Effect of Low Voltage Electrostatic Field-assisted Freezing on Quality of Seabuckthorn Fruit

In order to address the deterioration of quality of sea buckthorn berries after the common freezing-thawing, low-voltage electrostatic field (LVEF)-assisted freezing technology was used for sea buckthorn berries freezing. The freezing curves, water loss rate, ice crystal morphology, flavonoid content, polyphenol content, and microstructure of sea buckthorn berries were recorded to evaluated the quality changes of sea buckthorn berries treated by the LVEF-assisted freezing and the ordinary freezing at different temperatures (−20, −40, −80 ℃). Results showed that LVEF-assisted freezing improved the freezing rate of sea buckthorn berries, changed the morphology and distribution of ice crystals, alleviated the mechanical damage to the microstructure of the fruit tissues, and reduced the loss of juice after thawing. The flavonoid contents of sea buckthorn berries frozen at −20, −40 and −80 ℃ were 2029, 2212 and 2324 mg/100 g after thawing, and those of sea buckthorn berries frozen with LVEF-assisted freezing were 2156, 2284 and 2373 mg/100 g after thawing. The flavonoid content of electrostatic field-assisted freezing was significantly higher than that of ordinary freezing (P<0.05). LVEF-assisted freezing can retain the nutrients in sea buckthorn berries to a greater extent, and effectively improve the frozen quality of the berries.