Yes Amaranth stems are pickled with white foam because they contain some gases and moisture produced in the pickling process. This is a normal phenomenon and does not affect food safety. Salted amaranth stems can salt out green water at first, which is the reaction between salt water and amaranth stems when the temperature is high for four or five days at room temperature, then turn a little white after a day or two, and then slowly turn into small bubbles and white bubbles.