Undesirable changes in vacuum-packaged beef products during prolonged storage can present a problem to some consumers. Bacterial proteolysis and decarboxylation can release pressor amines, such as tyramine and histamine, that can be toxic when ingested by individuals taking monoamine oxidase-inhibiting drugs. This study determined the effect of carcass decontamination on bacterial growth and biogenic amine production in vacuum-packaged subprimals. Beef carcasses were treated with 200 ppm chlorine or 3% lactic acid sprays, fabricated, vacuum packaged, and stored at 1°C. Samples were evaluated up to 120 d for amine concentrations, total aerobic counts, and lactic acid bacteria. Of all the amines monitored, only tyramine was consistently detected over the course of the study. Significant levels of tyramine were detected starting at day 20 of storage in all treatments and controls. By day 60, the levels had increased to about 50 μg/g and continued to increase to about 180 μg/g by 120 d of storage. Tryptamine was detected in some samples by 60 d of storage, but the levels were variable and did not follow any trend. Initial aerobic plate counts ranged from 10-200 CFU/cm2, whereas lactic acid bacteria counts were from 6-46 CFU/cm2. Bacterial numbers increased exponentially until about day 60, when they leveled off at between 106-107 CFU/cm2, with no differences between any of the treatments and/or controls. Although the vacuum-packaged beef was organoleptically acceptable up to day 60 (day 90 for some samples), it could pose some risk to individuals sensitive to biogenic amines if the product is stored at 1°C or higher for 60 d or more.
1 Contribution No. 93-159-J from the Kansas Agricultural Experiment Station.