Baking & Snack - May 2004 - 105

FAT & OIL

SHORTENING AND DIETARY FAT DEFINITIONS
Active Oxygen Method (AOM). This is a means of testing the stability of an oil or
fat against oxidation. The sample is heated to 208°F (97.8°C), and air is bubbled
through it. The time required to develop a peroxide content of 100 meq per kg
is termed the AOM stability of the fat. This method is considered obsolete and is
being replaced by oil stability index, or OSI (see below).
Cholesterol. Humans obtain cholesterol, which is in all animal tissue, in two
ways: consumed in the diet (exogenous cholesterol) and synthesized by the body
(endogenous cholesterol). High intake of dietary cholesterol has been associated
with coronary heart disease.
Essential fatty acids. These are polyunsaturated fatty acids that cannot be
synthesized by the body but are needed for human growth and development.
Alpha-linolenic acid is a polyunsaturated (C18:3) omega-3 essential fatty acid and
a precursor to the omega-3 fatty acids eicosapentaenoic acid C20:5 (EPA) and
docosahexaenoic acid C22:6 (DHA). Linoleic acid is a polyunsaturated omega-6
essential fatty acid and a precursor of arachidonic acid C20:4 and a class of
prostaglandins different from those produced by omega-3 fatty acids.
Fatty acid nomenclature. Three numbers are used in shorthand designation of
natural fatty acids. The first is the number of carbon atoms in the chain, and the
second is the number of double bonds. For example, C18:0 contains 18 carbon
atoms and no double bonds (stearic acid). The third number, the number of carbon
atoms between the last double bond and the methyl end of the chain, is the omega
number, written using either the Greek letter omega (w) or as n-.
Hydrogenation. In the presence of a catalyst, hydrogen gas adds to a double
bond, decreasing the degree of unsaturation of a fat or oil. The catalyst can also
convert the natural cis double bond to the trans geometric isomer. Both changes
raise the melting point of the fat and increase its stability to autoxidation.
Melting point. Fats do not have sharp melting points (m.p.) like a pure organic

material. The complete, or capillary, melting point measures the disappearance of
the last trace of cloudiness, corresponding to an SFC of 0. The Wiley m.p. is the
temperature at which a disk of fat changes shape to a sphere (SFC of ~3). The dropping point, or Mettler m.p., is determined on a machine that records the temperature
at which the fat is liquid enough to flow through a small orifice (SFC of ~1).
Monounsaturated fatty acids. These are fatty acids with one double bond,
such as oleic acid. Although previous research suggested that monounsaturates
had a neutral effect on serum cholesterol, recent preliminary studies indicate that
monounsaturates may actually have a favorable effect.
Oil Stability Index (OSI). A newer, automated method for testing stability
against oxidation. Air is bubbled through oil, usually at 230°F (110°C), and the
time when rapid autoxidation begins is determined automatically. A 40-hour OSI
is equivalent to a 100-hour AOM.
Omega-3 fatty acids. These are certain polyunsaturated fatty acids. Alphalinolenic acid is converted to EPA, a precursor of a class of prostaglandins that
inhibit blood clotting (platelet aggregation). DHA is synthesized from EPA.
Polyunsaturated fatty acids. These are fatty acids with two or more double
bonds, such as the essential fatty acids linoleic and alpha-linolenic acids.
Saturated fatty acids. These are fatty acids with no double bonds, such as
stearic and palmitic acids. Studies show an association between increased intake
of saturated fatty acids and increased serum cholesterol.
Solid Fat Index/Content (SFI, SFC). If measured using a dilatometer, the ratio
of solid to liquid triglyceride in a shortening is called the Solid Fat Index (SFI).
This is not always a true measure of percentage of solid fat, as a completely solid
fat has an SFI of about 80. Pulsed nuclear magnetic resonance (pNMR) gives
a more accurate estimation of true solid fat percentage and is termed Solid Fat
Content (SFC).

VEGETABLE OILS
Numerous adaptations of the traditional vegetable oils are now being produced
and sold. To help in comparing these oils, this table gives fatty acid composition
for the five fatty acids of most interest: palmitic (C16:0), stearic (C18:0), oleic
(C18:1), linoleic (C18:2), and linolenic (C18:3). As natural products, the
composition will vary slightly, so the values here are whole numbers. The
expected variation is about ±0.5% for values of 10% or less and ±1% for
larger numbers.
Oil

C16:0

C18:0

C18:1

C18:2

C18:3

Linseed

Linolaa

Canola

Soybean

High Oleicb

Low Linolenicb

Low Saturateb, c

Sunflower

High Oleic

Mid Oleicf

d, e

UGG, Ltd., Canada
Optimum Quality Grains, LLC
cLoSatSoy
dTri-Sun, SVO Enterprises
eSeveral types of available high oleic sunflower oil range from 80% to 88% oleic acid.
fNuSun, National Sunflower Association
a

BAKERY SHORTENINGS:
TYPICAL PHYSICAL PROPERTIES
General chemical characteristics
Peroxide value:
Free fatty acid (as oleic acid):
Phosphorous content:

Shortening type
RBD oila
Lightly
hydrogenated oil
Deep-fat frying oil
All-purpose
Icingb
Wafer-filler fat
Sandwich-cookie
filler
Coating fat
Puff-pastry
margarine
General-use
margarine
a

1 meq per kg maximum
0.05% maximum
1 ppm maximum

Solid fat index
OSI
70°F 80°F 92°F 104°F hours,
21°C 27°C 33°C 40°C minimum

Melting
point
°C °F

0
<5

-
<1.5

47±3
28±3
32±3
55±4
38±3

32±3
20±2
25±2
39±3
24±2

50°F
10°C

-
-

4
10

<0 <32
15 60

25±2 12±1
<2
17±1 13±1 7±1
22±2 16±1 11±1
29±3 4±1
<1
18±1 9±1
<2

75
30
30
40
40

36 97
47 117
48 119
34 94
38 102

64±5 52±4 44±4 20±2
0
34±3 30±3 27±2 22±2 16±1

75
75

37 99
54 130

28±2 21±2 18±1 15±1 10±1

47 116

RBD = Refined, bleached and deodorized oil.
Contains 2% to 3% alpha-monoglyceride.

May 2004/ BAKERS PRODUCTION MANUAL / 105

Baking & Snack - May 2004

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