Development and performance evaluation of small-scale low-viscous juice continuous pasteurizer

Pasteurization is regarded as a critical unit operation in the juice processing chain because it extends the juice's shelf life. This study aimed to design, construct and assess the performance of the small-scale low-viscous juice continuous pasteurizer. The pasteurizer is equipped with three shell and tube heat exchangers (STHE) that operate on a counter-current flow system. During operation, raw juice is preheated in the regeneration section before being heated in the heating section to a specified pasteurization temperature. The juice is then held at pasteurization temperature in holding tubes for a specific period before being cooled in the regeneration and cooling section. The performance was evaluated by determining the maximum hot water temperature attainable, product pasteurization temperature and throughput at various pumping speeds of the product. With an initial heating time of 23 minutes, all product pump speeds over 792 rpm can yield a regeneration efficiency of about 50% with a throughput capacity of about 600 L/h. An automated control system can be used to adjust the pasteurizing temperatures. This enables effective use with a wide range of food products with pasteurization temperatures ranging from 72°C to 88°C under High-Temperature-Short-Time (HTST) processing. The logarithmic and quadratic polynomial models were found to be suitable for predicting throughput capacity and pasteurization temperature, respectively. The results from the validation showed R2 values of 97.52% and 99.28% for throughput capacity and pasteurization temperature, respectively. Juice pump speed did not affect the regeneration efficiency (p < 0.05). The pasteurizer is suitable for low-viscous food products.