Project : USDA ARS

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Research Project: Improved Utilization of Whole Pulses, Pulse Fractions, and Pulse Byproducts for Health-Promoting Food Ingredients and Biobased Products

Location: Functional Foods Research

2024 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
Pulse growers, processors, and commodity groups are increasingly promoting utilization and consumption of pulse-based food ingredients which has led to rapid commercialization of whole and enriched flours, and protein isolates and concentrates predominantly from peas, and other pulses such as lentils and chickpeas. Scientific understanding of these materials must catch up to the rising increase in demand and production of these pulse proteins and flours. Whole bean flours have some negative properties that limit their ability to replace wheat flour in certain food classes. As part of Sub-objectives 1.1 and 1.3, steam jet-cooking, a rapid and commercially scalable thermomechanical processing method, is being examined toward the goal of making bean flour more versatile and acceptable. Jet cooking in combination with other processing techniques is being investigated. The effect of drying (air-, drum-, and freeze-drying) method on the properties of steam jet-cooked navy bean flour was examined. The combined processing treatment provides a convenient pre-cooked powder in which navy beans can be incorporated into various food products such as spreads, dips, and beverages that broaden potential pulse-based food applications. Regarding raffinose family oligosaccharides (RFO, a soluble fiber component responsible for gas production and bloating), air-drying significantly reduced RFO content relative to the raw flour to a greater extent than either drum- or freeze-drying. Freeze drying gave powders closest in color to the raw navy bean flour while both air- and drum-dried treatments exhibited reduced the color lightness owing to browning and oxidation reactions. All three treatments approximately doubled the water solubility of the powders relative to the raw flour. All the drying methods were demonstrated to generate many new flavor components, and drum-dried produced the most flavor components. Analysis revealed the drum dried powders had the most desirable water solubility, viscosity, color, RFO content, and flavor properties. The familiar flavors of the various pulses can contribute specifically to the resulting flavor of food products when pulse flours are added for their beneficial nutritional properties. In support of Sub-objectives 1.3 and 2.1, whole flours were prepared for navy, kidney, pinto, and black beans, and chickpeas. These pulse flours were blended with various cereal flours to create a pulse-cereal flour composite and the flavor profiles and functional properties of these initial flour composites are being characterized. They will subsequently be thermomechanically processed in an effort to create new composite pulse-cereal powder products whose flavor is relatively bland with regards to a particular bean flavor, enabling higher levels of use in food applications. Isolation of high purity protein fractions from the pulse flours through alkaline-solubilization followed by acid precipitation is also being performed. The protein has been isolated in 75-90% purity as determined by nitrogen analysis. The protein classes are being determined using SDS Page gel electrophoresis and extent of denaturation examined by Fourier transform infrared (FTIR) spectroscopy differential scanning calorimetry (DSC). The development of new applications using starch and fiber side and waste streams of pulse protein processing is required to support the pulse protein industry. As part of Sub-objectives 1.1 and 1.3, navy and pinto bean starch was isolated from whole flour and lentil starch isolated from a commercial source of enriched starch-flour fraction. These starches were characterized by differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), nitrogen analysis to determine starch properties and purity. Experiments to determine amylose and amylopectin ratios are ongoing. Once these ratios are determined, pulse starches will be combined with guest molecules and thermomechanically processed to prepare pulse-based amylose inclusion complexes to examine their digestibility and potential for glycemic response control. Supporting Sub-objective 2.2, the rheological thickening and gelling properties of pure pulse starches supplemented with fatty acids are being investigated for their resistant and digestive attributes. Creating new higher value uses for pulse starch as amylose inclusion complexes through physical interactions (no chemical modification) will enable food processors to utilize pulse starch more effectively in food applications and open new markets for these underutilized starches. Despite the well-known health benefits of eating beans, gas production and bloating are a common health complaint, signs of potential chronic conditions, and barrier to their consumption. In support of Sub-objectives 1.1 and 2.1, in collaboration with University of Nebraska-Lincoln, Lincoln, Nebraska, Megasphaera elsdenii (M. elsdenii), one of the good gut bacteria, was shown to be related to gas production in humans during digestion of kidney beans in comparison to sweet potatoes. Moreover, in combination with other good gut bacteria, M. elsdenii can produce higher gas rates when digesting gas-producing components of sweet potatoes and kidney beans. Interestingly, the gas production when digesting kidney beans was significantly lower than for sweet potatoes. Previous research demonstrated that jet-cooked lentil and green pea flours reduced gas production by the microbiome after 24 h relative to the unprocessed pulses despite demonstrating that jet cooked pulse flours contain a higher level of gas promoting raffinose family oligosaccharides (RFO). Experiments to elucidate causes for this apparent dichotomy are ongoing. Understanding how processing influences the gut microbiome function is critical to medical communities and bean processors to create innovative food processing strategies and products, enhance the purpose of food, and provide consumers healthy food choices.

Accomplishments
1. Understanding gut microbiome through pulse consumption. Despite the well-known health benefits of eating beans, gas production and bloating are a barrier to their consumption and may signify potential chronic conditions related to the microorganisms in the human gut microbiome that can influence many aspects of overall health. ARS researchers in Peoria, Illinois, working with a research team at the University of Nebraska-Lincoln, Lincoln, Nebraska, examined the role of Megasphaera elsdenii (M. elsdenii), a specific bacteria not commonly present in the gut microbiome, on gas production. The researchers compared gas production during digestion between kidney beans and sweet potatoes and demonstrated M. elsdenii significantly increases gas production during digestion of beans or sweet potatoes. Significantly more gas was produced by sweet potatoes than kidney beans. The findings established the components utilized by M. elsdenii in gas production during digestion and support the importance of maintaining a healthy microbiome through a good diet. Understanding and identifying the microorganisms in the gut microbiome that influence bean digestion is critical to bean processors and medical community to help create innovative food processing strategies and bean-based products that provide consumers healthy food choices.

2. New navy bean powders to improve taste and health attributes for food ingredients. Although the dietary and nutritional benefits of whole beans are well established, many consumers are not inclined to use them. In response, pulse processors now produce a variety of bean flours and protein isolates. However, foods containing these bean ingredients are not readily accepted by consumers due to unique taste, texture, and nutritional issues. To overcome these issues, ARS researchers in Peoria, Illinois, developed a commercially viable direct-contact heating method to produce new navy bean powders for food and beverage applications. The method alters the starch and protein properties and the corresponding powders have concentration dependent viscosities and can hold almost three times as much water as the unprocessed flour. These findings provide basic understanding of the bean powders mouth feel and textural properties needed by bean processors and food manufacturers to develop new ingredients for bean-based spreads and dips that provide consumers a healthier and tastier food experience.

U.S. DEPARTMENT OF AGRICULTURE

Functional Foods Research: Peoria, IL