To prepare the concentrate: Once steam releases, open the pressure cooker and with a potato masher, mash the mangoes till all the pulp is off the stones and the pulp is well blended. Remove the skin pieces and add the sugar and mix well when hot only. Adjust the sugar as per your tasting. If you like very sweet, then add more quantity than mentioned in the recipe.You can store this concentrate in the refrigerator in an air tight container for about 4-5 days.