2012 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.
During the year, progress was made on project objectives 1-5 that contribute to components 1 and 3 of the National Program 306 Action Plan.
In the New Orleans, LA, ARS location, our survey of the Cotton Germplasm Database for accessions with unusual fatty acid profiles continued. Chromatography of the Gossypium hirsutum landraces was completed. Like the analysis of the Gossypium barbadense collection, a few accessions were identified that have a high oleic acid trait. We also started the integration of the prior year data although this part of the project is proceeding slower than expected. Four seed types with high oleic acid levels were grown at the winter nursery in Mexico to confirm that the trait was maintained. Analysis of these progeny seed showed that one accession produced good seed and fiber yields, and retained a high level of oleic acid (42%).
To find value in cottonseed’s unusual minor components, testing of our library of gossypol compounds continued. Gossypol, gossypolone, and apogossypolone were tested as growth inhibitors against ten fungi. Gossypolone showed complete inhibition of eight organisms. All three compounds showed at least some growth inhibitory effects against the other two organisms. In addition, the compounds also inhibited some Aspergillus species toxin production.
Our efforts to convert gossypol Schiff’s bases to stable secondary amines have not proved successful. This continues as a research goal. To better characterize these recalcitrant molecules, we have prepared single crystals of two of these compounds with the intention of conducting charge density studies to better understand their lack of reactivity.
Work also continued on the use of cottonseed proteins in wood adhesive formulations. This work was extended by adding crosslinking or denaturing agents to the formulations. Improved results were found by added sodium dodecyl sulfate, a denaturing reagent, but the other agents did not appear to improve adhesive performance. We also found that the methods used to prepare the isolates have some affect on adhesive properties. The influence of these procedures will be studied further. As the preparation of protein isolates adds cost to the formulations, some simple fractionation of cottonseed meal has been undertaken to isolate cheaper protein fractions for adhesive testing.
Efforts to lower trans-fat formation during cottonseed oil hydrogenation also continued. A reactor was built to conduct experiments at elevated hydrogen pressures. This system will also allow sampling over time. A set of experiments has started to study the influence of pressure on mixing, reaction rates, and trans-fatty acid formation. A preliminary set of data has been collected. Trans-fatty acid results are pending.
Among our collaborative efforts, a number of cottonseed isolates and concentrates have been prepared in support of Cotton, Inc. studies on the suitability of cottonseed components as aquaculture feed ingredients. In addition, we have completed a study to show that 90-95% of gossypol can be removed from commercial cottonseed meals by solvent extraction with acid.
Cottonseed oils naturally high in oleic acid. Accessions from our National Cottonseed Germplasm Collection have been identified with a high oleic acid trait (36-42% oleic acid). By growing a few of these wild photoperiodic varieties in the Winter Nursery in Mexico, ARS researchers in the Commodity Utilization Research Unit in New Orleans, Louisiana, have found one accession that produced good seed yields with reasonable fiber quality. The seeds will be grown in the upcoming year to recover sufficient oil to conduct functional property studies. This oil should have improved oxidative stability compared with normal cottonseed oil, which should be of interest to the oil processing industry.
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 content. In preliminary results, we observed equivalent or lower trans-fatty 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, have shown that cottonseed proteins can compete with soybean proteins in formulating interior wood adhesives. The effects of adding agents known to affect protein structure to the formulations are in progress. The results might provide a new valuable non-feed market for cottonseed proteins. The results will be of interest to cotton farmers, ginners, cottonseed marketers, and oil crushers.
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Pettigrew, W.T., Dowd, M.K. 2011. Varying planting dates or irrigation regimes alters cottonseed composition. Crop Science. 51:2155-2164.
Cheng, H.N., Dowd, M.K., Shogren, R.L., Biswas, A. 2011. Conversion of cotton byproducts to mixed cellulose esters. Carbohydrate Polymers. 86:1130-1136.
Sutivisedsak, N., Cheng, H.N., Dowd, M.K., Selling, G.W., Biswas, A. 2012. Evaluation of cotton byproducts as fillers for poly(lactic acid) and low density polyethylene. Industrial Crops and Products. 36:127-134.
Pettigrew, W.T., Dowd, M.K. 2012. Interactions between irrigation regimes and varieties result in altered cottonseed composition. Journal of Cotton Science. 16:42-52.
Mellon, J.E., Zelaya, C.A., Dowd, M.K., Beltz, S.B., Klich, M.A. 2012. Inhibitory effects of gossypol, gossypolone, and apogossypolone on a collection of economically important filamentous fungi. Journal of Agricultural and Food Chemistry. 60:2740-2745.
Biswas, A., Sharma, B.K., Vermillion, K., Willett, J.L., Cheng, H.N. 2011. Synethesis of cyclic ketal from soybean oil and fatty esters. Journal of Agricultural and Food Chemistry. 59(7):3066-3070.
Denton, T.T., Hardcastle, K.I., Dowd, M.K., Kiely, D.E. 2011. Characterization of D-glucaric acid using NMR, x-ray crystal structure, and MM3 molecular modeling analyses. Carbohydrate Research. 346:2551-2557.
Miri, M.J., Pritchard, B.P., Cheng, H.N. 2011. A versatile approach for modeling and simulating the tacticity of polymers. Journal of Molecular Modeling. 17:1767-1780.
Beisel, C.L., Dowd, M.K., Reilly, P.J. 2005. Conformational analysis of gossypol and its derivatives by molecular mechanics. Journal of Molecular Structure (Theochem). 730(1-3):51-58.
Dao, V-T., Dowd, M.K., Martin, M-T., Gaspard, C., Mayer, M., Michelot, R.J. 2004. Cytotoxicity of enantiomers of gossypol schiff's bases and optical stability of gossypolone. European Journal of Medicinal Chemistry. 39(7):619-624.
Lordelo, M.M., Davis, A.J., Calhoun, M.C., Dowd, M.K., Dale, N.M. 2005. Relative toxicity of gossypol enantiomers in broilers. Poultry Science. 84(9):1376-1382.