2011 Annual Report
1a.Objectives (from AD-416)
The principal goal of the project is to improve the postharvest utilization of cottonseed thereby increasing value of U.S. cotton crop. This will be achieved by developing an improved understanding of cottonseed’s oil, protein, and gossypol components. The objectives of the project are (1) to survey available accessions from the Genetic Resources Information Network (GRIN) cotton database for genotypes modified fatty acid profiles (2) to prepare a series of gossypol derivatives and study their bioactivity (3) to develop improved chromatographic methods for measuring low levels of gossypol (4) to study the potential use of cottonseed protein in adhesive formulations and (5) to modify cottonseed oil hydrogenation processes to reduce levels of trans fatty acids.
1b.Approach (from AD-416)
A number of analytical, chemical, microbial, and cell culture techniques will be employed to achieve the project goals. For fatty acid analysis, gas chromatography coupled with chemical derivatization will be used to profile the fatty acids from extracted cottonseed oil and hydrogenated oil samples. Laboratory synthesis methods will be used to generate gossypol derivatives and liquid chromatography methods will be used to separate and purify the resulting compounds. Microbial and cell culture assays will be used to study the bioactivity of the new compounds. Protein isolation methods will be used to recover cottonseed protein as concentrates and isolates, and these preparations will be used to formulate adhesive systems. Hot-plate pressing of plywood squares will be used to make samples to test for protein adhesive strength and durability. Modification of proteins will be achieved by chemical and physical methods.
Progress was made on a number of objectives. Our multi-year survey of the Cotton Germplasm Database for accessions with unusual oil fatty acid profiles was continued. Chromatography of the Gossypium barbadense (cotton plant) accessions was completed and chromatography of the Gossypium hirsutum landraces (cotton plant) has started. We have not started a statistical evaluation of the results but we did find accessions with oils having oleic acid levels approaching 40%, which is more than double the typical value of this acid and is a trait that would improve the oxidative stability of the oil. In addition, a collaborative study on the distribution of cottonseed oil fatty acids in current agronomic cotton varieties was finished. Variations existed among these varieties; the differences were relatively small and were not useful for breeding purposes.
Work was started on the use of cottonseed proteins in wood adhesive formulations. Protein isolates were prepared and used to make adhesives for gluing fiberboards and maple veneers. Initial results indicate that cottonseed protein isolates performed as well as soy protein isolates in comparable formulations for fiber boards. Under some conditions, the cottonseed proteins formed stronger glue joints that did the soy proteins. Protein denaturants appears to improve the adhesive strength of the cottonseed protein formulations in some applications.
As part of an effort to find value in cottonseed’s unusual minor components, a library of gossypol-type compounds is being synthesized and used to support bioactivity studies. Methylated derivatives of gossypolone, a partially oxidized form of gossypol, were prepared from a mixture of methylated gossypol compounds that were recovered from cotton roots. Preliminary antifungal studies were conducted with Aspergillus (A.) flavus, a fungal organism that infects cotton and produces toxins responsible for crop losses. Results from this work indicate that the gossypolone and apogossypolone were better A. flavus growth inhibitors than gossypol. The work also showed that methylated derivatives of these compounds were less inhibitory that the corresponding parent compound. From diffraction studies on these new compounds, the dimethyl form of gossypolone was found to form a crystal structure with an unusual ring structure.
Plasma gossypol levels were measured for two external collaborative projects that were focused on expanding the use of cottonseed products in animal feeds. One study focused on supplementing range fed deer with whole cottonseed. This work showed that when deer are fed a supplement containing whole cottonseed, the animals accumulate modest levels of gossypol in their bloodstreams over time. The levels observed, however, did not cause any ill effects. Once animals were removed from the supplement, plasma gossypol levels dropped rapidly and were less than 10% of their values after five weeks. In a separate study, gossypol levels were monitored in dairy cows fed Upland and Pima cottonseed products. In this work, extrusion processing reduced blood gossypol levels compared with the levels observed when the cottonseed was fed unprocessed.
Cottonseed oil hydrogenation. Processed foods containing high levels of trans-fatty acids (TFA) that are of some health concern and considerable research is underway to try to reduce the levels of these undesirable products in processed foods. Researchers in the Commodity Utilization Research Unit in New Orleans, Louisiana, have been studying alternative cottonseed oil hydrogenation conditions. Several commercial catalysts were studied, with the goal of finding conditions that minimize trans-fatty acid (TFA) content. In preliminary results, we observed equivalent or lower stearic and TFA acid levels in partially hydrogenated cottonseed oil, in comparison with levels reported for other hydrogenated oils in the literature. The results should be useful for reducing trans-fat levels in processed foods and should provide some marketing benefits that will be useful to the cottonseed oil industry.
Use of cottonseed proteins in adhesive formulations. Because there are currently only limited markets for the use of cottonseed proteins, expanded uses are highly desirable. ARS researchers in the Commodity Utilization Research Unit in New Orleans, Louisiana, did experiments that indicated that cottonseed proteins can compete with soybean proteins in formulating interior wood adhesives. The results might provide a new valuable non-feed market for cottonseed proteins. The presence of gossypol in cottonseed, which limits the food and feed use of cottonseed proteins, may be beneficial in this application. The results should be of interest to cotton farmers, ginners, cottonseed marketers, and oil crushers.
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Cheng, H.N., Biswas, A. 2011. Chemical modification of cotton-based natural materials: products from carboxymethylation. Carbohydrate Polymers. 84:1004-1010.
Cheng, H.N., Gu, Q. 2010. Synthesis of poly (aminoamides) via enzymatic means. In: Cheng, H.N., Gross, R.A., editors. Green Polymer Chemistry: Biocatalysis and Biomaterials. Washington, DC: ACS Symposium Series, Vol. 1043. pp. 255-263.
Cheng, H.N. 2010. Enzyme-catalyzed synthesis of polyamides and polypeptides. In: Loos, K., editor. Biocatalysis in Polymer Chemistry. Weinheim, Germany:Wiley-VCH. p. 131-141.
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Dailey Jr, O.D., Prevost, N.T., Strahan, G.D. 2009. Conversion of methyl oleate to branched-chain hydroxy fatty acid derivatives. Journal of the American Oil Chemists' Society. 86:1101-1114.
Dowd, M.K., Boykin, D.L., Meredith Jr, W.R., Campbell, B.T., Bourland, F.M., Gannaway, J.R., Glass, K.M., Zhang, J. 2010. Fatty acid profiles of cottonseed genotypes from the National Cotton Variety Trials. Journal of Cotton Science. 14:64-73.
Dowd, M.K., Kiely, D.E., Zhang, J. 2011. Monte Carlo-based searching as a tool to study carbohydrate structure. Carbohydrate Research. 346:1140-1148.
Zelaya, C.A., Stevens, E.D., Dowd, M.K. 2010. 6,6´-Dimethoxygossypolone. Acta Crystallographica Section C: Crystal Structure Communications. C66:o517-o520.
Bullock, S.L., Hewitt, D.G., Stanko, R.L., Dowd, M.K., Rutledge, J., Draeger, D.A. 2010. Plasma gossypol dynamics in white-tailed deer: Implications for whole cottonseed as a supplemental feed. Small Ruminant Research. 93:165-170.
Ye, W., Chang, H.-L., Wang, L.-S., Huang, Y.-W., Shu, S., Sugimoto, Y., Dowd, M.K., Wan, P.J., Lin, Y.C. 2010. Induction of apoptosis by (-)-gossypol-enriched cottonseed oil in human breast cancer cells. International Journal of Molecular Medicine. 26(1):113-119.
Wang, J., Wang, X., Chen, F., Wan, P.J., He, G., Li, Z. 2005. Development of competitive direct ELISA for gossypol analysis. Journal of Agriculture and Food Chemistry. 53(14):5513-5517.
Mellon, J.E., Zelaya, C.A., Dowd, M.K. 2011. Inhibitory effects of gossypol-related compounds on growth of Aspergillus flavus. Letters in Applied Microbiology. 52:406-412.