Effect of Different Decontamination Methods on Microbiological Aspects, Bioactive Constituents and Antibacterial Activity of Turmeric (Curcuma longa Linn.) Powder

Turmeric (Curcuma longa Linn.) has long been widely used for food, food additives, and traditional medicine. This study was aimed to assess effects of different decontamination procedures of turmeric rhizomes on microbiological quality and bioactive constituents of aseptically prepared turmeric powder. In addition, antibacterial activity of the powder on skin and wound pathogens was performed. The tested rhizomes were decontaminated by different methods including soaking in 70% (v/v) ethanol for 15 min, boiling in water for 15 min, boiling in 5% (v/v) acetic acid for 15 min, steaming at 100ºC for 15 min and autoclaving at 121ºC and 15 psi for 15 min. There were no foreign materials detected among the tested samples. The moisture content of each analyzed powder was similar (6.1±0.4%; v/w). The microbial contamination of the turmeric samples prepared from the ethanol soaked rhizome, water boiled rhizome, acetic acid boiled rhizome, and autoclaved rhizome were of satisfactory quality as required by the Thai Herbal Pharmacopoeia (THP) standard. Even though, the decontamination processes altered the contents of ethanol- and water-soluble extractives, curcuminoids, and volatile oils of the turmeric products but all of them conform to the THP standard. Among these techniques, the autoclave method was found to be sufficient for complete microbial decontamination without significantly affecting on the active constitutes of the turmeric powder.