| A. SCHORNO1,
M. C. Tulbek1, C. A. Hall, III2, and F. A.
Manthey. (1) Dept. of Cereal and Food Sciences, North Dakota State
University, 1250 Bolley Dr. Harris Hall, Fargo, ND 58105, (2) Dept. of
Cereal & Food Sciences, North Dakota State Univ., 324 Industrial
Agriculture & Communications Center, PO Box 5728, Fargo, ND 58105
Flaxseed use in foods has increased
during the last decade due to the presence of functional compounds such
as alpha-linolenic acid, lignans and fiber. Due to the high level of
polyunsaturated fatty acids, flaxseed is susceptible to lipid oxidation.
Thus enhancing stability of the oil is important for prolonging
shelf-life. Roasting has been applied to oilseeds to improve aroma,
flavor, and shelf life stability.
The objectives of this study were to
determine the physical and chemical properties of roasted flaxseed in
relation to lipid oxidation.
Omega flaxseed was roasted at 140, 160
and 180C in an air impingement oven (4, 8, 16 and 24 min.). Total lipid
extraction (dry basis), peroxide value and free fatty acid content were
determined in the roasted flaxseed. Fatty acid composition (palmitic,
stearic, oleic, linoleic and linolenic acids) was analyzed by gas
chromatography and color quality was determined by Minolta colorimeter.
Flaxseed brightness (L value) (r=-0.52,
P<0.01) and yellowness (b value) (r=-0.49, P<0.01) were significantly
correlated with free fatty acid content. Roasting significantly (P<0.05)
decreased the peroxide value. All roasted flaxseed samples (excluding
180C, 24 min.) were significantly (P<0.05) lower than control in terms
of free fatty acid. Total lipid extraction increased with temperature.
At 160 and 180C, roasted flaxseed had the highest oil yield. Generally,
fatty acid profile of flaxseed showed low variation. Linolenic acid
decreased when subjected to high temperatures and long processing times,
however roasted flaxseed was higher in linoleic acid than control at
each processing temperature.
Processing for 4 and 8 minutes at 140 and
160C showed superior quality flaxseed. Considering the reduction in
peroxide value and free fatty acid content, roasting might potentially
be used as a means of extending shelf life.
Available references:
Meyers, S., Tulbek, M.C., and Hall, C. 2004. Storage stability of
roasted flaxseed. Institute of Food Technologists (IFT) 2004 Las
Vegas.
Tulbek, M.C., Schorno, A., Meyers, S., Hall, C. and Manthey, F. 2004.
Chemical and sensory analysis and shelf stability of roasted flaxseed.
60th Flax Institute Meeting. March 17-19 2004, Fargo-ND
Schorno, A., Tulbek, M.C., C. Hall, F. Manthey. Evaluation of physical
and chemical properties of roasted flaxseed Institute of Food
Technologists (IFT) 2003 Chicago IL.
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