The effects of steam sterilization time and temperature on quality of turmeric powder (Curcuma longa L.) were studied. Fresh turmeric rhizome divided into 3 groups of 7 treatments. The first group were steam sterilization at 121๐C for 15, 10 and 5 minutes. The second group were steam sterilization at 115๐C, 110๐C and 105๐C for 15 minutes. The third group was the control group which not exposed to steam sterilization. The results showed that steam sterilization of turmeric at 121๐C for 15 minutes and 115๐C for 15 minutes had no microbial contamination and passed the standards of Thai Herbal Pharmacopoeia. The other five conditions were not qualified. Steam sterilization at 121๐C for 15 minutes had significantly (p