Histamine production by Raoultella ornithinolytica in mahi-mahi meat at various storage temperatures

Histamine production by Raoultella ornithinolytica in mahi-mahi meat at various storage temperatures

Mahi-mahi meat was inoculated with Raoultella ornithinolytica at 5.0 log CFU/g and stored at 20C, 4C, 15C, 25C, or 37C to investigate bacterial growth and formation of total volatile base nitrogen and histamine in mahi-mahi meat. R. ornithinolytica grew rapidly in samples stored at temperature above 15C. The histamine contents quickly increased to higher than 50 mg/100 g in samples stored at 25C and 37C within 12 hours as well as those stored at 15C within 48 hours. The total volatile base nitrogen contents increased to higher than the index level (30 mg/100 g) for fish decomposition at 25C within 48 hours and 37C within 24 hours. However, bacterial growth and histamine formation were controlled by cold storage of the samples at 4C or below. Once the frozen mahi-mahi samples stored at 20C for 2 months were thawed and stored at 25C after 24 hours, histamine started to accumulate rapidly (>50 mg/100 g of fish).