Concentration of Cucumber Juice Using Progressive Freeze Concentration for Total Phenolic Content Increment

摘要

Concentration process of cucumber juice is an essential step in cucumber extracts and juice production in the industry in order to minimise the volume and weight for storage and handling purposes besides to keep the quality of the products. Enriching total phenolic content (TPC) in cucumber juice that contributes to anti-oxidants characteristics is one of the objectives in this study due to high demand in the industries especially in food and beverages, pharmaceutical and cosmetology. Studies and researches are highly are need to overcome the limitations and shortcoming of the current methods in concentrating fruit juices which are evaporation, reverse osmosis, and freeze concentration. This research aims to study the effects of operating parameters on concentration process of cucumber juice which involved in progressive freeze concentration (PFC) process includes coolant temperature, stirrer speed, operation time and initial concentration. New design of PFC called as multiple probe cryo-concentration system (MPCC) was used throughout this process. The multiple probes inside the system were freeze out the solution and form an ice block layer by layer. During the ice crystallisation process, formation of ice crystal lattice will reject all impurities and leave behind highly concentrated of cucumber juice. The effect of coolant temperature, stirrer speed, operation time and initial concentration was investigated in this work. The investigation revealed that lower coolant temperature led to a better performance efficiency of the system at -12°C. Meanwhile, a higher stirrer speed and longer operation time gave a lower value of K and TPC increment at 350 rpm and 40 minutes, respectively. High initial concentration at 10 mg/ml was observed to give high value of K which is not favourable but at that value TPC increment is the best. Findings from this research have shown that PFC is a potential method to be engaged in fruit juice concentration, particularly for cucumber juice.