Production method for soluble material

A production method for a soluble material, comprising:

• causing
• a solid raw material containing
• (i) at least one hydrolyzable material selected from the group consisting of a protein, a carbohydrate and a lipid, or
• (ii) a fibrous material, or
• (iii) a fibrous material and at least one hydrolyzable material selected from the group consisting of a protein, a carbohydrate and a lipid, and
• water in an amount corresponding to 0.04 to 2.4 parts by weight with respect to 1 part by weight of a dry amount of the solid raw material
• to coexist (so that an amount of the water including water originally contained in the solid raw material reaches 0.04 to 2.4 parts by weight);
• applying a shearing force in a state where heating and pressurization are performed at 250 to 374° C. and in a pressure range equal to or higher than a vapor-liquid coexistence curve of water to hydrolyze at least a part of the hydrolyzable material and/or to amorphize at least a part of the fibrous material;
• and
• halting the pressurization to cause adiabatic expansion.