Comparative studies of meat V. Factors affecting the iodine number of the fat from the fatty and muscular tissues of cattle

Abstract

1. Carcasses of twenty-one fat cattle (from six cows, ten steers and five heifers, aged from 12 months to 12 years and representing seven breeds) have been dissected into nine joints, and the fatty and muscular tissue from each joint dissected and analysed for fat. The iodine number of each sample of fat has been determined.2. The fat in fatty tissues ranged from 28·3 to 96·7%, and in muscular tissues from 1·3 to 14·2%. Iodine numbers of fat from fatty tissues ranged from 34·0 to 69·0 and those of fat from muscular tissues from 45·9 to 73·2.3. By an analysis of covariance it has been possible to reduce these data to two families of regression lines—those for fatty tissue and those for muscular tissue.4. The equations for fatty tissue have the following generalized form:I.N. = A_FT + C_FT + J_FT + b₁F/FT,where A_FT = 55·6 ± 1·7 and is a general constant,C_FT is a series of constants for the various carcasses and ranges from +12·6 to −6·7,J_FT is a series of constants for the various joints and ranges from +6·6 to −10·3,b₁ is a general constant with the value −0·052(± 0·025),F/FT is the percentage of fat in any given sample of fatty tissue, and I.N. is its iodine number.5. A similar set of equations has been deduced for muscular tissue. Here, however, the relation between iodine number and percentage of fat is a rectangular hyperbola. Consequently, the inverse (Z) of the percentage of fat (in order to get a straight-line relationship) has been used.