Use of nisin for inhibition of Alicyclobacillus acidoterrestris in acidic drinks

The inhibitory effects of nisin on the growth of the thermoacidophilic spoilage bacterium Alicyclo-bacillus acidoterrestris were investigated for the purpose of preventing fiat-sour-type spoilage in acidic drinks. Minimum inhibitory concentration values of nisin against the spores were from less than 0.78 to 12.5 IU ml(-1) and from 25 to 100 IU ml(-1) on mYPGA plates at pH 3.4 and 4.2, respectively. The levels of nisin inhibition against the vegetative cells were, however, higher than those of the spores. In determining the effects of nisin, on the thermal resistance of A. acidoterrestris spores, the addition of nisin, contributed to the reduction of the thermal resistance of A. acidoterrestris spores in acidic drinks. Furthermore, the outgrowth of A. acidoterrestris spores was inhibited by the addition of 25-50 lU ml(-1) nisin in both orange and fruit-mixed drinks, but was not inhibited by the higher level (600 IU ml(-1)) addition in a clear-apple drink. From these findings, we conclude that if would be useful to add nisin for preventing the spoilage caused by A, acidoterrestris in all but clear-apple acidic drinks. (C) 2000 Academic Press.