Location: Functional Foods Research2018 Annual Report
Objective 1: Enable new commercial processes for separating, concentrating, isolating, modifying, and improving functional components of oilseed press cakes and pulses alone and with other components for viable food, feed and non-food applications. Sub-objective 1.1: Select and acquire feedstocks; analyze and separate components. Sub-objective 1.2: Improve fractions and components by processing, chemical modification, enzymatic treatment, or combination with other materials. Objective 2: Enable new commercial uses for components from oilseed press cakes and pulses in health-promoting food, feed and industrial applications. Sub-objective 2.1: Develop food applications for pulse components. Sub-objective 2.2: Develop non-food applications for oilseed press cake and pulse components.
Oilseed press cakes and pulse crops are two potentially valuable sources of functional food ingredients and biobased products from plant seed tissues which have not been fully exploited. New processing methods are critically needed in order to (1) identify new applications for currently low-value oilseed press cakes such as pennycress, coriander, and camelina, and (2) provide functional food ingredients from pulse crops in a form that facilitates incorporation into various food products while minimizing negative characteristics. In coordination with collaborating projects, pulse and press cake feedstocks will be obtained and their protein, starch, and fiber components separated by milling, extraction, or treatment with chemicals or enzymes. Thermo-mechanical processes such as steam jet cooking, steam explosion, and extrusion will be investigated as methods to separate, modify, or combine isolated components or remove undesirable components. Functional characteristics such as texture, particle size, microstructure, solubility, compatibility, and organoleptic properties will be determined and suitability for specific food and industrial applications will be investigated. The performance of prototype industrial products will be evaluated and the most efficient methods for the isolation of functional components determined. Anticipated biobased products include gums, adhesives, lubricants, thickeners, fibers, composite fillers, and coatings. Pulse fractions enriched in specific functional or nutritious ingredients will be incorporated into food formulations and evaluated for consumer acceptability. Successful utilization of these feedstocks will enhance the economic viability of the respective crops for farmers and thus provide agronomic benefits such as nitrogen fixation by legume crops and off-season cover crop benefits for oilseed producers.
Pulses are an excellent source of gluten-free, non-allergenic protein, soluble fiber, vitamins and minerals and offer advantages for replacement of and combination with cereal flours. However, their taste, color, and functionality present utilization problems. We have shown that thermomechanically processing black bean flour using steam jet cooking in tandem with pH treatment significantly altered its properties. The raw beige color flour could be turned into shades of red and purple as the acidity was changed, which may be a useful trait for certain food applications. Water absorption of the jet-cooked flours significantly increased compared to the raw flour and showed improved hydrophilicity and gelation capacities. Water solubility of the jet-cooked flours treated with acid (pH 3.0) remained unchanged compared to the raw flour while the solubility of the jet-cooked flours significantly decreased as the pH increased. The total phenolic content of all the treated black bean flours was lower than the raw flour and trended lower as the pH of the samples increased. The viscosity profiles of the jet-cooked flours were also significantly different than the raw black bean flour. Experiments are being conducted to fractionate navy bean flour into soluble and insoluble fractions after jet cooking to produce fractions containing different components and functionality for use in specific food applications. Water holding capacity (WHC) is an important functional property of pulse flours and their protein materials because it influences ingredient functionality and shelf stability. An interlaboratory study was conducted to evaluate the repeatability and reproducibility of a new method developed to measure the water holding capacity for pulses. Results demonstrated that the new method has good repeatability and reproducibility. Germination is an economical and low-cost process used to improve the nutritional value and functionality of food ingredients by converting macromolecules into more digestible molecules. But there is limited information on the effect of germination on the protein quality and functional properties of pulses. Investigation is underway to examine the protein quality and functional properties of flours from raw, soaked and germinated navy beans, lentils and pinto beans. A valuable protein-rich fraction can be obtained from pulse flours by air classification. However, the remaining fiber- and starch-rich byproduct fraction has limited applications since the altered protein and fiber content lead to different properties than for a pure starch. To improve the functional properties of these materials, research is underway to modify the protein solution properties of the starch-rich fraction by means of charge and pH changes. Resistant starch has a number of health benefits that include the control of diabetes and cardiovascular disease. Whole pulses have high resistant starch contents, but this benefit is lost if the pulses are milled to fine flours. Research is being conducted to maintain the resistant starch content of pulse flours both through control of the flour’s particle size and also by modification of the cell wall structure. The functionality of these flours will be examined in baked goods. Wheat bran, which is removed by roller milling, contains valuable nutrients but has physicochemical properties that contribute undesirable characteristics in whole wheat food products. Thermomechanical treatments were investigated as bran pretreatments to improve the physical properties in a collaborative study with researchers at the ARS in Wooster, Ohio. For this study, 1.5 kg quantities of wheat bran were processed by extrusion and by milling, steam jet cooking, and freeze-drying to enable investigation of their resulting hydration properties, dough preparation methods, and bread characteristics. The production of silver nanoparticles using amylose-sodium palmitate complexes as a capping agent and glucose as a reductant gave stable dispersions of nanoparticles that could be precipitated as microgel fragments upon acidification and subsequently dried. Phase contrast and transmission electron microscopy revealed that the reconstitution of gel fragments from the freeze-dried state yielded nanoparticles in the same size range (3-4 nm diameter) as those in freshly prepared dispersions. Starch nanoparticle dispersions were prepared by rapidly cooling jet-cooked starch-oleic acid complexes on ice. A method was developed to reconstitute the nanoparticles after freeze-drying. The reconstituted nanoparticle dispersions were combined with commercial styrene/butadiene emulsions to cast films having markedly improved tensile properties as the proportion of starch nanoparticles was increased. Technology was previously developed to prepare lightweight aerogels with high surface area and porosity from starch amylose inclusion complexes. Through a material transfer research agreement (MTRA) with global food ingredient company, this technology is being examined for potential food and ingredient delivery applications and adapted to use proprietary starches. Currently, amylose complexes are not commercially available as a large scale off-the-shelf food ingredient, although, there is interest in their potential as an encapsulant and delivery method for bioactive and flavor compounds. Dicarboxylic acids are proposed as alternative energy substrates that can improve glycemic control and exert beneficial metabolic effects in the treatment of diabetes. Initial experiments were performed to better understand the preparation and properties of amylose-dicarboxylic acid complexes. Amylose diacid complexes were prepared in an easily scalable process by steam jet cooking mixtures of various amylose-containing starches with various length dicarboxylic acids. The commercial use of certain low molecular weight flavor/aroma compounds is restricted due to their instability and volatility. Research with university collaborators have shown that these flavor compounds can be complexed by amylose in starch and that their complexation provides stability to the flavor/aroma compound. Experiments have demonstrated that the flavor compounds could be stabilized by amylose and may have application to food industry. Biting insects cost the U.S. cattle industry more than $2.4 billion annually. A team of ARS researchers from Lincoln, Nebraska and Peoria, Illinois have identified and developed a new bio-based biting insect repellent for the cattle industry. Laboratory testing showed the insect repelling compounds identified from coconut oil to work better than DEET. These compounds exhibited toxicity and repellency (> 1 week) against brown dog and lone star ticks, and bed bugs as well. The active ingredients appear to be animal safe and cost competitive, and have been formulated into an aqueous starch composite that has been scaled to 60 L. The material is currently undergoing a three-year farm animal evaluation against biting flies at the University of Nebraska cattle research farm in North Platte, Nebraska.
1. Modification of steam jet cooking procedure enhances properties of black bean flour. Improving the functional properties of pulse flours is necessary to increase the amount that can be added to various foods and increase the range of food types it can be used in. It was previously shown that excess steam jet cooking of pulse flours under standard conditions enabled the production of flours with reduced particle size, greater solubility, more uniform color, partial conversion of insoluble to soluble fiber, but no decrease in raffinose saccharides. ARS researchers in Peoria, Illinois have discovered that adjusting the pH (3-8) of black bean flour dispersions before jet cooking provided further useful modifications, including brightly colored pink and violet flours, degradation of raffinose saccharides, less reduction of total phenolics, lower viscosity on pasting, and more solublization of protein than flour jet cooked at the unadjusted pH of 6.5. These results prove that additional treatments combined with steam jet cooking can provide enhanced functional properties to pulse flours that broaden the potential range of food applications.
2. Development of pulse-based yogurt. Popularity and consumption of yogurt is on the rise in the United States. The demand for nutritious functional food ingredients and products is also rapidly expanding. Pulses are recognized a valuable functional food ingredient containing proteins, carbohydrates, dietary fiber, vitamins, minerals and phytochemicals. ARS researchers in Peoria, Illinois in collaboration with Human Environmental Sciences at University of Central Oklahoma, studied how the addition of chickpea flour to yogurt, which increased the protein content by up to 15%, influenced the physicochemical and sensory properties of the yogurt. Fortification of yogurt with chickpea flour promoted bacteria fermentation during yogurt making, reducing the processing time and providing a significant improvement in the texture, without negatively influencing its acceptability. Pulse flours have the potential of providing nutritional benefits and improving the health benefits of fermented dairy products such as yogurt. Addition of pulse flours in food products will meet consumer demand for protein fortification and also increase the market demand for pulses.
3. Reconstitution of freeze-dried silver nanoparticles made with starch-fatty acid salt complexes. The use of silver nanoparticles as an anti-microbial technology has rapidly expanded in response to the growing problem of acquired resistance to antibiotics. They are most often produced by converting silver nitrate into metallic silver with a reducing agent in the presence of a stabilizing polymer. Currently, starch is the preferred stabilizer and glucose is a widely used "green" reducing agent. Previous research has shown that jet cooked corn starch combined with a vegetable oil derivative to produce starch complexes can produce smaller and thus more effective silver nanoparticles by providing a slow release of silver ions to the reducing agent. ARS researchers in Peoria, Illinois found that gently treating these nanoparticle dispersions with dilute acid causes the starch complexes to form a gel, and that this gel can be freeze-dried and later reconstituted in water. The reconstituted nanoparticles were shown by transmission electron microscopy to be as small as those present in the preparations before forming the gel. Since the freeze-dried nanoparticle gel can be stored indefinitely, this new technology provides a way to easily obtain a marketable form of very small silver nanoparticles without having to establish the conditions and stringent requirements to produce the nanoparticles from the starting materials. This discovery will facilitate the simple incorporation of silver nanoparticles into a variety of consumer products such as fabrics, packaging films, and medical products.
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