The modern day Japanese Konjac is made by adding water to Konjac root powder which thickening it into a paste. The paste is then mixed with calcium hydroxide to make it alkaline, then heating it to solidify it. The mixture is kept frozen for a night and dried slowly to evaporate the water and alkaline as the final process. The Konjac Sponge is then shipped to oversea 
Dry sponge have long expiry date