A Mexican orange juice producer ordered a complete pasteurization system that uses an electrical heating method. The system from HRS Heat Exchangers maintains the properties of freshly squeezed juice — properties that are adversely affected during traditional pasteurization processes, says the company.
The HRS system uses ohmic heating, which uses electricity to rapidly and uniformly heat the product. The ohmic system works by passing electricity between two electrodes in the product in a 3.2' (1 m) ceramic tube, so the electricity has to pass through the product. The juice is heated to 221°F (105°C) within 1 sec, according to HRS Heat Exchangers. It then is held at this temperature for 4 sec before being cooled.
Once the juice has been pasteurized, it must be cooled quickly to prevent any additional quality changes. This is achieved using an HRS MI Series stainless steel shell-and-tube heat exchanger. The product is initially cooled by water with the recovered energy being used elsewhere in the process. A last cooling phase with glycol achieves a final product temperature of 35.6 to 39.2°F (2 to 4°C).
HRS supplied a complete pasteurization system to the Mexican juice producer, which included preheating and cooling elements. The final system designed and installed by HRS has the capacity to treat 18 tonnes (18,000 liters) of juice each hour.
Ohmic technology itself is not new, HRS notes, but this system is designed to ensure that the temperature curve is smooth. This helps to preserve product quality and improve process efficiency.