Alicyclobacillus in Orange Juice: Occurrence and Heat Resistance of Spores

Abstract

Spore suspensions of a pure culture of Alicyclobacillus acidoterrestris DSM 2498 were submitted to different heat treatments (60 degrees C for 60 min, 60 degrees C for 30 min, 70 degrees C for 20 min, 80 degrees C for 5 min, 80 degrees C for 10 min, 80 degrees C for 30 min, and boiling for 5 min) to determine the best activation conditions in orange juice. The best treatment for spore activation was shown to be 70 degrees C/20 min. Seventy-five samples of concentrated orange juice from 11 different suppliers were examined for the presence of thermophilic acid-tolerant spore formers by the most probable number technique using Bacillus acidocaldarius medium (BAM broth) and incubation at 44 degrees C for 5 days after a prior spore activation. After incubation, isolation was carried out using BAM agar medium incubating at 44 degrees C for 5 days. Typical colonies were submitted to a microscopic examination, evaluation for the presence of spores, and various biochemical tests. Of the orange juice samples examined, 14.7% were found to be positive for Alicyclobacillus. The thermal death time open tube method was used to determine the heat resistance of the spores of strains confirmed as being Alicyclobacillus. The D-values determined were in the range from 60.8 to 94.5 min at 85 degrees C, 10.0 to 20.6 min at 90 degrees C, and 2.5 to 8.7 min at 95 degrees C. The z-values were between 7.2 degrees C and 11.3 degrees C. The results demonstrated the occurrence of Alicyclobacillus in orange juice and the high heat resistance of the spores that could survive the heat treatments normally applied in the processing of orange juice.

Inactivation Kinetics of Alicyclobacillus acidoterrestris Spores in Orange Juice by Ohmic Heating: Effects of Voltage Gradient and Temperature on Inactivation

“…0.05). D-values for conventional treatment obtained in this study (15.11 min for 80uC and 7.84 min for 90uC) were lower than the D-values previously reported for inactivation of A. acidoterrestris spores in orange juice with a similar pH range (4,5,14,26,27). The z-values for conventional treatment (17.89uC) also are higher than those previously reported (4,5,14,26,27).…”

“…Heat resistance studies have indicated that Alicyclobacillus spores can survive the usual hot-fill processes that are used with commercial juices (4,5,14,(24)(25)(26)(27). Data also indicate that increasing the uBrix makes the spores more resistant to heat.…”

Quality and shelf life of orange juice aseptically packaged in PET bottles

“…The adverse effects of dissolved oxygen on fruit juice quality have been investigated by many researchers and include degradation of ascorbic acid, increased browning and growth of aerobic bacteria and moulds (Eiroa, Junqueira, & Schmidt, 1999;Kennedy, Rivera, Lloyd, Warner, & Jumel, 1992;Meydev et al, 1977;Soares & Hotchkiss, 1999;Solomon, Svanberg, & Sahlstrom, 1995). Traditional methods for juice packaging aim to reduce the exposure of the juice to oxygen through the use of high barrier materials such glass or foil laminates in brickpacks, with or without nitrogen flushing (Zerdin et al, 2003) or improving gas barrier of PET by blending with aromatic polyamides (Hu et al, 2005).…”

Semiquantitative determination of Alicyclobacillus acidoterrestris in orange juice by reverse‐ transcriptase polymerase chain reaction and capillary electrophoresis – laser induced fluorescence using microchip technology

“…Recently, the spoilage of fruit juice by the thermoacidophilic spore-forming bacterium Alicyclobacillus acidoterrestris has been observed on a worldwide level [1,2]. Fresh orange juice and orange juice concentrate are often contaminated with spores of A. acidoterrestris, which have survived the pasteurization process [3,4].…”