Location: Functional Foods Research
2022 Annual Report
Objectives
Objective 1: Develop innovative processes for pulses, pulse fractions, and pulse byproducts to enable increased commercial use of pulse-based ingredients.
Sub-objective 1.1: Enhance the nutritional and functional properties of pulse flours, fractions and byproducts by thermomechanical processing treatments alone or in combination with other physical treatments to obtain new pulse-based components and ingredients.
Sub-objective 1.2: Enhance the nutritional and functional properties of pulse flours, fractions and byproducts by germination or fermentation in combination with thermomechanical processing treatments and/or chemical modification.
Sub-objective 1.3: Enhance the nutritional and functional properties of pulse flours, fractions and byproducts by addition of fats and oils for composite formation, ligands for starch complex formation, or proteins and hydrocolloid gums for flavor, texture, or structure improvement.
Objective 2: Resolve the unknown physical and nutritional properties for foods and functional properties for non-foods prepared with increased levels of modified or concentrated pulse ingredients to enable the development of new products.
Sub-objective 2.1: Develop food applications from pulse components.
Sub-objective 2.2: Develop non-food applications from pulse components.
Approach
The dietary benefits of pulses are well established and are increasingly recognized as valuable sources of protein, fiber, antioxidants, and other nutrients. Although the production of pea, bean, and lentil flours and their protein products is increasing, there exist both (1) barriers to more widespread consumer acceptance and (2) a growing need to find uses for pulse processing byproducts such as a starch-rich milling fraction and hulls. Previous studies have shown effects of individual processing methods on pulse seeds, but very little is known about combinations of methods such as combining thermomechanical processing with biological and chemical treatments. The goal of this research is to develop innovative processing methods for pulses and pulse fractions involving combinations of either steam jet-cooking or extrusion with (1) germination and fermentation, and (2) with the strategic addition of exogenous proteins, hydrocolloids, lipids, and functional food ingredients. Research will focus on identifying synergistic treatment effects and utilizing component interactions to enhance the nutritional, structural and functional properties of pulse-based foods and food ingredient products. These new materials will be added to standard food formulations with the goal of maximizing the content of pulse-based ingredients or make totally pulse-based food products with marketable organoleptic properties. Non-food applications will also be investigated for selected pulse fractions based on their physical properties. The results of this research will enable expanded markets for pulse crops and therefore contribute to the sustainability of the pulse-based economy.
Progress Report
Large scale production and utilization of pulse-based prebiotics such as raffinose family oligosaccharides (RFO) that can support intestinal gut microbiota are important candidates for promoting human health alone or in combination with probiotics. Cooking or soaking pulses in water is a known method to extract RFO. However, the pulse cooking water (PCW) is routinely discarded although it contains significant amounts of beneficial RFO prebiotic compounds. As part of sub-objective 1.1, we have found that various high pressure thermal treatments enhanced the extraction and content of RFO and sugars in the cooking water relative to beans traditionally cooked in water at atmospheric pressure. The RFO-containing PCW fraction will be examined in yogurt preparation to increase beneficial prebiotic content in yogurt that can deliver both prebiotic and probiotic components.
Frost grape polysaccharide (FGP) is a novel arabinogalactan gum obtained from the stems of the native grape species Vitis riparia and is a potential gum arabic replacer. FGP is structurally analogous to gum arabic (global market estimated at U.S. $502.9 million by 2027 and forecasted to grow at a compound annual growth rate of 5.2% between 2020 to 2027). Gum arabic is mainly imported from Senegal and used extensively in the pharmaceutical, food, and beverage industry for its emulsifying and soluble dietary fiber properties. FGP has potential as a domestic replacement for gum Arabic for which price, quality, and availability can vary considerably. Currently, large amounts of water are required to isolate FGP due to the high viscosity of dilute solutions. In support of Sub-objective 1.1, we have been developing spray drying parameters to obtain FGP as a dry powder from these solutions which is important for scaling up its manufacture, and for storage and shipping purposes. Spray drying 2-3weight% FGP solutions using a co-current two-fluid atomization nozzle gave 50% yields of FGP as light tan powder. FGP is potentially a valuable source of soluble dietary fiber, and its soluble and insoluble dietary fiber content is being examined.
Steam explosion (subcritical water flash release) is a potentially useful and scalable thermomechanical approach to improving pulse flour by solubilizing nutritional components, improving flavor, and increasing digestibility. In a further study of applying steam explosion for improving buckwheat flour, it was determined that comparison of the physical and chemical properties of the processed flour with raw flour provided a better understanding of the processing effects than comparison with conventionally cooked flour.
Since jet-cooked starch-oil composites were previously shown to improve the juiciness and flavor of cooked beef patties, pulse flours are being processed to form similar gels with properties allowing a higher rate of incorporation as a meat extender/fat replacement with the added benefit of protein supplementation due to its presence in pulse flours. Steam jet cooking of pulse flours is also being adapted to form stable liquid suspensions of components suitable for the development of beverage formulations. Combinations of soluble and insoluble pulse components and various additives are being evaluated to determine how to achieve the properties necessary for a palatable beverage product. These efforts support subobjectives 1.3 and 2.1.
Starch properties can be modified through the addition of water insoluble compounds and the resulting complexes can be used to improve human health and improve food quality. Starch complexes are also a type of resistant starch, which is beneficial for glycemic control and gut health. Complexes between starch and insoluble dicarboxylic acids were simply prepared by steam jet cooking, isolated in good yields, and their properties investigated by instrumental and chemical techniques. They were found to be more heat stable than other starch complexes, which would provide the benefit of resistant starch in foods prepared or consumed at higher temperatures.
Light microscopy was performed on oleogels made with soybean oil supplemented with various modified fatty acids. Several different types of crystal formations were observed, varying both with the structure of the fatty acid and the concentration used in the oleogel. These oleogels, as alternatives to saturated fats, could be used to impart useful texture and flavor properties to processed pulse components (Sub-objective 1.3).
Accomplishments
1. Identified starch inclusion complexes with improved thermal stability. There is interest in improving the physical and functional properties of starch to overcome the shortcomings associated with native starches, especially, as many companies are reformulating products due to the limited availability and increasing price of many starches and hydrocolloids (gums and thickeners). The addition of water insoluble fatty acids (hydrocarbon chains attached to a single carboxyl group) is one method to modify starch and results in the formation of amylose inclusion complexes (AIC). This category of modified starch is oftentimes regarded as clean-label. ARS researchers in Peoria, Illinois, used an industrially viable processing technique known as steam jet cooking to prepare and subsequently characterize a series of AIC between starch and fatty acids that have two carboxyl groups attached on each end of a hydrocarbon chain (dicarboxylic acids). The additional carboxyl group better anchors the fatty acid into the complex, making the AIC more stable, as evidenced by its higher dissociation temperature. This enhanced stability improves starch properties and functionality by enabling the complexes to survive processing conditions and temperatures used to prepare foods and may show improved resistance to digestion which is beneficial for glycemic control and gut health.
