Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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their functioning. Accordingly, flavors are increas-

ingly sold entrapped in an appropriate delivery

system, either in powder or liquid form.

Legislation

0005 Flavor production is highly regulated in order to pro-

tect both the consumer and the workers involved in

their production. Since its inception in 1973, the

International Organization of the Flavor Industry

(IOFI) has developed a self-regulatory code of prac-

tice covering both of these aspects. Several of its

recommendations have been closely modeled by inter-

national regulatory bodies. These include standards

for natural flavorings and for thermal process flavors.

More recently, the Joint Food and Agriculture Organ-

ization/World Health Organization Expert Commit-

tee on Food Additives (JECFA) has been evaluating

the safety of chemically defined flavoring substances

under their conditions of use. Since 1997, JECFA has

cleared over 100 substances per year in a program

that may eventually examine over 2000 flavoring

substances claimed to be currently used. Work-place

hazard information systems are being put in place in

many countries. IOFI regularly updates recommenda-

tions on the work-place hazard classification of

flavoring ingredients according to the criteria laid

down by various governmental bodies.

Isolation of Natural Flavors

0006Isolation from natural products is the most important

and simplest method for producing natural flavors. It

is based on the physical properties of the flavors and

exploits technologies of a wide range of sophistica-

tion. The five principal isolation techniques used

fig0001 Figure 1 (see color plate 58) Yellowfin tuna. Reproduced from

Flavour Compounds, Production Methods, Encyclopaedia of Food

Science, Food Technology and Nutrition, Macrae R, Robinson RK

and Sadler MJ (eds), 1993, Academic Press.

fig0002 Figure 2 (see color plate 59) Effluents from food processing.

Reproduced from Flavour Compounds, Production Methods, En-

cyclopaedia of Food Science, Food Technology and Nutrition, Macrae

R, Robinson RK and Sadler MJ (eds), 1993, Academic Press.

fig0003Figure 3 (see color plate 60) Fruits of tropical climates: Zizy-

phus mauritiana Lam. (Indian jujube). Reproduced from Flavour

Compounds, Production Methods, Encyclopaedia of Food Science,

Food Technology and Nutrition, Macrae R, Robinson RK and Sadler

MJ (eds), 1993, Academic Press.

2518 FLAVOR (FLAVOUR) COMPOUNDS/Production Methods

on a production scale are, in decreasing order of

importance: (1) distillation; (2) extraction; (3) press-

ing; (4) filtration; and (5) chromatography. An over-

view of today’s standard technology equipment and

their typical applications is presented in Table 1.In

certain isolation procedures, acid and/or alkaline

adjustments (pH value control) are necessary. Apart

from the quality of the raw materials, the sensory

properties of the flavors obtained are strongly influ-

enced by the isolation technology (equipment and

processes) used. For this reason, the isolation route

to many natural flavors remains the unpatented but

nevertheless confidential ‘know-how’ of the various

flavor manufacturers (Figures 7–9). (See Chromatog-

raphy: High-performance Liquid Chromatography;

Gas Chromatography; Membrane Techniques: Prin-

ciples of Ultrafiltration.)

Production of Nature-Identical Flavors

0007Nature-identical flavors are mixtures of synthetic

nature-identical flavoring substances. These are

generally made from available chemical feedstocks

of plant or petrochemical origin and are, by defin-

ition, chemically identical to substances found in nat-

ural foods, herbs, spices, and essential oils. These

flavors often contain natural flavoring materials as

well but they must not contain flavoring substances

which have no counterpart in nature. Over 7000

fig0004 Figure 4 (see color plate 61) Road-side markets in Bangkok

displaying citrus, banana, rambutan, mango, and lychee. Repro-

duced from Flavour Compounds, Production Methods, Encyclo-

paedia of Food Science, Food Technology and Nutrition, Macrae R,

Robinson RK and Sadler MJ (eds), 1993, Academic Press.

fig0005 Figure 5 (see color plate 62) A collection of the more exotic

tropical fruit of South-east Asia. Courtesy of TA Cooke, Plant

Pathology, QDPI, Australia. Reproduced from Flavour Com-

pounds, Production Methods, Encyclopaedia of Food Science,

Food Technology and Nutrition, Macrae R, Robinson RK and Sadler

MJ (eds), 1993, Academic Press.

fig0006Figure 6 (see color plate 63) Fruits of tropical climates: Prunus

serotina var. salicifolia (capulin cherry). Reproduced from Flavour

Compounds, Production Methods, Encyclopaedia of Food Science,

Food Technology and Nutrition, Macrae R, Robinson RK and Sadler

MJ (eds), 1993, Academic Press.

FLAVOR (FLAVOUR) COMPOUNDS/Production Methods 2519

tbl0001 Table 1 Isolation techniques, equipment, and their application to the production of typical flavor types

Technique Equipment Physical property utilized Application to the production of

Distillation

Distillation Still with evaporator, and

condenser

Volatility of flavors

Fractional distillation Still with evaporator,

fractionating columns (1 to

several meters high), often

with packing

Volatility, differences in

boiling point of compounds

Folded citrus oils

(concentration by removal of

monoterpenes)

Distillation with

high-performance

condensing device

Recovery units Low boiling point of flavor Volatiles from concentration of

tomato, apple juice, red

fruits, exotic fruits, citrus

(essence oils) ! ‘add-back’

systems

Thin-film distillation Falling-film vaporizer with or

without rotating blades

Lowering of evaporation

temperature of a liquid thin

film as opposed to a bulky

mass

Distillation of volatiles from a

residue or of high-boiling

materials

Molecular distillation As above, but with extremely

low vacuum (10

5

bar) and

condenser close to

vaporizer

Distillation below the boiling

point in appropriate

equipment and at a certain

temperature/pressure

(mean free path)

Distillation of volatiles from a

residue or high-boiling

materials under mild

conditions

Steam distillation Still with condenser and two-

phase separator (þ inlet for

steam)

Boiling point of a nonmiscible

mixture is below the boiling

point of the lowest-boiling

component

Essential oils, for example,

flowers, aromatic plants,

and spices

Hydrodiffusion Vessel with horizontal pallets

holding material, steam

entering from the top then

condensed

Steam volatility of compounds Seed oils

Extraction

Extraction by nonpolar,

organic solvents and

concentration

Solubility of volatiles and

certain nonvolatiles (waxes)

Flower and plant concretes

(rose, jasmine, tuberose,

jonquil)

Extraction of concretes

by ethanol, concentration

Extractor

, filter, evaporator Solubility difference in ethanol

between volatiles and

waxes

Flower and plant absolute

(rose, jasmine, tuberose,

jonquil)

Extraction of plant exudates by

methanol, ethanol, or

toluene

Solubility Oleoresins such as pepper,

ginger, vanilla, copaiba

balsam, oakmoss resin,

galbanum resinoid

Extraction by supercritical

carbon dioxide

High-pressure equipment Specific solubility in

supercritical carbon dioxide

of compounds as a function

of temperature and

pressure

Various spices; hop oil

Liquid–liquid extraction Countercurrent solvent

extraction column; solvent

system: pentane/ethanol–

water

Different partition coefficient of

terpene hydrocarbons and

oxygenated compounds

(flavors) in the two solvent

phases

Deterpenized citrus oils

Pressing, filtration, and

chromatography

Pressing Various types of presses Mechanical destruction of

cells and oil glands

Juices, cold-pressed

(expressed) citrus peel oils

Mechanical filtration Sieve Mechanical separation

according to particle size

Removal of solids from liquids

(! clear juices) and/or

collection of crystalline

compounds

Ultrafiltration Membrane filters (pore size 1–

100 nm)

Separation according to size

of molecules, and/or

molecular aggregates

Separation of proteins, cell

material from low-

molecular-weight

chemicals, fruit juice

clarification

Continued

2520 FLAVOR (FLAVOUR) COMPOUNDS/Production Methods

volatile substances have so far been detected in

common foods. Some 6510 substances are reported

in a single compilation alone. However, not all have

sufficiently desirable flavoring properties for use in

nature-identical flavors. In countries such as the USA,

only flavoring materials which are ‘generally recog-

nized as safe’ (GRAS) by qualified experts may be

used. Currently, there are over 2000 flavoring mater-

ials on the GRAS lists published by the US Food and

Drug Administration and by the Flavor and Extract

Manufacturers’ Association of the USA. Of these,

some 1200 are nature-identical flavoring substances,

about 400 are extracts of botanicals, and 400 are

artificial (never identified in nature, such as ethyl

vanillin, ethyl maltol). (See Essential Oils: Properties

and Uses; Legislation: International Standards;

Codex.)

Technique Equipment Physical property utilized Application to the production of

Gas chromatography Automated, preparative gas

chromatograph

Differences in colligative

properties

Isolation and purification of

expensive volatile flavor

compounds

High-performance liquid

chromatography (HPLC)

Preparative HPLC apparatus Differences in polarity and/or

partition coefficient

Isolation and purification of

expensive nonvolatile flavor

compounds

Column chromatography Large columns filled with a

stationary phase, various

fluids

Polarity, partition coefficient,

charge, etc.

Mainly for expensive flavors

from aqueous reactions/

waste streams

Sometimes equipped with an ultrasonic sound vibrator.

fig0007 Figure 7 (see color plate 57) Flavor compounds: highly effi-

cient distillation columns. Reproduced from Flavour Compounds,

Production Methods, Encyclopaedia of Food Science, Food Technol-

ogy and Nutrition, Macrae R, Robinson RK and Sadler MJ (eds),

1993, Academic Press.

fig0008Figure 8 (see color plate 64) Filtration line for 450 hl output per

hour; consisting of FILTROstar candle-type precoat filter and

PVPP (polyvinyl pyrrolidone, a filter aid dispersed into a cellu-

lose-based matrix) stabilizing plant Filter-o-mat S. Reproduced

from Flavour Compounds, Production Methods, Encyclopaedia of

Food Science, Food Technology and Nutrition, Macrae R, Robinson

RK and Sadler MJ (eds), 1993, Academic Press.

Table 1 Continued

FLAVOR (FLAVOUR) COMPOUNDS/Production Methods 2521

Synthesis of Organic Compounds as

Flavorings

Controlled Chemical Synthesis

0008 The merits of chemical synthesis for the production of

flavor compounds were decisive for the development

of today’s high-quality flavors. Synthetic flavorings

excel because of their constant quality, favorable

price/performance ratio, unlimited supply, and toxi-

cological integrity. Chemical synthesis is used to pro-

duce compounds in quantities from a few hundred

grams up to hundreds of tons. Some examples of

typical commodity flavor chemicals are listed in

Table 2. They are commonly manufactured by large

chemical companies, some of which do not produce

and sell compounded flavors themselves. About 1000

small-scale items (with estimated consumptions of

0–500 kg year

1

) making up *1.1% by weight of

the totally consumed synthetic flavor compounds

are mostly produced by the flavor industry itself,

some even on laboratory and pilot plant scales.

These often strong-smelling items are not profitable

per se, but are absolutely essential for the creation of

good flavors.

0009 Common synthetic methods and reagents are used

to transform either petrochemicals or plant-derived

intermediates into flavorings. However, toxic re-

agents or intermediates are excluded. Rigorous con-

trol at all stages of manufacture insures that only

chemicals of the highest quality are produced. Indeed,

process and quality control is comparable to that used

in the pharmaceutical industry.

Transformations Using Living Biological Systems

0010Microorganisms (bacteria, yeasts, and molds) play a

very large role in the production of flavors in pre-

pared foods. Yeasts are responsible for the production

of flavor compounds in wine, beer, and bread. Cheese

and yogurt flavors are produced by bacteria and

molds. Such microorganisms have been exploited in

the production of either complete flavors or specific

flavor compounds, and the processes are generally

referred to as fermentations (Table 3). (See Fermented

Foods: Origins and Applications.)

0011Plant tissue cultures in bioreactors are being exten-

sively investigated on a research scale as a means of

obtaining a variety of flavor chemicals, e.g., citronel-

lal from Eucalyptus citriodora roots or mint oil from

Mentha piperita. However, because of low productiv-

ity and differences in the type of compounds produced

(as compared to the whole plant), this technology is

still far from commercial application. (See Biotech-

nology in Food Production.)

Synthesis Involving Isolated Enzyme Preparations

0012Enzymes are protein catalysts which both perform

and control the chemical reactions that occur in all

living systems. They are highly selective and can

sometimes be used in an isolated or partially purified

form to produce flavor compounds from suitable pre-

cursors. Many enzyme preparations are commercially

available and are used by the food and flavor indus-

tries. Table 4 gives some examples with important

applications. (See Enzymes: Uses in Food Processing.)

The Reaction Flavor Approach

0013Thermal processing of food, such as cooking,

broiling, roasting, or baking, has been used since

ancient times and is known to give rise to a variety

of flavors. These flavor tonalities can also be pro-

duced as such without their food systems by the

fig0009 Figure 9 (see color plate 65) Kieselgur filtration plant with

35 m

filtering area and slurry feeder DOSIMAT 500. Special

execution with automatic filtration monitoring. Reproduced from

Flavour Compounds, Production Methods, Encyclopaedia of Food

Science, Food Technology and Nutrition, Macrae R, Robinson RK

and Sadler MJ (eds), 1993, Academic Press.

tbl0002Table 2 Typical commodity flavor chemicals

Chemical Estimated annual consumption (tons)

Vanillin 7000

l-Menthol 9000

Methyl salicylate 1800

Benzaldehyde 500–700

Maltol and ethyl maltol 400–600

Acetaldehyde 400–500

Cinnamaldehyde 400–500

About 20% of this quantity is produced by synthesis.

2522 FLAVOR (FLAVOUR) COMPOUNDS/Production Methods

reaction flavor approach, which involves the carefully

controlled heating of a mixture of appropriate precur-

sors in a reactor vessel. Typical flavor tonalities are

roasted and broiled beef and chicken, bread, cereal,

cocoa, caramel, maple, and vegetables. Chemically

speaking, carbohydrates (in particular, their reducing

monomers), proteins, free amino acids, and lipids are

thermally degraded and transformed into numerous

oxygen-, nitrogen- and sulfur-containing five- and

six-membered heterocyclic flavor compounds to-

gether with a-diketones and aldehydes. More specif-

ically, reaction flavors produced by heating reducing

sugars and amino acids (resulting from protein hy-

drolysis) in addition to various other ingredients such

as nucleotides, phospholipids, and fats are called

Maillard-type flavors, the annual commercial value

of which has been estimated at some US$780 million.

The type of flavor thus obtained can be controlled

by the nature and ratio of amino acids and sugars

which are heated together; for example, cysteine and

methionine are essential for obtaining meat flavors

whilst proline plays an important role in the forma-

tion of bread and cereal flavors. (See Browning: Non-

enzymatic.)

Flavor Delivery Systems

0014Since flavors are never being consumed as such

but have always to be integrated into a food, the

best way of delivering flavor is of prime importance

to the flavor and food industry. Therefore, various

flavor delivery systems have been developed over

time. They usually consist of a taste-neutral carrier

which combines with a flavor, often stabilizes it,

may facilitate its transport and handling, and ultim-

ately provides a better release of the desired amount,

at the right place and time. They are sold as powder

or liquid flavor systems in addition to conventional

flavors.

0015Some flavor delivery systems are concerned primar-

ily with transport and handling issues and give little

protection to the flavor ingredients. More recent

encapsulation processes have been designed to extend

shelf-life in addition to giving functional flavor deliv-

ery in the finished food.

0016Encapsulation processes to make powder flavor

systems trap liquid flavors in a solid carrier matrix.

The most important encapsulation technologies are

spray drying, extrusion, molecular inclusion, and

tbl00 04 Table 4 Commerciallyavailableenzymepreparationswiththeirareasofutilizationintheflavorindustry

Enzyme(s)ReactiontypeApplications

a-AmylaseþglucoamylaseHydrolysisCornsyrup(dextrose)fromcornstarch

D-GlucoseisomeraseIsomerizationFructose-richsugars(invertsugars)fromcornsyrup(US

productionin2001:23.8millionpounds)

Lipases(esterases)HydrolysisofestersLipolyzedbutterfat,freefattyacidsfromtriglycerides,and

synthesisofestersfromalcoholsandcarboxylicacids

Proteases Hydrolysis of proteins and peptides Hydrolyzed vegetable and animal proteins

Enzyme-modified cheeses and cheese flavors (via degradation

of caseins), debittering of cheese flavors

Autolysis of yeast Yeast autolysates

Pectinase Hydrolysis Clarification of fruit juices

DatafromCornRefinersAssociation,Inc.,www.com.org;shipmentbymembers,US,updatedJuly2,2002.

tbl0003 Table 3 Microorganisms used in biotransformations/biosynthesis

Organism Reaction type Precursors and/or carbon source Flavor compound Sensory description

Bacteria

Acetobacter spp. Oxidation Ethanol Acetic acid Vinegar

Corynebacterium spp. Carbohydrate Monosodium glutamate Taste enhancer

Clostridium butyricum Glucose Butyric acid Cheese, dairy

Yeasts

Candida lipolytica or Oxidative degradation Ricinoleic acid g-Decalactone Peach

Sporobolomyces odorus

Molds

Penicillium roquefortii Hydrolysis, b-oxidation,

and decarboxylation

Fatty acid triglycerides Methyl alkyl ketones Blue cheese

Ceratocystis moniliformis Dextrose and urea Esters Fruity

Aspergillus niger Sugar cane Citric acid Acidic

FLAVOR (FLAVOUR) COMPOUNDS/Production Methods 2523

coacervation. All these processes lead to products

which differ from each other in particle type and

size, flavor load, chemical stability, hygroscopicity,

and flavor release characteristics. Furthermore, there

are notable differences in the process economics.

Spray drying is generally considered as the most ad-

vantageous encapsulation method, coacervation is

expensive, and molecular inclusion technology using

b-cyclodextrins has recently been introduced into the

marketplace as a result of a cost-lowering of b-cyclo-

dextrin, and its acceptance in the USA as a food

additive. Encapsulated flavors are also made by ex-

truding a molten (110–130



C) low-moisture blend of

carbohydrates, which contain a dispersed flavor, into

a cooled (18



C) solvent. The melt is hardened by

the rapid chilling into amorphous glass-like particu-

lates, which provide much better oxidative stability

than that obtained by spray drying. Frequently used

carriers for encapsulated powder flavors are modified

or hydrolyzed starches (e.g., maltodextrin), gum

arabic, proteins, and alginates.

0017 Another current way of entrapping and delivering

flavor is via liquid, stable emulsions. An oily flavor/

water mixture in the presence of an emulsifier is

passed through a high-pressure homogenizer. Often

the density of the oil phase is brought closer to that of

the aqueous phase by the addition of a high-density

weighting agent such as sucrose acetate iso-butyrate.

(See Extrusion Cooking: Principles and Practice;

Drying: Spray Drying.)

Storage, Packaging, and Distribution of

Flavors

0018 The storage, packaging, and distribution of flavors

requires consideration of numerous issues, including

flavor stability during storage, rules on acceptable

food packaging materials, regulations on the storage

and transport of flammable goods, rules on the avoid-

ance of certain materials (e.g., glass) in specific indus-

tries, environmental concerns and worker safety, not

to mention the special requirements of food manu-

factures. (See Sensory Evaluation: Taste; Spoilage:

Chemical and Enzymatic Spoilage; Storage Stability:

Parameters Affecting Storage Stability.)

See also: Biotechnology in Food Production;

Browning: Nonenzymatic; Chromatography: High-

performance Liquid Chromatography; Gas

Chromatography; Enzymes: Uses in Food Processing;

Essential Oils: Properties and Uses; Fermented Foods:

Origins and Applications; Herbs: Herbs and Their Uses;

Legislation: International Standards; Codex; Membrane

Techniques: Principles of Ultrafiltration; Sensory

Evaluation: Taste; Spoilage: Chemical and Enzymatic

Spoilage; Storage Stability: Parameters Affecting

Storage Stability

Further Reading

Ashurst PR (ed.) (1995) Food Flavourings, 2nd edn.

London: Blackie Academic and Professional Press.

Belitz H-D and Grosch W (1999) Food Chemistry, 2nd edn.

Berlin: Springer.

Contis ET, Ho C-T, Mussinan CJ, Parliment TH, Shahidi F

and Spanier AM (eds) (1998) Food Flavors: Formation,

Analysis and Packaging Influences. Amsterdam: Else-

vier.

Fisher C and Scott TR (1997) Food Flavours – Biology and

Chemistry. London: Royal Society of Chemistry.

Friberg SE and Larsson K (eds) (1997) Food Emulsions, 3rd

edn. New York: Marcel Dekker.

Gabelman A (ed.) (1994) Bioprocess Production of Flavor,

Fragrance, and Color Ingredients. New York: John

Wiley.

Maarse H and van der Heij DG (eds) (1994) Trends in

Flavour Research, Developments in Food Science,p.

35. Proceedings of the 7th Weurman Flavour Research

Symposium. Amsterdam: Elsevier.

Marsili R (ed.) (1997) Techniques for Analyzing Food

Aroma. New York: Marcel Dekker.

Nijssen LM, Visscher CA, Maarse H, Willemsens LC and

Boelens MH (eds) (1996) Volatile Compounds in Food,

7th edn. Zeist: TNO Nutrition and Food Research

Institute.

Noble RD and Stern SA (1995) Membrane Separation

Technology: Principles and Applications. Amsterdam:

Elsevier.

O’Brien J, Nursten HE, Crabbe MJC and Ames JM (eds)

(1998) The Maillard Reaction in Foods and Medicine.

Cambridge: Royal Society of Chemistry.

Parliment TH, Morello MJ and McGorrin RJ (eds) (1994)

Thermally Generated Flavors: Maillard, Microwave,

and Extrusion Processes, Washington, DC: American

Chemical Society.

Perry RH, Green DW and Maloney JO (eds) (1997) Perry’s

Chemical Engineering Handbook, 7th edn. New York:

McGraw-Hill.

Reineccius G (ed.) (1994) Source Book of Flavors, 2nd edn.

New York: Chapman & Hall.

Risch SJ and Reineccius GA (1995) Encapsulation and

Controlled Release of Food Ingredients. Washington,

DC: American Chemical Society.

Takeoka GR, Teranishi R, Williams PJ and Kobayashi A

(eds) (1996) Biotechnology for Improved Foods and

Flavors. Washington, DC: American Chemical Society.

Ziegler E and Ziegler H (eds) (1998) Flavourings: Pro-

duction, Composition, Applications, Regulations. Wein-

heim: Wiley-VCH.

2524 FLAVOR (FLAVOUR) COMPOUNDS/Production Methods

FLAXSEED

D H Morris, Mainstream Nutrition, Toronto, Ontario,

Canada

M Vaisey-Genser, The University of Manitoba,

Winnipeg, Manitoba, Canada

Background

0001 Flaxseed was one of the first plants domesticated

by humans about 8000–10 000 years ago. Ancient

peoples valued flaxseed for its medicinal properties;

its oil, which was used in cooking and in formulating

cosmetics; and its fiber, which was used to make linen

and sail cloth. The botanical name of flaxseed, Linum

usitatissimum of the family Linaceae, reflects its ver-

satility and importance in the economic and social

development of humans: The word usitatissimum is

Latin for ‘most useful.’ Flaxseed, or linseed as it is

sometimes called, is valued for many of the same

reasons today. This chapter describes the composition

of flaxseed and its health benefits, performance

properties, safety, and recommended intakes.

Composition

0002 Flaxseed is rich in fat, dietary fiber, and protein. The

composition of Canadian-grown flaxseed averages

41% fat, 28% total dietary fiber, 20% protein,

7.7% moisture, 3.5% ash, and 1% simple sugars.

The amount of fat in flaxseed can range from 38 to

47%, depending on the variety and growing condi-

tions. The proximate composition for common meas-

ures of whole and ground flaxseed and flaxseed oil is

shown in Table 1.

0003Flaxseed has a unique fatty acid profile, being fairly

low in saturated fatty acids and rich in a-linolenic acid

(ALA), the essential o-3 fatty acid (see Figure 1). Of

the total fatty acids in flaxseed, saturated fatty acids

constitute 9%; monounsaturated fatty acids, 18%;

and polyunsaturated fatty acids, 73%. Of the polyun-

saturated fatty acids, ALA constitutes the majority at

57% of total fatty acids, making flaxseed one of the

richest sources of this fatty acid. Linoleic acid, the

essential o-6 fatty acid, is present in a smaller amount

(16%). Because of its high ALA content, flaxseed has

an o-6/o-3 fatty acid ratio of 0.3:1. (See Fatty Acids:

Properties; Metabolism.)

tbl0001 Table 1 Proximate composition of flaxseed based on common measures

Form of flaxseed Weight

Common measure Energy Total fat

ALA

Protein

Total carbohydrate

Total dietary fiber

kcal kJ

Whole seed 100 450 1890 41 23 20 29 28

180 1 cup 810 3402 74 41 36 52 50

11 1 tbsp 50 210 4.5 2.5 2.2 3 3

4 1 tsp 18 76 1.6 0.9 0.8 1.2 1.1

Ground seed 130 1 cup 585 2457 53 30 26 38 36

8 g 1 tbsp 36 151 3.3 1.8 1.6 2.3 2.2

2.7 1 tsp 12 50 1.1 0.6 0.5 0.8 0.8

Flaxseed oil 100 884 3712 100 57

14 1 tbsp 124 520 14 8.0

5 1 tsp 44 185 5 2.8

Used with permission of the Flax Council of Canada. Based on a proximate analysis conducted by the Canadian Grain Commission, May 2001. The fat

content was determined using the American Oil Chemists’ Society (AOCS) Official Method Am 2–93. The moisture content was 7.7%.

Total carbohydrate includes available carbohydrate (1 g) and total dietary fiber (28 g) per 100 g of flaxseed.

Total dietary fiber includes insoluble fiber (19 g) and soluble fiber (9 g) per 100 g of flaxseed.

Total POLY (LA + ALA) = 73%

18% MONO

16% LA

57% ALA

9% SAT

fig0001Figure 1 Fatty acid composition of flaxseed oil, based on an

analysis conducted by the Canadian Grain Commission, May

2001. Abbreviations: ALA, a-linolenic acid; LA, linoleic acid;

MONO, monounsaturated fatty acids; POLY, polyunsaturated

fatty acids; SAT, saturated fatty acids.

FLAXSEED 2525

0004 Flaxseed provides about 28 g of total dietary fiber

per 100-g dry weight. (Dietary fiber is defined as the

edible parts of plants that are resistant to digestion

and absorption in the human small intestine but that

are completely or partially fermented in the large

intestine.) About one-third of flaxseed fiber is water-

soluble, consisting mainly of mucilage gum. The

remaining two-thirds is water-insoluble and consists

primarily of nonstarch polysaccharides such as cellu-

lose and lignin. The flaxseed lignan, secoisolarici-

resinol diglycoside (SDG), is a phenolic compound

related in structure to lignin.

0005 The amino acid profile of flaxseed protein is similar

to that of soybean protein. Flaxseed proteins are

albumins and globulins. The predominant globulins,

like linin, are less soluble and higher in molecular

weight than the albumins. Flaxseed also contains

minor amounts of essential vitamins like niacin,

folic acid and g-tocopherol, and minerals like potas-

sium and phosphorus.

Health Benefits

0006 Flaxseed has been called a functional food, because of

the health effects associated with its ALA and lignan

content. Functional foods have been defined as those

that offer health benefits in addition to what would

be expected from the food’s nutrient content. Because

of its wide-ranging health effects, flaxseed may help

in the clinical management of chronic conditions such

as cardiovascular disease (CVD), stroke, certain types

of cancer, and autoimmune diseases like systemic

lupus erythematosus.

Laxation

0007 The insoluble dietary fiber in flaxseed is likely respon-

sible for its laxative effect in young and elderly adults.

For instance, in a study of 10 healthy young adults,

bowel movements increased 30% during the 4-week

period when they ate two 25-g flaxseed muffins daily

compared with the control period, during which time

they ate muffins without flaxseed.

Cardiovascular Diseases

0008 The underlying cause of CVD is atherosclerosis. One

risk factor for CVD is elevated blood total cholesterol

concentrations. The results of clinical studies indicate

that flaxseed has a positive effect on blood lipids. In

one study of 10 healthy young men and women,

plasma total cholesterol was reduced 6% and low-

density-lipoprotein (LDL) cholesterol was reduced

9% following the consumption of flaxseed muffins

providing 50 g of ground flaxseed daily for 4 weeks.

Plasma high-density-lipoprotein (HDL) cholesterol

and triacylglycerol levels were unchanged during the

flaxseed supplementation period. In a study of 15

men and women with hyperlipidemia who had just

completed a trial of the effect of vitamin E supple-

mentation on serum lipids, adding 15 g of ground

flaxseed to their daily diet reduced total blood

cholesterol 7% and LDL cholesterol 11% without

changing HDL cholesterol levels. (See Cholesterol:

Role of Cholesterol in Heart Disease.)

0009The reductions in total cholesterol and LDL chol-

esterol achieved in these studies were likely due to

flaxseed’s dietary fiber and ALA content. Dietary

fiber is widely recognized as an agent that decreases

serum cholesterol levels and slows the development of

atherosclerotic lesions. Populations with high intakes

of dietary fiber have a lower risk of CVD and other

chronic diseases than populations with low fiber

intakes. ALA also affects the cardiovascular system.

In dogs, pure, infused preparations of ALA and the

long-chain o-3 fatty acids, eicosapentaenoic acid

(EPA) and docosahexaenoic acid (DHA), protected

against fatal arrhythmias. Although the mechanism

of action is not completely understood, ALA and

the other o-3 fatty acids are believed to regulate

membrane ion channels and heart muscle fiber excit-

ability, thus stabilizing the electrical signals of the

heart and helping prevent ventricular fibrillation

and arrhythmias.

0010Although there is no direct evidence that dietary

o-3 fatty acids are as effective in humans as pure fatty

acid preparations are in dogs, indirect evidence for a

dietary benefit of ALA is available from epidemiolo-

gic studies of diet and CVD risk. For example, re-

searchers in the Lyon Diet Heart Study hypothesized

that ALA may have antiarrhythmic actions that sig-

nificantly reduce fatal CVD events. They recruited

subjects who had survived a myocardial infarction.

Those subjects who consumed a typical Mediterra-

nean-style diet rich in ALA from many dietary sources

had a nearly 70% reduction in fatal cardiac deaths

compared with the group who consumed their usual

Western-type diets. An extended follow-up of the

study revealed that the protective effect of the Medi-

terranean diet was preserved – ALA, but not EPA and

DHA, was associated with protection against recur-

rence of myocardial infarction. Data from other epi-

demiologic studies, including the Health Professional

Follow-up Study, the Multiple Risk Factor Interven-

tion Trial, and the Nurses’ Health Study, suggest that

diets high in ALA are associated with a reduced risk

of fatal and nonfatal myocardial infarction, fatal

CVD, and death from all causes.

0011ALA also affects the process of atherosclerosis by

reducing inflammatory responses. Atherosclerosis is

an inflammatory disease that begins in infancy and

childhood when the earliest lesions, called fatty

2526 FLAXSEED

streaks, begin developing in arteries. Flaxseed may

influence the progression of atherosclerosis by

inhibiting the production of major systemic compon-

ents of inflammatory activity, including eicosanoids,

cytokines, and platelet-activating factor.

Cancer

0012 Flaxseed is a rich source of the lignan and phytoestro-

gen, SDG, which is a precursor of the mammalian

lignans, enterolactone and enterodiol. Phytoestrogens

are plant-derived compounds that can interfere with

estrogen metabolism in animals and humans. Lignans

may protect against certain types of cancer, particu-

larly the hormone-sensitive cancers such as those of

the breast, endometrium, and prostate, by interfering

with the metabolism of sex hormones. Flaxseed lig-

nans enhance the clearance of circulating estrogen,

and they inhibit the binding of sex hormones to cell

membranes by blocking cell-membrane receptors. In

rat mammary gland tissue, flaxseed lignans decreased

cell proliferation, the number of nuclear aberrations,

and tumor volume. Preliminary data from one human

study suggest a possible benefit of flaxseed consump-

tion by women with breast cancer. Overall, flaxseed

lignans, pure SDG, and flaxseed oil rich in ALA affect

the carcinogenic process at several points, including

initiation, promotion, and progression/growth of

tumors. (See Cancer: Diet in Cancer Prevention.)

Diabetes and Autoimmune Diseases

0013 Flaxseed affects the postprandial blood glucose re-

sponse in healthy young adults. In a study involving

nine young women, blood glucose decreased about

27% after two test meals were consumed. Studies of

the hypoglycemic effects of flaxseed among patients

with diabetes mellitus are under way. (See Diabetes

Mellitus: Etiology.)

0014 Flaxseed may be useful in the management of auto-

immune diseases like rheumatoid arthritis and sys-

temic lupus erythematosus through the actions of

ALA on proinflammatory eicosanoids and platelet-

activating factor (PAF). The one published study of

flaxseed oil’s effects on the clinical and subjective

assessment of symptoms associated with rheumatoid

arthritis found no significant differences between out-

comes in patients who consumed flaxseed oil com-

pared with safflower oil for 3 months. However, in

studies of normal, healthy volunteers, flaxseed re-

duced significantly the production of proinflamma-

tory eicosanoids that contribute to inflammation and

other immune responses. Dietary flaxseed also in-

hibits PAF, a powerful mediator of the immune re-

sponse. In studies involving patients with lupus

nephritis, a condition marked by chronic inflamma-

tion of the kidney, flaxseed consumption reduced

significantly PAF production and kidney inflamma-

tion and improved kidney function. Thus, a beneficial

role for flaxseed in managing autoimmune diseases

has been proposed, but more research is needed to

confirm its effects.

Other Health Benefits

0015Reports that flaxseed aids in treating the symptoms of

depression, irritable bowel syndrome, osteoporosis,

and menopause are largely anecdotal. Future research

will determine the effects of flaxseed’s components,

particularly the lignans and ALA, on the pathology

and treatment of these conditions.

Performance Properties

Market Forms

0016Flaxseedis marketedprimarilyas theintactwhole seed,

which is reddish brown, flat, and oval with a pointed

tip. The seed measures about 2.5 5.0 1.5 mm,

slightly larger than a sesame seed. Flaxseed is also

marketed in a coarsely ground form. Whole flaxseed

may be ground successfully in a home coffee grinder.

0017Flaxseed oil is available in health food stores either

in bottles for use with foods such as salads or in

capsules to be used as diet supplements. Oil for the

health food market is produced by ‘cold-pressing’

flaxseed where the maximum allowable temperature

is 35



C. The seed is cleaned, cracked, flaked between

rollers, and pressed in expellers filled with water-

cooled shafts. It is normally bottled in light-proof

containers to avoid photooxidation and refrigerated

to limit autoxidation.

Sensory Characteristics

0018Appearance, texture, and taste are the sensory fea-

tures that benefit from adding flaxseed to foods. The

reddish brown seed provides an attractive color con-

trast in products like yeast breads and muffins, in

cereals such as cream of wheat or corn meal/grits,

and in pancakes and potato latkes. Whole flaxseed

provides crunchiness and chewiness, textural features

that are less pronounced in the ground form. Experi-

enced sensory panelists have described the taste of

flaxseed as nutty and cereal-like with a slightly

fruity/bitter tang.

Food Uses

0019Flaxseed has been used in food over the centuries,

particularly in the Middle East and North Africa. In

Ethiopia, flaxseed is a key ingredient in porridge and,

when roasted, crushed and combined with split peas

and red pepper, in ‘w’et,’ a form of stew. There it is

also enjoyed as ‘ch’lk’a,’ a drink made from lightly

FLAXSEED 2527