Antimicrobial Effects of Selected Antioxidants in Laboratory Media and in Ground Pork

Butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tertiary butylhydroquinone (TBHQ) and propyl gallate (PG) at 0, 50, 100, 150, 200, 250, 300, 350, 400, 450 and 500 ppm and selected combinations at 0, 100, 200, 300 and 400 ppm in nutrient agar and in brain heart infusion were tested for antimicrobial activity on sixteen gram-negative and eight gram-positive bacteria. In general, in laboratory media the antioxidants inhibited gram-positive bacteria more than gram-negative bacteria. The antioxidants were more effective in nutrient agar (solid system) than in brain heart infusion (liquid system). In nutrient agar, BHA inhibited the greatest number of organisms followed by PG, TBHQ and BHT, respectively. In brain heart infusion, TBHQ inhibited the greatest number of organisms followed by PG, BHA and BHT, respectively. Of the six combinations tested, the TBHQ-PG combination inhibited the greatest number of organisms followed by BHA-PG, BHT-TBHQ, BHA-TBHQ, BHT-PG and BHA-BHT, respectively. Tests in ground pork indicated the four antioxidants at 100, 200 or 400 ppm significantly (P<0.05) reduced psychrotrophs, coliforms and fecal coliform counts after 4 wk of storage at 4°C. There were no significant differences between the control and the samples treated with antioxidants after either 1 or 2 wk of storage.