A method for preparing fermented onion extract with enhanced antioxidant activity, by placing onion raw materials in a fermentation environment at a temperature of 75 ° C and a relative humidity of 40%, and fermenting for 7 to 28 days to produce black onion with antioxidant activity And the high temperature and low humidity fermentation method of the present invention can not only effectively improve its antioxidant activity, but also because the fermentation process of the present invention is simple and only needs to be controlled under a single operating condition, it has the characteristics of easy control and Time requirements and resource consumption can be greatly reduced, and onions can be used more efficiently.一種提升抗氧化活性發酵洋蔥萃取物之製作方法，係將洋蔥原料置於溫度在75℃及相對濕度在40%之發酵環境下，發酵7~28天即可製成具抗氧化活性之黑洋蔥產品；而採用本發明之高溫低濕發酵方法，不但可有效提升其抗氧化活性，且由於本發明之發酵製程簡易，僅需控制在單一之操作條件，因而具有容易控制之特點，使所需時間需求及資源消耗可大幅降低，而能更高效率運用洋蔥。
