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Preservation and enhancement of the juice cloud with a continuous high pressure CO2 system

D. KINCAL¹, S. Hill¹, M. O. Balaban¹, M. R. Marshall¹, and R. E. Wildasin². (1) Food Science and Human Nutrition, University of Florida, Gainesville, FL 32611, (2) Applications Research and Development, Praxair, Inc., 7000 High Grove Boulevard Burr Ridge, Chicago, IL 60521-7595

JUSTIFICATION: Cloud is an important attribute for orange juice. Maintenance of cloud is significant in terms of visual appeal, some flavor compounds, and overall quality of the juice. Preservation and enhancement of the cloud can be achieved with a continuous high pressure CO2 system.

OBJECTIVES: The objective of this study was to design and build a pressurized CO2/juice prototype system, test its performance in preservation and enhancement of the orange juice cloud, and determine operating characteristics.

METHODS: The system was designed to continuously mix and pressurize a stream of juice with a stream of liquid CO2, pass it through a holding tube, and reduce the pressure at the exit to separate the juice from the CO2. Thermocouples monitored temperatures at various points. The gas and juice flow rates, as well as residence time in the holding tube could be adjusted. Fresh, unpasteurized orange juice was used. Absorbance value of the juice at 660 nm was used to determine the cloud value after centrifugation for 10 min at 320xg. Pressures from 20 to 103 MPa, residence times from 3 to 10 min were used.

RESULTS: For all treated samples, cloud was higher than that of initial juice (2-8 times). Upon refrigerated storage for 1 month, these values remained 2-4 times as the original. When pressure increased, cloud values also increased. For example, at 35 MPa and 8.6 min residence time, cloud value was 0.722, while control’s cloud was 0.312. The temperature of the juice never exceeded 25 C.

SIGNIFICANCE: This method has the potential to retain and enhance orange juice cloud with a continuous and economical system. While preserving the cloud juices at low temperatures, the system does not change the “fresh” attributes of the orange juice.