Title: Efficacy of supercritical carbon dioxide for inactivating Lactobacillus plantarum in apple cider Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 12, 2009
Publication Date: July 12, 2009
Citation: Yuk, H., Geveke, D.J., Zhang, H.Q. 2009. Efficacy of supercritical carbon dioxide for inactivating Lactobacillus plantarum in apple cider. [abstract]. International Association for Food Protection. p. 1. Technical Abstract: Juice makers have traditionally used thermal pasteurization to prevent deterioration by spoilage bacteria such as Lactobacillus plantarum; however this thermal processing causes adverse effects on product quality such as undesirable taste and destruction of heat sensitive nutrients. For this reason, nonthermal processing has been investigated and developed as an alternative to thermal pasteurization. Of non-thermal technologies, use of supercritical carbon dioxide (SCCO2) is promising in that carbon dioxide (CO2) is non-toxic, non-reactive, non-flammable, inexpensive, and environmentally safe. The objective of this study was to evaluate the efficacy of SCCO2 for inactivating L. plantarum in apple cider using a newly developed continuous system with a gas-liquid porous metal contactor. Pasteurized apple cider without preservatives was used for this study and apple cider inoculated with L. plantarum was processed using a SCCO2 system at a CO2 concentration range of 0 – 12% (g CO2/100 g product), outlet temperatures of 34, 38, and 42C, a system pressure of 7.6 MPa, and a flow rate of 1 L/min. Higher CO2 concentration and temperature significantly enhanced microbial reduction, resulting in 5.85 log reduction with 12% of CO2 at 42C. The degree of microbial injury significantly increased as CO2 concentration and treatment temperature increased. Morphological changes in SCCO2 processed cells were observed by SEM. SCCO2 treatment and refrigeration (4C) effectively inhibited the growth of L. plantarum during 28-day storage. Thus this study showed that supercritical carbon dioxide treatment is effective in eliminating L. plantarum and could be applicable for nonthermal pasteurization of apple cider.