There are some pretty solid criticisms on how it was tested.

Scientific debates surrounding Ricardo Castañón Gómez’s investigations into alleged Eucharistic miracles have centered on methodological concerns raised by forensic scientists, particularly regarding the Buenos Aires case of 1996. Critics argue that the testing protocols exhibited bias, with the selection of primarily pathologists and cardiologists predisposing results toward interpretations of human cardiac tissue without input from microbiologists or mycologists to explore alternative explanations. This approach, according to a 2024 analysis in the Journal of Forensic Science Research, reflects a lack of true blind testing, as the involvement of a camera crew may have signaled the sample’s significance to experts, potentially influencing their conclusions.

Questions about sample handling have been prominent, especially in the Buenos Aires investigation, where the host was stored in water for several years before analysis and handled by multiple individuals without personal protective equipment, heightening contamination risks. A forensic review highlights that no chain-of-custody documentation or spike controls were used to detect inhibitory substances, which could compromise DNA results showing only low concentrations of human genetic material. Furthermore, the absence of peer-reviewed publications for these findings has drawn scrutiny, as the studies have not undergone standard scientific validation processes, relying instead on reports from select experts without broader interdisciplinary review. Potential contamination from environmental factors, such as bacteria like Serratia marcescens or fungi producing reddish pigments, was not adequately ruled out, with control experiments demonstrating that unconsecrated wafers under similar conditions can yield comparable appearances due to microbial growth.

Speaking for myself, I would not personally take that test as adequate evidence of the supernatural.