Coliform Contamination on Cilantro from Large Grocery Chains

Cilantro is commonly used in cuisine around the world and has been attributed to many health benefits including helping cognitive fitness, reducing anxiety, lowering blood sugar, and anti-inflammatory effects. Alternatively, coliforms are known to cause food-borne illness and must be closely monitored. In this study, we evaluated the prevalence of coliforms in cilantro purchased from local grocery stores in April, August, and November of 2025 using Most Probable Number (MNP) test. The samples obtained in the spring and summer contained significant numbers of coliforms in all investigated stores, from 240 to >1100 per gram of fresh cilantro. We didn’t detect coliforms in cilantro purchased in late fall in either of the stores, which suggest that it was obtained from a different producer and potentially grown in a greenhouse.  We detected six types of colonies which were identified using the BIOLOG system and tested for antibiotic resistance. We also demonstrated that standard washing of the leaves decreased the number of coliforms by 50-80% across samples. The significance of this research is strong as it shows that coliforms are an issue in cilantro supplied in multiple local grocery stores. Additionally, there is a reduction in coliform numbers with washing, but further research should be done to see what producers show the cleanest cilantro, and if there is a better washing method than just water.