Edible dry bean powder chemical composition in relation to solvent retention capacities and pasting properties

The focus of this research was the evaluation of bean powders (particle size ≤ 0.5 mm), obtained from 25 Michigan-grown edible dry beans, for their starch and protein contents and relationships to their solvent retention capacities (SRCs) and pasting properties. Solvent retention capacities of the bean powders were tested with two different solvents, water (WRC) and lactic acid (LARC), following the American Association of Cereal Chemists International Approved Methods, with minor modifications. Protein content was measured using a microwave modified Kjeldahl method and pasting properties were measured by a Rapid Visco Analyzer. Starch content was analyzed using the Megazyme Total Starch Assay, following the same methods traditionally applied to wheat flour. Statistical analyses were conducted to determine significant differences (p=0.05) among varieties as well as correlations between tests conducted. Significant differences among the samples for all tests were observed. Protein content ranged from 16.31 (R12844) to 22.29 (Fuji) g/100g db (dry basis) and starch content ranged from 31.55 (Fuji) to 40.22 (Merlot) g/100g db. Furthermore, a wide range in WRC [from 1.56 (Powderhorn) to 2.43 (R12844) g/g db], in LARC [from 1.75 (Coop12064) to 2.88 (Montcalm) g/g db], and in pasting properties [final viscosity values ranged from 641.5 (Fuji) to 1844.0 (Merlot) cP] were observed among the cultivars. Positive correlations (r≥0.40, p≤0.05) were seen between each of the SRCs and pasting properties. Negative correlations (r≥-0.49, p≤0.02) were observed between protein content and pasting properties. No correlations were found between LARC and bean protein content, in contrast to wheat flour. Total starch content was correlated positively (r≥0.51, p≤0.01) with pasting properties, but no correlations between SRCs and total starch content were seen. This research helps to expand information about the physiochemical properties of edible dry bean powders. This could help bean breeders to select varieties for usage other than canning. As new applications for edible dry bean powders are proposed, e.g., as thickeners for salad dressing, the findings of this research would be useful to select dry beans with the desired qualities for their proposed applications.