engleski

The nutritional and antioxidant properties of strawberry tree (Arbutus unedo L.) fruit

Arbutus unedo L. grows in the Mediterranean as a wild evergreen shrub. It is used in folk medicine as an antiseptic, diuretic, laxative, and for treating cardiovascular and gastrointestinal diseases. It has also shown significant antiproliferative properties and its health benefits are mainly attributed to phenolic compounds such as flavonoids, phenolic acids, and tannins. Literature data reveals the strawberry tree fruit as a good source of polyphenols, vitamin C, and dietary fibers as well as minerals with significant potassium, calcium, and phosphorus content. Dried fruit contains 42-52% of sugar, dominantly fructose. Polyunsaturated fatty acids account for 58 to 66% of the total fat content, with linoleic, linolenic, and oleinic acid dominant and a highly favorable ratio of ω3/ω6 (0.09%). The aim of this study was to present literature data on the nutritional properties of A. unedo fruits and determine the polyphenolic content (total phenols, tannins, flavonoids, and phenolic acids) and antioxidative capacity of fruits collected at two different locations in Croatia (islands of Mali Lošinj and Koločep). Antioxidant capacity was estimated by DPPH (2, 2′-diphenyl-1-picrylhydrazyl), ABTS (2, 2′- azino-bis(3-ethylbenzthiazoline-6-sulphonic acid), and FRAP (Ferric reducing antioxidant power) assay. Average content of total phenols, tannins, flavonoids, and phenolic acids in extracts of liophylised fruit was 21.58 and 15.32 mg gallic acid equivalents/g dry weight (dw), 0.25 mg quercetin equivalents/g dw, and 8.30 mg rosmarinic acid equivalents/g dw, respectively. Strawberry tree fruit extracts showed good antiradical capacity (EC50 222.31 mg/L and 20.59 mg Trolox equivalents/g dw in DPPH and ABTS assays, respectively) and reducing power (0.28 mmol Fe(II)/g dw). Overall results point to higher polyphenolic content and stronger antioxidant properties of strawberry tree fruit compared with other berries. Due to the presence of large quantities of bioactive compounds, strawberry tree fruit may have great potential as a functional food.

Arbutus unedo fruit ; polyphenols ; antioxidant activity

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