Essential Elements in Dry and Canned Kidney Beans ( Phaseolus vulgaris L.)

Ten essential mineral elements were determined in dry and in canned kidney beans ( Phaseolus vulgaris L.). Samples were taken at different stages during the canning process to determine where changes in element content occurred. Canned kidney beans contained significantly lower concentrations of iron, magnesium, manganese, potassium, and zinc than dry kidney beans, on a dry weight basis. These decreases were probably caused by the elements being extracted out during soaking and blanching of the kidney beans and/or during the actual thermal processing where elements were extracted into the can liquid. There was a significant increase in calcium in the canned product and no significant difference in copper and phosphorus contents between the dry and canned products. Chloride and sodium content in canned kidney beans increased due to the sodium chloride content of the filling medium, and their concentrations varied depending on the concentration of the medium used. Retention of all elements, except chloride and sodium, ranged from 61 to 117% on a dry weight basis and from 19 to 36% on wet weight basis, retention being defined as the ratio of content in the canned to that in the dry product as received at the plant.