Process production of date syrup using ohmic heating under vacuum: Evaluating the impact of voltage gradient and pressure on energy consumption, efficiency, and quality characteristics.

This study investigates the production and quality assessment of date syrup utilizing an ohmic heating system under vacuum conditions. The primary objective was to evaluate the performance of this innovative technology in comparison to traditional direct heating methods, focusing on parameters such as energy consumption, preservation of product quality, and environmental sustainability. Date samples underwent processing at varying voltage gradients (10 to 25 v/cm) and pressures (55 to 100 kp) within the ohmic-vacuum system following initial preparation. Key parameters assessed included processing time, heating rate, specific energy consumption, energy efficiency, exergy efficiency, and colorimetric changes, alongside sensory attributes such as color, taste, and aroma. The findings demonstrated that an increase in voltage gradient significantly enhanced the heating rate and reduced processing time by up to 23%. The specific energy consumption was minimized at 91.2 MJ per kilogram of evaporated water when utilizing the highest voltage gradient (25 v/cm) in conjunction with the lowest pressure (55 kp). Energy efficiency peaked at 90% under atmospheric conditions (100 kp), while maximum exergy efficiency reached 41.12%. Notably, color changes in samples processed with the ohmic-vacuum method were substantially less pronounced than those observed in the traditional method. Sensory evaluations revealed enhancements in both color and taste quality in samples processed via ohmic-vacuum heating compared to traditional approaches. In conclusion, the implementation of ohmic heating under vacuum is advocated as an effective technology for sustainable date syrup production. This method not only diminishes energy consumption but also preserves the nutritional and sensory qualities of the product while significantly reducing processing time.