The preparation of rooibos (Aspalathus linearis) tea involves the introduction of water and long exposure to warm temperatures, both of which can contribute to microbial growth in plants. Unfortunately, researchers in South Africa say that most of the existing research on rooibos tea has focused on the tea’s health benefits and not on its microbial safety. In the case of rooibos tea and Salmonella risk in particular, research is warranted.
When rooibos is harvested and cut, it is combined with water for a fermentation process at temperatures of 38°C–42°C before a short steam pasteurization at 85°C–92°C. This steam pasteurization, however, may not be the best method for controlling Salmonella contamination. Previous studies have found Salmonella present in rooibos after pasteurization, and other opportunities for contamination, such as during storage and handling, still exist.
Cost-effective alternatives to managing and preventing Salmonella growth in rooibos tea include the use of Salmonella-specific bacteriophages, ozone treatment, and food radiation—all of which are explained in detail at the link above. Salmonella-specific bacteriophages can single out Salmonella, and this is already an effective strategy for the meat industry. With rooibos tea, such substances can be simply added to the water during fermentation. Ozone treatment is already used to combat Salmonella growth in the meat industry, and food radiation has proved useful with fruits and vegetables.
Manufacturers of loose-leaf rooibos should make sure to clearly state boiling instructions for consumers, as this step also kills a large number of microorganisms.
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