Samples of acidified sushi rice were tested for pH using an in-house NATA accredited method
(F 50.39) based on the AOAC 981.12 method using pH meter and buffers, or equivalent. The
determination of water activity (aw) used an in-house method (M14) based on the AOAC
978.18 method using detector liquid and refractometer, or equivalent.
Samples of raw fish were tested for the presence of histamine using an in-house NATA
accredited method (method F25) in which the histamine is extracted from the sample then
derivatised with orthophthaldehyde for High Performance Liquid Chromatography (HPLC)
analysis using fluorescence detection, or equivalent.
All microbiology samples were analysed within 24 hours of receipt at the laboratory using the
appropriate Australian Standard method as detailed in Table 1.
All statistical analysis was conducted using the analysis of variance, T-test and chi square test
from JMP® Professional Edition Ver. 5.