Long-Term Frozen Storage Impact on the Antioxidant Capacity and Chemical Composition of Sardinian Myrtle (Myrtus communis L.) Berries

The effects of frozen storage at -18 °C up to 6 months, on the antioxidant properties, chemical composition and other physicochemical properties of myrtle berries (Myrtus communis L.) has been evaluated. Berries showed a good resistance to storage decay, and weight loss remained after six months in the 15% range. Results showed that frozen storage up to 6 months affect individual antocyanins content in different ways. Nevertheless the total anthocyanins content was at the end of storage higher than in fresh fruits. The antioxidant capacity calculated with 2,2-diphenyl-1-picrylhidrazyl (DPPH) and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) increased during storage and the calculated r 2 showed a positive correlation with the total anthocyanins content. Gluconic and fumaric acid did not changed, quinic acid decreased while malic and shikimic acid increased. The total organic acid content during storage was higher than in fresh fruits causing a slight decrease in pH. Fructose and glucose increased with the same rate and the ratio fructose/glucose remained unchanged (1.06 ± 0.01), CIE L*a*b* coordinates showed a shift of the colour to tawny brown after six months storage.