Location: Plant Polymer Research
2020 Annual Report
Objectives
The long-term objective of this project is to develop novel products utilizing current and new co-products from the industrial processing of agricultural materials. As a result our research will reduce dependence on non-renewable materials and produce higher value products that will benefit a large segment of our economy.
Objective 1: Enable, from a technological standpoint, the commercial production of marketable products from the proteins in crops such as pennycress, camelina, soybean, cottonseed or corn. Sub-objective 1A. Establish pilot-scale extraction and biorefining techniques that generate protein-rich industrial feedstocks from plant crops, such as pennycress, camelina, soybeans, or cottonseed.
Sub-objective 1B. Determine ability to form solvent cast and melt processed films or articles, as well as surface and interfacial tension agents; determine if suitable chemical modifications of these proteins will provide products that can replace petroleum-based products.
Approach
Establish pilot-scale extraction and biorefining techniques that generate protein-rich industrial feedstocks from plant crops, such as pennycress, camelina, soybeans, or cottonseed. Determine ability to form solvent cast and melt processed films or articles, as well as surface and interfacial tension agents. Determine if suitable chemical modifications of these proteins will provide products that can replace petroleum-based products.
Progress Report
This is the final report for this project which terminated in May 2020. See the report for the replacement project, 5010-41000-180-00D, “New and Improved Co-Products from Specialty Crops” for additional information. Significant progress was made on both objectives which fall under National Program 306: Quality and Utilization of Agricultural Products, specifically Component 2, addressing Objective 1.3 of the ARS Strategic Plan.
Pennycress grows as a winter crop. Its oil is being developed as feedstock for biofuel. Research was carried out to develop optimum extraction conditions for larger scale protein removal from pennycress presscake (PPC). One process was based on the standard industrial approach using base (high pH) to extract the protein, precipitation of the protein by addition of acid (low pH), membrane purification, and freeze-drying to recover the protein. The second process used dilute saline extraction, membrane purification, and freeze-drying. A combination of technical innovations and mechanical (use of a high-volume centrifuge) modifications notably improved yield, purity, and solubility of the pennycress protein isolates (PPI). From 5 kg press cake, both processes had approximately 50% yields and produced high purity (92-99%) PPI. Yield and purity are markedly greater than those of the unoptimized method. PPI-saline was more soluble than PPI-acid at all pH.
The remaining solids left after pennycress protein extraction (PSS) and PPC were tested in polymer composites. Polymer blends were prepared using PPC and PSS with polylactic acid (PLA) using standard extrusion techniques. The PLA composites with PPC had greater ductility than control, while PLA composites with PSS had reduced physical properties. Both the PPI-acid and PPI-saline were tested as emulsifiers. Their emulsification properties increased at higher pH. PPI-saline was a much better emulsifier than PPI-acid. The emulsification properties were successfully demonstrated when both PPIs were found to be effective suspending agents for vanilla grounds in a proprietary media.
Research was done to assess the protein from improved hybrids (e.g., light color, high protein) of pennycress for novel value-added uses. Protein concentrates (70-75% protein) from two new specialty hybrids were produced using the saline extraction method described above. Purity is less than wild PPI from earlier work (97% protein). Like earlier results, the specialty pennycress protein concentrates had uniquely high solubility (65-75% soluble protein) across all pH tested.
Utilizing the high purity PPI-acid, films were prepared from formic acid (FA) solution. The high-quality plasticized PPI-acid films had tensile strength that was less than polypropylene but superior to other proteins. The elongation of the PPI-acid films approached that of polypropylene. With increased humidity, the films absorbed up to 35% water, which negatively affected physical properties. The pennycress films were good oxygen and water barriers. The high purity PPI-saline (see above) material had dramatically different properties. The PPI-saline was 4x more soluble than PPI-acid in FA and also formed high quality transparent plasticized films. The PPI-saline films had physical properties similar to other oilseed proteins, but lower than PPI-acid films. Both PPI films may find value in food packaging. Ribbon fibers could be electrospun using PPI with zein from FA solution.
Camelina has shown promise as a biodiesel source. Camelina that had been modified for improved oil traits (acetyl-triacylglycerols, acTAG) was evaluated for the impact these modifications have on protein extraction and properties. Protein was obtained from camelina-acTAG and wild camelina using the base extraction/acid precipitation route. Camelina-acTAG protein extract was double the amount of and was purer than wild camelina extract. Process modifications further improved protein yield by 5-10-fold and protein purity by 10-20% such that the extract is classified as a protein concentrate. Mucilage removal (degumming) prior to protein extraction increased protein yield for camelina-acTAG only. In addition, degumming improved the purity and solubility of the camelina protein concentrates from both sources. The protein from degummed camelina had markedly reduced viscosity.
Pilot-scale (5 kg) production of glandless cottonseed protein isolate was conducted using a method based on alkali extraction/acid precipitation. This process produced 1.5 kg of 95% purity protein isolate (CPI). The yield is 50% more than that of previous runs done by ARS-Southern Regional Research Center collaborators. The CPI was off-white or light brown, depending on freeze-drying conditions. The CPI had very high protein content (approximately 95%), was soluble in FA (23% solids), and provided quality clear, lightly colored films. Glycerol (GLY) and lactic acid (LA) were found to be good plasticizers. The moisture content of the films increased from 5-12% when the relative humidity (RH) increased from 30-70%. The physical properties of these films were similar to those from soybean and other proteins and, like other proteins, the film’s physical properties deteriorate quickly with elevated humidity (50% reduction in strength when going from 50-70% RH).
An integrated oil process for coriander was developed by ARS researchers in Peoria, Illinois, and its impact on protein extractability and functional properties was assessed. The starting materials (ground whole seed, dehulled seed, press cake from dehulled seed, steam-distilled dehulled seed, and press cake from steam-distilled dehulled seed) were defatted, and the protein was extracted using the standard method of base solubilization/acid precipitation. The process produced protein concentrates (82% protein) with high solubility and good foaming properties. Those samples that were steam distilled had reduced protein extractability. Coriander proteins’ excellent emulsifying properties were demonstrated when they were found to be effective suspending agents for vanilla grounds. Overall, the integrated oil extraction process has beneficial effects on coriander protein purity, solubility and foaming.
A NIFA-AFRI-funded research collaboration with Iowa State University evaluated the effects of high-power sonication (HPS) pre-treatment on the extraction and properties of legume proteins. Proximate composition of untreated soybean flakes and flours from soy, chickpea, and kidney bean were determined. Protein contents of the same sources were analyzed after HPS at two power levels and two durations. Results showed that HPS did not affect protein contents of soy samples; but, HPS reduced protein contents of kidney bean and chickpea flours, especially at higher power. These results demonstrate that employing HPS may impact the value of the final product.
In order to extract more value from corn, additional information concerning the use of zein (corn protein) is needed. As-is and glyoxal modified zein were processed using extrusion and injection molding techniques. Injection molding as-is zein was successful. It was determined that physical properties, molecular weight, and solubility did not change across the narrow melt conditions that were similar to the processing window of petroleum-based products. When zein is allowed to react with glyoxal in an extruder, the branched protein can be injection molded. Physical properties were similar to control but, more importantly, solvent resistance increased. The amount of glyoxal used and processing conditions affect processability and properties.
This lab pioneered zein electrospinning and defining the impact of extrusion conditions on properties. Funds were received to carry out collaborative research to determine the ability of zein to replace gluten in bread dough. Certain zein fiber formulations were found to provide higher quality bread doughs; however, the bread properties were not acceptable. When extruded zein was incorporated into dough, the dough and final bread were of similar quality to that of wheat.
To protect crops from pests, protein and starch derivatives were evaluated. Amylose inclusion complexes (AIC) were found to have value. AIC can be made from fatty amines (AIC-Am) or fatty acids (AIC-Ac); no new chemical bonds are formed. AIC-Am, when in solution or incorporated into a film or coated on cotton fabric, were effective against pathogenic microbes. Their performance was comparable to commercial pesticides. AIC-Am were also effective nematicides (nematodes reduce crop yield by approximately 10% globally). Many commercial nematicides are highly toxic; AICs are relatively safe. AIC-Am treated wood had increased water resistance, resisted dry rot, and killed termites. The AIC-Am was also shown to retard insect herbivory. Preliminary research suggests the AIC-Am does not damage plants, nor cause mammalian blood cells lysis.
High-value polymer blends were produced using AIC-Am or AIC-Ac. Polyvinyl alcohol and cellulosic blended films could be produced, having from 10-50% of either complex. The lower-cost films have increased biodegradability, water resistance, and improved physical properties. When AIC-Am was applied to paper or cotton, they had higher water resistance; the water may evaporate before being absorbed by the article.
Modified starches, gums and proteins are used as emulsifiers, but their use is limited by Government regulations or cost. The AIC-Ac (food grade) and AIC-Am were effective emulsifiers, competitive with more costly or less green commercial emulsifiers. Both versions of AIC are effective emulsifiers for natural oils which can control mosquito larvae. Many domestic and international outgoing Material Transfer Research Agreements were executed regarding the AIC technology for multiple end-uses. During the just completed project cycle, one U.S. Patent was filed concerning the AIC technology.
Accomplishments
1. Production of value-added gums and protein from camelina. Camelina is an annual winter crop with seed oil being developed as a nutraceutical and biodiesel source. However, its other seed components must also be utilized to maximize the value of camelina. ARS scientists in Peoria, Illinois, have developed an aqueous, industrially friendly process that produces camelina gums (mucilage) and high purity protein concentrates (CPC). These two products would have value in both food and non-food markets. The mucilage showed viscosity properties that are useful for thickeners and emulsifiers. Mucilage accounted for 42% of the starting meal and contained notable amounts of co-extracted protein, which provide the gum with higher value. By removing the mucilage first, the yield, purity, and product value of the CPC are increased. These attributes suggest that the CPC will have value as a protein additive in health drinks, as a viscosity agent, or as an emulsifier. The process developed is very robust, and both the mucilage and CPC may be transferred to other researchers or industry to develop new high-value markets for camelina. These new products will increase value and acceptance of camelina crop and subsequently benefit farmers, downstream processors, and consumers.
2. Improved emulsifier with pesticidal attributes. An emulsifier is a compound which allows two normally insoluble materials to form a stable blend (mayonnaise is an emulsion made of oil, eggs, and an emulsifier). Without the emulsifier, the two materials will separate. There is a constant need for improved industrial emulsifiers. Many industrial emulsifiers utilize carcinogenic or highly hazardous ingredients. Providing an effective alternative that is biobased, safe, and has pesticidal activity will be highly valued. ARS scientists in Peoria, Illinois, have developed an economical emulsifier that uses corn starch and a vegetable oil derivative which kills pests. This new emulsifier (called an AIC) forms suspensions of oil in water which are stable for months. The AIC also makes water slicker, allowing the AIC-water solution to more easily penetrate parts. This leads to more efficient cleaning. In addition, the AIC have been shown to be effective pesticides. It can control gram positive bacteria, yeast, mold, fungi and some insects (including termites). The ability to function as both an emulsifier and pesticide is highly attractive and should have high value. This technology will be able to replace imported emulsifiers or those that utilize hazardous ingredients or processes. These new products will result in new applications for corn starch benefiting corn producers, processors, and consumers.
Review Publications
Hay, W.T., McCormick, S.P., Hojilla-Evangelista, M.P., Bowman, M.J., Dunn, R.O., Teresi, J.M., Berhow, M.A., Vaughan, M.M. 2020. Changes in wheat nutritional content at elevated [CO2] alter Fusarium graminearum growth and mycotoxin production on grain. Journal of Agricultural and Food Chemistry. 68(23):6297-6307. https://doi.org/10.1021/acs.jafc.0c01308.
Muturi, E.J., Selling, G.W., Doll, K.M., Hay, W.T., Ramirez, J.L. 2020. Leptospermum scoparium essential oil is a promising source of mosquito larvicide and its toxicity is enhanced by a biobased emulsifier. PLoS One. 15(2):e0229076. https://doi.org/10.1371/journal.pone.0229076.
Biswas, A., Cheng, H.N., Evangelista, R.L., Hojilla-Evangelista, M.P., Boddu, V.M., Kim, S. 2020. Evaluation of composite films containing poly(vinyl alcohol) and cotton gin trash. Journal of Polymers and the Environment. 28:1998-2007. https://doi.org/10.1007/s10924-020-01742-7.
Muturi, E.J., Hay, W.T., Doll, K.M., Ramirez, J.L., Selling, G.W. 2020. Insecticidal activity of Commiphora erythraea essential oil and its emulsions against larvae of three mosquito species. Journal of Medical Entomology. 57(6):1835-1842. https://doi.org/10.1093/jme/tjaa097.
