Flax Research at North Dakota State University

PLANT PATHOLOGY

Dr. Jack Rasmussen
Supplying flax rust races for progeny testing in breeding program.

Dr. Carl Bradley 
Conducting flax disease surveys and evaluation of fungicide seed treatments on flax.

PLANT SCIENCES

Dr. Jack Carter
Responsible for cooperative "pass through" experiments feeding flax seed to receiving and finishing beef cattle at Kansas State University, Manhattan, KS; annual cadmium survey especially of Omega yellow flaxseed re export potential; pass through on feeding flaxseed oil to lower blood lipids, Medical School, Univ. Massachusetts, Worcester, and supplying ground flaxseed to Medical School, Columbia Univ., NY for 40 women one year feeding trial re hormonal reaction; flax consultant to ND Oilseed Council; and president, Flax Institute of the United States; retired professor emeritus.

Dr. Jim Hammond
Responsible for flax breeding and genetics project which produces new varieties; evaluation of low cadmium flax germplasm; flax variety trials and cooperative flax nurseries in U.S. and Canada.

Dr. Kirk Howatt
Developing new herbicides for weed control in flax.

Dr. Dale Williams
Seedstock project leader responsible for increasing new flax varieties to distribute to seed growers throughout North Dakota.

NORTHERN CROPS INSTITUTE

Wesley Twombly
Prepared extruded fish food containing the dehulled flaxseed for a fish feeding experiment.

CHEMISTRY

Dr. Sibi
Synthesized enterodiol and enterolactone, the metabolic products of LIGNANS.

AGRICULTURAL AND BIOSYSTEMS ENGINEERING 

Dr. Dennis Wiesenborn 

CEREAL AND FOOD SCIENCE 

Dr. Frank Manthey
Dr. Cliff Hall

The research team at North Dakota State University (NDSU) has taken a proactive approach to investigate food applications of flaxseed. Traditionally, flaxseed (also know as linseed) has been used as a drying oil for the paints and coating industry. However, yellow varieties (Omega) are well suited for food applications. The goal of the research team at NDSU is to provide sound scientific data to better understand the utilization of flaxseed as a food ingredient. The primary research focus is on postharvest issues that include storage stability of flaxseed, milling and oil extraction protocols, concentration of bioactive compounds, and quality evaluations of food systems containing flaxseed. The following are examples of current research activities at NDSU. 
  
Concentrating Bioactive Compounds. Dr. Dennis Wiesenborn is leading the effort to develop a dry, mechanical process for obtaining a hull rich fraction from flaxseed (1-2). The hull rich fraction is important because of the high lignan content. Lignans have been shown to have a positive impact on health (3-6). The fractionation process developed provide 2-3 times the lignan levels as whole ground flaxseed. Thus, the hull fraction appears to be a good source of lignans for functional food studies. In addition, hull free materials, a rich source of polyunsaturated lipids, are products of the fractionation process.

Solvent extraction has been found to be a successful method to concentrate lignans. Dr. Clifford Hall III has taken the lead to develop an extraction protocol using pilot scale equipment. Hydrolysis of the crude extract and removal of solvent yields an extract with 10 fold increase in lignan content over whole ground flaxseed.

Stability of Bioactive Compounds. As mention previously, oil extracted from flaxseed is high in unsaturated fatty acids. In particular, µ -linolenic acid (ALA) makes up roughly 52 % of the fatty acids of flaxseed oil (7). This fatty acid is considered essential for humans. The limiting factor for the addition of flaxseed oil into food systems is the instability of the oil to oxidation. The proper storage is critical for maintaining the oxidative stability of flaxseed oil. 

We have found in our laboratories at NDSU (Pizzey and Hall III, unpublished data) that hexane extracted flaxseed oil oxidized relatively quickly under slightly elevated temperatures (40E C) and in the presence of sunlight. Compared to freshly extracted oil, samples stored under sunlight had a 200 fold increase in peroxide values within 12 days while samples stored in the dark at 40E C had peroxide values 50 fold higher by day 12. Studies are underway to improve flaxseed oil stability.

Flaxseed Pasta as a Functional Food.Pasta is made from semolina and water. The simplicity of the ingredients and consumer popularity makes pasta an ideal model to evaluate the potential of flaxseed in functional foods. The research team of Hall III, Manthey, Wiesenborn, and Schwarz have been investigating the potential utilization of flaxseed as an ingredient in pasta. Manthey et al. (8) reported that particle size of the ground flaxseed was critical for producing flaxseed pasta products. Cooking loss was not significantly (P>0.05) different from the control, however, cooking firmness decreased as flaxseed addition increased. This was attributed to the gum (i.e. polysaccharide) fraction of the flaxseed hull, which has good water binding capacity (9-10) and may account for the cooking loss scores similar to the control pasta. Lee et al. (11) reported, at the American Association of Cereal Chemists’ meeting, that ALA content, and stability was not affected by the spaghetti processing method. A macaroni produced using 20% whole ground flaxseed also had remarkable storage stability. After eight months of storage, the oxidative indices, i.e. conjugated dienes and headspace analysis, were not significantly different from the freshly made pasta (control). In addition, fatty acid profiles were consistent throughout the storage. Additional studies in our laboratory included sensory evaluation of macaroni products.

Macaroni products containing 10 and 20 % were evaluated for flavor, appearance, texture and overall acceptability by general pasta consumers using a Hedonic scale. Overall acceptability was not significantly (P>0.05) different between pastas containing different levels of flaxseed. However, the flaxseed pastas were rated significantly lower for overall acceptability than a control (Cuppett, unpublished data). Many of the negative comments were with respect to appearance and the presence of specks in the pasta. Only the macaroni were evaluated and several individuals stated that the products were bland, which is a positive note considering that one would expect sauce or oil to provide the flavor. Additional studies are underway to assess the acceptability of the flaxseed macaroni in a cheese sauce. 

References 

1. Tostenson, K., Wiesenborn, D., Zhang, X., Kangas, N., and Schwarz, J. 2000. Evaluation of continuous processes for mechanical flaxseed fractionation. In Proceedings of the 58th Flax Institute of the United States. Fargo, ND. pp. 17-22. 
2. Madjusudhan, B., Wiesenborn, D., Schwarz, J., Tostenson, K. and Gillespie, J. 2000. A dry mechanical method for concentrating the lignan secoisolariciresinol diglucoside in flaxseed. Lebensm.-Wiss. U. –Technol. 33:268-275. 
3. Thompson, L.U., Rickard, S., Orcheson, L., and Seidl, M. 1996a. Flaxseed and its lignan and oil components reduce mammary tumor growth at a late stage of carcinogenesis. Carcinogenesis 17:1373-1376. 
4. Thompson, L.U., Seidl, M., Rickard, S., Orcheson, L., and Fong, H. 1996b. Antitumorigenic effect of a mammalian lignan precursor from flaxseed. Nutrition and Cancer 26:159-165. 
5. Jenab, M. and Thompson, L.U. 1996. The influence of flaxseed and lignans on colon carcinogenesis and glucuronidase activity. Carcinogensis. 17:1343-1348. 
6. Yuan, Y.V., Rickard, S.E. and Thompson, L.U. 1999. Short-term feeding of flaxseed or its lignan has minor influence on in vitro hepatic antioxidant status in young rats. Nutr. Res. 19:1233-1243. 
7. Hauman, B.F. 1998. Alternative source for n-3 fatty acids. Inform. 9:1108-1109, 1112, 1115-1116, 1118-1119. 
8. Manthey, F., Lee, R., and Kegode, R. 2000. Quality of spaghetti containing ground flaxseed. In Proceedings of the 58th Flax Institute of the United States. Fargo, ND. pp. 92-99. 
9. Bhatty, R. and Cherdkiatgumchai, P. 1990. Compositional analysis of laboratory-prepared and commercial samples of linseed meal and hull isolated from flax. J. Amer. Oil Chem. Soc. 67(2):79-84. 
10. Garden-Robinson, J. 1994. Flaxseed gum: extraction, composition, and selected applications, In Proceedings of the 58th Flax Institute of the United States. Fargo, ND. pp. 154-164. 
11. Lee, R., Manthey, F., and Hall III, C. 2000. Quality and " -linolenic acid content of spaghetti containing ground flaxseed. AACC, Annual Meeting. Kansas City. November 5-8. 

For additional information please contact Clifford Hall III at 701-231-6359 or Clifford.Hall@ndsu.nodak.edu, North Dakota State University, Department of Cereal and Food Sciences, room 324 IACC, Fargo, ND 58105