Boiling Dashi

If dashi is boiled, the umami content increases: if 20 g of bonito flakes are added to one litre of boiling water, the dashi contains 130 mg of amino acids; if they are put into cold water and quickly brought to the boil, it contains 140 mg; if they are soaked for 30 minutes and then brought to the boil it contains 145 mg. However, boiling the bonito flakes produces a tangy bitterness in the dashi’s taste, and the heat causes an unfavourable smell. Excessive application of heat is thus to be avoided.