Underberg, the herbal bitter in the small bottle wrapped in paper, has been made in Rheinberg since 1846 from a secret recipe with herbs from 43 countries. On 17 June 2025, the company’s anniversary, the family introduced its newest Geheimnisträger, keeper of the secret, to the staff: Ludwig Ruder, a 34-year-old grandson. Four members of the family and three Catholic priests now know the composition. The family says that guarding the secret guarantees the drink’s originality and quality.