Rapid dye reduction tests for the determination of microbiological quality of meat

Rapid dye reduction tests have been developed to determine the quality of meat. Three
chemical indicators, resazurin and two tetrazolium compounds, were used to correlate
the microbial numbers and reduction times in meat samples.Twenty-five surface
samples from sheep carcasses were subjected to each reduction test. Total viable counts
given were obtained at 37°C. Resazurin reduction time was 90-120 min when the
bacterial counts ranged from 1 . 51~06 to 7 . 71~0 6/cm2. Samples showing bacterial
counts between 1.5x 106 and 6.0x 106/cm2 reduced tetrazolium (NBT) in 360-390 min
whereas samples containing bacterial counts of 2.1 x 106/cm2 took 420-450 min to
reduce iodophenyl nitrophenyl tetrazolium (INT) dye. Regression equations relating
the number of organisms per cm2 and reduction time were applied to predict the
microbiological quality of meat samples from reduction time data. Among the three
dyes, resazurin gave the lowest reduction time.