat-hydrolyzing 
enzymes in commercial animal-fats which have not been heated to such a 
temperature that enzymic activity has been destroyed. It is therefore easy 
to understand the changes which subsequently take place in such fats when 
moisture, either atmospheric or inherent, is present. 
It is well known that oils and fats if kept from light, air, and moisture 
retain indefinitely their state of neutrality, whereas if they are not carefully 
preserved (even in imperfectly secured casks moist air may gain entrance) 
moisture produces free fatty acids and glycerine, accompanied by the 
disagreeable smell and acrid taste which can best be expressed in the 
statement that the oil or fat has become “ rancid.” 
In the light of the more recent knowledge regarding the nature of 
rancidity in fats it has been possible to devise a test which gives sensitive 
reactions in the presence of a rancidity which may even not be at the time 
detectable to the odour or taste, but which subsequent development reveals. 
This test is a modification of the Kreis reaction, and its adoption has 
provided a means of control which has hitherto been lacking at the point 
of manufacture. The following results have been found in the examination 
of edible fats :— 
Table IV. Edible Fat. 
Mutton. Beef. 
Moisture 
Free fatty acids .. 
Melting-point 
Titre 
Detritus 
Kreis test for rancidity 
Flavour and odour 
Colour 
0-06 per cent. 
0-35 per cent. 
.. 504° C. 
.. 494° C. 
None 
Negative 
Normal 
Clear white 
• >ioi- !i ' - 
0*05 per cent. 
0*27 per cent. 
48-8° C. 
46-5° C. 
None. 
Negative. 
Normal. 
Yellowish. 
Literature cited. 
1. W. I). Richardson, Premier Congres International du Froid, vol. 2. pp. 261-316, 
1908. 
2. T. E. Thorpe, Meat-extract, Did. App. Chem., 1912. 
3. T. E. Thorpe, Oils and Fats, Did. App. Chem., 1912. 
4. P. J. Fryer and F. E. Weston, Oils, Fats, and Waxes (Camb. Univ. Press), 1917. 
5. C. A. Mitchell, Edible Oils and Fats (Longmans), 1918. 
6. G. Martin, Animal and Vegetable Oils, Fats, and Waxes (Crosby Lockwood), 1920. 
7. H. C. Sherman, Food Products (Macmillan), 1914. 
8. F. W. Wilder, The Modern Packinghouse (Nickerson and Collins Co.), 1905. 
9. Report, Extract of Meat Commission, Lancet , Oct. 24, 1908, pp. 1233-44. 
10. S. Rideal, Premier Congres International du Froid, vol. 2, pp. 317-25, 1908. 
11. Report, Food Investigation Board, 1919 (H.M. Stationery Office). 
19. A. E. Vinson, Analyse ganger Tierkorper (Universitat zu Gottingen), 1904. 
13. L. D. Hall and A. D. Emmett, Bull. 158 (Univ. of Illinois), 1912. 
11. A. M. Wright, Trans. N.Z. Inst., vol, 45, pp. 1-17, 1913. 
15. A. M. Wright, Trans. N.Z. Inst., vol. 47, pp. 569-72, 1915. 
16. A. M. Wright, Trans. N.Z. Inst., vol. 43, pp. 1-6, 1911. 
17. A. M Wright, N.Z. Jour. Sci. & Tech., vol. 3, pp. 209-13, 1920. 
18. A. M. Wright, Proc. Cold Storage and Tee Assn., vol. 15, pp. 32-47, 1919. 
19. A. M. Wright, Proc. Cold Storage and Ice Assn., vol. 15, pp. 147-59, 1919. 
20. J. T. Critchell and J, Raymond, History of the Frozen-meat Trade (Constable and 
Co.), 1912. 
21. T. Bodrrier, Les Industries des Abattoirs (Balliere et Fils), 1897. 
22. L. Marchis, Le Froid industriel (Felix Alcan), 1913. 
23. A. M. Greene, Elements of Refrigeration (Chapman and Hall), 1916. 
