# Calculations of fatty acids in 100 g food and 100 g total fatty acids

When the fatty acids provided by a given weight of food are being calculated, allowance must be made for the fact that the total fat in a food includes triglycerides (of which a proportion is glycerol, i.e. not fatty acid), phospholipids and unsaponifiable components such as sterols.

In foods where the total fat is virtually all triglyceride, a correction factor based on the average chain length of the fatty acids present is adequate. The factors for foods containing appreciable amounts of phospholipids and unsaponifiable matter depend on the class of foodstuff. Suggested values for these factors are given in Table A5.1.

 Table A5.1 Conversion factors to be applied to total fat to give values for total fatty acids in the fat Food Factor Food Factor Wheat, barley and rye1 Beef3 wholegrain 0.72 lean 0.916 flour 0.67 fat 0.953 bran 0.82 Lamb, take as beef Oats, whole1 0.94 Pork4 Rice, milled1 0.85 lean 0.910 Milk and milk products 0.945 fat 0.953 Eggs2 0.83 Poultry 0.945 Fats and oils, all except coconut 0.956 Brain4 0.561 Coconut oil 0.942 Heart4 0.789 Vegetables and fruits 0.80 Kidney4 0.747 Avocado pears 0.956 Liver4 0.741 Nuts 0.956 Fish5 fatty 0.90 white 0.70

Sources:

1Weihrauch, Kinsella and Watt (1976).

2Posati, Kinsella and Watt (1975).

3Anderson, Kinsella and Watt (1975).

4Anderson (1976).

5Exler, Kinsella and Watt (1975).

These factors are used as in the following examples:

If 100 g goat milk contains 4.5 g fat, then

4.5 ¥ 0.945 = 4.25 g total fatty acids in 100 g goat milk

When individual fatty acid data are available, the values can be converted from a g/100 g food basis to g/100 g total fatty acid basis. For example, if 100 g goat milk contains 1.15 g palmitic acid, the following equation is applied to calculate palmitic acid in g/100 g total fatty acids:

100/4.25 ¥ 1.15 = 27 g/100 g total fatty acid

When data on fatty acids per 100 g total fatty acids and total fatty acids are available, they can be converted to a g/100 g food basis. For example, if we know that the palmitic acid level in goat milk is 27 g/100 g total fatty acids and the total fatty acid value is 4.25 g/100 g food, the following equation is applied to calculate palmitic acid in g/100 g food:

4.25 ¥ 27/100 = 1.15 g /100 food

Source: Paul and Southgate,1978