You need only about 1/8 teaspoon of powdered low-methoxyl pectin to thicken 1 cup of milk-based soup or sauce. If you want to thicken a soup or sauce that contains sugar, add about 1/8 teaspoon of high-methoxyl powdered pectin per cup of liquid, then boil it for about 30 seconds to activate. Use pectin sparingly. When used excessively, pectin causes the liquids it thickens to develop a high-gloss sheen and to set like gelatin.