Controlling Alicyclobacillus Acidoterrestric in Fruit Juices by Combination Treatments under Varying Acidic Conditions
Principal Investigator |
Dr. Dong-Hyun Kang |
Completion Date |
January 14, 2006 |
Mission |
Investigate manufacturing methods to reduce bacteria spores in commercial pasteurized apple juice at the production level. |
Problem Addressed
Alicyclobacillus acidoterrestris, a thermoacidophilic and spore-forming bacterium, has been identified as a spoilage organism in commercial pasteurized fruit juices. A. acidoterrestris spores, is resistant to the pasteurization treatments normally applied to acidic fruit juice products and can germinate and grow under storage conditions. It causes a flat sour type of spoilage and produces an offensive-smelling compound, guaiacol, and other taint chemicals.
Since it is resistant to thermal treatment, proper sanitation in addition to pasteurization heating, is required for apple juices and concentrates. While chemicals may be effective for killing A. acidoterrestris spores, consumer demand for minimally-processed foods dictates the need for the manufacturing industry to reduce the use of chemical additives and at the same time provide goods which are perceived to have received minimal physical processing.
Goal
To investigate the effectiveness of combined high pressure and heat treatment in reducing levels of A. acidoterrestris spores in commercial pasteurized apple juice.
Implications
The value of processed apple products in the United States was $207 million in 2003, of this 79 percent resulted from sales of apple juice or cider and more than half of that was produced by Washington. As noted in a National Food Processors Association survey, 35 percent of manufacturers experience spoilage consistent with Alicyclobacillus spp. Combining the results of these statistics, at least $0.41 million is lost as a result of Alicyclobacillus spp. spoilage in Washington State.
With the large amounts of apple juices and concentrates produced in Washington State, the spoilage caused by A. acidoterrestris often results in high economic losses to apple juice companies. Since A. acidoterrestris produces spores, it is very difficult to kill. Therefore, development of technologies to reduce levels of A. acidoterrestris spores and to sanitize apple juices without adding chemicals is important to extend the shelf-life of apple juice and prevent industrial economic losses.
Procedures
A. acidoterrestris spores were inoculated into apple juices and were treated with combined heat and high pressure. Each of three high pressure treatment (207, 414, and 621 MPa) was performed at each of four different temperatures (22, 45, 71, and 90°C).
The project found that treatment with high pressure alone at 22°C did not reduce spore numbers and that high temperature treatment alone did not reduce levels of A. acidoterrestris spores. However, the combination of high pressure and heat strongly reduced the number of A. acidoterrestris spores.
Techniques and Technologies Developed
Technology: Combination of heat and high pressure
for killing spores.
Significance: Heat or high pressure alone cannot kill A. acidoterrestris spores in apple juices. However, combined treatment of heat
and high pressure is very effective at killing A. acidoterrestris
spores.
Publications/Journal Articles From Project
S. Y. Lee, R. H. Dougherty, and D. H. Kang. 2002. “Effect of high pressure treatment combined heat on killing spores of Alicyclobacillus acidoterrestris in apple juices.” Applied and Environmental Microbiology 68: 4158-4161.
S. Y. Lee, P. M. Gray, R. H. Dougherty, and D. H. Kang. 2004. “The use of chlorine dioxide to control Alicyclobacillus acidoterrestris spores in aqueous suspension and on apples.” International Journal of Food Microbiology 92: 121-127.