Table Of ContentEagan Press Handbook Series
Fats Oils
and
Clyde E. Stauffer
Gl eagan·press
~
St.Paul,Minnesota,USA
Library of Congress Catalog Card Number: 96-83465
International Standard Book Number: 0-913250-90-2
©1996 by the American Association of Cereal Chemists, Inc.
All rights reserved.
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exclusion of others that may be suitable.
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About the Eagan Press Handbook Series
The Eagan PressHandbookseries wasdeveloped for food industry practitioners. It offers a
practical approach to understanding the basics of food ingredients, applications, and
processes-whether the reader is a research chemist wanting practical information compiled
in a single source or a purchasing agent trying to understand product specifications. The
handbook series is designed to reach a broad readership; the books are not limited to a
single product category but rather serve professionals in all segments of the food processing
industry and their allied suppliers.
In developing this series, Eagan Press recognized the need to fill the gap between the
highly fragmented, theoretical, and often not readily available information in the scientific
literature and the product-specificinformation available from suppliers. Itenlistedexperts in
specific areas to contribute their expertise to the development and fruition of this series.
The content of the books has been prepared in a rigorous manner, including substantial
peer review and editing, and ispresented in a user friendly format with definitions of terms,
examples, illustrations, and trouble-shooting tips. The result is a set of practical guides
containing information useful to those involved in product development, production,
testing, ingredient purchasing, engineering, and marketing aspects of the food industry.
Acknowledgment of Sponsors for Fats and Oils
Eagan Press would like to thank the following companies for their financial support of
this handbook:
ACHUMKO Corporation
Memphis, Tennessee
800/691-1106
AgProcessing (AGP)
Omaha, Nebraska
402/498-2281
Archer Daniels Midland
Decatur, Illinois
800/637-5866
Bunge Oils
St.Louis, Missouri
314/292-2000
C&TQuincy
Richmond,Virginia
800/284-6457
Quest International-SpecialtyLipidsDivision
Hoffman Estates, Illinois
800/621-4710
Eagan Press has designed this handbook series as practical guides serving the interests of
the food industry as a whole rather than the individual interests of any single company.
Nonetheless, corporate sponsorship has allowed these books to be more affordable for a wide
audience.
Contents
1. Functional Properties of Fats and Oils • 1
Functions in FoodSystems: functions in processing.sensoryfunctions. nutrition
FunctionalProperties: chemicalstructureand fatproperties.functional characteristics.
chemical reactions.fatand oilsourcesand compositions
2. Analytical Tests of Fats and Oils • 15
PhysicalTests: solidfatindex/content.melting point.cloudpoint.oxidative
stability. firedanger points.polarlipidsinfryingfat. sensory.plasticity
ChemicalTests: fattyacids.iodine value.oxidativedegradation. phosphorous
(residualgums)•unsaponifiablematerial
ProductSpecifications
3. Properties of Emulsifiers • 29
Functionsin FoodSystems: amphiphilic(polarand nonpolar)nature.emulsification.
foaming.wetting.interactionswith othercomponents
Functional Properties: emulsification-HLB•antistaling-complexingwith starch.proteinaggregationand
solution
EmulsifierTypes andApplications: emulsifiers.wetting agents.dough strengtheners.
filmformers
RegulatoryConsiderations
4. Refining and Production • 47
Processingand Refining: vegetableoils.animal fats. marineoils
Manufacture ofFoodFats and Oils: modification ofbaseoils.shortenings.margarines.
saladoils.fryingoils
Troubleshooting
5. Bakery Product Applications • 61
Functions in Baked Goods: product characteristics.processing
HardWheatProducts: bread,rolls.laminateddoughs.yeast-raiseddoughnuts
SoftWheatProducts:cake.cakedoughnuts.cookies.crackers.piecrust,biscuits•
fillerfatsandicings
Pan-ReleaseAgents
Troubleshooting
v
6. Frying Fats • 81
HeatTransferbyFat: masstransfer.temperaturegradients.optimumfryeroperation
Degradative Reactions DuringFrying: hydrolysis.oxidation.polymerization.smoking,ignition
SelectionofFryingFat: stability.suitability
Troubleshooting
7. Chocolate and Confectionery Coatings • 91
FunctionofFats andOils inEnrobingCompounds:flavor,texture.fatcrystallization
Chocolate Coating:origin,manufacture,processing.chocolatetypes•usage.extenders
Compound Coating: lauricfats. otherfatsources
Troubleshooting
8. Salad Dressings • 101
PourableSaladDressings: composition.oilcharacteristics.emulsifiersand thickeners
SpoonableSaladDressings: mayonnaise.starch-baseddressings
Troubleshooting
9. Nutritional Topics • 109
Role ofDietaryFats: calories.membranestructure.vitamins.essentialfattyadds, prostaglandins
Cholesterol and Atherosclerosis:positivecontributionsofcholesterol.bloodserumlipids
PolyunsaturatedFats and Cancer
10. Fat and Calorie Reduction in Foods • 119
Fat Substitutes: functionalexpectations.types
Reduced-FatProducts
Reduced-CalorieProducts
Appendix A. Nomenclature and Sources of Fatty Acids • 129
Appendix B. Composition of Fats and Oils • 131
Appendix C. Suggested Specifications for Industrial Shortenings
and Margarines • 133
Glossary • 137
Index. 145
vi
Functional Properties of
Fats and Oils
Functions in Food Systems
Fats and oils have always been an integral part of the human diet. Of
In This Chapter:
prime importance is their role as a calorie-dense food component-they
have nine kilocalories per gram versus four kilocalories per gram for Functions in Food
starch or protein. The present-day concern with obesity and high fat Systems
content is actually a historical and geographical anomaly. For the Functions in Processing
greater part of human existence, the search for adequate food energy SensoryFunctions
Nutrition
sources occupied a large segment of time, and fat was a prized
component of the diet. Functional Properties
The varied cultural preferences for traditional food fats spring, in Chemical Structure
part, from geographic roots. In colder climates (e.g., northern Europe) and Fat Properties
mostfats were derived from animal sources, and lard, tallow, and butter Functional
were the main fats. Thus, plastic shortenings were used in most culinary Characteristics
Chemical Reactions
recipes that were brought to North America by northern European
Fatand OilSources
immigrants. In warmer climates (e.g., Mediterranean countries),
and Compositions
vegetable oils, such as olive and sesame seed oils, were the predominant
available fats; the cuisine of these countries reflects this difference.
More recent times have seen a cross-cultural interchange in this respect,
but to some extentthe traditional patterns still exist.
It is difficult to adequately condense many large tables of data on the
availability and consumption of fats and oils, but one example can be
instructive. The annual per capita (adult) consumption of fats and oils
in the United States, as of the late 1980s, was approximately:
• 24 lb of salad and cookingoils
• 23 lb of bakeryshortening and frying fats
• 20 lb of fat from meat, poultry, fish, and cheese Plasticshortening-Afirmfat
thatcontains solidfat crystals
• 13 lb from butter, margarine, and other miscellaneous sources.
surrounded byoil.The
This total of 80 lb per person per year represents about 38% of the consistency orabilityto be
shapedand moldedisrelated
calories in the diet. With the recent push to reduce this number to
to type offat, type ofcrystals,
30%, the above numbers will probably decrease, but the proportions
and temperature.
will likely remain about the same.
Commercial (as opposed to home) use of fats and oils accounts for
Salad oil-Arefinedliquidoil
most of the shortening and frying fat category, some part of the salad thatdoes notcloud when
oil category, fats for margarine production, and many of the miscella stored under refrigeration
neous items (confectionery coatings, oil-based whipped toppings, coffee conditions.
2 / CHAPTERONE
whiteners, etc.). The specifications for these fats and oils are generally
more stringent than for fats and oils used in the home. Commercial
equipment and processes are more sensitive to variations in fat charac
teristics; the specified properties for the finished product are more
narrowly defined; and compensating for ingredient variation takes
longer than in home cooking. The people responsible for efficient op
eration of such a plant must understand how fat and oil properties
affect production and product characteristics and how to write and en
force specifications for these raw ingredients, so that the outcome is
satisfactory both to the consumer and to the owners of the plant.
FUNCTIONS IN PROCESSING
Shortening has an important functional role in processing baked
foods, which is discussed in more detail in Chapter S. It provides struc
ture in some products (for example, cookie dough) and lubrication in
others. In cookie dough and cake batters, shortening holds the finely
divided air bubbles that serve as the nuclei for leavening gases and give
a fine grain to the finished product. In roll-in doughs (Danish, puff pas
try), plastic fat prevents adjacent dough layers from knitting together
during proofing, so the final product has a flaky, many-layered struc
ture. Fat is the main structural element in the fillings and cream icings
used in and on bakery sweet goods of various sorts.
Fat for frying is important in many segments of the food industry:
potato chips and corn chips are deep-fried; nuts are roasted; cake
doughnuts, potatoes, and battered or breaded poultry or fish are fried.
These and other food items depend not only on the heat transfer prop
erties of fat, but also on the flavor imparted by the fat. The proper
choice and correct use of fat are necessary to obtain acceptable results
in these products.
SENSORY FUNCTIONS
Flavor. Fat contributes flavor to foods.This is most apparent in fried
Oxidation- Chemicalreaction
inwhichthe double bond on a foods, because absorbed fat becomes an integral part of the finished
lipidmolecule reactswith product. The flavor is the result of products of numerous reactions be
oxygen to produceavarietyof tween fat and other food components such as proteins and carbohy
chemicalproducts.The drates. Oxidation products of fat are also involved, giving a situation
consequencesofthisreaction
that is extremely complex in terms of the number of possible flavor
arelossofnutritionalvalueand
compounds present. Nevertheless, without these compounds, the prod
formation ofthe off-flavors
uct would not have the characteristics we have come to associate with
associatedwith rancidity.
fried foods. For example, when a taste panel assesses food fried in com
Reversion flavor-Mildoff pletely fresh (refined) oil, the typical comment is usually something
flavordeveloped byarefined like "tasteless."
oilwhen exposedto oxygen. Fat or oil can contribute flavor directly, either in a positive or nega
Reversion occurs rathereasily, tive sense. Olive oil, which has a unique flavor, is prized for gourmet
and theoff-flavor,while
salad dressings specifically because of the flavor notes it contributes. On
undesirable, isnot as
the other hand, if a fat or oil is exposed to air and allowed to oxidize
objectionableasrancidity
slightly, a flavor often develops that is referred to as a "reversion flavor."
caused byoxidation.
The characteristics of this flavor differ in different oils ("beany,"
FUNCTIONALPROPERTIES \ 3
"grassy," and "metallic" are some descriptive terms used), but it is in
variably considered to be negative in terms of productquality.
Texture. Several aspects of food texture (or mouthfeel) are attributable
to fat. It tenderizes the food, making it easier to bite and chew. It also
makes a food feel moister in the mouth. As an example of these two
aspects, consider the texture of steak-compared to a well-marbled
steak, the lean cut of meat is characterized as "tough" and "dry." Oil
also lubricates the food particles, helping to clear them from mouth
surfaces (teeth and palate) more readily.
These tenderizing and lubricating characteristics are primarily attrib
utable to the liquid fraction of the fat. Ifthe fat melting point is much
higher than body temperature, the fat does not melt in the mouth and
the residual solid portion gives a "waxy" mouthfeel, an undesirable
situation. This is particularly noticeable when the fat is a major com
ponent, as in fillings, icings, and confectionery coatings.
NUTRITION
As mentioned above, a major contribution of fat to the diet is as a
dense, easily stored source of calories. An example is pemmican, tradi
tionally used by Native Americans as rations when on an expedition
(either hunting or warfare). This was made by mixing shredded jerked Prostaglandins-Agroupof
specializedlipidsthat play
meat and dried berries in a container, then pouring melted animal fat
important metabolicrolesin
over the blend. While perhaps less appetizing than the products of the
humans.Theyareformed in
U.S. Quartermaster Corps, pemmican served the same purpose: a stor the bodyfrom dietary essential
age-stable, readily transportable source of food energy for consumption fattyacids.
during periods ofhigh energy expenditure.
Fat also makes other positive nutritional contributions. It carries fat
soluble vitamins (A, 0, and E). Its component fatty acids are metabo
lized by the body into phospholipids, which are essential parts of cell
membranes. Without the proper balance of saturated and unsaturated
fats, the membranes are eithertoo solid or too fluid, and cell integrity is
lost. Finally, certain polyunsaturated fatty acids are the precursors of
lipid hormones (prostaglandins) that are needed by the body. Ifthe diet
completely lacks these essential fatty acids, certain untoward symptoms
(hairloss, scaly skin, loss ofreproductive capability) appear.
Functional Properties
Before beginning the discussion of functional properties, certain Shortening-Atype offat
commonlyused terms should be defined: usedinbaking orfrying.The
name comesfrom theabilityto
• Fat is a natural lipid material that is more or less solid at room
tenderizeor"shorten" baked
temperature.
products.
• Oil is asimilar material that isliquid at room temperature.
Margarine-A product
• Shortening (mainly a baking term) is a fat or oil that contains
categorysimilarto dairybutter
no water.
incompositionand color.It
• Margarine is a fat containing up to 20% water as a water-in-oil contains80%fat, 16%water,
emulsion. and 4%other ingredientssuch
assalt.
4 / CHAPTERONE
Fattyacids- Agroupof CHEMICAL STRUCTURE AND FAT PROPERTIES
chemicalcompounds
Fatty acids. Fats are esters of fatty acids and glycerol. Most fats occur in
characterizedbyachainmade
the form of triglycerides, in which three fatty acids are attached to the
upofcarbonand hydrogen
atomsand havinga carboxylic glycerol. Fatty acids contain the carboxyl group (COOH) and an aliphatic
acid(COOH)groupon one carbon chain of variable length (Boxes 1-1 and 1-2). The general
endofthe molecule.They formula is R-COOH, where R is the aliphatic group. With few
differfrom eachotherinthe exceptions, fatty acids are linear, range in size from four to 24 carbons,
numberofcarbonatomsand
and contain an even number of carbons.
the numberand location of
The chains can be saturated (having no double bonds), monounsatu
doublebondsinthe chain.
rated (one double bond), or polyunsaturated (two or more double bonds).
When they exist unattached to
other compounds,they are Box 1-3 shows three fatty acids that each contain 18 carbons but have
called freefattyacids. different numbers of double bonds and thus differ in saturation. In ac
cordance with the Geneva system of nomenclature, the carbon atoms
Ester-Thechemicallinkage
thatholdsan alcoholgroup of fatty acid chains are numbered consecutively, starting with the car
(OH)and anacidgroup(such bon atom of the carboxyl group as number 1 and continuing to the
asCOOH)together.Anester carbon atom in the terminal methoxy group. A shorthand designation
bond istheconnection of fatty acidsisoften used, based on the number of carbon atoms in the
between afatty acidand
molecule and the degree of unsaturation (i.e., the number of double
glycerolinglycerides.
bonds in the molecule).The most common fatty acidsin edible fats and
Glycerol-Athree-carbon oils arethose containing 16 or 18 carbon atoms. These include the satu
chain,with each carbon
rated palmitic (CI6:0) and stearic (CI8:0) acids, the monounsaturated
containing analcohol group.
oleic acid (CI8:1), and the polyunsaturated acids-linoleic acid with
One, two, orthreefatty acids
two double bonds (CI8:2) and linolenic acid with three double bonds
maybeattachedtoglycerolto
givearnono-,di-, or (CI8:3). A list of natural fatty acids along with their common names,
triglyceride. designations, and main sources isgiven in Appendix Aat the end of the
book.
Triglyceride-Threefattyacids
attachedtoaglycerol Another namingconvention isapplied to unsaturated fatty acids that
molecule. Ifthethreefatty have a physiological function as prostaglandin precursors (see Chapter
acidsare thesame, itisa 9). These are the omega (00) fatty acids. The number of carbon atoms
simpletriglyceride; iftheyare between the double bond and the terminal methyl group is designated
differentfrom eachother, itisa
as 00 plus a number. For example, the end of the linoleic acid chain is
mixed triglyceride.Mixed
CH3(CHz)4CH=CH-,so linoleic acid istermed an 006 fatty acid (Box 1-4).
triglyceridesarethe most
Similarly, oleic acid is C18:1oo9 and linolenic acid is CI8:3oo3. The 003
commonchemicalcomponents
infatsand oils. fatty acids have some unique nutritional properties, which are con-
Box 1-1. Structure of a Fatty Acid Box 1-2. Terminology
This is asaturated fatty acid; it has no double The following all describe caproic acid,
bonds. the fatty acid shown in Box I-I.
Aliphaticcarbon chain CH3-CH2-CH2-CH2-CH2-COOH
i
Terminal
methyl group Carboxyl group
,-------,
H H H H H 0
C6:0
I I I I I II
H-C-C-C-C-C-C-OH
I I I I I
H H H H H
Fatty acid
FUNCTIONALPROPERTIES \ 5
nected with their conversion to a particular group of prostaglandins Carboxylgroup-The
(seeChapter 9). chemicalfunctionalgroup on
oneend ofafatty acid.Thisis
The chemical reactivity of unsaturated fatty acids is determined by
thesameasacarboxylicacid
the position as well as the number of the double bonds in the molecule.
(COOH),whichcan losea
Reactivity increases markedly with an increase in the number of double
proton and become COO',or
bonds, provided they are conjugated (separated only by one single bond) combinewithan alcoholgroup
or methylene-interrupted (separated by a -CHz-unit) (Box 1-5). If a fatty toform an ester.
acid has two isolated double bonds (separated by two or more methyl
Aliphatic- Describinga
ene units), its reactivity is only slightly greater than that of a fatty acid
straightchainofcarbonswith
that has only one double bond. These differences are important when
no branchingor ringstructure.
the fat is subjected to oxidation and also during the hydrogenation
process. Saturated- Describing a
In most naturally occurringunsaturated fatty acids, the double bonds carbonchain inwhichthe
carbons areconnected to each
are in the cisconfiguration. This means that the carbon chains on the
other bysinglebonds,drawn
asC-c. Ithasno carbon-to
carbon double bonds.
Box 1-3. Saturation
Monounsaturated
H H H H H H H H H H H H H H H H H 0
I I I I I I I I I I I I I I I I I I Describingafattyacidthat has
H-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-OH one doublebond (C=C)inthe
I I I I I I I I I I I I I I I I I carbonchain.Oleicacidisthe
H H H H H H H H H H H H H H H H H mostcommonofthese.
Stearic acid, C18:0 (unsaturated)
Polyunsaturated- Describing
afattyacidthat hasmore than
H H H H H H H H H H H H H H H 0 one doublebond (C=C)inthe
I I I I I I I I I I I I I I I II
carbonchain.Linoleicacidis
H-C-C- C-C-C-C- C- C-C=C-C-C-C-C-C-C-C-C- OH anexample.
I I I I I I I I I I I I I I I I I
H H H H H H H H H H H H H H H H H Omega fattyacids-Amethod
Oleicacid, C18:1 (monounsaturated) ofnomenclaturethat
designatesthe numberof
carbonsbetween the terminal
HHHHH H HHHHHH HO
-CH,group and thelastdouble
I I I I I I I I I I I I I II
bond inthe fatty acid.Thisis
H-C-C-C-C- C-C=C-C-C=C- C-C-C- C-C-C-C-C-OH
I I I I I I I I I I I I I I I I I usefulindiscussing the
physiologicalroleofcertain
H H H H H H H H H H H H H H H H H
polyunsaturatedfatty acids.
Linoleic acid, C18:2 (polyunsaturated)
Conjugated- Describinga
situation inwhichdouble
bondsbetweencarbonatoms
Box 1-4. An Omega Fatty Acid
occurinaserieswith onesingle
There are six carbons between the terminal methyl group and the bond inbetween (C=C-C=C).
double bond, so linoleic acid isdesignated an CiJ6 fatty acid.
Methylene-interrupted
Describing asituationinwhich
H H H H H H H H H H H H 0
I I I I I I I I I I I I II doublebonds between carbon
atoms occurin aserieswith
H-C- C-C-C-C-C=C-C-C=C-C- C-C- C- C- C-C-OH
two singlebonds in between
I I I I I I I I I I I I I I I I
(C=C-C-C=C).
H H H H H HH H H H H H H H H H
L...-.....I ..... --','-----'
CH=CH
Sixcarbons
