**4. Flax: a functional food**

It is appropriate to classify flax as a "functional food" due to the numerous health-promoting components found in both the seeds and the oil. Foods known as "functional foods" have potential health benefits in addition to its nutrient contents. L-arginine, cyanogenic glycosides (CNglcs), and omega-3 fatty acids can be mentioned among the active components in the seeds that cause its positive functions in the prevention and treatment of some chronic diseases. The consumer can currently choose between whole flaxseeds and milled flaxseed in the area of health-related functional foods. These goods are promoted as excellent providers of lignans, dietary fiber, and omega-3 fatty acids. Numerous common foods, including muffins, bread, crackers, tortillas, cereals, and snack bars, include whole flaxseeds. The commercial marketing of flaxseed products as sources of protein for food usage is extremely limited [38].

However, in recent years, some food manufacturing companies use flaxseed to create a pleasant nutty flavor in the preparing cereal and bakery products. Also, due to the fact that flaxseed does not contain gluten, some food companies use flax flour in the production of gluten-free food for celiac patients [39]. Some attempts have been made to fortify breads with flaxseed flour; however, some limitations have made the results not very satisfactory. For example, it has been reported that use of flaxseed flour for bread production resulted in poor texture, crumb color, graininess, volume, and crust color [40]. On the other hand, considering that flaxseed contains PUFA, the use of this plant in the bakery industry and exposure to high heat may cause the oxidation of fatty acids and the production of metabolites such as malondialdehyde (MDA), which have adverse effects on health [41]. However, Cunnane et al. were reported that cooking at the normal temperature and for a limited time does not significantly increase the production of MDA [42]. Antinutritional components included in flaxseed products present a significant obstacle to their use in food products. Linustatin, neolinustatin, and linamarin are CGs that can be found in flaxseed [43]. These substances are broken down by β-glucosidases when the cell structure is disturbed, generating small amounts of hydrogen cyanide, a potent respiratory inhibitor [44]. However, in some studies, it has been reported that usage from some methods such as extraction of flaxseed meal 2–3 times with methanol-ammonia-water, heat treatment, boiling for 5 min in

water, and dry and wet autoclaving can decrease CG in flaxseed [45, 46]. Linatine, an antagonist of vitamin B6 (pyridoxine), is also found in flaxseed. Generally, linatine concentrations range from 20 to 100 mg/kg. Before eating, heat processing could be required to eliminate these antinutritional elements [47].
