Food Chemistry

14.5 Analysis 665

Table 14.23.Fatty acid indicators suitable for determination of fat and oil origin

Fatty acid Content (%)a Indicator of

4:0 3. 7 Milk fat
12:0 45 Coconut-, palm kernel-, and babassu fat
18:1 (9) 65–85b Teaseed-, olive- and hazelnut oil
18:3 (9, 12, 15) 9 Soya-, rapeseed (also erucic acid free) oil
18:2 (9, 12) 50–70 Sunflower-, corn germ-, cottonseed-, wheat germ-, and soya oil
22:0 3 Peanut oil
20:4 (5, 8, 11, 14) 0 .1–0.6Animalfat
18:1 (9, 12-OH) 80 Castor bean oil
Trans-fatty acids Partiallyor fully hydrogenated oil/fatc
Methyl-branched
fatty acids 0 .2–1.6Animalfatd
aWhen value range is omitted fatty acid percentage composition is given as an average value.
bA high percentage of this acid is a characteristic indicator.
cHere precautions are needed: animal fat, e. g. from beef, might contain up to 10% trans fatty acids.
dIt is relatively high in marine oils (approx. 1%).

Table 14.24.Fatty acid composition of sunflower oil

Fatty acid Per cent by weight

Average Variation rangea

16:0 6. 23 .0–10. 0
16:1 0. 08 < 0. 1
18:0 4. 75 1 .0–10. 0
18:1 (9) 19. 8 14–65
18:2 (9, 12) 67. 0 20–75
18:3 (9, 12, 15) 0. 08 < 0. 7
20:0 0. 34 < 1. 5
20:1 0. 15 < 0. 5
22:0 0. 89 < 1. 0
aGerman guide values.

Table 14.25.E-factor of various oils for linoleic acid

Oils/fats E-factor

Sunflower 1. 2
Corn 1. 3
Soybean 1. 3
Rapeseed 1. 7
Peanut 1. 7

with the help of HPLC and GC (cf. 3.3.1.4). An
example is the detection of foreign fat in milk
fat. From extensive data on the triacylglyceride
composition (GC differentiation according to the
C-number), formulas have been developed which
permit the detection of all important plant and
animal fats up to a limiting value of 2–5 percent
by weight. The older method, which is based

on a decrease in the butyric acid concentration

due to the foreign fat, does not safely detect an

addition of 20 percent by weight because of the

biological variation (3.5–4.5w/w percent 4:0).

14.5.2.4 Minor Constituents

Some fats which can not be unequivocally dis-

tinguished by their fatty acid or triacylglyceride

composition may be identified by analysis of the

unsaponifiable minor constituents. Examples are

given in Table 14.26.

Table 14.26.Fat or oil identification by analysis of un-

saponifiable constituents

Analysis Identification

Squalene Olive or rice oil

and fish liver oil

Campesterol/stigmasterola Cocoa butter

(cf. 3.8.2.3.1) substitutes

Carotene (cf. 3.8.4.5) Raw palm oil

γ-/β-Tocopherolb(cf. Table 3.51) Corn oil

γ-Tocopherol (cf. Table 3.51) Wheat germ oil

α-/γ-Tocopherolb(cf. Table 3.51) Sunflower oil

γ-/δ-Tocopherolb(cf. Table 3.51) Soybean oil

Cholesterolc(cf. 3.8.2.2.1) Animal fat

aConcentration ratios are characteristic.

bConcentration of individual compounds and their con-

centration ratios are characteristic.

cCholesterol concentration must exceed by 5% the to-

tal sterol fraction.