Modulating a prebiotic food source influences inflammation and immune-regulating gut microbes and metabolites: insights from the BE GONE trial.

BACKGROUND: Accessible prebiotic foods hold strong potential to jointly target gut health and metabolic health in high-risk patients. The BE GONE trial targeted the gut microbiota of obese surveillance patients with a history of colorectal neoplasia through a straightforward bean intervention. METHODS: This low-risk, non-invasive dietary intervention trial was conducted at MD Anderson Cancer Center (Houston, TX, USA). Following a 4-week equilibration, patients were randomized to continue their usual diet without beans (control) or to add a daily cup of study beans to their usual diet (intervention) with immediate crossover at 8-weeks. Stool and fasting blood were collected every 4 weeks to assess the primary outcome of intra and inter-individual changes in the gut microbiome and in circulating markers and metabolites within 8 weeks. This study was registered on ClinicalTrials.gov as NCT02843425, recruitment is complete and long-term follow-up continues. FINDINGS: Of the 55 patients randomized by intervention sequence, 87% completed the 16-week trial, demonstrating an increase on-intervention in diversity [n = 48; linear mixed effect and 95% CI for inverse Simpson index: 0.16 (0.02, 0.30); p = 0.02] and shifts in multiple bacteria indicative of prebiotic efficacy, including increased Faecalibacterium, Eubacterium and Bifidobacterium (all p < 0.05). The circulating metabolome showed parallel shifts in nutrient and microbiome-derived metabolites, including increased pipecolic acid and decreased indole (all p < 0.002) that regressed upon returning to the usual diet. No significant changes were observed in circulating lipoproteins within 8 weeks; however, proteomic biomarkers of intestinal and systemic inflammatory response, fibroblast-growth factor-19 increased, and interleukin-10 receptor-α decreased (p = 0.01). INTERPRETATION: These findings underscore the prebiotic and potential therapeutic role of beans to enhance the gut microbiome and to regulate host markers associated with metabolic obesity and colorectal cancer, while further emphasizing the need for consistent and sustainable dietary adjustments in high-risk patients. FUNDING: This study was funded by the American Cancer Society.

Dry beans (Phaseolus vulgaris L.) modulate the kinetics of lipid digestion in vitro: Impact of the bean matrix and processing.

The lipid-lowering effect of dry beans and their impact on lipid and cholesterol metabolism have been established. This study investigates the underlying mechanisms of this effect and explore how the structural integrity of processed beans influences their ability to modulate lipolysis using the INFOGEST static in vitro digestion model. Dietary fiber (DF) fractions were found to decrease lipolysis by increasing the digesta viscosity, leading to depletion-flocculation and/or coalescence of lipid droplets. Bean flours exhibited a more pronounced reduction in lipolysis compared to DF. Furthermore, different levels of bean structural integrity showed varying effects on modulating lipolysis, with medium-sized bean particles demonstrating a stronger reduction. Hydrothermal treatment compromised the ability of beans to modulate lipid digestion, while hydrostatic-pressure treatment (600 MPa/5min) enhanced the effect. These findings highlight that the lipid-lowering effect of beans is not solely attributed to DF but also to the overall bean matrix, which can be manipulated through processing techniques.

Nutrient and popping characteristics of Wyoming-grown Peruvian popping beans.

American consumers fall short of dietary fiber intake recommended by dietary guidelines. Beans provide protein and fiber, however, less than 14% of adults include them in their daily diets. Nuña beans (Phaseolus vulgaris L.), a class of common beans originated in South America and cultivated for growth in North America, possess a unique set of characteristics including flavor profile, popping ability, and nutrient content that may appeal to consumers. The purpose of this study was to evaluate a unique line of Wyoming-grown popping beans to (1) determine nutrient characteristics and (2) assess popping percentage and shelf stability. Crude protein content was determined for five lines grown in Wyoming utilizing the Dumas method for nitrogen quantification. Total fatty acid content and a fatty acid profile for one line (CO49957) was determined by gas-liquid chromatography. Popping percentage was assessed by heating beans in canola oil in a cast iron pan to induce popping. Storage duration impact on popping was evaluated on CO49957 at 6, 12, and 15 months after harvest. Crude protein content was significantly different between all five lines. Total fatty acid content of CO49957 averaged 2.90 g/100 g wet weight. Average fatty acid profile of CO49957 popped in canola oil comprised oleic acid (41.4%), linoleic acid (20.4%), α-linolenic acid (18.6%), palmitic acid (10.4%), and stearic acid (2.23%). Popping percentage was 90% (baseline), 100% (6 months), 87% (12 months), and 80% (15 months). Popping beans provide plant-based protein and fiber while maintaining adequate levels of popping percentage with prolonged storage.

Effect of growing conditions and postharvest processing on arabica coffee bean physical quality features and defects.

The individual and interaction effects of elevation, production system (PS), shade and postharvest processing (PHP) on the ratio of dry beans to red cherries and the green bean physical quality features and defects of arabica coffee in southwestern Ethiopia were evaluated. The results showed that, with increasing elevation, the proportions of the total defected beans and large beans decreased while that of medium beans increased. Moreover, the proportion of secondary defects, 1000 seed weight and bean volume were higher for lowland and midland coffees than for highland coffee, but bean density was higher for highland than for lowland and midland coffees. The proportion of the total defected beans was also higher for modern plantation coffee in lowland than for modern plantation and semi-plantation coffees in midland and highland, but the 1000 seed weight was lower for semi-plantation coffee in highland than for modern plantation coffee in lowland and midland. The ratio of primary and secondary defects respectively was higher for dry- and wet-processed coffee in lowland than for dry- and wet-processed coffees in midland and highland. But, the ratio of small beans was lower for wet-processed coffee in lowland than for dry-processed coffee across elevations. The ratio of dry beans to red cherries and the 100 beans volume were higher for wet-processed modern plantation and semi-plantation coffees in midland than for dry-processed coffees of both production systems across elevations. However, the ratio of large beans was higher (1) for wet-processed modern plantation coffee in lowland than for dry- and wet-processed coffees of both production systems across elevations, and (2) for coffee that was grown without shade and wet-processed in lowland than for other coffees. Bean density was higher for dry-processed modern plantation and semi-plantation coffee in midland and highland, respectively than for other coffees across elevations. Overall, these results underlined the primary effects of elevation and PS, and the complex interaction effects between PHP and PS or shade on the ratio of dry beans to red cherries and the physical features and defects of green arabica coffee beans.

Cradle-to-grave life cycle assessment of production and consumption of pulses in the United States.

Environmental impact associated with production and consumption of pulses in the United States was evaluated using life cycle assessment (LCA). The system boundary was set to cradle-to-grave with a functional unit of 60 g (dry basis) of pulses consumed in a US household. Varieties of pulses modeled in the study included field pea (Pisum sativum), lentil (Lens culinaris), chickpea (Cicer arietinum), and dry bean. Three methods of cooking pulses at the consumer stage tested in the study were cooking in open vessel on electric cooking range (OVC), cooking in stovetop pressure cooker on electric cooking range (SPC), and cooking in electric pressure cooker (EPC). OVC formed the base scenario against which all other scenarios were compared. The environmental impact of pulses varied with type of pulse crop, cooking method, and the batch size. Consumption of approximately 60 g of dry pulses resulted in the greatest environmental impact for OVC. The consumer stage contributed at least 83, 81, 76, 75, and 87 percent for global warming potential (GWP), fossil resource scarcity (FRS), water consumption (WC), freshwater eutrophication (FE), and marine eutrophication (ME), respectively for this scenario. EPC resulted in the greatest decrease in the environmental impact, compared to OVC, for GWP, FRS, FE, and ME for all pulse varieties, which was validated in the uncertainty analysis. SPC, on the other hand, decreased the impact across these categories only for chickpea and dry bean. The uncertainty analysis suggested that the differences associated with cooking methods in the mean land use and water consumption scores of pulses were statistically non-significant. The impact categories were also highly sensitive to the mass of pulses cooked in a batch. Increasing the reference flow in OVC to 1 kg decreased the environmental impact of pulses by 49-87 percent for all impact categories, excluding land use. Overall, the study identified the consumer stage as the hotspot for environmental impact in the supply chain of pulses in the United States. The large contribution of the consumer stage to the overall environmental impact of pulses was attributed to electricity consumption for cooking and associated upstream emissions.

Pulse processing affects gas production by gut bacteria during in vitro fecal fermentation.

Flatulence is one barrier to pulse consumption for many people. Therefore, we examined how processing affects gas production by the microbiome in three classes of pulses. Processing did not affect gas production from Navy beans. However, in Pardina lentils and green peas, (-1.9 ± 0.3 mL/24 h, p < 0.001; -2.3 ± 0.3 mL/24 h, p < 0.001, respectively). In Pardina lentils and green peas, germination diminished carbohydrate utilization by the microbiome compared with unprocessed samples. In Pardina lentils germination reduced abundance germination resulted in the greatest reduction in gas production among six processing methods of amplicon sequence variants (ASVs) from Bacteroides and Lachnospiraceae and reduced propionate production compared with unprocessed samples. In green peas, germination reduced ASVs from Lachnospiraceae, including one from Roseburia, and reduced proportion of butyrate production during fermentation. Three ASVs from Clostridium sensu stricto (cluster 1), Megasphaera elsdenii, and unclassified Veillonellaceae, were strongly associated with increased gas production across all samples (ρ = 0.67-0.69, p < 0.001). This study showed that processing can reduce gas production by the microbiome in some pulses, but also reduces saccharolytic fermentation and production of beneficial microbial metabolites.

Iron Concentrations in Biofortified Beans and Nonbiofortified Marketplace Varieties in East Africa Are Similar.

BACKGROUND: The predominant bean iron (Fe) biofortification approach is to breed for high Fe concentration and assumes the average Fe concentration is 50 µg/g. This approach also assumes that a 40 µg/g increase is sustainable and Fe bioavailability will not decrease to negate the increase in Fe. OBJECTIVE: The overall objective was to determine if bean Fe biofortification via breeding for high Fe is producing beans with higher Fe concentration relative to nonbiofortified lines found in the East Africa marketplace. METHODS: Seventy-six marketplace samples (East Africa Marketplace Collection; EAMC), and 154 genotypes known to be representative of the marketplace were collected from breeders in the Pan-Africa Bean Research Alliance (designated the East Africa Breeder Collection; EABC). Within the EAMC and EABC were 18 and 35 samples, respectively, that were released as biofortified lines. All samples were measured for Fe concentration. The Caco-2 cell bioassay assessed Fe bioavailability of the EAMC. Biofortified versus nonbiofortified samples were compared by the appropriate t-test or ANOVA. RESULTS: The Fe concentration of the 58 nonbiofortified EAMC lines was (mean ± SD [range]) 71 ± 9 µg/g (52-93 µg/g) which did not differ significantly from the 18 biofortified EAMC varieties (71 ± 11 µg/g [55-94 µg/g]). The Fe concentration of the 119 nonbiofortified EABC varieties was 66 ± 7 µg/g (51-90 µg/g) which was significantly different (P < 0.0001) from the 35 EABC biofortified lines (73 ± 9 µg/g [60-91 µg/g]). However, the EABC biofortified lines were not different from the nonbiofortified EAMC samples. In the Caco-2 cell bioassay, biofortified EAMC varieties did not deliver more Fe compared with nonbiofortified EAMC varieties. CONCLUSIONS: The assumptions of the high Fe bean biofortification approach are not met in the East African marketplace. Iron concentration and bioavailability measurement indicate the biofortified bean varieties are providing no additional dietary Fe.

Determination of Soluble Mono, Di, and Oligosaccharide Content in 23 Dry Beans (Phaseolus vulgaris L.).

Beans provide a rich source of plant-based proteins and carbohydrates. It is well documented in the literature that the raffinose family of oligosaccharides (RFOs: raffinose, stachyose, and verbascose) is linked with flatulence issues. In this study, the soluble sugar content of 23 dry beans was investigated using a newly developed and validated analytical method with high-performance anion-exchange chromatography coupled to an amperometric pulse detection. All seven sugars (galactose, glucose, fructose, sucrose, raffinose, stachyose, and verbascose) showed good linearity (r2 ≥ 0.99) between 0.156 and 20 µg/mL. The limit of detection and quantification were determined as 0.01-0.11 µg/mL and 0.04-0.32 µg/mL, respectively. Significant variations in the profiles and concentrations of individual and total sugars were observed in 23 dry beans. Sucrose and stachyose were the two prominent soluble sugars combinedly representing an average of 86% of the total soluble sugars. Yellow split beans, large lima, and black eyed peas contained higher amounts of total soluble sugars (79.8-83.6 mg/g), whereas lower amounts were observed in speckled butter peas and lentils (53.6-56.6 mg/g). Garbanzo beans contained maximum levels of mono and disaccharides (MD), and yellow split beans showed the highest levels of RFOs. Based on the hierarchical cluster analysis of the total soluble sugars (TS), MD, RFOs, and MD/RFOs ratio, 23 beans can be classified into five groups. The average TS content and the MD/RFOs ratios of the five groups were determined as group 1 (TS = 55.1 mg/g and MD/RFOs = 0.30), group 2 (TS = 77.6 mg/g and MD/RFOs = 0.31), group 3 (TS = 78.3 mg/g and MD/RFOs = 0.51), group 4 (TS = 59.1 mg/g and MD/RFOs = 1.06), and group 5 (TS = 68.5 mg/g and MD/RFOs = 0.62). This information is useful for researchers, food industries, and consumers that are looking for plant-based protein source as an alternative to animal proteins with reduced flatulence problems.

Reduced retort processing time improves canning quality of fast-cooking dry beans (Phaseolus vulgaris L.).

BACKGROUND: While it is generally accepted that fast-cooking germplasm benefits consumers, benefits to the canning industry have not been established. Genotypes with good canning quality withstand the canning process while remaining intact with good appearance, but canning protocols used by breeders typically involve long processing times that may overcook some genotypes. The goal of this study was to identify whether cooking time influences canning quality in dry beans and whether reducing processing time could improve canning quality of fast-cooking genotypes. RESULTS: A set of 20 yellow bean genotypes including Ervilha, PI527538 and 18 derived recombinant inbred lines were selected for their varied cooking times. By comparing the genotypes processed across five retort times, differences in canning quality were identified. All genotypes performed better when processed for less time than the standard 45 min, but canning quality was highest at 10 min for fast- and medium-cooking genotypes and 15 min for slow-cooking genotypes. Cooking time was correlated positively with texture and intactness and negatively with washed-drained weights, indicating that slower cooking beans have higher canning quality. Color changed with retort processing such that longer times produced darker beans with more red and yellow. CONCLUSIONS: While fast-cooking beans exhibited lower canning quality at standard processing times, reduced retort processing time allowed them to meet quality standards while still maintaining food safety. By accounting for cooking time as a component of canning quality, breeders can develop varieties that are convenient and cost efficient for preparation for both consumers and the canning industry. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.

Manipulation of the dry bean (Phaseolus vulgaris L.) matrix by hydrothermal and high-pressure treatments: Impact on in vitro bile salt-binding ability.

The capacity of high-fiber foods to sequester BS during digestion is considered a mechanism to lower serum-cholesterol. We investigated the effect of hydrothermal (HT) and high-hydrostatic-pressure (HHP) on the bile salt (BS)-binding ability of dry beans, and how this relates to changes in bean microstructure, fiber content (insoluble-IDF/soluble-SDF), and viscosity. HT and HHP-600 MPa led to significant IDF reduction, including resistant starch (RS), whereas 150-450 MPa significantly increased RS, without modifying IDF/SDF content. Microscopy analysis showed that heating disrupted the bean cell wall integrity, protein matrix and starch granules more severely than 600 MPa; however, tightly-packed complexes of globular starch granules-protein-cell wall fiber formed at HHP ≤ 450 MPa. While HT significantly reduced BS-binding efficiency despite no viscosity change, HHP-treatments maintained or enhanced BS-retention. 600 MPa-treatment induced the maximum BS-binding ability and viscosity. These results demonstrate that BS-binding by beans is not solely based on their fiber content or viscosity, but is influenced by additional microstructural factors.

The BE GONE trial study protocol: a randomized crossover dietary intervention of dry beans targeting the gut microbiome of overweight and obese patients with a history of colorectal polyps or cancer.

BACKGROUND: Mouse and human studies support the promise of dry beans to improve metabolic health and to lower cancer risk. In overweight/obese patients with a history of colorectal polyps or cancer, the Beans to Enrich the Gut microbiome vs. Obesity's Negative Effects (BE GONE) trial will test whether and how an increase in the consumption of pre-cooked, canned dry beans within the context of usual diet and lifestyle can enhance the gut landscape to improve metabolic health and reduce cancer risk. METHODS/DESIGN: This randomized crossover trial is designed to characterize changes in (1) host markers spanning lipid metabolism, inflammation, and obesity-related cancer risk; (2) compositional and functional profiles of the fecal microbiome; and (3) host and microbial metabolites. With each subject serving as their own control, the trial will compare the participant's usual diet with (intervention) and without (control) dry beans. Canned, pre-cooked dry beans are provided to participants and the usual diet continually assessed and monitored. Following a 4-week run-in and equilibration period, each participant provides a total of 5 fasting blood and 6 stool samples over a total period of 16 weeks. The intervention consists of a 2-week ramp-up of dry bean intake to 1 cup/d, which is then continued for an additional 6 weeks. Intra- and inter-individual outcomes are assessed across each crossover period with consideration of the joint or modifying effects of the usual diet and baseline microbiome. DISCUSSION: The BE GONE trial is evaluating a scalable dietary prevention strategy targeting the gut microbiome of high-risk patients to mitigate the metabolic and inflammatory effects of adiposity that influence colorectal cancer risk, recurrence, and survival. The overarching scientific goal is to further elucidate interactions between diet, the gut microbiome, and host metabolism. Improved understanding of the diet-microbiota interplay and effective means to target these relationships will be key to the future of clinical and public health approaches to cancer and other major diet- and obesity-related diseases. TRIAL REGISTRATION: This protocol is registered with the U.S. National Institutes of Health trial registry, ClinicalTrials.gov, under the identifier NCT02843425. First posted July 25, 2016; last verified January 25, 2019.

Effect of extrusion on folic acid concentration and mineral element dialyzability in Great Northern beans (Phaseolus vulgaris L.).

Great Northern beans (GNB) contain appreciable magnesium (Mg), potassium (K), phosphorus (P), and iron (Fe), together with the heat-labile vitamin, folate, and the anti-nutritional compound phytate. Thus, the objective was to increase dialyzability of essential mineral elements while degrading phytate and minimizing destruction of folate through extrusion of GNB. Extrusion resulted in significant (p < 0.05) increases in dialyzability of Mg, P, K, and Fe by as much as 50%, 30%, 5%, and 79%, respectively, while decreasing cadmium (Cd) dialyzability. Screw speed (SS) had a significant quadratic effect on dialyzability of all elements. Low MC resulted in a significant reduction (46%) in phytate, although this was accompanied by as much as 24% destruction of folate. In conclusion, low barrel temperature, medium MC and high SS were identified as the optimum conditions to maximize essential mineral element dialyzability and folate retention while minimizing phytate and dialyzable Cd.

Demonstrating a Nutritional Advantage to the Fast-Cooking Dry Bean (Phaseolus vulgaris L.).

Dry beans (Phaseolus vulgaris L.) are a nutrient-dense food rich in protein and micronutrients. Despite their nutritional benefits, long cooking times limit the consumption of dry beans worldwide, especially in nations where fuelwood for cooking is often expensive or scarce. This study evaluated the nutritive value of 12 dry edible bean lines that vary for cooking time (20-89 min) from four market classes (yellow, cranberry, light red kidney, and red mottled) of economic importance in bean-consuming regions of Africa and the Americas. When compared to their slower cooking counterparts within each market class, fast-cooking dry beans retain more protein and minerals while maintaining similar starch and fiber densities when fully cooked. For example, some of the highest protein and mineral retention values were measured in the fast-cooking yellow bean cultivar Cebo Cela, which offered 20% more protein, 10% more iron, and 10% more zinc with each serving when compared with Canario, a slow-cooking yellow bean that requires twice the cooking time to become palatable. A Caco-2 cell culture model also revealed the bioavailability of iron is significantly higher in faster cooking entries (r = -0.537, P = 0.009) as compared to slower cooking entries in the same market class. These findings suggest that fast-cooking bean varieties have improved nutritive value through greater nutrient retention and improved iron bioavailability.

Common Bean: A Legume Model on the Rise for Unraveling Responses and Adaptations to Iron, Zinc, and Phosphate Deficiencies.

Common bean (Phaseolus vulgaris) was domesticated ∼8000 years ago in the Americas and today is a staple food worldwide. Besides caloric intake, common bean is also an important source of protein and micronutrients and it is widely appreciated in developing countries for their affordability (compared to animal protein) and its long storage life. As a legume, common bean also has the economic and environmental benefit of associating with nitrogen-fixing bacteria, thus reducing the use of synthetic fertilizers, which is key for sustainable agriculture. Despite significant advances in the plant nutrition field, the mechanisms underlying the adaptation of common bean to low nutrient input remains largely unknown. The recent release of the common bean genome offers, for the first time, the possibility of applying techniques and approaches that have been exclusive to model plants to study the adaptive responses of common bean to challenging environments. In this review, we discuss the hallmarks of common bean domestication and subsequent distribution around the globe. We also discuss recent advances in phosphate, iron, and zinc homeostasis, as these nutrients often limit plant growth, development, and yield. In addition, iron and zinc are major targets of crop biofortification to improve human nutrition. Developing common bean varieties able to thrive under nutrient limiting conditions will have a major impact on human nutrition, particularly in countries where dry beans are the main source of carbohydrates, protein and minerals.

Physicochemical Properties and in Vitro Digestibility of Cooked Regular and Nondarkening Cranberry Beans (Phaseolus vulgaris L.) and Their Effects on Bioaccessibility, Phenolic Composition, and Antioxidant Activity.

Cranberry beans from regular (RR) and nondarkening (CND) genotypes were pressure cooked, and free, conjugated, and bound phenolics were analyzed. Simulated in vitro gastrointestinal digestion was used to assess the bioaccessibility of these phenolic fractions. Total phenolic content decreased after cooking and digestion, whereas individual phenolic compounds were affected differently. Cooking significantly increased the release of bound ferulic and sinapic acids and flavanols, whereas digestion released p-coumaric, ferulic, and sinapic acids in both genotypes, and p-hydroxybenzoic acid, epicatechin, and catechin in only RR. Bioaccessibility of phenolics in RR and CND was 8.75 and 14.69%, respectively. Difference in total phenolics was smaller after digestion, and enzymes potentially secreted by colonic bacteria released similar amounts of phenolic acids in both varieties. Resistant and slowly digestible starch contents showed no differences between RR and CND. These results suggest that the lower phenolic content in raw CND may not completely negate its impact on gut health.

Amino Acid, Organic Acid, and Sugar Profiles of 3 Dry Bean (Phaseolus vulgaris L.) Varieties.

In this study, we compared the amino acid, organic acid and sugar profiles of 3 different varieties of dry beans (black bean [BB], dark red bean [DRB], and cranberry bean [CB]). The efficiency of the 2 commonly used extraction solvents (water and methanol:chloroform:water [2.5:1:1, v/v/v/]) for cultivar differentiation based on their metabolic profile was also investigated. The results showed that the BB contained the highest concentration of amino acids followed by DRB and CB samples. Phenylalanine, a precursor for the biosynthesis of phenolic secondary metabolites was detected at low concentration in CB samples and correlated with the reduced anthocyanins content in CB extract as documented in the published literature. Comparing the extractability of 2 extraction solvents, methanol:chloroform:water (2.5:1:1, v/v/v/) showed higher recoveries of amino acids from 3 beans, whereas, sugars were extracted in higher concentration with water. Analytically, gas chromatography detected sugars (9), amino acids (11), and organic acids (3) in a single run after derivatization of the extracts. In comparison, ion chromatography detected only sugars in a single run without any derivatization step with the tested procedure. Bean samples are better differentiated by the sugar content extracted with water as compared to the aqueous organic solvent extracts using partial least-square discriminant analysis.

Site-specific distribution and competitive ability of indigenous bean-nodulating rhizobia isolated from organic fields in Minnesota.

Organic dry bean production systems have received increasing interest in many regions of the US, including Minnesota. Thus, improving biological N2 fixation would be highly beneficial for organic crop production. To date, only limited work has been done to select efficient N2-fixing rhizobia for organic dry bean production. In this study, soil samples from 25 organic fields in Minnesota, with a previous cropping history of dry beans, soybeans or both, were collected during May to July 2012. Genetic diversity of indigenous dry bean-rhizobia (511 isolates) was determined by using horizontal, fluorophore-enhanced, repetitive, extragenic, and palindromic-PCR (HFERP) DNA fingerprinting and isolates were classified as belonging to 58 different genotypes. The more abundant rhizobia isolated from bean nodules comprised 35.6% of the population. None of the isolates were identical to commonly-used commercial strains used in the U.S., including Rhizobium tropici CIAT899. Seventeen predominant genotypes were shown to represent two main species, Rhizobium leguminosarum bv. phaseoli (67.1%) and Rhizobium etli (30.2%). One of the indigenous strains, orgK9, displayed efficient N2-fixation and competitive ability relative to the commercial strains tested. The lack of large numbers of indigenous dry bean-rhizobia at most study sites will be useful to avoid competition problems between inoculant strains and indigenous rhizobia. This will allow inoculation with highly effective N2-fixing rhizobia, thus resulting in improved crop productivity. Our results highlight the existence of site-specific rhizobial genotypes in different organic fields and identify strains that may prove useful as novel inoculants for organic dry bean production systems.

Characterization of free, conjugated and bound phenolics and lipophilic antioxidants in regular- and non-darkening cranberry beans (Phaseolus vulgaris L.).

Cranberry beans (Phaseolus vulgaris L.) from 7 different cultivars were characterized for phytochemicals and assessed for antioxidant activities. In vitro colorimetric methods were used to measure total phenolic (TPC) and total proanthocyanidin (PAC) contents. Free, conjugated and bound phenolic acids and flavonoids were also identified and quantified using HPLC-DAD/ESI-MS(n). Regular-darkening (RD) seeds contained higher TPC, PAC and flavonoids which were absent in the non-darkening (ND) seeds. Bound and conjugated phenolics in RD and ND mainly included cinnamic and benzoic acids. DPPH, FRAP and ORAC showed strong positive correlation with TPC, PAC, and with specific phenolics such as free catechin and bound p-hydroxybenzoic acid. Lipophilic extracts were rich in polyunsaturated fatty acids (69.20-76.89%). Carotenoid and tocopherol were limited to γ-tocopherol and ß-carotene. Results from this study can contribute to the development of cranberry bean cultivars with increased health benefits and addresses specific phenolic contributors to antioxidant activity.

Effects of combined traditional processing methods on the nutritional quality of beans.

Consumption of dry beans is limited by long cooking times thus high fuel requirement. The bioavailability of nutrients in beans is also limited due to presence of antinutrients such as phytates and tannins. Little research has been done on combined processing methods for production of nutritious fast cooking bean flour and the effect of combined treatments on nutritional quality of beans has not previously determined. The aim of this study was to reduce cooking time and enhance the nutritional value of dry beans. Specifically to: develop protocols for production of fast cooking bean flours and assess the effect of processing on the nutritional characteristics of the flours. Dry beans (K131 variety) were soaked for 12 h; sprouted for 48 h; dehulled and steamed for 25 and 15 min for whole and dehulled beans respectively or roasted at 170°C for 45 and 15 min for whole and dehulled beans respectively. Dehulling eliminated phytates and tannins and increased protein digestibility. In vitro protein digestibility and mineral (iron and zinc) extractability were negatively correlated with tannin and phytate content. Total available carbohydrates were highest in moist heat-treated bean flours. Overall, combined processing of beans improved the nutritional quality of dry beans and the resulting precooked flours need less cooking time compared to whole dry beans.