Assessment of spore contamination in pepper by determination of dipicolinic acid with a highly sensitive HPLC approach

A protocol for quantification of dipicolinic acid (DPA) in spices by high-performance liquid chromatography (HPLC) with post-column complexation and fluorescence detection was developed. DPA is a specific component of bacterial endospores and can be used for rapid assessment of endospore contamination without the need of cultivation. The highly sensitive approach was used to determine the DPA contents of whole black, white and green peppercorns. For conversion into endospore numbers, the DPA content of endospores of Bacillus subtilis, one of the most frequently detected species of spore-forming bacteria in pepper, was used. Estimated total spore numbers were highest for black pepper (1.6 × 108 spores g−1), for white and green pepper lower endospore loads were determined (about 8 × 107 spores g−1 in each case).