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United States Department of Agriculture

Agricultural Research Service

Research Project: Amylose Helical Inclusion Complexes for Food and Industrial Applications

Location: Functional Foods Research Unit

2011 Annual Report


1a.Objectives (from AD-416)
The overall project goal is to develop new technologies for producing amylose helical inclusion complexes on a large scale that provide new biobased applications to replace existing petrochemical-derived products, covalently modified starches, and natural gums using energy-efficient, green manufacturing techniques. Helical inclusion complexes of amylose and various ligands have been described in the literature, but they are typically produced in small quantities using various solvents and alkaline solutions. The goal of this project is to characterize thermomechanically-produced amylose helical inclusion complexes and investigate commercial applications based on their chemical and physical properties. Specific objectives are: Objective 1. Develop biobased, environmentally friendly technology for producing amylose helical inclusion complexes with anionic ligands which are functional in applications such as water-dispersible surfactants and lubricants. Objective 2. Develop biobased, environmentally friendly technology for producing amylose helical inclusion complexes with cationic ligands which are functional in applications such as papermaking retention aids and flocculating agents. Objective 3. Develop biobased, environmentally friendly technology for producing amylose helical inclusion complexes and spherulites with uncharged ligands which are functional in applications such as controlled-release agents, microbial production substrates and dispersants.


1b.Approach (from AD-416)
Steam jet cooking technology will be investigated as an efficient method for producing amylose helical inclusion complexes with functional properties relevant to a wide range of food and industrial applications. Whereas many types of such complexes have been prepared in small quantities under laboratory conditions, this research will focus on developing thermomechanical production methods using only starch, water, and specific ligands of interest to form complexes that can be used for applications currently employing covalently modified starches, expensive natural gums, and other materials. Preliminary experiments with high amylose starch and sodium palmitate have demonstrated that amylose inclusion complexes could be readily formed in high yields in jet cooked starch dispersions. A series of anionic, cationic, and uncharged ligands will be investigated in terms of ability to form complexes thermomechanically with various commodity starches such as normal dent, high amylose, and waxy cornstarch, and their morphological, chemical, and physical properties will be determined. Specific ligands will be chosen for particular end-use applications, including surfactants, lubricants, papermaking retention aids, flocculating agents, and controlled release agents for food and non-food products. The complexes possessing crystalline spherulite morphology will be investigated as solid supports for the growth of microbes in liquid culture and as a dispersal medium for microbial products. For each application, the best ligands will be selected from available candidates, sufficient quantities of amylose inclusion complexes will be prepared using steam jet cooking methods, and laboratory tests will be performed to determine the performance of the complexes for the specific end use. As the efficacy of these products are successfully demonstrated, prototype products will be prepared and collaboration with the private sector will be sought for transfer of the technology to the private sector for field testing and market development.


3.Progress Report
The discovery that dispersions of amylose-sodium palmitate complexes formed reversible gel structure in response to subtle changes in pH, concentration, and temperature led to a patent application and investigations utilizing this phenomenon for application development. Significant progress was made in solving product development and commercial scale production problems in collaboration with starch-oil composite licensees. (1) Sodium palmitate added to jet-cooked high amylose corn starch formed helical inclusion complexes whose viscosity is controllable by pH, salt, and temperature. Potential applications include thickeners, dispersants for lipids, and natural gum replacements. (2) Commercial scale production of anti-microbial lotions was developed in collaboration with a CRADA partner and licensee. Steam flow, pressure, flow rate, and holding temperature were adjusted to yield lotions with suitable lipid droplet size, viscosity, and sufficiently cooked starch. (3) Amylose complex spherulites similar to those made by jet cooking were formed in a laboratory microwave reactor, permitting small quantities to be made for application development and characterization. (4) Carbon black dispersed by solutions of amylose/sodium palmitate complexes flocculated during storage. However, carbon black composites made with jet-cooked cornstarch and passed through a laboratory homogenizer had long-term stability due to the adherence of a starch film to the particles. This provides a method for delivering washable carbon black in aqueous coating or printing applications. (5) High amylose starch was co-jet cooked with beeswax to determine which beeswax constituents formed helical inclusion complexes with amylose. Microscopy revealed the formation of spherical aggregates of helical inclusion complexes, confirmed by X-ray diffraction. This research provides evidence of selective complexation by amylose of components of a heterogeneous natural material. (6) Amylose/sodium palmitate complexes were mixed with rubber latex and precipitated by acidification to form a dried powder, potentially useful for making starch-reinforced rubber products. (7) Composites made with jet-cooked waxy cornstarch and essential oils of cinnamon and oregano were investigated as antimicrobial coatings on fresh spinach leaves inoculated with a non-pathogenic strain of E. coli. Compared with composites made with canola oil, microbial growth was inhibited from 10**3 to 10**6 times depending on storage time. This demonstrated the potential of starch-lipid composites to provide antimicrobial protection to fresh produce as a liquid film coating. (8) Amylose/sodium palmitate complexes in solutions were exchanged with silver salts to form amylose/silver palmitate complexes. On reduction, these formed nanometer-scale particles as demonstrated by transmission electron microscopy. A potential application of these materials is antimicrobial coatings or films. (9) Encapsulating UV-absorbing feruloyated soybean oil components (Soyscreen) with jet-cooked starch increased the UV protection for hydrophobic conidia of a biocontrol fungus in laboratory experiments using balsa wood as a substrate.


4.Accomplishments
1. Stimulus-responsive liquids and gels based on amylose-sodium palmitate complexes. Many food and industrial products are thickened or emulsified by using expensive natural gums or surfactant chemicals. Agricultural Research Service scientists in the Functional Foods Research Unit at the National Center for Agricultural Utilization Research in Peoria, IL used steam jet cooking to disperse corn starch and sodium palmitate, a component of vegetable oil, to obtain solutions of a molecular complex formed from the amylose component of starch and sodium palmitate. The resulting liquid dispersions were found to thicken and form soft or firm gels with subtle changes in pH, salt content, or concentration. The surfactant properties of these complexes provide an effective medium for delivery of a wide range of oily materials in different physical forms. Steam jet cooking provides a commercially scalable method of producing large quantities of these complexes for investigating potential applications and developing products such as food thickening agents, detergents, lubricants, cosmetics, lotions, or non-food home and garden products. A U.S. Patent Application describing this technology was filed which will enable its development as a green platform technology for biobased products.

2. Stable carbon black/starch composites obtained by homogenization treatment. This research showed that cheap and renewable corn starch can be utilized to effectively disperse hydrophobic carbon black into water. Numerous approaches have been used in research and industrial efforts to chemically modify carbon black, so that it can be dispersed in water for specific applications. Agricultural Research Service scientists in the Functional Foods Research Unit at the National Center for Agricultural Utilization Research in Peoria, IL have found that passing jet-cooked cornstarch mixed with carbon black through a laboratory homogenizer resulted in finely dispersed particles which remained so during storage without the use of emulsifiers. Chemical, instrumental, and electron microscope analyses provided evidence of an adhering starch film on carbon black particles similar in size to the original carbon black used. This technology can be used for washable, water-based carbon black applications for printing and coating applications without the use of covalently modified carbon black or chemical surfactants that may be expensive, non-biodegradable, and whose production requires toxic reagents or negatively impacts the environment. Potential products include water-based ink, paint, and coating applications, asphalt sealants and colorants for decorative concrete or textiles.

3. Commercial scale production of anti-microbial lotions based on amylose/fatty acid salt complexes. Cornstarch-based lotions for delivery of antimicrobial agents to the skin were developed by Agricultural Research Service scientists in the Functional Foods Research Unit at the National Center for Agricultural Utilization Research in Peoria, IL in collaboration with a licensee under a CRADA. By using the amylose fraction of cornstarch and chemically combining it with a fatty acid salt derived from vegetable oil, a non-tacky formulation with sufficient viscosity was obtained. In order to enable production of this formulation on a commercial scale by the collaborator, steam flow, temperature/pressure, product flow rate, and post-cooking holding temperature were investigated to determine the best conditions for producing a quality product. Lotions with suitable lipid droplet size, viscosity, and freedom from insufficiently cooked starch granules were obtained. These lotions have been previously shown to provide longer lasting antimicrobial protection than other products due to the film-forming ability of the starch and oil components used. It is now possible to produce this product in commercial quantities.


Review Publications
Behle, R.W., Compton, D.L., Kenar, J.A., Shapiro Ilan, D.I. 2011. Improving formulations for biopesticides: Enhanced ultraviolet protection for beneficial microbes. Journal of ASTM International. 8(1):137-157.

Mohamed, A., Xu, J., Singh, M. 2010. Yeast leavened banana-bread: formulation, processing, color and texture analysis. Food Chemistry. 118:620-626.

Carpenter, C.A., Kenar, J.A., Price, N.P. 2010. Preparation of saturated and unsaturated fatty acid hydrazides and long chain C-glycoside Ketohydrazones. Green Chemistry. 12(11):2012-2018. DOI: 10.1039/c0gc00372g.

Byars, J.A., Fanta, G.F., Felker, F.C. 2011. Rheological properties of starch-oil composites with high oil:starch ratios. Cereal Chemistry. 88(3):260-263.

Shogren, R.L., Peterson, S.C., Evans, K.O., Kenar, J.A. 2011. Preparation and characterization of cellulose gels from corn cobs. Carbohydrate Polymers. 86(3):1351-1357. DOI: 10.1016/j.carbpol.2011.06.035.

Last Modified: 11/26/2014
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