[Sodium and potassium content of some fresh, frozen and canned vegetables]

Sodium and potassium content was determined in fresh, frozen and canned green peas, corn and green beans, as well as in fresh and canned tomatoes. Flame photometry was the method used for this analysis, as the AOAC recommends. Among the fresh products tested, green beans yielded the lowest sodium and potassium contents, with 2.2 and 150.2 mg/100 g, respectively. The highest sodium content was found in green peas, with 31.8 mg/100 g, and the highest potassium values were determined in tomatoes and green peas, with 271.7 and 271.3 mg/100 g, values which are not statistically different. In regard to frozen products, green beans also presented the lowest values of these cations, with 3.0 mg/100 g sodium, and 111.0 mg/100 g potassium. The highest averages were detected in green peas, with a sodium content of 149.4 mg/100 g, and 145.1 mg/100 g potassium. In general, all canned products tested showed higher sodium and lower potassium values than those found in fresh or frozen products. The highest sodium content (317.3 mg/100 g) was found in canned green peas, and the lowest (127.4 mg/100 g), in canned tomatoes. With respect to potassium, the highest values corresponded to canned tomatoes, with 168.8 mg/100 g, and the lowest to corn, with 7.6 mg/100 g.