The quality improvement of kava beverage by a non-thermal dense phase carbon dioxide pasteurization.

MongJan Hsieh, Dr. Alvin S. Huang, and Dr. Murat O. Balaban

Kava is a traditional Polynesian beverage, popular in Hawaii and many South Pacific locations. Traditional, unpasteurized kava drinks have a shelf life of less than three days with refrigeration at 4°C. A new cold pasteurization technology, dense-phase carbon dioxide (DP-CO₂) has been shown to effectively reduce bacteria counts, up to a 5-log reduction, while retaining a fresh-like taste in several fruits drinks. This study was to examine the effectiveness of DP-CO₂ on the bacteria reduction in a freshly prepared kava extract. A continuous DP-CO₂ system, located at the University of Florida, was used. Kava extract was prepared on site in Florida, with material shipped frozen from Hawaii. The treatment condition was set at a pressure of 34.5 MPa, 13% (v/v) CO₂ injection, and a residence time of 7 minutes. The initial pH of the kava was 6.3 and as reduced to 5.5 after processing. The microbial counts for before and after treatment were approximately 4.0 × 10⁵ CFU/mL and 1.0 × 10² CFU/mL, respectively. The DP-CO₂ system was able to produce an initial 3-log reduction. After 8 weeks of refrigerated storage at 4°C, the microbial count was 4.0 × 10³ CFU/mL. The study demonstrated that at the current setting the bacterial reduction was not sufficient to produce a shelf-stable product. The high amount of starch suspension and type of bacteria species present in the kava could have resulted a less than expected bacteria count.