54F-8

D. DEL POZO-INSFRAN, M. O. Balaban, and S. T. Talcott. Dept. of Food Science and Human Nutrition, Univ. of Florida, 359 FSHN Bldg., Newell Dr., PO Box 110370, Gainesville, FL 32611-0370

Dense phase-CO2 processing (DP-CO2) is a promising alternative to thermal pasteurization, potentially reducing microbial loads without negatively affecting food phytochemicals or sensory characteristics. To prove this concept, the microbial destruction, phytochemical stability, and organoleptic properties of DP-CO2 processed muscadine grape juice was compared to a thermally pasteurized control juice (75° C, 15 sec). Treatments were additionally evaluated during storage for 30 days at 4° C. A central composite design was initially conducted to determine DP-CO2 processing parameters (1.2-40.2 MPa, 0-15.7% CO₂) which achieved >5 log reduction of aerobic microorganisms and yeast/mold: D-1 (34.5MPa, 8% CO₂) and D-2 (34.5MPa, 16% CO₂). Chemical analyses included anthocyanin 3,5-diglycosides by HPLC, antioxidant capacity (AOX; ORAC assay), and total phenolics (Folin's assay). Sensory attributes of fresh and processed juices were compared using difference-from-control and ranking tests (60 panelists). Scanning electron microscopy was used to investigate changes in microbial microstructure due to DP-CO2. Thermal pasteurization decreased anthocyanins by 16%, total phenolics by 26%, and AOX by 10% whereas no change was observed for DP-CO2 processed juices. Independently of processing parameters, DP-CO2 juices retained higher anthocyanin (202.6 mg/L), total phenolic (429 mg/L), and AOX (6.4 µM Trolox-equivalents/mL) content than thermally pasteurized juices after 30 days of storage. Comparable color intensity, flavor, aroma, and overall likeability were observed between non-pasteurized and DP-CO2 processed juices. Panelists preferred the color and ranked both DP-CO2 juices higher than the heat-pasteurized. Micrographic observation aided in the mechanism of microbial inactivation and concluded that explosive decompression of the microbial cell along with changes in cell membrane occurred during DP-CO2. Similar microbial stability was observed between DP-CO2 and thermally-pasteurized juices during storage. DP-CO2 served to protect phytochemical and antioxidant levels throughout processing and storage without comprising microbial stability or sensory attributes of the juices.

Session 54F, Nonthermal Processing: General I
2:00 PM - 5:30 PM, Monday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana