Flax - Current Uses & Future Applications

Flax flower

INTRODUCTION

Flax or linseed is among the oldest crop plants cultivated for the purpose of oil and fiber. It belongs to the genus Linum and family Linaceae. It is an annual herbaceous plant with shallow root system.

The common names flax and linseed are used in North America and Asia, respectively, for L. usitatissimum. Oilseed varieties and fiber varieties are specialized development of this species.

The cultivars grown primarily for seed/oil purpose are relatively short in height and possess more secondary branches and seed bolls (seed capsule). The cultivars grown for fiber purpose are tall growing with straight culms and have fewer secondary branches.

The Mediterranean and Southwest Asia have both been proposed as the center of origin; however the exact location is uncertain. The initial use of flax has also been debated. Based on archeological evidence, it was proposed that flax was used first for fiber.

Flax, while a minor crop, is grown in a wide range of countries, climates and for many different products. Because of its adaptability and product diversity, it is being considered as a platform for the development of novel bioproducts. Research on use of flax for bioproduct production is being conducted in Australia, North America, Europe and Asia. The objective of this paper is to discuss the various applications, demands and developments of an under utilized oilseed crop, flax.

A little bit of history:

• The archaeological evidence of flax cultivation dates back to >6000 BC and it is considered as one of the oldest and most useful crops. Components of flax have diverse uses. Cultivar development of flax is currently focused on enhancing the oil content and nutritional value to meet the demand of nutraceutical market supply, as an alternate source of fish oil, a rich source of eicosapentaenoic acid and docosahexaenoic acid.

• Flax seed is also rich in soluble and insoluble fibers and lignans, makes it useful as a dietary supplement. Intake of flaxseed in daily diet may reduce the risk of cardiovascular diseases such as coronary heart disease and stroke. There is also evidence that flax has anticancer effects in breast, prostate and colon cancers.

• Book made of Flax

  Flax fiber is used in the textile industry for linen cloth and also in paper industry. The residues remaining after the oil extraction from linseed contains about 35-40% protein and 3-4% oil, a rich source of feed to livestock like cattle and buffalo.

• Flax is naturally high in polyunsaturated fatty acids (PUFA), more specifically in omega-3 fatty acids; and hence flax seed as a component of poultry meal, can provide omega-3 enriched eggs. Rapid drying linseed oil is used for several purposes in industry, including paint and flooring (linoleum) industries. Because of its novel oil profile, flax may also be a suitable platform crop for synthesis of specialized industrial and nutraceutical products.

Area and Production of Flax:

Flax was grown in 47 countries in 2004 with the seed production of 1.903 million metric tonnes . Canada has the highest area and production of flax in the world followed by China, USA, India and EU. In 2006, Canada produced 1.014 million tonnes of flax seed from an area of about 800 thousand hectares .

The Canadian prairie (Manitoba, Saskatchewan and Alberta) is the major flax growing area in Canada. In the USA, flax has been grown primarily in North Dakota, South Dakota, Minnesota and Montana. In India, flax is grown mainly in Uttar Pradesh, Madhya Pradesh and Maharashtra, with three states accounting for about 74% of the linseed output in India. In India, flax is grown primarily for oil, although in temperate hill regions like Himachal Pradesh, it is grown for fiber on a small scale. Flax for fiber purpose is grown primarily in China, Russia, Egypt, and near the northwestern European coast for the production of high quality linen and several other products.

Flax for Human Consumption:

Flax was being used as a food source and natural laxative dating back as far as the ancient Greeks and Egyptians. It was also being used as a food in Asia and Africa. The unique and diverse properties of flax are reviving interest in this crop. In 2005, approximately 200 new food and personal care products were introduced in the US market containing flax or flax ingredients, which suggests that flax based products have the highest growth potentials in functional food industry.

Conventional flax seed, containing a mixture of the fatty acids, is rich in two essential fatty acids, alphalinolenic acid and linoleic acid omega-6.

Flax is the richest source of ALA, a precursor for the synthesis of very long chain polyunsaturated fatty acid, eicosapentaenoic acid and docosahexaenoic acid .

The omega-3 fatty acids, particularly DHA, are required for the optimal development of nervous system and maturation of visual acuity (retina) in preterm and term infants.

Flax for Edible Oil:

The direct use of unprocessed conventional flax oil in the human diet is limited by product stability. Linseed oil with high ALA is highly susceptible to oxidation and polymerization. While these properties make it suitable for other industrial applications, it limits the direct substitution of flax oil in place of canola (Brassica napus) or corn (Zea mays) oil. The oil properties of flax are so unique that considerable effort is being expended to emulate the fatty acid profile. Modification of soybean oil (Glycin max) and canola oil using conventional and molecular approaches to enhance the ALA content and therefore the health benefits and to replace fish oils in the diet are an extremely active area of research.

Flax For Functional Food:

Functional or nutraceuticals are foods that claimed to have health-promoting or disease-prevention properties in addition to basic nutritional properties in the food. Many health-claims have been made for whole flax seed, flax meal and milled flax.

A recent study in Europe indicate that the consumption of flax oil for 12 weeks (one tablespoon, providing 8 g ALA/day) in daily diet lowered blood pressure significantly in middle aged men with high blood cholesterol levels. A role of the flax oil in preventing thrombosis has been reported in a study by 40% increase in the activated protein ratio in a population who consumed flax oil diet for six weeks . In a study of 50 men with high blood cholesterol levels who consumed one table spoon of flax oil daily for 12 weeks reduced 48% C-reactive protein (CRP) and 32% serum amyloid A (SAA) levels.

Flax Fiber and its Uses:

For centuries, flax fiber has occupied a prominent place in textile industry. Flax fiber was used by the prehistoric Lake Dwellers of Switzerland for the production of linen > 5000 years BP. The art of weaving flax fiber to linen may have originated in Egypt because winding-clothes for the bodies of the Pharaohs of Egypt were composed of flax fiber. It was then introduced in India, where, before the use of cotton, linen was worn by many tribes. The early colonists brought flax for fiber to the United States. With the increased area and production of cotton and invention of cotton gin in USA, the use of flax linen for textile declined.

Flax fiber is soft, lustrous and flexible. It is stronger than cotton fiber but less elastic. Fiber obtained from flax is known for its length, strength and fineness; however chemical composition and diameter are also important. In comparison to industrial wood particles, flax particles were characterized by higher length to thickness and length to width ratios and lower bulk density. The best grades are used for linen fabrics such as damasks, lace and sheeting. Coarser grades are used for the manufacturing of twine and rope.

After extraction of bast fiber from flax stem, 80% of the remains fiber can be separated mechanically. This material can be converted into pulp and can be used for manufacturing papers. Flax fiber is also a raw material for the paper industry for the use of printed banknotes and paper for cigarettes. There are several advantages of using flax fibers for industrial applications. It is a biodegradable, renewable raw material, nonabrasive. However, for technical uses, the mechanical properties like tensile strength, elastic modules it may not be suitable. The relation between the cost of production and the comparative advantages of the fiber may limit the use of flax in large scale applications.

Flax as an Animal Feed:

Flax is integrated into animal rations in several forms; whole seed, oil supplements, hulls, or as meal. Meal, known as LSOM or linseed cake in Europe and Asia, respectively, is the residue after the extraction of oil from seeds. This valuable feed product can be used to supplement the diets of both ruminants and non-ruminants.

The quantity of hull in flax seed meal is about 38%, twice the level in canola or soybean meals. The fine fraction obtained as a byproduct of dehulling (a process of preparing flaxseed for value added industrial products) could be a potential ingredient in pet food; whereas the medium and mix fractions can be blended into poultry feed formulations . Flax seed oil is also used in mixed pet diets, including dogs, cats and horses. The essential fatty acids (ALA and LA) present in flax seed contribute to a lustrous coat, help prevent dry skin and dandruff, and also help in reducing digestive and skin problems in animals.

The omega-3 enriched eggs are produced by increasing ground flax seed to 10-20% of the diet of laying hens. Eggs produced from this diet formula would be ten times higher in omega-3 fatty acids than conventional eggs . A single omega-3 enriched egg provides half of the optimal daily intake of ALA and about one quarter of EPA and DHA .

Flax for Industrial Use:

When some flax oil is exposed to air, the double bonds of ALA react with oxygen and result in relatively soft, durable film. This property is known as “drying” quality of linseed oil, is responsible for extensive use in manufacturing varnishes, oilcloth, printer’s ink, imitation leather and also as an anti-spalling and curing agent for concrete surfaces on highways. The drying quality of oil can be improved by addition of metal catalyst to promote oxidation and also by partially pre-oxidizing oil through exposure to the air. Along with the use of flax oil as an oil paint carrier, it is also being used as a painting medium, making oil paints more fluid, transparent and glossy. Linseed oil can also be used as “finishing oil” for wooden furniture to prevent it from denting. It does not cover the surface of wood but soaks into the pores, leaving a shiny but not glossy surface. It is used by billiards/pool cue manufacturers on the shaft portion of the cue.

Linseed oil is the most important raw material used to make the flooring from linoleum. In the process of linoleum manufacturing, oxidized linseed oil is mixed with rosin and other raw material to form linoleum granules, which are pressed onto a jute backing, making linoleum sheets. This natural material made from a sustainable resource is long lasting and attractive.

Conclusion:

An oil seed come fiber crop, flax (Linum usitatissimum L.) has been used by humans from more than 6000 years and it is among the first plants domesticated. The utilization of flax for various purposes including industry, nutraceutical, bio- pharmaceutical, fiber, animal feed and human food is continuing to develop.

Increasing cost of artificial fibers and the advantages of natural flax fiber, new technology and equipments for growing, harvesting of flax is useful to make flax a model plant species. New improved methods of retting flax, more efficient processes at each stage of linen manufacture point towards a possible upturn of the utilization of flax fiber than its current limited use, especially in North America. There is a demand for alternative sources of VLCPUFA and the possibility of obtaining them from higher plants in commercial quantity is particularly attractive.

As no oil-seed species produces such products naturally, genetically engineering would be required to synthesize these fatty acids. Because flax already contains the precursor to VLCPUFA and the highest value of ALA, it may be a choice platform species. Linoleum and other flax based materials such as linen will become increasingly popular as governments and consumers turn to products with smaller environmental footprints. There are also opportunities for production of sustainable bio-products and green building materials. The molecular and gene expression experiments are not widely studied in flax, which may also expand the applications and uses of flax in future. Several constrains must be overcome to facilitate the further development of flax and flax bioproducts.

Because flax is a minor crop, it has not received significant research resources compared to other North American oilseeds such as canola and soybean. While flax can be easily transformed, and herbicide resistant traits have been developed to increase the agronomic yield of flax, constraints in the European market for transgenic LSO meal effectively block this pathway of crop improvement and economic enhancement . The public sector remains the primary contributor to flax breeding and research because the lack of commercial prospects limits the interest of the private sector. Currently, a lack of basic knowledge of flax genomics, and a concerted effort in flax breeding limits rapid development of flax for bioproducts.