Banana blossom is a type of vegetable that can be used as a source of fiber. The previous studies showed that the addition of banana blossoms to the baby tuna shredded caused a decrease in the number of microbes compared to control. Histamine-forming bacteria in baby tuna originated from indigenous bacteria and contaminants such as Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, and Lactobacillus plantarum. This study was aimed to find out how much water-soluble extract of banana blossom anti-bacterial against histamine-forming bacteria. Testing of anti-bacterial ingredients in banana blossom Musa acuminata water-soluble extract with LC-HNMR, toxicity testing, and amino acid testing. The studies using the Kirby Bauer method and corroborated by SEM observations showed that water-soluble extract of banana blossom Musa acuminata had low anti-bacterial properties for Lactobacillus plantarum and Klebsiella pneumonia but not for Escherichia coli and Pseudomonas aeruginosa. Further testing of the anti-bacterial substance water-soluble extract of banana blossom was histidine, proline, isoleucine, threonine, and glutamic acid. This extract categorized as a non-toxic substance