Dietary fiber (AOAC 2011.25) analysis of fast cooking yellow beans (Phaseolus vulgaris L.) with high iron bioavailability

Authors: SADOHARA, RIE - Michigan State University; Wiesinger, Jason; THOMPSON, HENRY - Colorado State University; Glahn, Raymond; Cichy, Karen

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2024
Publication Date: 12/2/2024
Citation: Sadohara, R., Wiesinger, J.A., Thompson, H., Glahn, R.P., Cichy, K.A. 2024. Dietary fiber (AOAC 2011.25) analysis of fast cooking yellow beans (Phaseolus vulgaris L.) with high iron bioavailability. Journal of the Science of Food and Agriculture. Vol. 10. https://doi.org/10.1016/j.crfs.2024.100942.
DOI: https://doi.org/10.1016/j.crfs.2024.100942

Interpretive Summary: Dry bean cooking time is an important characteristic for consumers. In some regions of the world beans with shorter cooking times receive a premium price at the market. Beans with shorter cooking times may have nutritional tradeoffs and/or benefits. Prior research on a small sample of bean cultivars has shown that beans with shorter cooking times have reduced dietary fiber, but provide more bioavailable iron during digestion. The goal of this research was to evaluate the relationship between cooking time and dietary fiber and iron bioavailability on a larger set of bean cultivars within five market classes of yellow beans. In total, 295 cultivars were grown in a single environment in Michigan in 2018. Their cooking times were measured and a group of 52 yellow and eight non-yellow genotypes were selected based on cooking time, and classified as either, fast, moderate, or slow cooking. The total dietary fiber, including soluble, insoluble, and oligosaccharides was measured on the cooked samples (AOAC 2011.25). The iron bioavailability of cooked beans was measured with an in vitro Caco2 bioassay, which is used an endothelial model for digestion in upper intestine of humans. Yellow beans with shorter cooking times were found to have less total and insoluble dietary fiber and higher iron bioavailability. The soluble dietary and oligosaccharides concentrations of fast cooking yellow beans were similar to slow cooking beans, indicating that nutritional differences between fast and slow cooking beans are specific to their insoluble dietary fiber profiles. These results help explain why beans with shorter cooking times are often perceived as easier to digest. The development of easy to prepare, and easy-to-digest yellow beans could be an innovative food option to help address the DF needs of busy consumers.

Technical Abstract: Some yellow-colored market classes of dry bean (Phaseolus vulgaris L.) are valued by consumers as an easy-to-digest, fast cooking alternative to darker colored red and black beans, which in comparison generally have longer cooking times and reduced iron bioavailability. There is evidence that cooking time of dry beans is linked to the dietary fiber content and may also contribute to nutrient digestibility and bioavailability. Therefore, 52 fast-, moderate-, and slow-cooking yellow beans with diverse iron bioavailability from five market classes (Amarillo, Canario, Green-yellow, Manteca, and Mayocoba) were selected for total dietary fiber (TDF) = insoluble (IDF) + soluble (SDF) + oligosaccharides (OLIGO) analysis using method AOAC2011.25. Wide variations in the concentrations of IDF (16.0 – 23.1%), SDF (1.6 – 7.7%), OLIGO (1.5 – 3.4%), and TDF (20.6 – 31.3%) were detected among the yellow beans with various cooking times. Lower concentrations of IDF in yellow beans were associated with shorter cooking times and higher iron bioavailability. The larger sized Andean yellow beans had more SDF than Middle American. One Mayocoba breeding line from Puerto Rico, PR1146-124, had 42% less OLGIOs than average, and may be useful for breeding for consumer acceptability. Fast cooking yellow beans provide the same SDF and OLGIO concentrations as conventional yellow beans but have the added benefit of shorter cooking times (convenience) and provide more bioavailable iron after cooking.