EFFECT OF IMMATURE AND OFF-COLORED SEEDS ON THE LIPID QUALITY OF MILLED FLAXSEED

ABSTRACT

The effect of visibly inferior flaxseed (Linum usitatissimum L.) on the lipid quality of milled flaxseed was investigated. Flaxseed was aspirated and separated into low-, medium- and high-density fractions. All density fractions contained≤0.1% broken seed,≤0.4% contrasting seed and≤0.25% extraneous material. The low-density fraction contained the most immature (2.8%) and off-colored seed (4.1%). Immature seed had a lipid content of 40.8%, a peroxide value (PV) of 2.69 meq/kg and a free fatty acid (FFA) content of 1.06%. The off-colored seed had a lipid content of 38.1%, a PV of 5.79 meq/kg, and a FFA content of 1.89%. Hand-cleaned seed (averaged across fraction density) had a lipid content of 41.4%, a PV of 0.41 meq/kg and FFA content of 0.37%. The removal of seed defects improved flaxseed quality and improved lipid quality in the low-density fraction.

PRACTICAL APPLICATIONS

Lipid oxidation is a major concern when using milled flaxseed as a food ingredient. These results indicate the importance of removing off-colored and immature flaxseed. Seed lots that contain immature and off-colored seed likely will have poor lipid quality and, when milled, be more susceptible to lipid oxidation during storage than will seed lots free of immature and off-colored seed.