Technical Talk – April 2006

Fabulous Flax

This column is written by Dr. John Michaelides of the Guelph Food Technology Centre.

Question: Why use flax in baked goods, what are the benefits, and how can I get the most out of this ingredient in my products?

Answer: Flaxseeds are small oval seeds resembling sesame and are either dark brown or blonde in colour. In Canada, flax is mainly grown on the prairies. For thousands of years, flaxseed has been consumed by humans around the world and especially in the Middle East, China and other Far East countries, and the fibre from the flax stalks has been used for the manufacture of linen.

Flaxseed contains a variety of compounds that are proven to be beneficial to human and animal health. It is the highest plant source of alpha-linolenic acid (ALA), an omega-3 polyunsaturated fatty acid with many scientifically and medically documented health benefits. ALA is considered to be one of the essential fatty acids because it cannot be synthesized by the human body. The ALA in the human diet is converted into the long chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which also contribute substantially to human health and well-being. Flaxseed oil contains 50 to 57 per cent ALA. Some blonde varieties, which were developed to provide stability of the oil (i.e. resistance to oxidation over time), contain only a small amount of ALA. This type of flax is called Linola and should not be used in food products if they are designed to deliver the omega-3 health benefits.

Flaxseed also contains substantial amounts of dietary fibre, 25 to 28 per cent of which are mostly soluble, due to the mucilage that covers the seed. These seeds also are a significant source of protein at about 20 per cent.

The second major health benefit of flaxseed can be attributed to the plant phytoestrogens known as lignans. Flaxseed is the highest plant source of such compounds. It contains as much as 75 to 750 times more lignans than any other plant source. These plant lignans are converted in the intestine to mammalian lignans which, in turn, aid the human body in fighting against many major diseases such as breast cancer, kidney malfunction, diabetes, etc. Flaxseed is also packed with many other phyto-nutrients such as phenolics, flavonoids, other antioxidants, and potassium.

As a rich source of active compounds, flaxseed provides many health benefits, such as the prevention of cardiovascular disease, cancer (especially breast cancer), diabetes and kidney disease. As part of a regular diet, flaxseed contributes to bone health and the strength of the immune system, helps in the prevention of obesity, and eases menopausal symptoms.
In baked goods, flaxseed has been used very extensively to produce a variety of products. In many cases it is used as whole seed in the dough or batter and also as a decoration, sprinkled on the surface of baked goods such as bread. We need to take into account, however, that when we eat whole flaxseeds, we will gain only very limited health benefits. The flaxseed will pass through the gastrointestinal system undigested. The only health benefits we will gain will be from the portion of it that constitutes the mucilage, and from the odd broken seed due to chewing. In order to realize the full health benefits, it is necessary to use ground flaxseed in food products.

The intact whole flaxseed is very stable and will not pose any problems with oxidation and rancid flavours in the product. Ground flaxseed, on the other hand, has a limited shelf life and a careful selection of this ingredient is needed in order to achieve the desired shelf life of the food product. Some suppliers provide specialized ground flaxseed ingredients with a long shelf life that can be used in baked goods.

Here is a summary of some points to consider when you are putting flaxseed in your bakery products:
•    Flaxseed added as the whole seed may not deliver all the health benefits, since the whole seed will not be digested and will pass through the GI tract intact.

•     Ground flaxseed has a limited shelf life. The grinding process may produce heat that will damage the omega oils and start the oxidation process. However, there are ingredient suppliers who can guarantee long shelf-life ground flaxseed.

•    You can decrease or eliminate shortening or other added oils in bakery foods when you use ground flaxseed in products such as bagels, breads, whole wheat muffins, etc.

•    Ground flaxseed in baked goods increases dough's water absorption and you will need to add more water to the formula. The American Institute of Baking recommends, as a starting guideline, the addition of 75 lbs of extra water for every 100 lbs of added flaxseed.

•    In bread products, the use of substantial amounts of ground flaxseed may require an increase in yeast levels.

•    Flaxseed may cause excessive browning of baked goods. You may need to lower the oven temperature in order to compensate for that effect.

•    Finely ground flaxseed may result in a better loaf volume in breads.

•    Flaxseed imparts a nutty flavour in baked goods when used as a major ingredient, and has relatively little effect on flavour when added in small amounts.

Flax, throughout the history of human civilization, has been consumed as food (seed), used to make clothing (stalks for linen), and to produce industrial materials (linseed oil in paints). We are now rediscovering the importance of this plant in our diet and health. The recognition of the importance of the omega-3 fatty acids for human health, as well as the discovery of the significance of the phytoestrogens such as lignans for the prevention of certain diseases, will continue to elevate the interest and the demand for bakery products containing flaxseed.

For more information, or fee for service help with product or process development needs please contact the GFTC at (519) 821 1246, by fax at (519) 836 1281, by e-mail at gftc@gftc.ca