Thawing effect on the growth and histamine formation of Klebsiella aerogenes in broth and artificially contaminated mackerel Novalia Rachmawati (a,b*), Radestya Triwibowo (a,b), Shane Powell (b), Mark Tamplin (b), and Tom Ross (b)
a) Research Centre for Marine and Fisheries Product Processing and Biotechnology, Ministry of Marine Affairs and Fisheries, Jakarta, Indonesia
b) Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia
*) novalia.rachmawati[at]kkp.go.id
Abstract
Histamine is a major hazard found in pindang, a traditionally prepared fish from Indonesia, and has caused several cases of histamine fish poisoning. Growth and histamine formation of Klebsiella aerogenes under conditions mimicking the processing of pindang were studied in broth and artificially contaminated Blue mackerel, Scomber australasicus. K. aerogenes was grown to two different cell densities. In broth, the culture was frozen at minus 20 degree C for 72 h and thawed at 4, 18 and 25 degree C for 4 h. Fish was contaminated with K. aerogenes before freezing, and thawing was done at 25 degree C for 4 h. K. aerogenes was reduced after freezing, and no bacterial growth was observed during subsequent thawing. Cooking the fish was sufficient to kill the isolate, as no colonies were found in cooked pindang. Histamine in broth increased during thawing and decreased after cooking, while in fish the histamine decreased during thawing and remained stable after cooking. Histamine production during thawing was more pronounced in treatment with high initial count than treatment with low initial counts. High pre-contamination levels of histamine in fish could not be eliminated with the current cooking practice of pindang, therefore raw fish used should met requirements as set by the Indonesian standard to avoid histamine accumulation.
Keywords: histamine, thawing, pindang, processing
Topic: Fisheries Product Technology and Food Safety (International)
