ABSTRACT
This study aimed to explore the main biochemical components and the antioxidant capacity of five strawberry tree fruits using three antioxidant essays within the ecotypic comparison scheme, to find out the most valuable fruit presenting disease-preventing properties. Total phenols, total flavonoids, total anthocyanins, antioxidant activity (DPPH, ABTS, and ß-Carotene bleaching assays), pH, titratable acidity, soluble solids, and moisture content were investigated in five strawberry tree genotypes belonging to several areas in Morocco. Phenolic compounds were also identified using high performance chromatography (HPLC), with a diode array detector (DAD). High significant differences (p Ë 0.05) were revealed among the examined genotypes regarding their total phenols (25.37-39.06 mg gallic acid equivalents (GAE)/g Dry weight (DW), total flavonoids (3.30-7.07 mg RE/g Dry weight (DW), total anthocyanins (0.15-0.64 mg cya-3-glu/100g Dry weight (DW), pH (2.44-3.92), titratable acidity (0.65-1.01 g malic acid/100g Fresh weight (FW), and soluble solids (14.83-18.53%). The average radical scavenging capacity, assessed using three methods, exhibited the following concentration ranges: 3.33-21.08, 2.25-19.58, and 1.08-13 mg Ascorbic Equivalent (AAE/g Dry weight(DW) for the DPPH scavenging test, ABTS, and ß-carotene bleaching, respectively. Seventeen phenolic compounds were identified in sampled cultivars. Gallocatechol and catechin were found to be the major phenolic compounds. The correlation matrix revealed significant correlations among investigated variables, particularly ABTS and DPPH. The principal component analysis showed that the first three components formed 90.25% of the total variance. The following variables: chlorogenic acid, ellagic acid derivative, ellagic acid, rutin, and cyanidin-30.5-diglucoside, were the most involved in the total variance. The results revealed highly promising physico-biochemical profiles within the studied strawberry tree genotypes.
ABSTRACT
There are not many exhaustive works emphasizing the amount of genetic diversity among the strawberry tree (Arbutus unedo L) genotypes in Morocco. This work aims to assess the biochemical composition of strawberry tree fruits, as well as to establish the variation of this composition among them. In this study, total phenols (TP), total flavonoids (TF), condensed tannins (CT) and hydrolyzable tannins (HT), total anthocyanins (TA), and free radical scavenging activity through ABTS were investigated in strawberry tree fruits. Furthermore, qualitative and quantitative analyses of individual phenolic compounds by high-performance liquid chromatography (HPLC) were carried out. Color parameters such as lightness (L *), Chroma (c *), and hue angle (h°) were also investigated. All studied variables showed highly significant differences among all samples with the exception of hydrolyzable tannins and chromatic coordinates. TP varied from 22.63 ± 1.74 to 39.06 ± 2.44 mg GAE/g DW, TF varied from 3.30 ± 0.60 to 8.62 ± 1.10 mg RE/g DW, and TA ranged between 0.12 ± 0.06 and 0.66 ± 0.15 mg cya-3-glu/100 g DW. In addition, CT and HT amounts were in the range of 10.41 ± 1.07-16.08 ± 1.50 mg TAE/g DW and 4.08 ± 2.43-6.34 ± 3.47 TAE/g DW, respectively. Moreover, the IC50 value (ABTS) ranged between 1.75 and 19.58 mg AAE/g DW. 17 phenolic compounds were detected in strawberry tree fruits. Gallocatechol and catechin were the most abundant phenolic compounds. Matrix of correlations revealed significant positive and negative correlations among variables particularly c *, a *, and b *. Principal component analysis (PCA) showed that the first three components formed than 68% of the total inertia. The following variables gallic acid, protocatechuic, gallocatechin, gallic acid derivative, chlorogenic acid, syringic acid, ellagic acid derivative II, L *, and h * were the most involved in the total variance explained. Hierarchical clustering classified samples into one main cluster, with a single branch. The results highlight a high biochemical diversity within studied strawberry genotypes, which is probably more genetically related.
