HRS Helps Orange Juice Producer Exploit Novel Pasteurisation Techniques - Case Study

Challenges

Pasteurisation is a well-established method for increasing the shelf life of juice and reducing the likelihood of microbiological spoilage, but it requires the use of heat, which adversely affects product quality. The popular High-Temperature, Short-Time (HTST) pasteurisation technique aims to limit these adverse effects by cutting the amount of time that the product is exposed to heat. However, it still takes time to evenly heat the product, adding to the total processing time and increasing the risk of adversely altering the product’s organoleptic properties.

Solution

Ohmic heating, which uses electricity to rapidly and uniformly heat the product, has been scientifically shown to be highly effective at inactivating bacteria, yeast and moulds while maintaining the flavours and quality of fruit juice.¹

HRS was approached by a leading Mexican fruit juice producer who wanted to use ohmic pasteurisation. HRS supplied a complete pasteurisation system which included pre-heating and cooling elements as per the client’s request.

Results

The final system designed and installed by HRS has the capacity to treat 18,000 litres (18 tonnes) of juice each hour. Once the juice has been pasteurised it is important to cool it as quickly as possible 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, while a final cooling phase with glycol achieves a final product temperature of 2-4°C.

What is ohmic heating?

The ohmic system works by passing electricity between two electrodes in the product in a 1 m ceramic tube, so the electricity has to pass through the product. The result is that the juice is heated up to 105°C within one second. It is then held at this temperature for four seconds before being cooled. Ohmic technology itself is not new, but this system uses the latest electronics to ensure that the temperature curve is very smooth, which not only helps to preserve product quality but also improves process efficiency.