High voltage electric field as a green technology preserves the appearance of apple juice during cold storage

Abstract

To match the “No additive” trend and aim to reduce waste, High Voltage Electrostatic Field (HVEF) is a sustainable, green technology that not only preserves juice by inactivating microbes but mitigates undesirable changes in appearance. This study applied HVEF at 0 (control), 100, 300, and 600 kV/m on apple (Malus domestica ‘Red Delicious’) juice during seven days of cold storage to reduce the browning and explore the mechanism of HVEF's impact on juice quality parameters, including color, polyphenol oxidase, phenylalanine ammonia-lyase, turbidity, and pectin methylesterase activities. After samples were subjected to 2 h of HVEF and stored at 4 °C for 7 days, the appearance of the 600 kV/m treatment had the highest brightness. 600 kV/m treatment resulted in the lowest color change (ΔE of 6.3%), while the control group experienced the highest ΔE (84.2%). HVEF-treatment samples reduced polyphenol oxidase activity by 67% compared to the untreated sample. During the first five days of storage, phenylalanine ammonia-lyase activity was effectively inhibited in HVEF-treatment samples. 600 kV/m resulted in the lowest decrease (7.7%) in turbidity, comparable to 16.9% for the control sample. HVEF effectively inhibited pectin methylesterase activity by 43.7% during the first five days of storage. This green technology can be utilized for juice manufacturing to comply with the United Nations Sustainable Development Goals (SDGs).