Microbiology Insights

¹Division of Microbiology, Center for Food Safety and Applied Nutrition, Food and Drug Administration, 5100 Paint Branch Parkway, College Park, MD 20740, U.S.A. ²Northeast Regional Laboratory, Food and Drug Administration, 158-15 Liberty Ave., Jamaica, NY 11433, U.S.A.

Abstract

Various herbal teas including German chamomile, Chrysanthemum Vascuflow herb tea, hop, jasmine and orange flowers, sweet marjoram, spearmint and thyme leaves, and papaya-mint tea as well as coffee substitutes (Bambu instant Swiss, Teeccino chocolate-mint, and Teeccino Mediterranean Espresso) were analyzed for fungal contamination and the presence of aerobic mesophilic bacteria (APC). The results of this investigation showed that fungal counts reached levels as high as 5.8 × 105 colony forming units (cfu) per gram. German chamomile harbored the highest fungal contamination. The most common fungi found in herbal teas were Aspergillus niger, Penicillium spp., Eurotium rubrum, E. chevalieri, A. flavus, Fusarium spp., Alternaria alternata, and yeasts. Among the coffee substitutes, only the chocolate-mint coffee was contaminated with low numbers (<1.0 × 10³ cfu g⁻¹) of E. rubrum, Ulocladium spp. and Phoma spp., and with yeasts (<100–6.8 × 10³ cfu g⁻¹). Aerobic mesophilic bacteria were recovered from 100% of the herbal tea, chocolate-mint and Mediterranean Espresso, and from 50% of the Bambu instant Swiss coffee samples. The highest APC counts of 1.2 × 10⁷ cfu g⁻¹ were observed in spearmint leaves.