Trehalose is disaccharide derived from starch, formed by two glucose units. Mushrooms, seaweed, yeast, algae, and seawater are rich in trehalose which has high moisture retention. Dried mushroom is rehydrated in water because it contains trehalose.
Some of the characteristics of trehalose, which exists in many animals, plants, and microorganisms in nature, are inhibiting discoloration, denaturation of protein, starch retrogradation, and moisture absorption as well as having freezing resistance and keeping freshness.
All living creatures including human-beings cannot survive without water. It has been known since old days that some completely dried up living creatures bring back to life by providing them with only small amount of water.
For example, living creatures such as a plant named selaginella living in deserts, water bear (tardigrade), and yeast bring back to life only by providing them with water even after they have been completely dried up for several years.
The cause of this “strange phenomenon” was unknown for many years. However, it was recently discovered that the sugar inside the cells of those living creatures are heavily involved with this “strange phenomenon.”
The sugar is called “trehalose,” which is believed to protect cells as a water substitute. Trehalose is also called “sugar of life” or “sugar of regeneration.”
There is an interesting story in the Exodus of the Old Testament (Scene where Moses was leading Israelites to escape from Egypt to Israel).
According to the revelation of God - Yahweh, Israelites were eating white “flake-like things” lying on the surface of the wilderness as a bread substitute to avoid starvation while wandering in the desert. They called this “manna,” which tasted like a wafer with honey. They kept eating it for 40 years until they reached to Land of Canaan.
One of the mannas appeared in this story is trehala manna which contains a lot of trehalose. The word trehalose was derived from it.