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Strawberry tree fruit (Arbutus unedo L.) as a valuable ingredient for functional food production

The Republic of Croatia has a long tradition in fruit growing due to its geographical position, climatic conditions and high quality of fruit crops. The autochthonous fruit varieties are characterized by good morphological/pomological properties, but their nutritional and biological potential is underestimated. The fruits of the strawberry tree (Arbutus unedo L.) are an underappreciated fruit species in Croatia, whose potential for cultivation and consumption has not yet been sufficiently utilized. Therefore, it can be considered as an excellent raw material for the production of functional foods, which are under increasing demand by consumers. The aim of this study was to investigate the chemical and biological value of strawberry tree fruit collected in October 2021 in island Mali Lošinj, Croatia. Among the chemical properties, soluble solids content (SSC), pH, total carbohydrates, lipids, crude protein, crude cellulose, crude energy and sugar content were determined. Among bioactive compounds, total phenolic content (TPC), total flavonoids (TF), anthocyanins (ANT), hydroxycinnamic acids (HCA), flavonols (FL) and condensed tannins (CT) were analyzed. The obtained results showed that strawberry fruit samples contained high SSC (38 %), pH 4.6, total carbohydrates 30, 28 g/100 g, lipids <0, 5 g/100 g, crude protein 0, 67 g/100 g, crude cellulose 6, 43 g/100 g, and crude energy 136, 7 kcal/100 g. The HPLC determination of sugar composition revealed that fructose was the predominant compound (8, 79 g/100 g) followed by glucose (4.36 g/100 g). Other sugars, like sucrose, lactose and maltose were found <LOQ (below the limit of quantification of the method) in concentrations less than 0, 35 g/100 g. The results of the determination of bioactive compounds also showed that strawberry tree fruit is an excellent source of various biological compounds. Accordingly, TPC was found at a concentration of 524, 69 ±10, 64 mg GAE/100 g. Among all bioactive compounds CT were found with the highest levels (39 %), followed by HCA (6, 3 %). Moreover, the results indicated that HCA derivatives are more widely distributed than flavonoid derivatives, as TF were found at a percentage of 2, 6 %. The anthocyanins responsible for the red color of strawberry fruit were detected at a concentration of 6, 00 mg Cyd-3- gal/100 g. Since CT are the dominant subclass of phenolic compounds from strawberry tree, it is not surprising that FL as monomeric units were also found in a greater amount than anthocyanins (12, 58 g QE/100 g). From the results obtained it can be concluded that strawberry tree fruit is an excellent raw material that has not been sufficiently explored and exploited for processing. The good chemical properties of strawberry tree fruit suggest that it can also be added to various functional products as an additive, for example in the 3D printing of food.

Strawberry tree fruit ; Arbutus unedo L. ; functional food ; chemical composition ; bioactive compounds

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