Experimental Hydrate Phase Equilibrium Data Relevant to Bitter Melon, Pineapple, and Grape Juice Concentration

One of the major challenges experienced by the fruit juice industry is the steady rise in energy costs. Hence, it is of industrial interest to find possible environmentally friendly measures that reduce energy consumption while cost-effectively maintaining the quality of manufactured products. Hydrate-based juice concentration technology can be used to overcome this challenge. In the present work, experimental hydrate phase equilibrium conditions of three systems involving juices (system 1, CO₂ + grape juice; system 2, CO₂ + pineapple juice; system 3, CO₂ + bitter melon juice) were measured using an isochoric pressure search method. The temperature and pressure ranges for reported experimental data were 272.6-282.3 K and 1.17-3.85 MPa, respectively. Results have shown that a decrease in water cut from 98.3 to 88.5 ± 2.53 wt % could shift the hydrate phase equilibrium conditions toward higher pressures and lower temperatures. This proved that all investigated juices exhibited inhibitory effects on gas hydrate formation. To properly assess the energy requirements for this novel technology, molar hydrate dissociation enthalpies were estimated using the Clausius-Clapeyron relations under different measurement conditions. Finally, it was established that a hydrate-based fruit juice concentration technology would be a credible alternative to existing commercial technologies, on the basis of the dehydration ratio of 57% obtained in the present study.