Microbial Stability, Phytochemical Retention, and Organoleptic Attributes of Dense Phase CO2 Processed Muscadine Grape Juice

Abstract

Dense phase CO2 processing (DP-CO2) is a promising alternative to thermal pasteurization potentially inactivating microorganisms without affecting food phytochemicals or organoleptic characteristics. To demonstrate these effects, studies were conducted by changing processing pressure and CO2 concentration in relation to microbial destruction. Subsequent storage stability (10 weeks at 4 degrees C) of muscadine grape juice processed by DP-CO2 (34.5 MPa at 8% or 16% CO2) was evaluated and compared to a heat-pasteurized juice (75 degrees C, 15 s). Thermal pasteurization decreased anthocyanins (16%), soluble phenolics (26%), and antioxidant capacity (10%) whereas no changes were observed for both DP-CO2 juices. DP-CO2 juices also retained higher anthocyanins (335 mg/L), polyphenolics (473 mg/L), and antioxidant capacity (10.9 micromol of Trolox equivalents/mL) than thermally pasteurized juices at the end of storage. Insignificant differences in sensory attributes (color, flavor, aroma, and overall likeability) were observed between unprocessed and DP-CO2 juices, while significant differences were observed between unprocessed and heat-pasteurized juices. Panelists preferred DP-CO2 over heat-pasteurized juices throughout the first 6 weeks of storage, whereby the growth of yeast and mold adversely affected the juice aroma. Comparable microbial counts were observed between DP-CO2 and thermally pasteurized juices during the first 5 weeks of storage. DP-CO2 protected phytochemicals in muscadine juice during processing and storage without compromising microbial stability or sensory attributes over 5 weeks of storage.