15D-12 |
Inactivation of Alicyclobacillus acidoterestris (AAT) in orange, apple and tomato juice by high hydrostatic pressure (HHP) |
H. ALPAS1, L. Alma, and F. Bozoglu. (1) Food Engineering Department, Middle East Technical University, Ankara, 06531, Turkey Alicyclobacillus acidoterrestris (AAT), a thermoacidophilic, non pathogenic and spore-forming bacterium has been detected in several spoiled commercial pasteurized fruit juices. Although the occurrence is not very common, it can prove extremely expensive for the manufacturer, as it is not associated with extensive gas production or even acid production, but with strong, medicinal-like flavour taints which develop sporadically in containers of shelf-stable products. The objective was to study the inactivation of AAT by HHP in BAM broth, orange, apple and tomato juices. Fresh cells of AAT from overnight culture were suspended in BAM (Bacillus Acidocaldarius Medium) broth (pH=3.0) to about 107 cells/ml and pressurized at 350 and 450 MPa at 35, 45 and 50oC for 5, 10 and 20 min. Fruit juices inoculated with AAT cells to about 106 cells/ml were pressurized at 350 MPa at 50oC for 20 min. The viability loss of AAT vegetative cells pressurized at 350 MPa at 35, 45 and 50oC for 20 min were 1.60, 2.87 and 4.70 log cycles, respectively. Increasing the pressure to 450 MPa at the same time-temperature combinations caused an additional 1-log cycle reduction. For comparison, heat treatment at 50oC and 60oC for 20 min caused only 1.13 and 1.23 log-cycle reduction in viability, respectively, showing the effectiveness of HHP treatment on inactivation of AAT vegetative cells. The inactivation in orange, apple and tomato juices after HHP treatment (350 MPa, 50oC, 20 min) were 4.40, 4.64 and 4.06 log-cycles, respectively. The results revealed that, HHP treatment-at the experimental conditions studied-can be highly effective on inactivation of AAT vegetative cells and can be used in fruit juice production as an alternative to pasteurization against spoilage caused by AAT.
Session 15D, Food Microbiology: Fruits and vegetables
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