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چکیده
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This study investigated the effects of continuous ohmic heating (COH; 15 and 30 V/cm) and continuous microwave heating (CMW) at different temperatures (60, 70, and 80 °C) on Botrytis cinerea inactivation, quality parameters, and energy efficiency in black grape juice processing. COH at 30 V/cm achieved 94.7% reduction in B. cinerea population, surpassing the 88.9% reduction obtained through CMW heating. The specific energy consumption of COH (163.8-291.1 kJ/kg grape juice) was significantly lower than CMW heating (329.1-526.4 kJ/kg grape juice), with COH demonstrating superior energy efficiency (71.5-88.3%) compared to CMW (41.3-46.2%). While both methods enhanced total phenolic content, CMW heating at 80°C showed the highest increase (22.7%). COH at 30 V/cm better preserved antioxidant capacity across all temperatures (70.70-71.86%). The pH remained within acceptable ranges (3.54-3.87) for all treatments. Total soluble solids showed minimal variation under MW heating but decreased slightly with COH treatment. These findings suggest that COH, particularly at 30 V/cm, offers an energy-efficient alternative to CMW heating for black grape juice processing, providing effective microbial inactivation while maintaining product quality. Industrial Relevance: This research provides valuable insights for the grape juice processing industry seeking to optimize their pasteurization operations. The comparative analysis of ohmic and microwave heating methods offers practical guidance for manufacturers considering technology upgrades or process improvements. The demonstrated superior energy efficiency of ohmic heating (71.5-88.3% versus 41.3-46.2% for microwave) translates to potential cost savings in industrial operations, particularly significant for large-scale production facilities. The higher B. cinerea inactivation rates achieved (up to 94.7% reduction) while maintaining product quality addresses industry concerns regarding food safety and shelf-life extension. Furthermore, the enhancement of bioactive compounds during processing, particularly the increase in total phenolic content (up to 22.7%), aligns with growing consumer demand for functional beverages. The detailed analysis of specific energy consumption provides manufacturers with concrete data for cost-benefit analyses when evaluating processing technologies. These findings are particularly relevant for juice processors looking to upgrade their traditional thermal processing systems to more efficient alternatives that can maintain product quality while reducing operational costs.
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