The present invention relates to a method for manufacturing mulberry tea to increase the content of γ-aminobutyric acid. It mainly makes a mulberry raw material immersed in water at an ambient temperature with ultrasonic oscillation treatment at first. After withering and infrared radiation, the first anaerobic fermentation is processed, such that the glutamate contained in said mulberry raw material is converted into the γ-aminobutyric acid (GABA). After that, the first aerobic mixing is processed, subsequently with the second anaerobic fermentation, the second aerobic mixing and the third anaerobic fermentation processed, the content of γ-aminobutyric acid(GABA) is increased.本發明係有關於一種增加γ-胺基丁酸含量之桑樹茶製造方法,其主要係先將桑樹原料於常溫下加水浸泡並經超音波振盪處理後,進行萎凋並經紅外線照射後,進行第一次厭氧發酵,使得該桑樹原料內含之麩胺酸轉化成γ-胺基丁酸(GABA),再進行一次有氧攪拌,接著再進行二次厭氧發酵、二次有氧攪拌與三次厭氧發酵,以提高γ-胺基丁酸(GABA)含量。
