Sulfur fumigation, a better or worse choice in preservation of Traditional Chinese Medicine?

Sulfur fumigation (SF) in Traditional Chinese Medicine (TCM) is a highly efficient and important traditional preservation method in China. This method has generated a great deal of concern and has been disputed in the last few years because of its uncertain safety. SF can alter the quality of TCMs by damaging the bioactive compounds, changing chemical profiles, and generating detrimental exogenous materials. However, SF is still widely used in the herbal medicinal industry because of its various benefits, such as its pesticidal and anti-bacterial effects, easy operation, and low-cost. This review contains the current situation, chemical mechanism and reactions during SF, the pharmacological and pharmacokinetic research, and the influence of quality caused by SF. In addition, a quantification-operation sulfur fumigation device (QOSFD), which can maintain the quality of TCMs by controlling the SF processing parameters, has been designed and introduced. The key technologies of this device involve controlling the O2 content and the temperature of SO2 as well as the quantification of sulfur in SF. This device can reduce the possibility of reaction between bioactive compounds and sulfur/sulfurous acid, as well as control the limitation of SO2 residues. The QOSFD is regarded as a promising preservation technique in the field of TCM, medicinal materials, agriculture, and fruit industry.