Location: Functional Foods Research2012 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, 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:
Experiments with a variety of ligands, including cationic and polymeric ligands, provided valuable insight into the chemical criteria for their use in forming amylose inclusion complexes with steam jet cooked corn starch, and have enabled investigation of new potential applications. (1) Spherulites from amylose-fatty acid complexes made by microwave processing were compared with those made by steam jet cooking. Morphologies of spherulites made from non-defatted high amylose starch was similar using both methods, but microwave processing allowed adjustment of processing conditions to increase spherulite yield. Spherulites prepared from defatted starch with specific fatty acids added had different morphologies, suggesting a role for native starch lipids in determining spherulite type. (2) Silver nanoparticles stabilized by amylose-sodium palmitate complexes were characterized by spectroscopy, X-ray diffraction, and transmission electron microscopy. They were found to be smaller and more water soluble than those prepared with commercial soluble starch. Viscosity control by pH adjustment and precipitation of the nanoparticles upon acidification were shown. (3) High amylose corn starch was jet cooked with a polymeric ligand, ethylene/acrylic acid copolymer (EAA), to form stable dispersions of nano-sized EAA micelles made more hydrophilic by partial complexing with amylose. (4) Amylose-sodium palmitate complexes performed similarly to guar gum as a tackifier for hydromulch used for soil erosion control and hydroseeding. Expanding markets for guar gum are making it prohibitively expensive. (5) Rheology of dispersions of amylose-sodium palmitate complexes prepared with blends of normal and high amylose corn starch was compared with that of dispersions of complexes prepared previously with high amylose corn starch. The higher amylopectin content of less expensive normal corn starch was shown to decrease the gel strength. (6) Amylose complexes were prepared with a cationic amine ligand, octadecyl amine hydrochloride. Viscosity of these dispersions increased and the complexes precipitated with increase in pH, analogous to the response to acidification of complexes with sodium palmitate, an anionic ligand. (7) Both water soluble amylose-sodium palmitate and spherulites made from amylose-fatty acid complexes were found to be almost completely non-resistant to enzyme hydrolysis, likely due to complete dissolution of amylose by jet cooking and prevention of any amylose retrogradation by complexation. (8) Thermal degradation of starch in water was examined using a turbidimeter and size exclusion chromatography. Amylopectin was permanently solubilized, and amylose retrograded on cooling, but both were degraded in molecular weight by higher temperatures. (9) Penetration into leaf tissue of antimicrobial essential oils from starch-oil composites applied as coatings to fresh spinach leaves was determined by extracting washed leaves with hexane followed by gas chromatography. More cinnamaldehyde entered tissues from cinnamon oil than carvacrol from oregano oil, consistent with the higher degree of antimicrobial protection with cinnamon oil observed previously.
1. Water-soluble starch-based silver nanoparticles. Silver nanoparticles (AgNP) have been recently exploited as an antimicrobial agent and many carriers and stabilizers, including starch, have been investigated. However, when AgNP are made using starch as a stabilizer, the nanoparticles tend to be relatively large and the solubility of the dispersions is limited. Agriculture Research Service scientists in the Functional Foods Research Unit at the National Center for Agricultural Utilization Research, Peoria, IL, prepared AgNP dispersions with amylose-sodium palmitate complexes prepared by steam jet cooking. Compared with AgNP made with commercial soluble starch, this method produced smaller AgNP, which are expected to be more effective as antimicrobial agents. The dispersions exhibited the useful characteristics of amylose-sodium complex dispersions such as the ability to: (1) easily re-dissolve dried AgNP dispersions; (2) adjust dispersion viscosity by varying the pH; and (3) precipitate the AgNP material by addition of acid, so as to deposit the AgNP on surfaces or fabrics. This new approach to starch-based AgNP will allow expanded applications and improved performance.
2. Starch-based tackifier for hydromulch to replace guar gum. Hydromulches are widely used for control of soil erosion and establishment of grass seedlings. However, the tackifier commonly used to bind the fibrous components together and improve retention during rain is guar gum, which is becoming prohibitively expensive due to expanding alternate markets for the gum. Agriculture Research Service scientists in the Functional Foods Research Unit at the National Center for Agricultural Utilization Research, Peoria, IL, investigated various alternatives, including amylose-sodium palmitate complexes produced from corn starch and vegetable oil, as tackifiers and binding agents. They found that the performance of the amylose-sodium palmitate complexes closely resembled that of guar gum. As a relatively inexpensive and effective alternative to guar gum, the amylose complexes would also provide cost-saving benefits for the many industries that utilize an estimated 150,000 tons of the natural gum per year. These include meat, dairy, baked goods, textile, paper, pharmaceuticals, cosmetics, and others including, potentially, the natural gas hydraulic fracturing industry whose recent rapid expansion has contributed substantially to guar gum price increases.Byars, J.A., Fanta, G.F., Kenar, J.A., Felker, F.C. 2012. Influence of pH and temperature on the rheological properties of aqueous dispersions of starch-sodium palmitate complexes. Carbohydrate Polymers. 88:91-95.