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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Plant, Soil and Nutrition Research » Research » Research Project #437310

Research Project: Advancing the Nutritional Quality of Staple Food Crops for Improved Intestinal Function and Health

Location: Plant, Soil and Nutrition Research

2022 Annual Report

Objective 1: In collaboration with plant breeders, utilize in vitro, in vivo, and analytical techniques to evaluate Fe bioavailability in staple food crops (beans, wheat, maize) for the purpose of developing crops that serve as an improved source of Fe. [NP107, C1, PS1A] Sub-objective 1.A. Collaborate with breeders to develop bean varieties with enhanced Fe bioavailability that can deliver more absorbable Fe and be a highly sustainable source of dietary Fe. Sub-objective 1.B. Characterize the potential genotype x environment (GxE) interactions that influence Fe content and Fe bioavailability in beans; and determine if either content, bioavailability or both can be sustainable approaches to improve Fe nutrition from beans. Sub-objective 1.C. Collaborate with breeders to characterize Fe bioavailability and Fe concentration from the different components of the maize and wheat grain, and search for QTL for enhanced Fe bioavailability and content of these components. Objective 2. Characterize the individual and interactive effects of dietary minerals (Fe and Zn), phytochemicals and prebiotics common to staple foods (chickpea, bean, wheat, lentil) on the intestinal microbiome and intestinal brush border membrane functionality. [NP107, C3, PS3B] Sub-objective 2.A. Evaluate the effect of natural prebiotics and phytochemicals extracted from staple food crops on mineral (Fe, Zn) dietary bioavailability and absorption in vivo (Gallus gallus).

As iron and zinc deficiencies are affecting approximately 30% of the world’s populations, including about 15% of the US population, the focus of this research plan is to improve iron bioavailability in staple food crops and to further increase their consumer appeal. Further, we aim to characterize the individual and interactive effects of dietary minerals (Fe and Zn), phytochemicals and prebiotics common to staple foods (chickpea, bean, wheat, lentil) on the intestinal microbiome and intestinal brush border membrane functionality. This will be done in order to evaluate the effect of natural prebiotics and phytochemicals extracted from staple food crops on mineral (Fe, Zn) dietary bioavailability and absorption in vivo (Gallus gallus). In addition, as the newly accepted body “organ”, the intestinal microbiome plays a vital role in the functionality, absorption and digestion capabilities of the intestine; hence, we aim to characterize the microbiome response to dietary plant origin bioactive compounds that may contribute to intestinal functionality and overall health. To accomplish the above, we will employ our established screening tools of an iron bioavailability bioassay and a poultry model that reflects human nutrition. In conjunction, we will make use of techniques such as mass spectroscopy, marker assisted molecular breeding, our Zinc Status biomarker, gene expression, microscopy, and state of the art microbial profiling techniques. With this unique combination of tools, we expect to develop staple food crops with enhanced iron nutrition and elucidate factors that can improve zinc nutrition from staple food crops, and thereby contribute to alleviation of two of the leading micronutrient deficiencies in the world. We will also expand knowledge of how the intestinal microbiome is affected by dietary iron, zinc, phytochemicals and prebiotics. Overall, this knowledge will further contribute to food innovations with enhanced nutrition and improve human health both domestically and abroad.

Progress Report
Developing Fast Cooking Dry Beans with Improved Iron Nutrition. As in previous years, research on beans, specifically the yellow bean market class was a major focus of this fiscal year. Significant progress continues on identifying and developing bean varieties that provide enhanced Fe nutrition. We now have yellow bean varieties, both domestically and abroad with collaborators in Uganda, Zambia and Tanzania, that are established as fast cooking with high iron bioavailability. The USDA has provided their Andean and Yellow bean diversity collections to these nations for breeding and evaluation. A manuscript is currently in preparation demonstrating how fast cooking yellow beans from the USDA breeding programs were selected by farmers participating in field trials at the University of Zambia. More importantly, the fast cooking yellow beans selected by farmers had significantly higher iron bioavailability when compared to local commercial beans and “biofortified varieties.” This information has the potential to change government policy in Zambia because biofortified varieties are promoted to farmers as being more nutritious, but their iron content and iron bioavailability is much lower than locally produced yellow beans, such as the landrace Lusaka. In summary, our studies demonstrate that our yellow beans are delivering more absorbable Fe relative to lines common to the marketplace and food system in those regions. Supporting International Breeding Programs. A germplasm screening of over 140 biofortified varieties and breeding lines from CIAT-Uganda is currently being conducted to measure the cooking time, mineral content and iron bioavailability of their most useful breeding material. This information will be used to help breeders evaluate new parental lines that can provide fast cooking times and high iron bioavailability to their breeding programs among the Pan-Africa Breeding and Research Alliance (PABRA). Domestic Genotype by Environment (G x E) Studies. Two years of evaluation for mineral content and iron bioavailability in a large group of fast and slow cooking yellow beans produced in Michigan (normal soil pH 7) and Nebraska (high soil pH > 8) is now completed. This study aims to determine the likelihood of producing high iron bioavailable yellow beans domestically for the use as a specialty market class devoted to addressing the iron needs of vulnerable populations in the United States and globally. Although iron concentrations of yellow beans are reduced when produced in locations with high soil pH (e.g. Nebraska), several yellow bean lines still delivered high amounts of bioavailable iron, regardless of production environment or seed iron levels. This research shows that the high iron bioavailable trait in certain yellow beans (Mayocoba and Manteca) is stable across production environments, unlike iron content, which is very suspectable to soil and growing conditions. This research will provide farmers in the United States and aboard an opportunity to grow yellow beans with enhanced iron nutrition under less-than-ideal growing conditions. A manuscript detailing these findings is now in preparation. Dietary Fiber Analysis of Fast Cooking Yellow Beans. This project evaluated the relationship between total dietary fiber, cooking time, and iron bioavailability in a large group of yellow beans selected from the USDA’s Yellow Bean Collection (est. 2018). There was a significant relationship between the total dietary fiber (AOAC 2011.25) concentrations and cooking times of yellow beans, which were collected from each of the major bean-consuming regions of the world. In addition, there was a significant relationship between the insoluble dietary fiber concentrations and iron bioavailability of yellow beans, indicating that new breeding targets for insoluble dietary fiber can be implemented to further enhance the iron bioavailability of new bean varieties. These findings support more recent investigations that show fast cooking beans have thinner seed coats and thinner cotyledon cell walls, which are the two main insoluble components of dry beans. A manuscript describing the results of this study is near completion. Yellow By Yellow Recombinant Inbred Line (YYRIL) Mapping Population. Completed measuring the mineral content and iron bioavailability of a Manteca yellow bean (Ervilha) x Njano yellow bean (PI527538) mapping population (400+ RILS over two field seasons) to identify promising molecular markers (QTL) for the high iron bioavailability trait in fast cooking Manteca yellow beans. A QTL located near the j allele on chromosome 10 has been identified as a strong candidate marker for high iron bioavailability in beans after cooking. The j allele is characterized as an important region of the genome that inhibits the production of condensed tannins (procyanidins and cinnamtannins) in the seed coats of yellow beans. A manuscript describing the results of this study is near completion. Beans as an Ingredient. Bean flour is a highly nutritive, plant-based ingredient with potential for great utility in many food products, including snacks, pasta and baked goods. However, there is little information on how processing effects the sensory qualities and the iron bioavailability of bean-based products such as pasta. Heat treated flours from commercial varieties of white kidney, yellow and black beans, were processed into pastas using high\low extrusion and drying temperatures. Bean pastas made with high extrusion\high drying temperature (H\H) had more favorable sensory attributes and better texture than those made with high extrusion\low drying temperature (H\L). Whereas bean pastas made with low extrusion\low drying temperature (L\L) were unacceptable. H\H pastas favored longer cooking time (8.6 – 13.8 min) versus those extruded at lower temperature (5.0 –5.7min). High extrusion temperature (100 °C) with drying temperature high (90 °C) improved iron bioavailability from yellow and white kidney bean pastas as compared to black bean pasta. Cultivar, extrusion and drying temperatures are critical for producing bean pastas with high iron bioavailability. Bean Pasta Feeding Trial. Previous studies using our cell culture (in vitro) model have indicated that the cotyledon cell wall of beans and other pulse crops is a significant factor in the bioavailability of iron. Breaking the cotyledon cell wall through processing has been shown to enhance iron delivery unless there are other factors present such as seed coat polyphenols that complex iron and prevent utilization to hemoglobin formation. Therefore, in this fiscal year we conducted an animal feeding trial to confirm the in vitro observations. To do so, we formulated bean flours from white and black beans, converting each bean flour into pasta to break up cell walls, and then formulating the pasta into a diet that would be similar to meals of a school lunch program. The pasta diets were also compared to diets using whole beans (cell walls intact). As predicted by the in vitro studies, the white bean pasta diet provided the most bioavailable iron, closely followed by the white bean diet. Both the black bean and black bean pasta diets exhibited low iron bioavailability, and effect that can be attributed to the presence of the seed coat polyphenols (anthocyanins and procyanidins) that provide the black color of the seed coat. This study is significant as it demonstrates how processing can provide enhanced iron nutrition from pulse crops such as beans. By converting a crop, such as the common bean, into a popular food such as pasta, and demonstrating enhanced nutritional benefit, this study provides insight for food manufacturers to produce more nutritious foods. Such innovation can increase consumer preference for beans and bean products, thus helping to fulfil the USDA objective of increasing pulse consumption in the United States. Flavonoid Evaluation in Dry Beans. Over the past year, we have established the capability to quantify approximately 28 of the major flavonoids in 10 different dry bean market classes. This capability has taken several years to achieve, as most labs who measure flavonoids in foods only provide qualitative analysis and not the actual quantity of a given flavonoid. At present this capability is being applied to develop breeding objectives for the next generations of beans, identifying genes that provide optimal seed coat color, antioxidant benefits, anti-obesogenic benefits, anti-diabetic benefits and enhanced iron bioavailability. Such capability can have numerous applications to a multitude of other foods such as fruits and vegetables that are a significant source of dietary flavonoids. Factors Influencing Iron Nutrition From Maize: Maize is a staple food for many communities with high levels of iron deficiency anemia. Improving iron bioavailability in maize via biofortification and or processing can aid in alleviating iron deficiency anemia. Previous studies of only a small number of maize and supermarket products indicated that degermination could improve the Fe bioavailability from maize. Therefore, the objective work in this fiscal year was to expand this research and evaluate bioavailable iron, iron concentrations, and phytate concentrations of whole and degerminated (germ fraction removed) maize with a Maize Nutrition Panel (MNP) of 52 diverse genotypes. Our results confirmed previous research showing that the germ fraction is a strong inhibitory component for many maize varieties. Degermination greatly reduced phytate content and phytate:Fe molar ratio; Fe concentrations were positively correlated with phytate, and negatively correlated with phytate:Fe molar ratios for most maize groups. This study suggests that Fe nutrition from maize can be enhanced via degermination and or by selecting genotypes where the inhibitory effect of the germ fraction is relatively low.

1. High bioavailable iron yellow beans for domestic production and abroad. The common bean has been targeted as a staple food crop to enhance Fe nutrition both domestically and abroad. ARS scientists at Cornell University, Ithaca, New York, has identified and developed yellow beans that provide fast cooking times and more bioavailable iron regardless of growing and soil conditions in United States. The new yellow beans are now being evaluated for performance and consumer acceptance at international breeding programs throughout East Africa and the Caribbean. The initial reports confirm that the new yellow beans outperform local commercial biofortified varieties in field trials held in Uganda and Zambia. This research demonstrates that these yellow bean lines deliver significantly more absorbable iron relative to other beans in the food system, delivering more nutritious beans that are preferred by consumers.

2. Flavonoid analysis capability. Quantification of flavonoids in food is a challenging technical task, requiring expensive instrumentation and highly skilled scientists. ARS scientists at Cornell University, Ithaca, New York, have firmly established capability to quantify approximately 28 of the major flavonoids in foods, most notably, the major flavonoids that are found in seed coats of the common bean. This capability has taken several years to achieve; however, due to the addition of a highly skilled technician and ARS investment in instrumentation we now have this capability that can be applied to a multitude of research objectives. Currently, this method is being applied to develop breeding of the next generations of beans, identifying genes that provide optimal seed coat color, antioxidant benefits, anti-obesogenic benefits, anti-diabetic benefits and enhanced iron bioavailability.

Review Publications
Glahn, R.P. 2022. The caco-2 cell bioassay for measurement of food iron bioavailability. The Journal of Visualized Experiments (JoVE). 182. Article e63859.
Alandy, V., Fleige, L., Glahn, R.P. 2019. Iron bioavailability of fortified maize and sorghum porridges. Journal of Nutritional Health & Food Science. 7(3):1-6.
Beasely, J.T., Bonneau, J.P., Moreno-Moyano, L.T., Callahan, D.L., Howell, K.S., Tako, E., Taylor, J., Glahn, R.P., Appels, R., Johnson, A.A. 2021. Multi-year field evaluation of nicotianamine biofortified bread wheat. Plant Journal. 109:1168-1182.
Cichy, K.A., Chiu, C., Isaacs, K., Glahn, R.P. 2022. Dry bean biofortification with iron and zinc. In: Kumar, Shiv, Dikshit, Harsh Kumar, Mishra, Gyan Prakash, Singh, Akanksha, editors. Biofortification of Staple Crops. Singapore. Springer. p. 225-270.