A Continuous High Pressure Carbon Dioxide System for Microbial Reduction in Orange Juice

Abstract

: A continuous high‐pressure carbon dioxide system, run at ambient conditions, was tested on its performance in reducing both natural and inoculated microbial loads. The prototype system continuously processes orange juice with carbon dioxide (CO2) at high pressures. A central composite design was originally used to examine the variables of pressure, residence time, and CO2/juice ratio. For microbial reduction, residence time was the major factor followed by pressure. The CO2/juice ratio showed no influence on microbial load, and in this equipment, was difficult to control. The unit was able to cause a 5‐log reduction of the natural flora in spoiled juice, and could attain a 5‐log decrease in numbers of pathogenic Escherichia coli O157:H7, Salmonella typhimurium, and Listeriamonocytogenes. No viable cells of E. coli O157:H7 orS. typhimurium were cultured after the treated juices were stored at room temperature (22 °C) for 14 d. Thus, non‐thermal pathogen reduction is possible with this system.

Non-thermal inactivation of Escherichia coli K12 in buffered peptone water using a pilot-plant scale supercritical carbon dioxide system with a gas–liquid porous metal contactor

“…Although the micro-bubble system seems to be more effective at inactivating E. coli with lower CO 2 concentrations, temperatures, and shorter residence times than in the present study, results obtained using different SCCO 2 systems are difficult to compare because of numerous variations in the system including flow rate. In fact, the continuous system used in this study has the capability to process 1 L/min at 7.6 MPa, whereas systems reported in previous studies (Gunes et al, 2006;Kincal et al, 2005;Shimoda et al, 1998) used lower flow rates or higher pressures than the present system. Another difficulty in comparing results is the difference in the physical and chemical properties of the suspending medium such as growth media and water, probably resulting in different solubility of CO 2 (Garcia- Gonzalez et al, 2007).…”

“…Ballestra, Silva, and Cuq (1996) investigated the inactivation of Escherichia coli in physiological saline, and Kincal et al (2005) and Gunes, Blum, and Hotchkiss (2006) reported that bacterial contaminants were effectively removed from juice products by SCCO 2 . In addition, SCCO 2 treatment has been applied to inactivate Gram-positive lactic acid bacteria (Hong, Park, & Pyun, 1999), yeast (Lin, Yang, & q Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture.…”

“…The pressurized mixture is temperature-controlled in holding coils (12 m  3.8 mm). Residence time is about 10 min and the highest flow rate in the literature is less than 130 mL/min (Gunes et al, 2006;Kincal et al, 2005). The Mitsubishi Kakoki system pumps liquid CO 2 and liquid feed to a treating vessel (8.0 cm ID  115 cm long; 5.8 L volume).…”

Inactivation of polyphenol oxidase in muscadine grape juice by dense phase-CO2 processing

“…However, enzyme inactivation may not be complete following DP-CO 2 and there is the potential for residual enzymes following processing and storage to negatively impact food quality and phytochemical retention. Limited information exists with respect to the eVects of DP-CO 2 on enzyme activity (Kincal et al, 2005;Tisi, 2004), especially with regards to anthocyanin-containing foods such as grape juice. Additionally, many of the studies that evaluated novel processing technologies for enzyme inactivation do not take into account storage stability of the product (BoV et al, 2003;Corwin & Shellhammer, 2002;Park et al, 2002).…”

Recent Advances in the Application of Non Thermal Methods for the Prevention of Salmonella in Foods

“…Studies involving the use of HPCD for the inactivation of S. Typhimurium (Kim et al, 2007;Erkmen and Karaman, 2001;Erkmen 2000;Wei et al, 1991) have clearly reported the microbial strain, pressure applied, pH of the medium, type of medium and temperature to be important factors for the inactivation. S. Typhimurium in orange juice was effectively reduced by 5-6 logs when subjected to continuous dense phase carbon dioxide (DPCD) for 10 min at 21-107 MPa and 25 °C (Kincal et al, 2005) whereas in another study reduction as high as 8 logs was achieved when the growth media was changed to physiological saline (PS) or phosphate buffer solution (Kim et al, 2007). Kim et al (2007) also analyzed the structural changes in S. Typhimurium cells upon the application of super-critical CO 2 .…”