To evaluate the effect of aging on solar salts produced in Korea, the chemical compositions of the solar salts, including their heavy metal contents, were analyzed after they were aged for one-year (OA) and for three years (TA). The average contents of the components were: sodium chloride; 81.4% (OA) and 90.9% (TA), chloride; 57.7% (OA) and 65.0% (TA), moisture content; 4.7% (TA) and 12.0% (OA), insoluble solids; 0.03% (OA) and 0.04% (TA), and SO4 ions; and 0.57% (TA) and 0.85% (OA). No significant difference was found, however, in the heavy metal contents. Heavy metals such as As, Pb, and Hg were detected with values far below the maximum permissible limit, and Cd was not detected in the salts. The TA solar salts showed higher values of sodium chloride, chloride, and insoluble solids than the OA solar salts, but the TA solar salts had lower moisture and SO4 values. These results clearly indicate that the levels of heavy metals in the OA and TA solar salts that are produced in Korea are safe.

The growth inhibition effect of Doenjang that was prepared with various kinds of solar salt was investigated. Doenjang was prepared using the bacterial koji and five kind of salt with 12% salt concentration (w/w): purified salt Doenjang, one-year aged solar salt Doenjang, four-year aged solar salt Doenjang, topan solar salt Doenjang, and boiled solar salt Doenjang. The Doenjangs were fermented and aged for 18 months. The growth inhibition effects of the water extracts and the methanol extracts of the Doenjangs were measured on AGS human gastric adenocarcinoma cells, HT-29 colon carcinoma cells, and BJ human foreskin normal cells using MTT assay. The water and methanol extracts of the Doenjang samples showed growth inhibition effects on the cancer cells, in the following order of the samples with the strongest to the weakest effect: the four-year aged solar salt Doenjang, the topan solar salt Doenjang, the boiled solar salt Doenjang, the one-year aged solar salt Doenjang, and the purified salt Doenjang. The methanol extracts of the four-year aged solar salt Doenjang (AGS: 55% and HT-29: 48%) showed the strongest growth inhibition effect. In addition, decreased cancer cell numbers and morphological changes in the cancer cells (AGS and HT-29) were observed when the methanol extract of the four-year aged solar salt Doenjang was treated. None of the Doenjang extracts showed a growth inhibition effect on the BJ normal cells, though.