Flax is grown for its seeds, which can be ground into a meal or turned into
linseed oil, a product used as a
nutritional supplement and as an ingredient in many
wood-finishing products. Flax is also grown as an
ornamental plant in gardens. Moreover, flax fibers are used to make linen. The
specific epithet in its binomial name,
usitatissimum, means "most useful". Flax fibers taken from the stem of the plant are two to three times as strong as cotton fibers. Additionally, flax fibers are naturally smooth and straight. Europe and North America both depended on flax for plant-based cloth until the 19th century, when cotton overtook flax as the most common plant for making
rag-based paper. Flax is grown on the Canadian
prairies for linseed oil, which is used as a drying oil in paints and varnishes and in products such as
linoleum and
printing inks. Linseed meal, the by-product of producing linseed oil from flax seeds, is used as
livestock fodder.
Flax seeds Flax seeds occur in brown and yellow (golden) varieties. Most types of these basic varieties have similar
nutritional characteristics and equal numbers of short-chain
omega-3 fatty acids. Yellow flax seeds, called solin (
trade name "
Linola"), have a similar oil profile to brown flax seeds and both are very high in omega-3s (
alpha-linolenic acid (ALA), specifically). Flax seeds produce a
vegetable oil known as flax seed oil or
linseed oil, which is one of the oldest commercial oils. It is an
edible oil obtained by
expeller pressing and sometimes followed by
solvent extraction. Solvent-processed flax seed oil has been used for centuries as a
drying oil in painting and varnishing.
Culinary A 100-gram portion of ground flax seed supplies about of
food energy, 41g of fat, 28g of fiber, and 20g of protein. Whole flax seeds are chemically stable, but ground flax seed meal, because of
oxidation, may go
rancid when left exposed to air at room temperature in as little as a week. Refrigeration and storage in sealed containers will keep ground flax seed meal for a longer period before it turns rancid. Under conditions similar to those found in commercial bakeries, trained sensory panelists could not detect differences between bread made with freshly ground flax seed and bread made with flax seed that had been
milled four months earlier and stored at room temperature. If packed immediately without exposure to air and light, milled flax seed is stable against excessive oxidation when stored for nine months at room temperature, and under
warehouse conditions, for 20 months at ambient temperatures. Three
phenolic glucosides—
secoisolariciresinol diglucoside,
p-coumaric acid glucoside, and
ferulic acid glucoside—are present in commercial bread containing flax seed.
Nutrition Flax seeds are 7% water, 18%
protein, 29%
carbohydrates, and 42% fat (see table). In as a reference amount, flax seeds provide 534
kilocalories and contain high levels (20% or more of the
Daily Value, DV) of protein,
dietary fiber, several
B vitamins, and
dietary minerals. Flax seed oil contains 53% 18:3 omega-3 fatty acids (mostly ALA) and 13% 18:2 omega-6 fatty acids. Another meta-analysis showed that consumption of flax seeds for more than 12 weeks produced small reductions in
systolic blood pressure and
diastolic blood pressure. A third showed that consuming flax seed or its derivatives may reduce total and
LDL-cholesterol in the blood, with greater benefits in women and people with high
cholesterol. A fourth showed a small reduction in
c-reactive protein (a marker of inflammation) only in persons with a body mass index greater than 30.
Linseed oil Safety Flax seed and its oil are
generally recognized as safe for human consumption. Like many common foods, flax contains small amounts of cyanogenic
glycoside, which is nontoxic when consumed in typical amounts. Typical concentrations (for example, 0.48% in a sample of defatted dehusked flax seed meal) can be removed by special processing. Flax seed is a potential allergen in both adults and children.
Fodder After crushing the seeds to extract linseed oil, the resultant linseed meal is a
protein-rich
feed for
ruminants,
rabbits, and fish. The high omega-3 fatty acid (
ALA) content of linseed meal "softens" milk, eggs, and meat, which means it causes a higher
unsaturated fat content and thus lowers its storage time. Another disadvantage of the meal and seed is that it contains a
vitamin B6 (
pyridoxine) antagonist, and may require this vitamin be supplemented, especially in
chickens, and furthermore linseeds contain 2–7% of
mucilage (fibre), which may be beneficial in humans In the US, flax-based feed for ruminants is often somewhat more expensive than other feeds on a nutrient basis.
Sheep feeding on low quality
forage are able to eat a large amount of linseed meal, up to 40% in one test, with positive consequences. It has been fed as a supplement to
water buffaloes in India and provided a better diet than forage alone, but not as good as when substituted with
soy meal. It is considered an inferior protein supplement for swine because of its fibre, vitamin antagonist, high omega-3 content, and its low lysine content, and can only be used in small amounts in the feed. Although it may increase the omega-3 content in eggs and meat, it is also an inferior and potentially toxic feed for poultry, although it can be used in small amounts. The meal is an adequate and traditional source of protein for rabbits at 8–10%. Its use in fish feeds is limited. This would have led to widespread death, but the plan was eventually abandoned for
Operation Overlord.
Flax fibers shop once used to prepare flax fibers.
North Ayrshire, Scotland. Flax fiber is extracted from the
bast beneath the surface of the stem of the flax plant. Flax fiber is soft, lustrous, and flexible; bundles of fiber have the appearance of blonde hair, hence the description "flaxen" hair. It is stronger than cotton fiber, but less elastic. The use of flax fibers dates back tens of millennia; Industrial-scale flax fiber processing existed in antiquity. A
Bronze Age factory dedicated to flax processing was discovered in
Euonymeia, Greece. The best grades are used for fabrics such as
damasks,
lace, and
sheeting. Coarser grades are used for the manufacturing of
twine and
rope, and historically, for
canvas and
webbing equipment. Flax fiber is a raw material used in the high-quality paper industry for the use of printed
banknotes, laboratory paper (
blotting and
filter),
rolling paper for
cigarettes, and
tea bags.
Flax mills for spinning flaxen
yarn were invented by
John Kendrew and
Thomas Porthouse of
Darlington,
England, in 1787. New methods of processing flax have led to renewed interest in the use of flax as an industrial fiber.
Preparation for spinning ; C =
cortex; BF =
bast fibers; P =
phloem; X =
xylem; Pi =
pith (Germany) Before the flax fibers can be spun into linen, they must be separated from the rest of the stalk. The first step in this process is
retting, which is the process of rotting away the inner stalk, leaving the outer parts intact. At this point, straw, or coarse outer stem (
cortex and
epidermis), is still remaining. To remove this, the flax is "broken", the straw is broken up into small, short bits, while the actual fiber is left unharmed.
Scutching scrapes the outer straw from the fiber. The stems are then pulled through "hackles", which act like combs to remove the straw and some shorter fibers out of the long fiber.
Retting flax Several methods are used for retting flax. It can be retted in a pond, stream, field, or tank. When the retting is complete, the bundles of flax feel soft and slimy, and quite a few fibers stand out from the stalks. When wrapped around a finger, the inner woody part springs away from the fibers. Pond retting is the fastest. It consists of placing the flax in a pool of water which will not evaporate. It generally takes place in a shallow pool which will warm up dramatically in the sun; the process may take from a few days to a few weeks. Pond-retted flax is traditionally considered of lower quality, possibly because the product can become dirty, and is easily over-retted, damaging the fiber. This form of retting also produces quite an odor. Stream retting is similar to pool retting, but the flax is submerged in bundles in a stream or river. This generally takes two or three weeks longer than pond retting, but the end product is less likely to be dirty, does not smell as bad, and because the water is cooler, is less likely to be over-retted. Both pond and stream retting were traditionally used less because they pollute the waters used for the process. In field retting, the flax is laid out in a large field, and dew is allowed to collect on it. This process normally takes a month or more but is generally considered to provide the highest quality flax fibers, and it produces the least pollution. Retting can also be done in a plastic trash can or any type of water-tight container of wood, concrete, earthenware, or plastic. Metal containers will not work, as acid is produced when retting, and it would
corrode the metal. If the water temperature is kept at , the retting process under these conditions takes 4 or 5 days. If the water is colder, it takes longer. Scum collects at the top, and an odor is given off the same as in pond retting. 'Enzymatic' retting of flax has been researched as a technique to engineer fibers with specific properties.
Dressing the flax File:Harfleur - Compagnons duellistes - teillage du lin.jpg|Breaking flax File:Harfleur - Compagnons duellistes - battage du lin.jpg|Scutching flax File:Harfleur - Compagnons duellistes - peignage du lin.jpg|Heckling flax File:Flax fibers.JPG|Flax fiber in different forms, before and after processing Dressing the flax is the process of removing the straw from the fibers. Dressing consists of three steps: breaking, scutching, and heckling. The breaking breaks up the straw. Some of the straw is scraped from the fibers in the scutching process, and finally, the fiber is pulled through heckles to remove the last bits of straw. Breaking breaks up the straw into short segments.
Scutching removes some of the
straw from the fiber.
Heckling is pulling the fiber through various sizes of
heckling combs or heckles. A heckle is a bed of "nails"—sharp, long-tapered, tempered, polished steel pins driven into wooden blocks at regular spacing. ==Genetically modified flax contamination==