PURPOSE: To prevent deterioration of taste and flavor of coffee and to enable long-term preservation of coffee, by adding rutin, tea flavonoid, rosemary extract, sage extract and sodium citrate to extraction solvent to coffee or solvent- extracted coffee liquid.

CONSTITUTION: Coffee is extracted batchwise or using a counter-current extraction column. In the above process, the extraction solvent and/or a solvent- extracted liquid is added with a deterioration-preventing agent comprising rutin, tea flavonoid, rosemary extract extracted with water, hydrated alcohol, etc., sage extract and/or sodium citrate. Coffee can be extracted without deteriorating the characteristic taste and flavor of roasted coffee and the obtained coffee extract liquid is resistant to deterioration of quality.