Effect of Ozone Treatment on Mechanical and Chemical Properties of Sea-Buckthorn (Hippophaë rhamnoides L.) Fruit

During storage, sea-buckthorn berries which are a valuable source of bioactive compounds, gradually lose their optimum mechanical properties and chemical characteristics. Mechanical and chemical properties of sea-buckthorn berries were examined in fruit exposed to gaseous ozone at a rate of 10 and 50 ppm for 15 minutes. Ozonation process did not impact mechanical properties (except for elastic modulus) or morphological characteristics, but it resulted in decreased water loss, on average by 5.21%, in fruit kept in cold storage for 14 days, as well as increased pH and reduced acidity of sea-buckthorn berries on average by 9.03% and 20.0% (for ozone concentration of 50 ppm) compared to the control sample. Polyphenol contents in sea-buckthorn berries were identified using UPLC-PDA-MS/MS. Out of all the identified polyphenols, the findings showed the highest contents of flavone glycosides, represented e.g., by isorhamnetin-3-O-rutinoside. The contents of bioactive compounds (ascorbic acid, total polyphenols or polyphenol profile) as well as antioxidant activity (measured using DPPH^. and ABTS^+. assays) were different, depending on the variety and possibly were affected by the timing of sea-buckthorn fruit harvest.