Location: Plant Polymer Research
2023 Annual Report
Objectives
Objective 1: Increase the value of amylose inclusion complexes (AICs) produced from various carbohydrates and ligands for use as emulsifiers, film blends or surface treatments for paper products.
Sub-Objective 1A: Develop effective emulsifiers based on AIC using high-amylose corn (HAC) or other polysaccharides, complexed with the salts of fatty acids or amines, using economical manufacturing techniques.
Sub-Objective 1B: Produce higher value polymer blends or cellulosics using amylose inclusion complex materials made with lower-cost starches, such as normal corn food-grade starch (FGS) or corn flour, and fatty acids/amines or their salts.
Objective 2: Resolve the underlying lab and pilot-scale extraction and biorefining techniques that generate protein-rich industrial feedstocks from plant crops, such as camelina or sorghum, define their functional properties, and enable industrial production and commercialization.
Approach
This project plans to increase the value of existing and new crops by developing higher value amylose and protein products. Recent research has shown that starch processed from corn can provide high-value amylose inclusion complexes with vegetable oil derivatives (ex. fatty acid or amine salts) in excellent yield and at low cost. To transfer this technology to industry, it is critical to determine the impact of the amount and source of amylose on the attributes of the resulting complex. Protein-rich crops such as camelina or sorghum, which are not produced in high quantities in the U.S., have the potential to provide additional higher revenue streams to U.S. farmers. While the U.S. is the world’s leader in sorghum production, the use of sorghum is currently generally relegated to feed uses. Given the similarities between sorghum and corn, it is expected that sorghum value can be increased by utilizing its component fractions, as has been done to corn. Camelina has shown value as a winter-grown oilseed crop, but new uses are needed for the components of the resulting seed press cakes. Improved extraction techniques are needed to increase the value of both crops. This research will: 1) enable new approaches to produce and use amylose complexes and establish their physicochemical properties, and 2) innovate and evaluate extraction techniques, as well as identify uses for proteinaceous materials from crops such as sorghum and camelina. Improved utilization of current and future crops will enhance the value of these crops in new and existing markets.
Progress Report
In support of Objective 1, Sub-objective 1A, research continued on the use of amylose inclusion complexes (AIC) as emulsifiers or surfactants. Emulsifiers are used to combine materials that normally do not mix well (such as oil in water) into one blended product. There are food (salad dressing) and non-food (paint) applications. Surfactants are materials that make water ‘slicker’, this is of value in cleaning applications. The presence of a bio-based surfactant/emulsifier will allow products such as cleaners, adhesives, foams, and food products to have at least equivalent performance to petroleum-based products. We have found that AIC made from corn can produce effective food and industrial emulsifiers and surfactants. An AIC is a physical mix formed from starch and a vegetable oil derivative (called a ligand, either a fatty acid or amine salt). Fatty acid ligands derived from plant oils were obtained from researchers in the Bio-Oils Research Unit in Peoria, Illinois. The fatty acids came from camelina, coconut, coriander, citrus, cuphea, hemp and meadowfoam. Hydrolyzed vegetable shortening was also used to generate fatty acid. These fatty acid salts successfully produced AICs that were similar to those AIC made using pure ligands obtained from laboratory chemical suppliers. These AIC were evaluated as surfactants and emulsifiers. These vegetable oil-based AIC were more effective surfactants than the pure saturated fatty acid salt AICs, having lower surface tension (of value in cleaning applications). There was a general trend observed where vegetable oils with more unsaturation have somewhat higher surface tension (potentially less value). For example, the fatty acid AIC derived from meadowfoam (100% unsaturated) had higher surface tension than the AIC made using cuphea (17% unsaturated). This ability to control surface tension will allow companies to design detergents that will fit the need of a given application. Emulsions could be prepared from these plant oil-derived AICs. The plant-based AICs provided solutions with similar viscosities to other products used in these applications. These results demonstrate that AIC produced from vegetable oils can provide valued food grade emulsifiers and cleaning products.
In support of Objective 1, Sub-objective 1A, fundamental work necessary for defining the value of fatty amine salt AICs as emulsifiers and surfactants was generated. Fatty acid amine salts with an even number of carbons from C10 through C18 were used to make AICs. The C10 AIC did not form a quality AIC (poor water solubility). Therefore, further studies were carried out using AIC amine salts having twelve carbons (C12AIC), fourteen carbons (C14AIC), sixteen carbons (C16AIC) and eighteen carbons (C18AIC). The melting and freezing temperatures were determined to increase linearly as the number of carbons in the fatty amine salt increased. The C12AIC had provided a more heterogenous solution than the others, reducing its value. The fatty amine salt AICs solutions had much lower surface tensions than the fatty acid salt AIC with similar ligand lengths. This will have value to detergent producers interested in higher performance cleaners. The critical micelle concentrations , where the AIC begins to function as a surfactant (equivalent to ‘how much surfactant is needed’), is about 50% less than the fatty acid salt AIC alternatives. These fatty amine salt AICs are competitive with petroleum-based surfactants and can be produced using a much greener process. These fatty amine salt AICs form emulsions that are superior to that of the commercial starch-based, guar gum, or protein (soybean) based emulsifiers. The performance of these AICs in this application, combined with their previously determined antimicrobial and pesticidal performance, is such that they will have value in applications where emulsions or cleaning performance combined with pesticidal activity are needed.
In support of Objective 1, Sub-objective 1A, to better evaluate the performance of other fatty amine salt AICs, fatty secondary, tertiary and quaternary salt AICs were produced and evaluated. These AICs were all produced in near 100% yield and had similar physical properties when compared to the AICs made from the analogous primary amine salts. The surface tension of solutions made using these substituted amine salts were in general higher than that of the analogous primary amine salts. However, by careful manipulation of the starch and ligand, AICs can be produced having surface tensions competitive with non-biobased silicon-based surfactants. This ability to directly compete with the non-biobased silicon-based systems will allow more biodegradable biobased systems to replace silicon based systems in emulsifying or wetting applications.
In support of Objective 2, research continued on the production of proteins from non-traditional sources. Plant-based proteins have high demand currently for the alternative protein markets (2022 global market=US$12.2B). Camelina is a winter annual crop being cultivated as a biodiesel feedstock and potential source of novel protein. Previous bench-scale work applied degumming and base extraction/acid precipitation to produce a protein concentrate from a camelina line modified for enhanced oil traits. In research under Objective 2 that was conducted to support the milestone of defining process conditions for pilot-scale production of camelina proteins, substantial progress was made to develop approaches for isolating proteins from new varieties of pennycress, another winter annual crop in the same family as camelina. The new pennycress varieties with specialized traits (low fiber, high protein/oil, yellow seed color instead of black) have been developed to establish the plants as unique cover crops and as cash crops for oil (as biodiesel source) and protein. The new specialty varieties’ protein extractability and properties are still unknown. Through a funded collaboration with an industrial partner, we developed an improved method for isolating protein from new high value golden pennycress varieties and determined protein yield and properties. Using the industrially relevant processes - cold pressing, alcohol defatting and saline extraction, variety TT8 had much greater protein recovery and purity than variety TTG1. The TT8 variety also provided a protein that was more soluble in acidic media and had superior foaming and emulsification properties. The protein from both new varieties showed improved functional properties over those of wild type pennycress protein. Highly soluble proteins are usually preferred by industry, given that protein solubility affects other functional properties. The foaming and emulsification (blending incompatible liquids like water and oil) traits of the golden pennycress protein isolates indicate potential use in whipped dairy products, shaving creams, foamed glues, dairy beverage alternatives, protein shakes, yogurt, salad dressings, baked goods, and paints. These results showed that high purity pennycress protein with enhanced properties can be isolated from specialty golden pennycress by using this newly developed environmentally friendly and industrially relevant protein isolation method.
Improved techniques for extracting plant proteins from soybeans and other crops are needed to maximize the amount and quality of the protein product. In additional research under Objective 2, substantial progress was made to assess high-power sonication (HPS, the use of sound waves to impart energy) as an alternative physical technology to produce plant proteins with greater yield and enhanced functional properties. Through a funded research collaboration with Iowa State University, we determined six optimal conditions for HPS-assisted protein extraction from soybean flour or flakes and evaluated the impact of HPS on protein yield, composition, and properties. Regardless of starting material, HPS treatment generally increased protein yield and produced high purity (at least 90% protein) extracts that met the classification for soy protein isolate (SPI). While HPS reduced the solubility of flour-SPI, especially when using the shorter extraction, the values were still markedly greater than those reported for conventionally prepared SPI. Proteins with higher solubility have greater value, given that protein solubility affects other functional properties. The optimized HPS-extraction time settings resulted in SPI emulsifying properties (blending incompatible liquids like oil and water) that were superior to those of conventionally prepared SPI, as well as produced substantial and stable foams. These results demonstrate that the optimized HPS treatments were beneficial for soy protein recoveries and properties, thus increasing the value of this crop.
In further support of Objective 2, efforts were put forth to increase the value of commodity and specialty agricultural materials. Proteins from peas, soybeans, and crickets were combined and thermally treated to provide an alternative to traditional meats. Samples were prepared and compared with 80 and 90% hamburger and the plant-based protein – Beyond Meat(TM). The samples produced have properties (such as hardness, springiness and chewiness) that bracket those of commercial products. Through a partnership with the Functional Food Research Unit, Peoria, Illinois, it is anticipated that additional research efforts will result in a product that is competitive with commercial offerings.
Accomplishments
1. Environmentally friendly protein production from new pennycress varieties. Pennycress is a winter crop that is being cultivated as an off-season cash cover crop (for biofuel and protein) that will provide an additional revenue stream to farmers while also increasing the soil quality. New and improved pennycress varieties have been developed as a novel source of plant-based protein; research is needed to assess their protein extractability and the functionally important properties of these proteins. ARS researchers in Peoria, Illinois, developed an environmentally friendly method for extracting protein from new pennycress varieties. This new industrially relevant method produced high-purity protein that is highly soluble in acidic environments (like whey protein) and has excellent foaming (important in whipped dairy products, yogurt, or dairy beverage alternatives) and emulsifying (useful in salad dressing or as meat binders) properties, thus increasing the value of the recovered protein. In addition, this process used ethanol, a non-petroleum-based solvent, to initially extract oil from pennycress and therefore, aligns better with consumer-preferred ‘clean’-labelled products. The new protein products serve as an additional revenue stream for pennycress, will increase the value and adoption of pennycress crops, and subsequently benefit farmers, downstream processors, consumers and the environment (i.e., soil health and water quality initiatives).
2. High-power sonication for improved plant protein extraction and properties. High-power sonication (HPS, using sound wave energy to enhance chemical and physical transformations) is a green processing technology to enhance poor yields and limited functionality of plant-based proteins. Through a funded research collaboration with Iowa State University, ARS researchers in Peoria, Illinois, evaluated the impact of optimized conditions for HPS-assisted protein extraction from soybean flour or flakes on protein yield, composition, and properties. HPS treatment generally increased protein yield and produced high purity (at least 90% protein) soy protein isolate (SPI). The optimized HPS-extraction time settings resulted in SPI with superior solubility, foaming, and emulsifying property (ability to blend two unmixable liquids like water and oil) compared with conventionally prepared SPI. These results demonstrate that the industrially relevant optimized HPS treatments were beneficial for soybean protein recoveries and properties (2022 soy protein isolate global market=US$3.0B), thus increasing the value of this crop. This information will benefit downstream processors of legumes and contribute to higher revenue for all participants in the value-chain.
3. Production of high value biobased surfactants and emulsifiers. Emulsifiers are used to combine two liquids that are not compatible (for example, vinegar and oil) while surfactants are used to reduce the surface tension of water and allow solutions to penetrate into small spaces (for example, cleaning dirt-filled crevices). Current commercial emulsifiers include chemically altered starch (food usage limits), gum Arabic, and soy protein. Commercial surfactants include sodium lauryl sulfate (SLS) and polyethylene oxide (PEO), both of which are made using toxic non-biobased agents. ARS researchers in Peoria, Illinois, have demonstrated that amylose inclusion complexes (AIC) made from food grade starch and vegetable oil derivatives are very effective emulsifiers or surfactants. The AIC have unique value depending on the vegetable oil chosen. Some AICs are effective food grade emulsifiers and can be used in limitless amounts, which allows greater latitude in the production of food products. Other AICs provide surfactants competitive with SLS and PEO products. The AIC is made in near 100% yield using a common industrial process. This new high value domestic biobased/biodegradable emulsifier/surfactant will benefit corn growers, processors, and the consumer by generating new uses for agricultural products and replace agents that require toxic precursors.
Review Publications
Hojilla-Evangelista, M.P., Evangelista, R.L., Selling, G.W., Ulmasov, T. 2023. Extraction and properties of proteins in covercress, new pennycress varieties developed as cover crop and alternative plant protein source. Journal of the American Oil Chemists' Society. 100(4):329-341. https://doi.org/10.1002/aocs.12675.
Selling, G.W., Hay, W.T., Evans, K.O., Peterson, S.C., Utt, K.D. 2023. Improved hydroxypropyl methylcellulose films through incorporation of amylose-N-1-hexadecylammonuium chloride inclusion complexes. Industrial Crops and Products. 194. Article 116352. https://doi.org/10.1016/j.indcrop.2023.116352.
