The Growth Risk of the Thermoanaerobacterium sp. in Tomato Products

Abstract

In this study, we investigated the growth risk of Thermoanaerobacterium sp. in tomato products which has not been clarified in previous study excepted for tomato juice. As a result, the growth of Thermoanaerobacterium sp. was not observed in various tomato products with refractive index (RI, index for soluble solid content concentration) 8.0 or more, and pH 4.2 - 4.6. On the other hand, the growth of Thermoanaerobacterium sp. in modified TGC media of pH 4.2 - 4.6 was observed in the range of RI 8.0 but was not observed in the range of RI 19.5 or more. These results suggested that there were other growth inhibitors of Thermoanaerobacterium sp. in tomato products besides RI. Therefore, we investigated the growth risk of Thermoanaerobacterium sp. by adding organic acids contained in tomato products, citric acid, malic acid, and pyroglutamic acid, to a modified TGC medium. As a result, when citric acid alone contained more than 0.52％, no growth was observed, and the coexistence effect of organic acids was not confirmed. These results suggested that citric acid contributes to the growth inhibition of Thermoanaerobacterium sp. in tomato products.