Application of bacteriocin RC20975 in apple juice

Alicyclobacillus acidoterrestris is one of the most spoilage-causing bacteria in fruit juices. In this paper, controlling A. acidoterrestris in apple juice by bacteriocin RC20975 was described. Twenty-one strains of A. acidoterrestris were used to investigate the activity spectrum of bacteriocin RC20975 in apple juice with the result that 16 strains were sensitive. The ratio of activity in apple juice to the activity in laboratory medium was 42%. The reduction of antimicrobial activity in apple juice might be due to problems related to its interaction with food components. Adsorption of bacteriocin RC20975 to A. acidoterrestris cells varied according to the strains and the testing conditions (pH and temperatures). In an acid environment (pH 3 and pH 5), the adsorption was higher than that of the neutral environment. Dynamic model of killing bacteria was built under the condition of different temperatures with the addition of bacteriocin. Electron microscopy examination of vegetative cells revealed substantial cell damage and bacterial lysis after bacteriocin treatment. Although the endospores could not be killed, the addition of bacteriocin RC20975 contributed to the reduction of the thermal resistance of A. acidoterrestris spores in apple juice. In sum, bacteriocin RC20975 was proved to have a good effect on killing A. acidoterrestris in apple juice.